Fettled Bike 2. 1979 Yamaha DT175MX Restoration.

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Back to the thread...





In the interest of continuity I intend to put the bare bones of the paranoia thread here to the present day.
We are still late summer 2022 at the moment.

Plenty of teeth gnashing yet.

Meanwhile VFR gets the same going over as the DT by the appraiser. That bike was 10x more complex than the DT but had not been messed with by a complete red arsed Baboon. As a result it was just a normal restoration with no real angst. Hardest part was scouring the world for NOS original rubber brake hoses and piping as it came fitted with Goodrich braided ones.
Resto completed Xmas day 2019 when I fitted the mirrors and closed out the build. True to form, my luck dictated that the weather would be wet, cold and horrible for another 5 months and I had to wait till the end of April 2020 to test ride it.
An interminable wait.

Dating photo from the valuation report. At 25 years old, it will not start to be seen to be really collectable for at least another 10 years.
This is the bike I put some miles on without fear of something breaking or fear of devaluing it. Every bush, bearing and seal is new. It was built to be as the brand new bike I had in 97, but to ride and enjoy as it should be.
The Gen 4 VFR750 was billed by the motorcycle magazines of the time as the best alround motorcycle ever made. I will go along with that. I never found a better one and always regretted trading it in for a Honda CBR1100xx Super Blackbird. I knew I had made a big mistake within 20 miles.

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Had to settle on a new black goodridge hose at the rear. New original rear hose was completely unobtanable despite months of looking daily.

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What have I done? By the time I got the Blackbird home, I knew I was an idiot. A very very nice bike to be sure, but it aint no VFR.

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Wading through the thick tapestry of life one day at a time.

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We are now arriving at the start of the paranoid thread. I will quickly cover my thoughts at that time. No point in covering that entire thread again. It is available for anyone to see.

Over the summer of 2022 I was happily riding the bike around and put about 180 miles on it since the rebuild.

Towards the end of the summer, I was still getting up the nerve to try another full throttle run to check WOT carburation. I have a suspicion it is running a little on the rich side.
I resolved to run a few more tanks of fuel through before trying again.

I pulled into the yard on what was to be the last ride of the year, and the missus spoke out.. "Should it rattle like that?" .

Huh? I lifted my visor and switched off the ignition to hear her better.

" Does it always rattle like that? "

"It is called fin resonance. The cooling fins amplify the sound of the piston going up and down the cylinder, all air coolled two strokes do it".

Oh.

I trotted into the house to rid myself of helmet, gloves and jacket before wheeling the bike into the conservatory for what turned out to be its long winter sleep.

Autumn turned to winter, Xmas came and went and the bike slept on. The only disturbance was the click on and off of the wall socket switch every month or so, to encourage the battery charger to top up the battery. Otherwise, the conservatory being unheated was devoid of life.
I avoid entering as much as possible, because heat from the house will enter and cause condensation.
The ventilation windows are open all year round to avoid rapid temperature fluctuations and condensation forming on the bike.
The blinds are kept closed to help stabilise the temperature and to prevent UV damage.

I do not cover it for the same reason. Covers prevent good ventilation and can hold condensation in. Besides the bike is a decorative item. Pleasing to the eye. Better than any pot figurine on a shelf.

And the bike is now purely a decorative item to be admired from the comfort of the living room sofa.
What the feck is the point of having a bike that you want to ride and built to ride but are unable to ride it? I loved it, but I made the decision to move it on and buy something else.
Come springtime, it was going up for sale....

I was completely ignorant of the time bomb ticking away inside..

Modern art sculpture sat in its showcase. No good to me.

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Wading through the thick tapestry of life one day at a time.

[Easy-X]

Ummm... you don't mention but did you leave it that long with petrol in the tank and float bowls? Personally I would have also removed the battery entirely especially for an old skool lead acid one.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

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Little Yeller wearing its plastic bag as mentioned previously.

As the the vapour space above the tank increases temp and pressure, the bag inflates. As it cools down, the expelled vapour gets sucked back out of the bag back into the tank.

It avoids fresh moisture laden air getting drawn into the tank each time it breathes.


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Alkylate fuel has a storage life of five years in a typical fuel tank. Thick end of £30 a gallon though....

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But saves having to do this..

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Wading through the thick tapestry of life one day at a time.

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Spring arrives and time to recommision the devil bike.

Fuel on, carb leak. Hit carb with screwdriver handle, leak stops. Start her up and take her for a spin around the village.

No issues so i put her away. Time to put an ad on Ebay.

Got a couple of blokes very interested from the get go, sending many texts asking questions and generally sounding favourable. I can understand their caution, it was up for less than it was valued at, but it was still a very sizeable chunk of change.

Another weekend and a quick ride around the village to keep everything shipshape and ready for the anticipated viewings. Pulled off my helmet and noted it did sound rattly, more than I would have liked, but not alarmingly so.

Did it sound like that before? Could not remember.

However, it had a new rebore, a new genuine Yamaha piston, new little end bearing, new mains and the big end checked very carefully for radial play, excessive side play and smoothness with no apparent problems.

So what is there to go wrong? I shrugged my shoulders, it must just be me used to quiet running four strokes for the last 15 or so years. Everything that could have caused the rattle had been done.

Another bloke rang up from Torquay, he had one just like it when he was 17 and wanted to relive his youth.
Again I explained that it could not be ridden without devaluing it, but he was very excited. Must have rung me four further times that night.

That rattle was on my mind constantly. How could I sell it to some decent bloke as a very substantial investment if I was not 100% happy with it?

If it was any other bike but the devil bike I would not have been so concerned. I have known far worse that were ridden daily without problems.

I said I could not part with it, mentioned I was unhappy about a rattle that suddenly started, he texted again the next morning and agreed it was best left alone and I pulled the ad. I would take my time to evaluate further...

It turned out to be the right decision.
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Wading through the thick tapestry of life one day at a time.

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Another couple of rides out, again was the rattle getting worse or not?

I thought that I would sort it one way or the other and do a full throttle plug chop.

So bike out in the yard, looked at my carpet slippered foot, shook my head and went back in to put my trainers on.
Last time I was too lazy to change my footwear, my foot slipped on the kickstart and fired one of my slippers into low earth orbit. My how that hurt.

Got the bike started and sat on her holding the RPM at around 2000 to warm her up gently and once she would hold an even tickover, went into the house to get my jacket, helmet and gloves.
30 seconds later I was at the back door, bike ticking over in the yard.

Yikes, she sounded absolutely horrendous. Like a handful of change getting shook up in a coffee can. That was not a rattle, it was a downright knock.
Whatever was going wrong was going wrong very fast.

Paranoid thoughts were flipping across my mind.

Knew I should have pressed the crank apart and fitted new big end kit. Had the big end failed?.....
Was it the little end breaking up?
Did I blow the piston on the failed wide open throttle run?
Has the oil pump stopped delivering and blown the motor? I know I should have checked the output when I bled it.

It did not quite sound like the crank, but what was it? It had a rebore and it kicks up straight away, it idles reliably and seemed to pull OK.
Then I remembered it had developed a slight misfire above 5000 rpm when I put it away. Was it related? Was it metal on the plug electrodes?
Has the timing slipped and the engine is busily eating itself a neat hole in the piston crown?

Whatever it was, this is the devil bike and it would be the worst case scenario. How I wish I never set eyes on it.
No matter how much care and attention is lavished on it, it completely refuses to be a reliable machine.
Sharing the conservatory with the bike is my watch tinkering lab and I put as much care and attention into that bike as I do with watch movements...
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Wading through the thick tapestry of life one day at a time.

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That bike should run like a swiss watch, yet it absolutely refuses to.

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So I pulled off the head and had a look.

No hole or signs of detonation on the piston crown. I suppose thats something to be glad about, but no, it meant it is a bigger problem.
Looking down the bore revealed no big score marks and bringing piston to the top and giving it an exploratory push back and forth revealed little slop. Oh no. Job is getting bigger.

Time to lift off the barrel...
Nothing jumps out at me. Oh jeeze. Is it the crank or the tranny?

Crank still feels fine. Smooth and free turning. No slop in the big end. No slop in the little end and no excessive side play.
Piston is showing no scoring or any signs of the black death of incipient seizure.
Rings not scored or showing any sign of being gap bound.

I look up the bore from the bottom instead of the top. What the hell am I looking at?

I am looking at two perfect imprints of the piston intake windows embossed on the cylinder wall. I never in 40 years of spannering saw the like before. And this has happened in less than 200 miles.

Japanese high quality piston. Nothing untoward other than a little blowby on the thrust side.
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Never ever saw the like before. Then again, I never bought a bike from a demon before either.
Intake window imprinted on the cylinder just above the intake port and strange scuffing marks. I know the ports were radiused top and bottom after the rebore because I took off the sharp edges myself at work with my riffler files, to make sure, so that is not the cause.
What on earth.....

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Wading through the thick tapestry of life one day at a time.

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At least I now knew where the knock is originating, but my now paranoid brain is going into hyperdrive.

Apart from being a bike cast out of hell for becoming plain too evil and driving Beelzibub into a wild frenzy, why has it managed to destroy a fresh rebore in less than 200 miles?

My private thoughts were that it was poor lubrication. The damage is confined to the thrust side of the cylinder.

The pump was working when I bled it and I am of the old school that still adds a splash of two stroke to a full tank just.... because. I tell myself it is to prevent fuel tank corrosion and lube the carb slide. But I know it is just a bit more paranoia. I cannot trust the bike to hold together without my lucky rituals.
As said earlier, should have checked pump max output instead of just setting the cable and checking min pump stroke clearance.

Was it the BelRay SI7 I was using? Is it naff these days?
I used BelRay lubricants exclusively back in the day when I had a stable of two strokes with no problems.
BelRay MC1 in my pure competition bikes at 50:1 and SI7 in my autolube equipped road bikes. Thousands of miles / hours run without problems and never needed a rebore.
My old, last of the air coolled YZ250 was a bit harsh with the rings and would lose its crispness after a few months, requiring replacement rings, but never any serious bore wear.

Had the pump just stopped delivering and the only oil the motor was getting was the splash I put in the tank, just enough to keep the bearings lubed, but not enough to prevent bore wear?

Was it dirt in the intake? Did the silly old sod leave a ton of dirt in the intake? Stripped the airbox fittings and carb off. Nope, everything was clean as a whistle. No dirt was jammed into joints or little nooks and crannies. Air filter was new, freshly oiled and fitted less than 200 miles before. In addition, the piston skirt was not scored. If it had been eating lumps of dirt it would have been.
So no, I could not blame the demon who sold me the bike.

So why had I not noticed it before?
When the bike was first started and test run, everything seemed normal.
When I started riding it, my typical ritual was to get the bike out, go put on my helmet and gloves, start the bike and warm it up till it would hold a steady idle.
Then I would go open all the gates to the outside world.
The back yard is like Fort Knox. By the time I got the three gates open to the road, the bike was warmed up enough to ride away.
Coming home, I would switch off the bike, then go get rid of helmet and gloves before putting it away.
So I suppose it is a combination of a gradual worsening of the noise, not expecting trouble and always having my helmet on when the bike was running.

The Missus sure put me in my place.

I took the barrel to work and put one of my bore gauges down for a comparative check. The bore appeared round at the top and round at the bottom. It was NOT round in the middle and furthermore was .25mm or so bigger in the middleve than the bottom.

What the feckity feck.

I jumped to the conclusion immediately that my friendly local car engine reconditioners had mucked up the job and ruined my cylinder.
When I fitted the cylinder, nothing seemed untoward, but then I never checked. Just trusted them to have done it right.

I knew I had a pic of the build after I fitted the barrel in my provenance file. I dug it out and there it was, the gently smoking Colt Government 1911 model .45.

The camera had picked up something that was not visible to the naked eye. I suspected the boring bar had chattered badly around the ports, either because of inexperience of boring a two stroke barrel by the operator and going too fast, poor or worn equipment or both.
The final hone had missed a portion of the cylinder wall because it was too deep for the hone to reach. You can see the difference in the hone marks almost half way between the top of the cylinder and the exhaust where they had done it by hand. A definite band different from the hone job above.

I showed the pics to my tame precision engineer and he confirmed it. They had screwed up the bore and tried to cover it up by hand honing the chatter marks out in the localised area. They had used very course stones to speed things up.
Must have taken hours with an expanding hone in a drill.....

My luck has held to its usual form. Screwed up rebore attempt. The dark shadow above the port is where the hone could not reach. The difference in hone pattern around the ports is where they tried to correct it by hand.

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So we have a bike that has now around 2000 miles on the clock from new.
It came with a completely unworn, but rust pitted barrel necessitating a rebore. Something that the demon should have done as part of his "rebuild".

To ensure that the deep pitting would clear in one rebore attempt, I made the decision to jump immediately to a 0.5mm oversize piston.

The rebore was not a success and 200 miles later, it was touch and go whether a 0.75mm over bore job would clear, such was the damage caused by the piston tipping over and ramming itself into the cylinder wall.
So was looking at a max oversize rebore... On a bike with 2000 miles from new?

That is not right. A 2000 mile bike should be on a std bore.

I looked at my options.

1. Send it to the foremost two stroke specialist in the UK (PJ Motorcycle Engineers) to inspect the cylinder, do the rebore and suck it up.

2. Send it to the same specialist and have a new liner made and fitted at three times the price?

Of course, to be fair to the bike and its future custodians, there was really only the one option.

Barrel was stripped of all the hardware, taken to work, beadblasted, cleaned out and all the threads tapped out before being parcelled up and sent for a new liner fitting.
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Wading through the thick tapestry of life one day at a time.

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New genuine std piston packed with the barrel and sent to PJME.

The barrel is going to be a six week turnaround, so job stopped. Oil injection line, fuel line and carb slide disconnected and carb put to one side.
Nothing to do but wait.
And wait.
And wait.

A month goes by and the devil bike slumbers. The Sun shines, the skies are blue and the conservatory floor mirrors it nicely.
What! Why is the floor blue?

It seems that the devil bike got bored waiting and after a full month of only a couple of drips of oil in the aerosol lid to catch any oil dripping that may drip from the oil injection line, it suddenly and without warning decided to empty its full 2stroke oil tank all over the conservatory floor in less than 24 hours.


Thick end of £20 worth of BelRay SI7 busily trying to dye the floor tile grout blue.

Why? I had no idea. Ideas were suggested and checked.. Favourite being, was the tank breather hose blocked or kinked allowing the pressure to rise in the tank due to the heat in the conservatory? Duly checked and nope. Breather was in fine fettle.
Why after a full month with only a couple of drips getting past the check valve did it suddenly dump everything?

I doooooooont knowww Marcie.

Beelzibub appeared at my side, patted my shoulder knowingly and offered me a Valium. He said they do help.
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Wading through the thick tapestry of life one day at a time.

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Oil pump seal kit and new check valve ball and spring arrived... Oil pump for the rebuilding of.

Found a bit of dirt stuck to the check valve seat which is the most likely culprit for the leak, but why? Everything has been completely stationary for a month. Why leak now?

Oil pump thoroughly cleaned out. Oil tank thoroughly cleaned out (again) and oil supply line to the pump thoroughly cleaned out.
Pump refitted and waiting for the cylinder barrel to arrive to check max output.

I had a week off work and the day I broke up, I had a notification that a parcel had been delivered and was waiting in the shed. Only one parcel being eagerly awaited and indeed it was the barrel.

Of course, being a driveline engineer with my particular specialty being the deep overhaul of medium and heavy duty diesel engines, I have fitted literally hundreds upon hundreds of cylinder liners of every type. Wet, dry, prefinished, post finished, slip fit, interference fit, you name it. So I was very interested in seeing what they had done.

Have to say the workmanship is superb.
If you did not know it was there, you would not notice the join between the upper flange and the counterbore, such is the fit.
Obviously been made, then fitted using liquid nitrogen and then bored to size afterwards, hence the very high accuracy of fitting. Without a doubt, those join lines would be a hermetic seal.
Likewise at the bottom, you could hardly see the join.
The ports were spot on, no mismatching or ridges between the barrel and cylinder. If I handed the barrel to someone who did not know it had a new liner fitted, they would not know.

The final honed finish was superb. In all very pleased. I can recommend PJME.
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Wading through the thick tapestry of life one day at a time.

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So we now have the bike back together. I cast a gimlet eye at the oil pump cover and flip it the bird.
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Screwed off the fuel cap and peered inside. Roughly 3/4 of a tank. Guess about a gallon of fuel. Scratched my head a little and decided to add about 150 cc of two stroke to the tank.
Guestimate around 32:1 mix.

I do NOT trust that freaking oil pump even with new seals.

So we get the bike outside and ready to fire up. Ignition on, second kick and she is away. Sounds nice, but then after the previous soundtrack of a dumper truck falling over a cliff, anything will sound nice.

Ignition off and oil pump cover removed. Pump bled from bleed screw and injection pipe pulled off carb.
Start her up again, push the pulley right back against the spring and up and away, oil and bubbles pushing up the line in one direction only, so it is pumping.

Give my measuring cylinder a good clean out, set the idle to 2000rpm and spin the pulley to the top of the ramp and hold.
Push the measuring cylinder under the oil line and start to count 200 pump strokes.
Is it pumping sufficient oil?

A quick check of the good book and my 5ml in the cylinder agrees with the book, so the pump is delivering correctly.

However I still do not trust it. It gets another dirty look and two fingers before the cover is refitted. I resolve to run at least two tanks of premix till the rings are bedded in and pump output rechecked at least twice over the period; however given that I am not allowed to put miles on the soddin thing, this may take years...

Time for a test run. Surprisingly, with premix and oil pump, the exhaust was not smoky. I was expecting to be leaving a thick fog behind me, but no, no drama.
Until I gradually built up speed to around 3/4 throttle and 5000 rpm in top. Extreme vibration and very rough running. What the feck was going wrong now? I thought the big end had broken up.

Close throttle, vibration stops. Tentatively open throttle, normal running, close throttle still normal, open throttle fully..Horrible clatter and vibration. Half throttle, perfectly normal.

Obviously a real rough misfire, I have never felt the like before. It felt mechanical, not combustion related.
I surmised that the CDI was going waaay over advanced for some reason. But why is it throttle position related, not RPM related?

Only thing I could think of that would be throttle position related would be a peak voltage bleed, either a bad plug, or bad ignition coil...

Put the soddin thing away in a great huff, gave it the finger with both hands because one would not sufficiently convey the extent of my loathing and stalked off in disgust.
I pondered over a beer or six that evening and remembered that it had developed a slight misfire at the end of the previous season.
Now suppose that was the start of the peak volts bleed. It occurred with a cylinder that was toast. I had a new cylinder and higher compression now. That would make the misfire worse.

​​​​​​Not messing, new plug and new coil ordered. I do not care which it was, I just want it gone. The coil resistance was double checked during the build and the plug was a brand new one for the full throttle carburation test. It had less than 25 miles on it.
In the meantime I will go over the entire ignition system with a fine tooth comb.

The paranoia quotient was off the scale....

I could hear the old git who sold me it chuckling away to himself. Good thing is that when the old git and the chuckling are in your head, you can mentally set a pack of dogs on him.

I feel much better now.
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Wading through the thick tapestry of life one day at a time.

[Easy-X]

I had to be that guy but I'm pretty sure you need to jet differently for premix vs. petrol + oil pump
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

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So with a new plug and new ignition coil on order, I set about checking the system out.
Unplugged the stator harness wires dealing with the CDI and the 7 wires from the CDI at the other end and checked them for a high resistance.
Nothing. They were good.
Paranoia kicks in with its typical lack of patience. Is the NoS CDI I bought actually faulty? It was cheap, very much so compared to others appearing nowadays. At the time, it was the only one available.
Was it cheap because some cycle shop in the US had changed one under warranty 40 years ago, and the old unit found itself back on the shelf?
Was it cheap because it was "open box" and the seller could not determine if it was in fact brand new, or a very lightly used old one?

I found myself looking on Rex's website and about to buy a replacement CDI.
Had to take a hold of my left ear with my left hand and pull me into a corner to have a word with myself.
Stop letting your paranoia about the devil bike make you impulsive and take a shotgun approach.
Cool down and work the problem as you are trained to do. Be patient.

So deep intake of breath and start again...

Most likely point of failure given the circumstances is the high speed coil..

High speed coil checked and everything seems fine. Within tolerance

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Next likely culprit is the trigger coil. Checked and within spec.

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Source coil. Checked and in spec.

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At least it confirmed what I already knew, the fault was on the HT side. I can never recall coming across a LT fault that caused a misfire at a specific throttle opening. Yes, loose connections getting jolted by bumps in the road causing misfires, but generally a bad LT side either works or it doesn't.

Checked the primary and secondary on the ignition coil and everything, as before during the build was fine. However there was a tiny line of rust where the core enters the windings. Had this rust penetrated inside and was allowing a path for the PV to leak to ground under high load?

Coil and spark plug went in the bin. Stringent isolation procedures were in operation.

Finally I removed the rotor and stator to replace the new left hand crank seal with a better IT175 example and before the nut was put back, I checked the rotor and stator timing marks again to ensure everything was peachy.
My luck would be to tighten the nut, then find I had a senior moment and the marks were out, and having to pull the rotor again, so checking first meant they would be fine.

I did have a moment of consternation when setting up the gauge and checking the marks. They were miles out. What the fecking great halls of hell was going on....File Attachment:
Then it came to me. A senior moment where experience can work against you. Timing a motor from the front usually means it is turning clockwise.
The DT is turning anticlockwise. Doh!

Timing marks just fine.
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Wading through the thick tapestry of life one day at a time.

[stinkwheel]

Although experience has taught me that if you're not checking timing on a motorbike with a strobe and timing disc/keyed marks, you're not really checking timing. All you're doing is getting it running so you can get a strobe on it.

I've spent many wasted hours chasing a fuelling fault on the assumption I'd checked the static timing to then strobe it and find it was way off. Factors like backlash, width of trigger, inconsistencies with pickup and rotor position, electronic delays, wobbly cams and worn advance springs.

Noteable ones being on my enfields which can have up to 11 degrees of backlash on the timing gears or on one (quite expensive) aftermarket electronic system which was bang on fully retarded but was wandering all over the place on advance (to the point I took it off and put the points back on because they were at least consistant).

Static timing will also tell you nothing about the advanced timing and how much time does a bike spend being ridden just off idle (especially a 125 2t)? Only one way to check that.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

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Back to the thread...


So the rain stops, a strange golden glowing ball appears in the sky and the roads dry out briefly.

I take her out for a spin, about 15 miles of my usual run to bed in the rings a little more and with mag hanging out in the breeze to ensure max airflow around the coils to see if overheating coils are the problem.

No misfire.

Next test, fit the generator cover and try again. No misfire.

Looks like as predicted, it was something bad in the HT system. My gut feeling is coil, but either way, both coil and plug had already been ceremoniously disposed of by way of allowing them time to contemplate their fate.

Pedal bin lid open. Plug held by tip between finger and thumb over bin. Long drop there boyo. Bye.
Coil dangled by its ht lead. Pause. Goodbye.

After the test ride, the cylinder was lovely and quiet (as far as an air coolled two stroke goes) but I noticed on idle, a distinct rattle to the transmission. Something I never heard before, probably because of the previous cylinder clatter. AAAAARGH damn this infernal machine, will it ever end?

I thought about calling in an exorcist or buying a large crystal of white quartz to draw out the evilness overnight. But no , further investigation revealed that the clatter went away with clutch pulled in and bike in gear.

So likely some slop in the clutch basket, but it felt fine during the build. Had the rivets come loose?

More paranoia. Has it trashed the basket?

Shoulders slumped, I rode it in the conservatory and noticed the headlight was not lit. Tried the on off switch, yes it was fully forward and therefore on. Bulb blown or wiring connection broken?

Trivial thing to fix, but something snapped.

Just fecking great. I hate that pile of ... Words fail me. There is nothing contained in the human language that amply demonstrates my feelings of hatred for that bike, the guy from hong kong for starting the ball rolling on this endless round of mental torture and of the demon himself.
I would so like to grab him by the scruff of his miserable neck and throw him headfirst into a dustbin.

I am now fixing things that was supposedly fixed when I bought it, things that I subsequently thought I had previously fixed to a high standard, and now needed fixing again. How far is this mad merry go round going to turn? Absolutely everything has been attended to. Only original bit of the original "restoration" was the powder coating on the frame.
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Wading through the thick tapestry of life one day at a time.

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A few beers and a good nights sleep later, I resolved to grab the devil bike by its evil little handlebars and set to disembowelling it.
So first things first. Drain the transmission. What a stupid long drain plug thread that is. It looks like it could almost bolt the tank on. Ridiculous, but then I guess they did not want ham fisted owners stripping the thread.
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Plug out and viewing the flowing oil with a faint feeling of dread. Will I find the shiny particles of death making pretty swirling patterns in the oil, or worst still, bigger chunks?

Thankfully nothing in the oil, it was relatively clean. Just a few hundred miles of general friction plate dust discolouring it slightly.
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Kickstart lever, shaft protector collar and seal protector shim off , followed by the oil pipes and tach cable. Clutch cover removed.

I was not wanting to see three things, but I had a prefered order of not wanting to see them.

1. Clutch centre nut loose. Not a big deal to repair, but embarrassing as hell to have to relate my incompetence on here afterwards.

2. Clutch basket rivets come loose. If the basket rivet holes have ovalled, then the basket is trash.

3. Destroyed input shaft bearing. I do not even want to go there.

Oil is OK. No metal in it. An encouraging sign.
https://live.staticflickr.com/65535/53056778234_318369923d_h.jpg

Clutch plates out. Nothing wrong there. Clutch nut is tight and locking tab is secure. I so wanted it to be loose...

https://live.staticflickr.com/65535/53056010522_7ed6a14560_h.jpg

Around 2mm slop between primary gear and basket. When I built the motor there was none. What is going on. The rivets are not loose... Happily the shaft bearing looks to be ok.


Why does it have slop now? I have seen some clutch baskets on larger bikes have anti shock springs in the primary gear, but this is not the case here. Why has it got free movement? It was not something I ever gave any thought to at all previously. I just assumed there was just a usual small amount of play between the rivets and the clutch boss and excessive play was loose rivets.

A quick look on the internet revealed that the DT175 clutch basket has damping rubbers between the clutch boss and the primary gear. Well I never. You learn something new every day.

I found references on how to replace these worn rubbers, but they are not supplied separate by Yamaha. The basket is a sealed unit.
apparently as the rubbers age, they lose their elasticity and resilience, shrink and get compressed, allowing slop in the basket.
It looked like a NOS clutch basket from the US was on the cards, but after several hours of tracking down and finding obscure references and pics of the rubbers in the hope that they were used as a maybe a fuel tank damping rubber elsewhere on a Yamaha and I could identify it.
I came across a company in Germany, quite by accident during my searching, that had replacements manufactured and were selling them. Duly ordered. Expensive, but cheaper than a NOS basket.

I mentioned before that this has been a horrendous merry go round of anguish, but karma is watching and long discontinued and rare parts in new, or pretty much as new condition, have suddenly made themselves available at the exact time I needed them. Take the exhaust. It was not pretty and I was constantly searching for a better replacement.
The very day it blew itself apart and I really, really needed one, a new advert appeared on ebay with one in almost new condition.

Seemed a shame to junk my basket as the bike had done less than 2000 miles and the basket was otherwise unworn.

And no, I did not identify anywhere that the rubbers had been utilised elsewhere. Clutch basket only.

I could strip the basket at home. Drill out the rivets by hand, tap a thread in the basket fingers to accept a bolt and reassemble. Or I could wait till Monday and having access to a largish machine shop at work and a small team of excellent machinists, get them to do it for me with far higher precision.

I recall they highly prize Jaffa Cakes with their breaktime teas and coffees. When word gets out that a packet of Jaffa cakes is in the building, the machinists leave no bolt, bearing or cover plate unturned until they have located and raided the packet.

Packet of Jaffas duly purchased in readiness.
____________________
Wading through the thick tapestry of life one day at a time.

[tinkicker]

I take the basket into work and armed with a pack of Jaffas enter the machine shop.
Instant interest from the lads and one by one they sidle over, with one eye on the pack and the other on me.
I explain what I needed doing and thought that maybe the rear cover plate holes should be countersunk and csk bolts fitted instead of the low dome heads supplied in the kit to better keep the plate aligned and in balance.

I was given the look. You know the one, the one with one eye closed as if assessing if you are being serious.
It was pointed out that as the plate was going to have to be drilled out from 5mm (5mm rivets) to 6mm to accomodate the new bolts, it was better from a balance and alignment point of view to remove as little material as possible and to ream the holes to very very slightly larger than the diameter of bolt.
I was then told I would be more gainfully employed by making the tea and coffee to go with the Jaffas, while the misters did the work.

10 minutes later I was back with the beverages and the rivets were drilled out, the threads were tapped and the cover plate was getting reamed to size with a tapered reamer. Took some doing because inexplicably, the plate was hardened steel. They burned out a 5.5mm cobalt drill bit on the first hole and ended up having to use a carbide bit before finishing with the reamer.
Glad I did not try it at home with hand drill now.

In case you were wondering what it looks like in the basket.. I never knew those rubbers existed.

Bare basket with new holes tapped and ready.
https://live.staticflickr.com/65535/53067218382_0504bfb862_h.jpg

Basket with (old) rubbers fitted. I fitted the new ones and reassembled the basket at home.
I work for a very accomodating company who really value their workforce, most often turning a blind eye to "home jobs" shennanigans during quiet periods, but I had burned up enough company time that day and the bearing that the locomotive transmission I was building was waiting for had arrived.
Reassembling it in works time would have been taking the piss.

https://live.staticflickr.com/65535/53067218397_76192041fb_h.jpg

And primary gear fitted onto the rubbers. The new rubbers were a very tight fit in the chambers, whearas the old ones in the pic have clearly shrunk and are a very loose fit.

The three small holes in the primary gear housed rubber "pegs" sandwiched between the cover plate and the basket.
I think the purpose of these pegs were to dampen any chatter between the gear and the basket, much like the large O ring did on earlier models.
They had flattened or worn, so I just cut new ones to an appropriate length with about 2mm of compression from 8.3mm nitrile rubber O ring stock. Fitted a treat.
https://live.staticflickr.com/65535/53067995629_c4d2858bc4_h.jpg

Built the bike back up, took it into the yard and fired her up. No sound from the transmission with clutch pulled or otherwise, just the slight whir and chatter of the transmission gear teeth responding to the firing impulses at low idle speed.

Just need the rain to go away before I can test ride it.
____________________
Wading through the thick tapestry of life one day at a time.

[stinkwheel]

Just to pre-warn you. The clutch on your VFR does have dampener springs and I garauntee it will at some point start rattling. Usually in the region of 30k miles or so.

Maybe worth deciding now that when it happens if you'd prefer to a) Spring £500 for a new one basket. b) Source springs or shims, grind off the rivetts, dismantle it re-assemble with the slop taken out then rivett it back together. or c) Ignore it, maybe fit a louder exhaust.

Most people choose option c). Used ones are a non-starter, they all rattle. I have three VFR clutch baskets, they all sound like maraccas.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[tinkicker]

[stinkwheel]

Wind your neck in. You posted pictures of your VFR on this very thread and you also got upset about slop on a clutch basket. You even mentioned the sprung type I was referring to. The clutch on your VFR WILL start rattling, they all do, just as surely as the original reg/rec will burn out if it's left how and where it was fitted by the factory (feel how hot the frame spar it's bolted to gets after a long run). Balancing the carbs makes it quieter for sure but the slop is still there. Just trying to pre-empt a meltdown when it happens because you clearly get upset when things aren't absolutely perfect and while the VFR750 is one of the best bikes honda ever made, it still has its problems.

One should also strobe ignition timing if one can, you clearly know how to. I'm not going to concede that point. Especially if you're getting on a high horse about education of future readers of this thread.

I've owned a lot of 2-strokes and the only one that had an ignition advance was my powervalve. Currently have three in the household. I'd assumed an air-cooled, piston ported stroker from the 70's would be on fixed timing. Clearly I was wrong, it's interesting and probably explains why they were such quick bikes. I'm actually impressed it has electronic ignition, I'd have fully expected it to be on points like my wifes YB100 which probably appeared in the same catalogue back in the day.

Oh, and I've hand wound two, split coil AC/DC stators. I also rewired the charging system of the afore-mentioned YB100 (which has pretty much the same system as your DT) so it has much cleaner DC output and more voltage regulation than simply hoping the battery acts as a sink for the electrical mess that's being thrown at it. You can rig a 4-wire C50/70/90 reg/rec unit to them and bin the original diode before it anniahlates into a puff of stinky selenium fumes and kills yet another battery. There you go, some constructive advice for future readers right there.


And yes, I'm also yanking your chain. You left it dangling
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[tinkicker]

[stinkwheel]

I'm learning loads, it's interesting content and I'm grateful for you posting it.

It also reinforces to me why I don't generally sell bikes to strangers because you never know who's going to buy them and what they expect. I'll admit, there are differences because that bike was sold to you as "fully overhauled and restored." and it was clearly far from that but equally, it seems like you were expecting a concorse show bike. Me, I have low expectations when I buy a bike and believe nothing the seller tells me I haven't seen with my own eyes. From that description, I'd have probably expected something that was relatively clean and mostly working.

Admittedly, you didn't get either and are justifiably pissed off, although some of the more fine details, I'd have taken as expected of a 40+ year old bike. The leaking tank would have had me kicking stuff round the workshop though. I'm frankly amazed at the tenacity with which you've stuck to the OEM build, I was aware people did this kind of thing but had never knowingly met one, it's a real insight into the process... Although I'm pleased you threw away the yamaha plug cap, that would have been a step too far.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.