Fettled Bike 2. 1979 Yamaha DT175MX Restoration.

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the carb top parts in my new ultrasonic.
Did the bottom end of the carb yesterday and also rebuilt that this morning.
My old machine was little more than a jewelry cleaner that I used for cleaning watch movement parts. Carbs were left partially uncovered and needed turning regularly.
New one has plenty enough capacity to dunk carbs easily, even though it is only 3 litre. It, being the more powerful pro model also has 4x the power of the old one.

Waiting for the machine to reach its set temp. While waiting I built the top end and carb body. I was not going to do the cap, but I just wanted to have another play with the machine before tossing out the cleaning fluid.

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The offending item. That ebay special jet cost a fiver. The genuine one from Fowlers cost fifteen quid. I thought a 130 jet was a 130 jet, was a 130 jet and gave it little thought. A tenner saved is a lot.
That tenner saving cost me well over a hundred quid to put right the damage that jet caused.
If you take anything from this thread, it is do not skimp on carb jets. It may well bite you on the ass.


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Also got the engine in the frame and the right side of the motor built up. She has strong compression at the kickstart. A bit more insurance..that plug is a B9ES. I went for a step cooler since the bike will be ridden pretty much wide open most of the time. Rural roads, little traffic and 60mph limits round these parts. I read somewhere that the B8ES is borderline hot for open highway use.

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Sprocket and chain refitted on left side. Needs carb, left case, exhaust, wiring, tank and seat refitting and she is repaired.
Stomach is growling so I need lunch. May or may not do a bit more this afternoon.
Also need to remember to bring home the neutral switch from work. I took it out when warming the cases to drop the new transmission bearings in....and forgot it.

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

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To purloin a phrase from Motley Crue.. Kickstart my Heart.

Carb on, exhaust on, wiring connected, fuel tank plopped on. Fuel feed connected. Autolube pump bled.

Ignition on. Kick. Kick ring a ding ding.

Ran it long enough to set idle and check autolube pump was stroking. It was.

Pulled back the pulley to observe max pump stroke output. Looked like it should from what I remembered from last time I checked this un and the 100 output. Since I never disturbed the pump or any adjustments, and it is stroking, I will call that ok. I have no premixed fuel to run it long enough to measure output and I do not want to idle it for a few minutes with just the build lube inside. Injection pipe refitted and let it warm up for five minutes.

Sounds good and has six in the box.

Just need to fit the carb vent pipework, button down the tank, refit the oil pump cover and generator cover, and she is pretty much ready for a gentle road test. Piston rings have already been heat cycled and bedded in.

It was pretty smoky in there as the build oil was burned off.

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

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Road test time. Took her out on a run arround the village perimeter. Probably around three miles.

She pulls fairly strongly through the gears and behaved impeccably.
She feels different somehow, more refined. Perhaps now the carb has been put back to stock settings and with genuine parts, the carburation is right.

Although I have not taken her above 5000rpm yet, I can still detect that slight vibration through the pegs at 5000rpm, but I had a notion as to what it could be over the winter.
I think it is the chain running over the new nylon chain tensioner block. It has not yet worn enough to allow the chain rollers to glide across it and I am feeling the edges of the sideplates hitting the edge and sliding over the block.
The tensioner arm is bolted to the same frame crossmember that the pegs are fastened to....
Once the sideplates have worn their grooves into the block and the chain is gliding across on its rollers, I expect the vibration to go away completely.

Back where she belongs.. On a very chilly day. My nose has not stopped running yet..

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

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Epilogue.


And there you have it. A sad tale of disappointment, anger and a trial of a bike. Beware the ebay restorer. His idea of what constitutes a restored bike may be very different from yours.

I trusted this guy because he was a college motor vehicle lecturer and presumed he had a good idea about motor vehicle systems. Turned out not so much... It was quite literally a deathtrap.
Of course, I have only myself to blame for the holy piston debacle, buy cheap chinese ebay crap and spin the roulette wheel..

In the end I had changed every single bearing, bush and oil seal on the bike, even if they looked perfect and completely rewired the electrical system.

The final bearings were the ones in the transmission, even though they looked perfect, and done less than 2000 miles from new, we are dealing with the devil bike and it needed no excuse to screw me over again. I did not dare reuse them. Hand in pocket again.
The only thing left of the original " restoration" is the stove enamelled frame and he had that done professionally.

I must have completely overhauled over 100 two stroke motorcycles in my professional career and none of them were so testing as the devil bike. It absolutely refused to play ball. I thought I was losing my mind... It let me get away with nothing.
If what looked on inspection to be a perfectly serviceable part that you would reuse without thinking, it would fail on the devil bike. It demanded perfection.


Of course she rides like a brand new bike now and has just rolled over 200 miles since the rebuild. Damn what the classic bike appraiser said, I built it to ride and ride her I will.

She usually gets ridden a couple of times a month when I have the time and has behaved like an angel. Of course, she now has a cylinder head temp gauge and I keep a close eye on what is happening temp wise. The danger zone starts at 240C and I have set the temp alarm at 195C a very conservative setting, but she has not approached that.

First world problems, three restored bikes to ride and so little time to ride them. They are my toys for when I retire in six years...

Money spent now, means less money to have to spend then.

A nice trip of maybe 40 miles on a lovely sunny day a week or two ago... I once again have the brand spanking new DT175MX I so regretted selling back when I was 17, or as close to it as humanly possible.
And no, I am not going to trade it in for a Honda CB250N Superdream.

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CHT gauge. She stays well in the safe zone and I will remove at the end of the season. Max temp seen so far is 172C. Max temp alarm at 195C. A long way from 240C because the piston heats up far quicker than the head and it buys me some time to shut off before the piston suffers.
As said, she stays at a very safe temp. I may be losing a couple of horsepower by not jetting her to run closer to max temp, but I am happy to have a cool piston crown. She is not for racing. Also handy for warming her up. Once the gauge hits 100C I know she can be safely ridden normally.
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Hope you enjoyed the thread..
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Wading through the thick tapestry of life one day at a time.