Dealing with the DT

[WD Forte]

Oh yeah ,the old anti backlash quantum tunneling diode.
Yamaha kept quiet about it as they nicked the idea from NASA
who got it from a hairy little alien who got it off a guy in a canteen on
Tatooine apparently.
Didn't catch on though, cant get the parts see?
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bikers smell of wee

[Easy-X]

Oh well, it was a nice theory while it lasted. Just tried slowly kicking it over and the tacho cable still rotates anticlockwise

So....

Either I have somehow fucked the internal cogs and gears so badly that they work in reverse or the 1G1 Euro model rotates in a different direction to all the other DTs

Neither option seems credible!
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[stinkwheel]

[Sister Sledge]

Back in the olden days when I was a teenager we tried making a Yamaha run backwards. We tried changing the timing to such a degree that it might happen but no - we couldn't make it happen.
I hear the words of people taking the Michael out of you for those components. You know your electrickery - ask yourself - could a single diode in that harness do anything useful? Perhaps in a radio but surely not a bike??

I've a feeling the drive is from another manufacturer or perhaps the tacho innards are and with a Yammy dial plonked on top.
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CCM 404 DS

[Easy-X]

Yes, it doesn't make much sense that a diode would do anything much to AC apart from half-rectify it I must have stumbled across some 40+ year running joke All I know is: it is a thing that Yamaha retro-fitted to later bikes, if it goes wrong the bike won't start and people replace the faulty part with, what looks like, a generic rectifier diode (from the component package - could be anything really.)

Then again there's a chunk of components Yamaha fit to bikes in certain markets. The most obvious being the spark arrester on US exhausts (or mufflers if you prefer!) I assume such a thing would restrict the flow; certainly it's regarded with disdain.

Just for reference, here's the tachometer parts page for the DT175C which is AFAIK the closest US version to my European 1G1:

https://images.cmsnl.com/img/partslists/yamaha-dt175-1975-usa-speedometertachometer_bigyau1081d-7_3625.gif

My tachometer exactly matches these connections. Anyhoo, I don't think that's the problem as it operates as expected when connected to a drill.

Here are the internal parts:

https://images.cmsnl.com/img/partslists/yamaha-dt175-1975-usa-tachometer-gear_bigyau1081b-5_3f26.gif

Parts 3 and 5 are the crucial ones. As you can see, it's not possible to get these the wrong way round! And if someone were to ask me to guess which way things should rotate just from looking at that shitty picture I'd still say clockwise!

Maybe it does have the wrong parts in it Certainly a brief scout of eBay shows Kwak parts that look similar but the sweep of the gear teeth is in the opposite direction to Yamaha parts.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Sister Sledge]

The way I look at it with a manufacturer is if they make say the drive gears in the engine for the tacho - they'll continue with the design if it works. They wouldn't suddenly start making gears with an opposite direction bevel.
I've seen many cases where people have some knackered clocks on the bars but the dial face and external casing is fine. The person has then 'peeled' open the clock casing and replaced the internal mechanism. I watched such a video recently but can't remember what it was - I suspect yours is one of those. Does your tacho show signs of being opened? Damage, doesn't quite look right? dial face rivets/screws appear to have been messed with?
If not then you'll either have to re-invent a thresher drive belt to drive it or perhaps borrow another old Yammy tacho to see which way it goes.
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CCM 404 DS

[stinkwheel]

[Easy-X]

Nice thought but sadly no. Apart from the chrome starting to go in a few places the tachometer is mint and sealed in the same "tamperproof" way the speedo is. Anyhoo, the tachometer is operating as expected it's the engine output that's reversed.

There's a tiny <1% chance IMHO that parts from another manufacturer might fit this bike. Kwak gear meshes look like mirrors of the Yamaha parts from what I've seen on eBay.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

Quick update: wrong parts.

The parts in my bike are mirrors of the "proper" parts (tacho drive and worm gear/cog) photos to follow...
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

I started today by stripping out the oil pump:

https://i.imgur.com/gfdprHU.jpg?1

Drained the oil and took the crank case cover off, only needed to remove the footpeg arm, kicker and brake switch - nice and easy.

Let's see what's inside:

https://i.imgur.com/nWID3sP.jpg?1

The big white cog is for the oil pump - that'll be going soon - and above is the tacho drive. Conspicuous is the sweep of the teeth: going the wrong fricking way

Hard to tell about the main cog from this angle:

https://i.imgur.com/pcmzKEl.jpg?1

Ye gods! Yes, that's wrong too:

https://i.imgur.com/QU5NmNd.jpg?1

I would imagine it went something like this...

Clocks and cables were deleted when it had its short "let's go off road!" period and the parts that found their way in there are "that looks like it fits!" from an autojumble

Now I'm wondering whether to just lob on an angle drive or hunt around for the correct parts

Anyhoo, worry about that later. Here's the tidy pump delete:

https://i.imgur.com/x3zbKk8.jpg?1

I've saved all the pump bits in a plastic tub in case someone in the future wants to go "full purity" and restore it back.

In other news (that doesn't make for exciting photos) I dropped the battery in and reconnected all the ancillary electrics. And it mostly all works!

Engine off, ignition on the sidelight switch works front and back. Neutral light works. Engine on the headlamp works - the difference between high and low beam seems negligible

Brake light. Front switch has a lot of travel before it works, might replace that. Rear switch is sticky but I already have replacement at the ready.

Indicators are the only thing that truly don't work. The relay clicks, the fronts come on but not the back. No flashing Neutral light dips which indicates a big power drain. I'll do some testing on the flasher unit tonight (probably toast) and take another look at the loom if needed.

Just for fun I threw on the new tank and seat:

https://i.imgur.com/0pdzJpa.jpg?1

This is what it's all about The tank will require a little percussive maintenance to fit but the main thing is it matches the line of the seat.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

~£50 for the correct engine parts to fix the tacho.

~£35 for an angle drive

<addendum> after a load of hunting about I've got the engine parts down to £35. Had resort to ordering from the US for the plastic cog

Seems the parts currently in the engine are for a DT125.

<further addendum> oh! I have a spare bottom end. Could I pinch the parts from that? Damn... DT125 bottom end, that figures. Wonder if the tacho parts are missing from it!
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

Pretty miserable weather today so I thought I'd make a new throttle cable. The old one looks like this:

https://i.imgur.com/gG4BKDw.jpg?1

It has a splitter affair in the middle common to 2-strokes. If you're not familiar with automix oil systems the throttle cable is in 3 parts: the top bit and the 2 bottom bits in a Y configuration. Turn the throttle and you pull up the carb slide and turn a dial on the oil pump which allows an increase in stroke length and hence more oil is pumped into the fuel.

Of course I could just leave the oil end flapping about in the cavity where the pump used to be - what could possibly go wrong Seems untidy though.

Anyhoo, in the vein of "how hard can it be?" I thought I'd make a new throttle cable. I'm sure somewhere there's an off-the-shelf one (or companies make to order) but that sounded unnecessarily expensive when there's an opportunity to cock things up learn

Here's how it turned out:

https://i.imgur.com/8F5do2P.jpg?1

There are plenty of articles about making cables but I'll just lay out my top tips...

The carb end is probably pre-made, check this actually fits your slide! Too big and you might manage to file it down. Too small and you're probably done before you start (depending on what brass ends you have available.)

Top tip number two: you'll have off-cuts of cable and spare ends. Practice on these first

Painfully obvious but needs restating: make sure you have all the relevant bits in the assembly in the correct place before getting busy with the lead!

Finally, and most important: clean and flux! Good flux makes a big difference DO NOT think you can do without it.

Regarding the tacho gear: lo and behold the gubbins is completely absent from the 125 bottom end I have spare so I think the mystery is solved!
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[redeem ouzzer]

Make sure you plug the oil injector elbow in the carb if you've junked all the autoshite gubbins. A length of oil pipe with a bolt in the end will suffice.
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Be a REAL MAN!

[Easy-X]

[Easy-X]

Well that's the sunlight frittered away on not very much

Got the newly made throttle cable back on the bike. Even found an old cable to steal a spring: one of those you put on the cable in case it touches the engine or exhaust.

Had another look at the wiring. New flasher doesn't seem to work I bypassed it and just had the indicators "always-on" hmm, front and gauge light all look fine. Backs? nothing. Then I took the bulbs out and all the earthing is corroded. Resigned myself to stripping them back off the bike for a date with some wire wool.

Still not sure about the flasher but as I have the back lights & battery to hand now very easy to test off the bike.

Few things left. Fuel tank I might look at tomorrow - actually I have a few of these on hand now so no panic. Exhaust though...

Viewers of a sensitive disposition may want to look away now:

https://i.imgur.com/E4yu8BI.jpg?1

Eeeek! Yes, I've cut the bend off the original silencer and I'm going to mate it up with a £10 eBay jobbie

"WTF, man, have you completely lost the plot?! Think of the purity!!!"

Unfortunately the only good source of these "mufflers" is the US. They're not the best sort of object to be going through the postal system so unit cost + postage + import fee we're talking silly money for something that frankly isn't much better than what I have.

I did look for "proper" 2-stroke silencers but the styling doesn't suit an old-skool bike. This cheapo unit is at least black and not silly faux carbon-fibre. I think it suits the bike quite well so fuck the purity
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Sister Sledge]

What's that flange bottom left? Did it come with an exhaust?
Please tell me it's not a galvanised safety rail base??
Remember: Zinc will vapourise if the host metal (steel) is heated to red heat. Those zinc fumes are bad news for lungs.
Might also not be what I think it is so ignore me! (but for reference - zinc = bad)
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CCM 404 DS

[Easy-X]

That bit bolts onto the base of the silencer with a circular gasket. It looks to be bright zinc plated. Don't worry, not going to weld the pieces together I'm just going to join them with a piece of silicone and some clamps.

Turns out the flasher relay works fine. However, both back indicator units had 12V bulbs in I fished about for a 6V to test with and compare: 6V is eye-searing, 12V is an ember (on a 6V bike battery.) Time to order new bulbs! (Note to self: check bulbs on headlamp and tail light.)
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

Not much time today as I had two jobs to go to

Still, I had a go at battering the underside of a Chinesium Tank (see the black one in the previous post.) Needs about another 5mm clearance so I've gone with brute force and ignorance (MAPP torch + hammer) and I can see why people get into metalwork! Something very satisfying about shaping metal.

It's now a near perfect fit but light's gone One more round of battering and then I'll tackle brazing on some mounting pegs.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Suntan Sid]

I reckon this could be made to fit:-

https://www.feked.com/yamaha-ty175-250-j-type-alloy-exhaust-silencer-twinshock-models.html
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"Everybody needs money, that's why they call it money!"

[Easy-X]

[Easy-X]

Indicators all have 6V bulbs so flasher relay works okay now. There are also 12V headlamp and sidelight bulbs

The Chinesium tank has shaped up nicely and so had the sunshine today so rather than brazing or soldering I thought it best to get the bike on the road!

Gave one of my spare tanks a rinse out and thought I'd better look at the petcock:

https://i.imgur.com/KdvGheu.jpg?2

How many holes do you see I went a bit mad with the carb cleaner to clear it but not until after I drilled out that left screw Mixed some 40:1 and checked fuel would actually come out the pipe - I'd only mixed a litre so switched to reserve - and it fairly poured through. Added an in-line filter to be on the safe side and here we are:

https://i.imgur.com/fXsFf8e.jpg?1

So that's a tank from something or other, certainly not a DT175 but it's a close fit. Cheap seat cable tied on. New exhaust fitted. All electrics tested and working.

It took a few kicks to get going but not unexpected considering the carb was dry. First time in gear it stalled so I adjusted out the clutch cable.

First problem: the clutch cable is brand new but the adjusters are all wound out to the max Might be able to wind it in a little but even so it's not as one might expect.

Second problem: rider incompetence Probably not helped by the first problem but I've never ridden one of these old 2-strokes before so I'm bound to misjudge gear changes and stall the thing which brings me onto...

Third problem: it's a bitch to start! I think the first time it stalled putting it into gear I managed to restart it first kick. After that it just didn't want to play ball About the only thing that half worked was to let the cylinder breath for a bit, choke on and then three or four good kicks in quick succession. I think I got it going once with no chock and a bit of throttle. The DT125 bottom end with the starter motor is looking mighty tempting right now

To be fair I've done zero tuning on the thing so all of the above is literally starting line stuff. And the engine seems okay once it get's going. I should really look on the bright side: it handles great, wheels go round, front brake is excellent (though the back still needs adjustment) all the electrics work.

I think I'd have a little look at the carb but it looks like a storm tomorrow
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Sister Sledge]

Hard to tell from your description but a 20 second video of the engine running might help us steer you towards any starting problems (if there are any!). Tis an old design and starting will be more a challenge.
Think about chain saws - they never start first try.

Question: Is that the correct chain guard? Looks short?? Stands out immediately to my eye that.
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CCM 404 DS

[Easy-X]

I sat down last night after sweating my c*ck off repeatedly kicking the bike over and had a think...

Everything, and I mean almost everything, bar the clutch and engine starting is damn near perfect so I should stop beating myself up about it Anyhoo, now is not the time to fret as when I had a think about it the carb has, AFAIK, never been cleaned in thirty years so, err... maybe I should start there! Oh and I, um, forgot to plug the oil feed hole on the carb too so complementary air leak didn't help

It as been suggested to me the clutch may just be a bit seized. The cheap fix being to clamp the lever over night and see how it goes. No great bother to drop the crank case covers and take a look; I have to drain the oil to put the correct tacho parts back inside and possibly refit the oil pump for the auto lube system.

The only non-original parts are the tank, seat and exhaust. Chain guard is exactly how they were, back in the day.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Easy-X]

What shitty weather Didn't fancy going out in it to tune up the carb or whatever so I busied myself with indoor stuff.

I stumbled across a mint oil pump for bugger all money. Not 100% the same but I had a swap about with parts and did a proper rebuild this time:

https://i.imgur.com/cjQE7r0.jpg?1

Once I've got the engine starting and running smoothly I plan to dump the oil, drop the side off, refit the correct tacho gears and add the pump back. Of course the complication is the old carb probably being set up for premix jetting but I have the spare Chinese carb and stacks of jets so I'm sure there's lot's of "fun" to be had sorting that out

Oh, and shout out to Stinkwheel! I had a play about with the MAPP torch and silver solder. Pre-fluxed rods, dead easy
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[WD Forte]

I've been musing over getting a MAPP torch
whatcha bin doing with it?
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bikers smell of wee