Mild hybrid TY attn David Lahey/Julz

[TayIpsilon]

525C chassis, 487 cases, 525 barrel/piston/head (sadly on backwards but too lazy and cheap to use my spare headgasket)/carb body, DT100 slide and cap as original was missing.

Happy about the neutral switch and the tacho drive and she runs quite soundly so unlikely to swap in the TY bottom end it came with any time soon. Loving the wide ratios while i'm still finding my feet too.

[David Lahey]

Go

The neutral light switch will be pretty handy in sections because you will get a warning if it gets knocked out of gear
Apart from the neutral switch and the tacho drive saying it is something special, the magneto cover is a different shape to the Ty175 cover, and the TY175 clutch cover does not have "YAMAHA" cast into it
I'm impressed that you got the exhaust pipe to fit with the head on backwards

Good to see it at last. Thankyou TayIpsilon

[TayIpsilon]

Dunno how they got it on as it does foul the head, but that was two owners ago when it was built as a learn to ride trail bike for someone of small years and stature.

Figure while it works and shows no appreciable danger to the pipe or head i'll leave her sealed. It could however be why the muffler is not fitted and very missing. Not really had a good look at the angles but it seals at the barrel so if bent its perhaps best that its not disturbed. Not that its an aesthetic pluspoint, but i've bunged a folded up quantity of aluminium flyscreen in the exit of the expansion box. Keeps the barking noise to an acceptable level and is a far less obtrusive tone than with it straight through.



There was seat with this one but no guards or muffler. The other 76 came with a half useable rear guard and the correct muffler but no seat.

[Julz]

Pretty sure that his is not the same bike as the one that I owned. Interestingly the one I had was the same year and tank colour.

The guy I bought mine from was a builder of 2 stroke race bikes with low slung hand built chromoly frames. I wondered why it had a different model crankcase. Not sure if it had the 525 head, but from memory it was marked as 171cc. It is possible that he put the bike together using parts from different donor bikes - as this one seems to be.

I found the bike to be too peppy and quick to rev (not enough flywheel weight?). At the time I was just getting into trials riding and found it to be too much for me. The TY175 that I just bought for my boys is much more tractable, but still seems to have plenty of power.

[Gary B]

I reckon the Bottom end is off an early DT175 or DT125.
They both had tacho's & instrument lights fitted.
I just did a prefix search & 487 comes up as a 1974 DT125

Back in the day Yamaha shared many bottom ends and it was common to hear of guys with 175 barrels fitted to 125 dirt bikes.
Hell I even manged to fit RD350 barrels onto my RD250 when I was on my "L" plates.
These bikes even shared the same base gaskets

May help if you need to get bits in the future.

Cheers,

[TayIpsilon]

Only irritation so far is the degree of slop in the shifter and upon looking where the B has a grease nipple, and the 1n4 is missing one from, the dt countershaft cover being separate to the mag cover uses that hole as the second fastener point and i have doubts its ever had its mechanism greased since day dot. Might delve into the spares motor and see if its roller is any improvement.

[David Lahey]

It's usually just the pivot holes for the shifter shaft get worn and for an economical repair, both can be bushed with steel or aluminium without pulling the motor apart

[TayIpsilon]

Might be a good inspection for tomorrow. May lube the others while 'i'm about it too.

[TayIpsilon]

Looks as though i'll be a-bushin sometime in the future. Outer cap is pretty flogged but got a spare with the box of DT100 (sd model it turns out, 1977) parts the carb slide came out of. Inner is still most of the problem but theres less slop than there was for now.

Anyone doing up a 77 dt100 by chance? Was in the shed the other day and found i've got a pretty good exhaust header for one that i'll never use.

Last query for a while: most of the case and cover screws are all stuffed. Has somebody done a kit of engine fasteners for these bikes, preferably allen screws or 8 mm hex heads with integral flange washers like my suzuki GS uses but in stainless? Found kits from the states but the freight is more than the part.

Thanks for your time, glen.

[David Lahey]

Yes Glen, John Cane in the UK does stainless steel socket head screw kits for the TY twinshock motors.
If you wanted to buy them from a bolt supplier locally, the lengths might be in the Yamaha parts book. Not sure though.
I recently bought one of those sets for TY175 and when combined with a few other parts from John, the freight was not as expensive as it would be just for the screw kit.
http://www.tytrials.co.uk/trailandtrial ... TY175.html
http://www.tytrials.co.uk/trailandtrial ... TY175.html