Ty Mono Build Problems

[grizwald]

Hi have nearly finished my TY mono rebuild . I've found a few problems on the way & would like to discuss them. My bike has a YZ 250 front brake plate fitted & iv'e had to machine a extended torque lug for the fork leg/ brake plate,anyone else had to do this? I also found that the carb had had a few DIY mods on it that didn't work very well.Corrected this by adjusting the float height to 23mm with the float tang just seating in the float valve slot, next fitted 42 pilot jet, highly vented air box lid, 145 main jet & needle back in the std position , air screw 1, 1/2 turns out. Bike now starts easily & runs like a top. Plastic petrol tanks don't fit very well on ty's & they seem to ooz fuel vapour & discolour (i'm thinking of getting some tank covers made). Put plenty of rubber tube compressed into the fins on head & barrel this will deaden the ringing. Question i need a good quiet exhaust silencer for the TY any ideas other than making your own? Regards Grizwald.

[pitley]

I used a W E S go silencer on my pinky, does the job a treat, quiet enough i feel.

Sorry cant help with the other problems tho..

[grizwald]

Thanks Pitley, Is the WES silencer quiet or fairly noisey? Mine sounds like an old Greeves at the moment.

[roester]

Repacking your silencer or putting a new one on is well worth doing. The WES silencers have a good reputation and are fairly quiet.

Repacking the middle box also makes a huge difference - it not only quietens it but also makes the power much smoother and 'waffley'. If it hasn't been done for years, if ever, it will be in a real state with most of the packing wrecked and the holes in the core blocked. It is a fiddly job to cut it open as there are several chambers, and the metal is thin so you need a decent and patient welder to put it back together. It is quite a lot of effort but I think it is one of the jobs that makes the most difference to an old mono Yam. I cut a section off the back of the mid box (with a thin blade) and then cut into the chamber inside of that - if you are feeling keen you can also cut the front face off as well whilst still retaining the shape and main structure.

If it still sounds like a Greeves is it worth checking the main bearings and piston as well?

The Yams came with rubber blocks in the finning and you can pick these up on eBay or from a breakers pretty cheaply if you need them.

If the tank doesn't fit well it is probably because you've got an earlier Yam that came with a steel tank, or perhaps the rubber mounts are missing.

Great bikes the TY250 mono. Good luck.