Hi Everyone,

You'd actually think a lower temp would be sufficient for refitting the liner cos the liner is cold & not subject to expansion to the degree it is in removal.


(have to go; more soon)

John if you do the sums on thermal expansion the liner will have "0" clearance when the barrel is ...

Quick metal/ JB weld / Devcon FasMetal are all epoxy based products and as such can't take the heat required to get a sleeve to drop in. It would have to be applied after the sleeve is in. Up that transfer passage would be a bit tricky once the sleeve is in, to match the inlet port would be do-able ...

As John has pointed out the bridge width on the intake could be an issue. If the crinkle rear transfer passage is wider than intake bridge you would need to weld the alloy passage in the barrel and bring it's width down before it is bored out to take the bigger sleeve. All possible but not ...

Maintaining the shape of the top part of the transfer ports is the most critical so taking 2 mm from the top and 5mm for the bottom should work ok. That gives only a little bit of barrel to remove to get the match at the transfer top. Be careful after the sleeves goes into the barrel(don't press it ...

Hi Everyone,

Just sharing an update on where I am up to and wondering if anyone can Help? The crinkly fin 44M cylinder slides straight on to 247 bottom end but is 7 mm higher than 247 so we have pressed the sleeves out. Now we are looking at boring the crinkly fin cylinder to take the 247 sleeve ...

Not the best stuff to weld but it is quite possible. The position of the thread should be easy to find by putting the selector fork in the middle at the drum end and marking the spot.

Do you have any dimensions of the piston, it may be possible to substiute something else. Need to know things like diameter, overall length, pin centre to top outside edge, pin diameter and ring peg locations.
I had a quick search and it seems that the old 360cc Yamaha piston come close at 80mm ...

Hi all, im new to this forum, i have aquired a 74 model ty250a it does run but as soon as you try and apply throttle it dies but if you wind up the throttle screw it will slowly increase in revs from everything ive read these things should be fairly hard to kick over this one doesnt seem to be does ...

The manual says 6:1 compression I read this as 6 times 14psi (atmosphere) = 94 psi. But I doubt this accurate. Have just pulled mine apart had 100 psi if I kicked it a few times. The piston rattles in the bore and there is almost 1/2 a mil of clearance. Have ordered a 71.0 Piston & will get it ...

Looks like it could be a 1964 K10 80cc.