gt380 pistons...how to get 'em in !!!!

[Ramjam]

not as easy as the haynes manual makes out. Just lower them in and watch the rings etc.
Well, i'm stuck, half way through a rebuild and i would dearly appreciate any tips of how to lower those barrels down.

thanks awfully


MJ in Beirut

[ConnerVT]

Why, it's really as simple as Haynes says it is. Having the engine on a lazy Susan swivel, a goose neck holding your eyeballs, and 4 hands doesn't hurt, either.

I remember it was a pain in the @ss when I did my twin (and I had to pull it apart, and do it again ). I've read that it may be easier first putting the piston into the cylinder (one circlip installed already in the piston), then sliding the cylinder on, inserting the bearing and pin, and then the other circlip. Haven't tried this, but may give it a shot this winter.

Good luck.

[Craig380]

The way I do it is this:

1) Check the piston ring gaps are correct (0.15 to 0.35mm with new rings)
2) Check and check again that the rings are the correct way up (lettering facing upwards) and the end gaps are over the locating pegs
3) Hold the cylinder in one hand and use your other hand to squeeze the piston rings really tight, with your fingers above the wrist pin on one side and your thumb above the pin on the other
4) You can then insert the piston gently into the cylinder, keep squeezing the rings and your fingers will fit into the cutaways in the cylinder liner.
5) Don't force the piston, it should slide in with a gentle push.
6) When the piston rings are fully engaged, lower the cylinder gently onto the studs on the cases

[oldjapanesebikes]

And the only thing I'd add to Craig380's note is also to use lots of oil.

[mike1161]

All good advice, another trick I've used is as you're easing the cylinder down, if there are any places the ring is hanging up a bit, use a wooden popsicle stick to gently press in the ring at that point. It's soft enough that it won't damage the rings. Suppose you could also use some type of thin plastic stick, too.