17 thousandths of an inch?

[Pevrilito]

Hi good people,

Thoughts on this welcome...

Ok - an xt350 rebored up a bit to ???cc (bloke told me when i got it), 60-odd thousand miles.

Lumpy running, farts and bangs - especially when dropping off the revs - tends to then stall and stay stalled for a few sweaty, cursing minutes until she'll boot up and pull off sweetly enough (for a while (maybe 5 minutes and/or until i lay off the revs again))

After a few months of fiddling and finding that timing, electrics, carburation all hunky-dory i got to my limit (tether-wise and practical mechanical!) and took it to mechanic.

The exhaust heats up too much and, after a boot or two, he thought compression was down, but it seems that this is sporadic...

A-ha! Sticky exhaust valve-y type problem, you'd think, but he says no... he reckons that the [a] the cylinder is an oval shape by 17 thou and [b] its a touch too big anyway (on the phone just now he said something about 40 somethings - but I didn't quite catch the units - whereas the upper limit should be 35(?)

He reckons it can't be ground round (because its been ground out to max already) and so it'd need a new barrel (either ground to fit my piston or plus an original piston)

===================================

Sorry for maybe too much detail, but I'm a bit of learner on bike mechanic- stuff...anyway, how does that sound?

If compression is the problem, how does this explanation fit with it being sporadic?

Why does it play up and die when the load on the engine is reducing?

17 thou doesn't seem like much to me (or is it?)

Is it not poss to just get slightly larger piston rings?

Worth the rebuild...?...or, bearing in mind the mileage, is the bike a dog and it's time to take it whimpering round the back of the shed??
(interesting thread elsewhere re. the 200k+ mileages btw).

Hmm - well, cheeers for reading people.

C u on the road one day (he says with crosssed fingers)

;-)

Pev


ps.
I got this bike to learn some basic mechanic-ing before i go to the Americas and buy one out there...you can therefore imgine my pleasure at finding myself landed with a lemon from day 3!

teehee
;-)

hasta pronto...