srx barrel

[guest668]

hi just taken barrel of the 400 got one small score mark on the cylinder wall would this be a problem? measured diameter at top = 86.90 mm and bottom measured 86.72 mm wasnt able to measure middle do these measurements sound acceptable ? i dont have any tolerance limits to go by.  also piston rings seem to coma away from piston easily i this normal? and some float play in the con rod from side to side should there be some play there... im wondering if its to allow for expansion due to heat? any ideas many thanks

[Steve Lake]

float is ok, and the top/bottom tolerance looks ok, but the back/front...left/right (i.e. ovality) is more important.
try getting the bore honed, if this takes the scoring out all you need is some new rings
if a rebore is required then obviously a new piston/rings/pin will be required too, and i'm not sure how available they are, you'll probably get them from a good yamaha dealer (from their main european stores in Holland) AT A PRICE, it is also possible that wiseco do them, about £100 from wiseco i should think.
i have a couple of 400 barrels here, i'll check the measurements.

[guest668]

thanks steve that would be a great help...i`ve seen piston set and rings on e bay for £180 ouch!!! might take it to bike shop or engineers to get it looked at...would it be wise to replace valve seals as well?

[Dick Scratcher]

Take your piston and barrel to a reputable piston specialist, I use F.W.Thornton of Shrewsbury 01743 357081 (not much use if you live in Scotland or anywhere else of significant distance mind you), and they should be able to fix you up at a fraction of dealer cost.

[guest668]

thanks would they do postal service i wonder?

[Dick Scratcher]

Worth a try. They're the 'dogs' when it comes to pistons and the like, even to the extent of getting them made specially if there's an adequate market. They import stuff from various countries and as far away as Australia.