Do i REALLY need to replace the piston rings?
 

K3 sv650s 16.5k miles on it

Here are the measurements

All the rings thicknesses are spot on the upper limit, 1.19 1st ring & .99mm 2nd ring. so no issues there.

In bore end gap (tested at the top middle & bottom or the bore) limit is .7mm (anything above this is a fail)

1st rings (front & rear) .3mm (well within)
2nd rings (front & rear .35mm (well within again)

The issue i'm having is out the bore end gaps.

1st rings (front and rear) limit is 7.6mm - they measure 8-9mm
2nd rings (front and rear) limit is 8.8mm - they measure 10-11mm

Everything else is absolutely fine!

Advice appreciated as i am just about to start the big push to get the top end rebuilt. :p

Re: Do i REALLY need to replace the piston rings?
 

I really would not worry about the out of bore end gaps, the in bore is the key one and they sound fine.

Re: Do i REALLY need to replace the piston rings?
 

I agree, as long as there is a continuous contact around the circumference of the ring, normally displayed as a matt finish. Less than the lower limit might give concern.

Re: Do i REALLY need to replace the piston rings?
 

They are perfectly fine! 7.6mm & 8.8mm are minimum limits. you are thinking about it the wrong way around, if you know what I mean. The larger the free or out of bore end gaps are then the more firmly they are pressing against the cylinder bore when assembled, and therefore making a better seal. Below the minimum limits they are not springy enough to press firmly against the bore when assembled. Hope this helps.

Re: Do i REALLY need to replace the piston rings?
 

I think that if you have gone that far already why not just replace them, Its common practice at work to change them anyways regardless of wear its a tad money wasting but preventative maintaince is the word they use.
Also have you measured the bore to ensure no taper???

Cheers Gaz

Re: Do i REALLY need to replace the piston rings?
 

This. You have perfectly serviceable piston rings, no problem using them again.

Re: Do i REALLY need to replace the piston rings?
 

If they were mine, from what you say, I'd put them back in. They've only done 16k, just broken in. (make sure they are the right way up!)

Re: Do i REALLY need to replace the piston rings?
 

ned your spot on, that is exactly the way i was thinking wrongly. it now looks like there is little wear and i bet if i bought a new set and put them side to side there would hardly be any difference in the tolerances and id be kicking myself with the unecessary expense! As a note both manuals the suzuki one and the haynes do not show the correct method for checking the free end gaps and what you should expect. I suppose the suzuki manual expects the reader to be a mechanic but once again the hanynes fails on describing this. Thanks to everyone who replied and i hope this thread will be of use to those who do this in the future :)

Re: Do i REALLY need to replace the piston rings?
 

at only 16,5k why would you have to take the engine to bits in the first place.unless sv's are less reliable than other suzukis i would think the rings would be good for a 100k with reg oil changes

Re: Do i REALLY need to replace the piston rings?
 

Do a search mate, my k3's gearbox lost a dog ..... complete rebuild!