.018 a lot too much ring gap?

[beachedflunkey]

...Or just a little too much gap for brand new rings - the old ones had .025. If .018 is a lot too much gap, am I looking at boring up a size? It seems like my piston clearance was fine but I guess I better double check that too :banghead:

 

[#ZERO]

The factory manual says .008 ~ .016in installed ring end gap but this is for a stock engine.

http://www.drmikesandy.com/xh2o/Yamaha SuperJet Service Manual.pdf

What kind of pistons are you running?

 

[beachedflunkey]

pretty sure they are yamaha pistons. might be wiseco's. motor is stock other than the first two bores. Yeah I know it should be .016 max, I'm just hoping .018 ain't that bad.

 

[Prem1x]

Almost not worth putting them in. What is the piston to cylinder wall clearance?

 

[just joe]

Unless you are racing, I think up to .020" is fine. So does Randy at Watcon... we've discussed ring gap and piston/wall clearance in depth, but I'm sure others will disagree. While I'm at it, I also think .008" is tight, .012" to .014" is what I target.

 

[Crab]

My new 750 has about .0195 with fresh bore and rings right out of the box, wiseco pro lites.

 

[ski4]

subscribing to this one to see what thefinal consensus is

 

[#ZERO]

My new 750 has about .0195 with fresh bore and rings right out of the box, wiseco pro lites.

My last set of 84mm Wiseco pistons had a .014 ring end gap, what piston clearance were you using?

 

[Kaveman]

Keep in mind that these are NEW rings. Once you run them an hour or so the rings are going to seat themselves in the bore. As this happens the ring end gap will increase. I would check the 6 bore measurements and compare them to the actual piston size and advertised size. Most likely you will find either the rings are wrong or the piston and bore are worn beyond service limits.

 

[beachedflunkey]

Thanks for the replies. I gotta try and get access to some tools to double check clearance again. Buying a "running, recently rebuilt" used motor was supposed to be easy. :banghead: