Stuck in a mess here. I got 75.25mm OEM pistons without the rings. Now I can't find 75.25 mm rings without spending another ~200 more since the only place that sells them is Honda. Can I use rings made for 75.5mm bore by filing them? I understand there will be more friction. But has anyone done it?

I'm talking about a 0.001" or .25mm difference which isn't much.

Let me know. Thanks.

 

Yes it's possible and they will work. So long as your end gap is within spec it should be fine. I was told by a go-kart racer that they intentionally use oversized rings to reduce the ring tension. Which reduces the friction.

I've used oversized rings to get a specific end gap I was after. I never thought to check the ring tension while assembling that engine.

 

Interesting... Would it not increase ring tension and consequently, friction? Since you're putting rings meant for a bigger bore into a smaller bore. Filing them is going to be a pain though.

Thanks!

 

Again info I was told by a go-kart racer. I have yet to verify or deny this claim.

I do know the oversize ring can be filed down to accept a smaller bore.

 

Once the ring end-gap is established (so as not to make the ring bind or deflect in the bore), place the ring inside the cylinder bore parallel to the block deck surface and at least 1.5" down from the top. Shine a flashlight from below focusing the light at the area where the ring outside edge meets the cylinder wall. If you can see light between the ring edge and the cylinder wall, anywhere except the end gap area obviously, this ring will not work and you will have to pony up the $$$ for the genuine Honda rings.

No light means a good seal. Ring tension may be another matter. My gut says that the difference would be nominal since most manufacturers utilize low tension rings for Imports unless you request otherwise, however, I have never built an engine using an over-sized ring for a street driven car, so I cannot comment on the long term effects of doing so. Don't forget to trim the oil scraper ring to make sure it doesn't bind in the cylinder bores as well.

 

I was actually planning on using low tension rings in 75.25mm and have got a custom set made by Total Seal. The conundrum is that I'm wary of using those rings after reading some of their reviews. The 75.5mm rings are a backup because these engines were not sold where I live and the ring thicknesses (1.0-1.2-2.0) match nothing that was sold here.

Thanks for the tips! Also, what are the short term effects of using these? I would assume nothing really, but would like to hear from you since you seem to have tried this.