Top End

[kgordon7378]

I recently rebuilt the motor on my 88. I only ride, recreational, and plan on doing new rings as my compression is down to about 120ish in the altitude (denver, CO). Should i hone the cylinder? What should i expect my compression to be with a new set of rings? Thanks
Keith

[ESR350r]

It all depends on how bad the cylinder walls are, if there are small scratches hone it, if you can get your finger nail caught in it bore it. Check your compression now to see what it should be close to after your next rebuild. Just know that if you run the same size piston as before and you hone it you will lose compression because the piston does not have the clearance as before.

[wilkin250r]

You said you recently rebuilt it, and your compression is at 120? That's bad. I don't mean to sound insulting, but you did a terrible job on your rebuild...

[kgordon7378]

I should clarify. I did a full rebuild, top and bottom end. I have since put many hours on it, and know its time for rings. I would agree that only 120 after a rebuild would mean a bad rebuild, or a leak somewhere, yet it does have alot of hours, and was tested at over 9000 ft. What should the compression be for a stock motor at sea level or at the altitude.

[370kingR]

You need to compare apples to apples with your bike. You dont know of anyone else with a 250r in your area that you can do a compression check on to see how it compares? That number sounds low but that is some high elevation and that will certainly drop that number significantly.

OR

Just take the cylinder off and get it checked out for out of roundness, or too much wear. Usually signs of that at the top of the cylinder where the rings stop, there will be a lip if theres good wear. Check the ring end gap, that will tell you either the rings or the cylinder walls are worn. And finally, check the piston for signs of rubbing, scoring, ect.....

PM me if you need a new cylinder and piston. They are very nicly ported and ready to go. Brand new Honda cylinder, brand new wieco performance piston, even a brand new head with acorn nuts. All for $350.00. No exchange, no core, in stock for pump gas or race gas. (for you Kgordon7378, i suggest the race gas, higher compression) Thanks

KingR

[kgordon7378]

So i got a chance to get started. I checked the compression before pulling the thing apart. I actually had close to 140ish in the altitiude. The piston looks clean, except the exhaust port, where there is some dark lines. The cylinder looks good as well, with some of the marks from the previous hone left in it. I am trying to decide if i should just put the rings on it and run it, or if i should do a piston and all. I already have the rings ready to go.