new rings not sealing

[Davidgx200]

I recently installed new rings on my 6.5 clone it ran strong for a week then after a couple days of sitting when I started it the motor idles off and on til it dies only running with throttle wide open when I pull the plug it's covered in oil so I pulled the head off and spin the piston to the bottom of the bore and wipe the oil out when I pull the cord as the engine spins i see a little mist of oil back in the bore above the piston. Anyone got any advice for making the rings seal or do I have to order new rings and try again? Thanks for any help.

 

[devino246]

Did you hone the cylinder when you replaced the rings?

 

[cumminsbayou4x4]

how much compression did it have. you could have over honed it and need to put a bigger piston in it now. if you didn't hone it at all you should have a problem except at start up it may smoke a little

 

[Kaptain Krunch]

how much compression did it have. you could have over honed it and need to put a bigger piston in it now. if you didn't hone it at all you should have a problem except at start up it may smoke a little

wrong. Honing to the point of needing an oversized piston is almost impossible with anything your average DIYer has. Not honing the cylinder could cause the rings to glaze over and not seal.

 

[jamyers]

Oil rings need attention, not compression rings.

Easy stuff first - it's not overfilled with oil is it?


Sent from my iPhone using Tapatalk

 

[Davidgx200]

I bought a new block and used the same rings but was only spinning 6000rpms expecting 7500+rpms with my setup. I spoke with Tom at ARC Racing and he said you must use new rings in a new cylinder try that first when I installed the rings it ran strong at 7500rpms for about a week. then after a few days I went outside and it didn't start with 1 pull like normal. when it did white smoke out the header, died when closing the choke only running at wot. I didnt hone the block was less than a month old and cylinder was smooth and not alot of oil. barely enough of to notice with one pull while head was off and piston cycled several strokes. But it adds up to alot of oil on the plug when running.

 

[fowler]

The smooth cylinder is the problem

It should have been honed to fit the new rings even if its new

Did u replace the oil ring when u changed the rings
The rings u have will be glazed over and not sealing properly

 

[Kaptain Krunch]

Also, breaking in new rings is important. One constant rpm glazes rings quickly, try varying it for the first few rides.

 

[Davidgx200]

Yes new oil rings with the set. Honing is the problem doesn't make sense to me I was told the old ones were shaped from the Old block the news ones being new would shape to the cylinder they are installed in.

 

[fowler]

Honing puts little scratches in the block in a cross hatch pattern
about 30* ( double check that)

I've forgotten what it does exactly but basically it will bed the rings in
A perfectly smooth bore and perfectly smooth rings will create a perfect seal only if both are perfectly round

But neither is perfectly round so it must be bedded in

The glazing is when the rings get a coat of crap that makes the bad sealing situation worse
The same thing can happen to the valves

 

[devino246]

I bought a new block and used the same rings but was only spinning 6000rpms expecting 7500+rpms with my setup. I spoke with Tom at ARC Racing and he said you must use new rings in a new cylinder try that first when I installed the rings it ran strong at 7500rpms for about a week. then after a few days I went outside and it didn't start with 1 pull like normal. when it did white smoke out the header, died when closing the choke only running at wot. I didnt hone the block was less than a month old and cylinder was smooth and not alot of oil. barely enough of to notice with one pull while head was off and piston cycled several strokes. But it adds up to alot of oil on the plug when running.

First, you ran old rings in a new cylinder and glazed the new cylinder. Then you replaced the rings, ran them in a glazed cylinder, and likely glazed the rings. You need to hone the cylinder, replace the rings, and then break the new rings. Don't got flooring the engine as soon as you start it. Keep the rpm reasonably low and don't maintain any one engine rpm for any amount of time. Run it off the kart for a good half hour or more, then put it on the kart and drive lightly, varrying the rpm.