Sticky rings

Steve,

are you saying the rings stick in the grooves after running the engine or straight out of the box? If it's the latter you should have sent them back to where you got them, if it's the former then I think there's something wrong with your bore finish possibly, engine oil used or lubrication system,

Simon.

Rather than grinding the rings, I would put the pistons in the lathe and very carefully open out the ring recesses a thou or so. I have had Hepolite pistons where the ring lands (the bits between the recess) have tended to flow plastically and make the rings stick. I have also had the lands break off after only a few hundred miles of running in. When I sent them back, Hepolite merely accused me of thrashing the bike and wouldn't entertain replacing the pistons. Not the best customer service.I have never had problems with after-market pistons but over the years have had plenty of Hepolite problems. Heretical I know, but that's just my experience. I am sure Anna will leap to Hepolite's defence, but I wouldn't go back to them.

Gordon.

Strange regarding the Hepolite problems. The Commando's running AE (Federal Mogul) pistons and have had no problems. Same when I have used AE Hepolite too and the bike gets taken up to 6,000rpm regularly. Lapping the rings is quite normal to achieve a flat surface, especially after filing, so is possibly the best bet. Also to check for bore ovality a bore gauge is best. No more than 0.0002" (2/10ths of a thou) ovality after boring and honing,

Simon.

I really think you would be better off paying someone with a lathe to widen the piston ring grooves in the pistons. That way, if you ever need to replace the rings you will be able to do so without all the bother of reducing their thickness before fitting them.

Colin.

Previously steve_marshall wrote:

Simon - I do have an internal mic but I don't trust myself to get it square enough to measure to that kind of tolerance.

When I look at these pistons and bores I really think a few hundred miles, tops.

Rings are 0.0625" which looks 'right' must be the pistons which are out of spec. - I will have to lap down to 0.061"

Cheeers

Steve

Steve, as you already know,its one way or t other, either way will get the job done,but for me after you have lapped the six rings,the pistons will still be out of spec.as will the rings to a certain extent after lapping,.during which,you will probably have to try fit once or twice,and could finish up breaking one --or even two God forbid.

I kind of look down the road to the next guy doing this job,( dont weall?) he too will have the same problem as you have now if you lap the rings.So for me, its the pistons that are not right,I think I would get those sorted if it were me.

As an aside,I noted in your initial post, your comment that you bought a new set of Hepolite +40 piston rings.I must say I would dearly like to know where from,as I am in dire need of a set myself at +40 to fit my AE pistons,so any chance?. This message goes to anyone else in the club who could maybe help me.

Cheers, Mel.

Steve

The barbarous practice of fitting filed down o/s rings will cause you far more grief than an oversize ring gap. If you havn't assembled it yet give this some serious thought.

Bill

Previously bill_moline wrote:

Steve

The barbarous practice of fitting filed down o/s rings will cause you far more grief than an oversize ring gap. If you havn't assembled it yet give this some serious thought.

Bill

Bill, could you explain in more detail please? I've known many reputable engine builders & engineers to use this method to acheive correct ring gaps &, indeed, have done so myself with no issues whatsoever, although I use a carborundum stone, not a file. I wouldn't perhaps recomend filing a +60 ring to fit a STD bore but if you're using the next o/s up, what 'grief' does it cause?

Regards, Tim