I recently bought a 1974 Honda XL250 K1. I had the bike running and could gas it to high rpm. The problem was it burned oil and had a knocking which I assumed was piston slap. I tore down the top end to discover bad scoring inside the cylinder.

What I want to know is if I can use a hone to widen the cylinder to the next piston size (+.25mm). Can an 80 grit hone remove enough steel or is this a job that can only be done with a milling machine?

Thanks

It is best to bore it first then hone . This will get the bore prefectly round again .Then follow thru with a good rigid hone like a sunnen AN syle hone (not the spring loaded kind) .

Pete Payne said:

This is dead on.
But, if you like, try an Sunnen AN hone with lube as long as you like. Mostly, hones will not remove too much metal if you keep it nice and lubed. See if you can remove the scoring and try new rings... should work better if you can get the scoring out. Then there will not be cavities for oil to hide, from the rings, in.
But Pete Payne has the correct method ... My suggestion will only work if the scoring is light to moderate. -BIG DAN:thumbsup:

going to big on a sunnen, thanks

Honestly, take it in and have it bored.
It does not cost much and you'll be very happy with the finished job.
Also, check your crank for side play.
If you grab the end of it and wiggle it back and forth it should have no more than about 1/32" of play.

motoxmann said:

+1. Cylinders don't wear evenly - the greatest amount of wear will be near the top on the thust (front) side and the hone will want to follow this. Getting the bore parallel and perpendicular to the base gasket face would be a royal PITA.

The only problem I can forsee is that if the bore is really shagged then +0.25mm may not be enough. An experienced engineer at a good machine shop will be able to measure the wear, eyeball the scoring and make an assessment - as the best way to refinish a cylinder is to get the piston first and then bore + hone the cylinder to suit be prepared to get a +0.5mm piston rather than a +.25mm one that you end up not being able to use.