yz450 cylinder hone

i recently rebuilt the top end of my bike (2009 yz450) and didnt read before doing it that they should be installed dry and then cycled without oil to help the rings seat. well needless to say its slightly burning oil. when you blip the throttle a small puff of blue smoke. so i ordered another set of gaskets and rings and im going to hone the cylinder this time to deglaze it.

what hone should i get? there are two different ones for nikasil cylinders both are aluminum oxide...one is 320 grit and one is 240 grit. Both say they are to be used on nikasil cylinders

I doubt the oil on the rings had anything to do with how well they would seat... Seating the rings happens in the first 20 minutes from what I've read, and to seat them properly you need to ride the bike under load hard for that amount of time.

Other than that, sounds like your on the right track and it's possible that the cylinder needs to be honed again as it is slightly out of round...

I'm not sure on the grit for that type of hone, but I know for a straight cylinder like those in a 4 stroke with no ports (2 stroke) a ball hone will work just fine. I think it was a 95mm ball hone to be exact...

You don't want to remove any material so if the hone your looking at has any kind of abrasive pads or the like in it, it's a no no as it will remove the nikasil. You just want to re-shape the cylinder which a ball hone will do.

Just measure the width of the top of the bore on the jug and then go about a 1/4 bigger.

If I'm not mistaken the bore is like 98mm and you would want a 102mm ball hone.

according to others doing the assembly wet and not dry will cause problems i assembled everything with oil coating the cylinder. The cylinder is a 95mm bore and another reason im thinking the rings didnt seal was i did not hone the cylinder in the first place.

rings. just the rings.

think about how they work. modern motorcycle motors have very little ring tension. you have a very limited amount of time for the rings to acheive the proper seal.

will the sky fall and your motor not run if you oil the rings? no. if you get really out of hand with the oil they will never seal and it will use oil from the get go.

when oil is on the face of the rings your are creating a path for more oil to get past the rings.the oil control ring is constantly fighting to keep the oil out.if it has oil on it how can it do its job when the motor fires during the most critical part of its life?

you never ever ever ever want oil on the rings or above them.

Hmmmmm. :excuseme: I've always oiled my cylinders & rings on assembly, and have never noticed any ill effects. I've done this on cast iron car blocks/cylinders, steel sleeved bike cylinders (2-stroke & 4-strokes), and nikasil plated cylinders. :busted:

I'd be willing to bet if a recently rebuilt engine puffs a small amount of oil that it's not due to oil on the piston/cylinder during assembly, and more likely would be some other cause......

Jimmie

If you need to remove material from your cylinder, then have it honed properly on a rigid diamond hone. Otherwise you will wreak havoc with the ports. If all you want to do is bust the glaze, use scotchbrite & WD40. Been there and done it.....:excuseme:

Hmmmmm. :excuseme: I've always oiled my cylinders & rings on assembly, and have never noticed any ill effects. I've done this on cast iron car blocks/cylinders, steel sleeved bike cylinders (2-stroke & 4-strokes), and nikasil plated cylinders. :busted:

+1 :busted:

yup just wanna bust the glaze off the clyinder so im probably going to use scotchbrite and the cylinder has no ports on it...its a 4 stroke. And even after talking to JE they suggest only putting oil on the piston skirt and NOT on the rings

Either of those hones will work fine. But as you stated I would try the scotch brite since its significantly cheaper. I am going to try this myself in the future. I'm almost certain the glaze is why the rings haven't seated and not from oil but just oil the skirt as you already stated.

If you need to remove material from your cylinder, then have it honed properly on a rigid diamond hone. Otherwise you will wreak havoc with the ports. If all you want to do is bust the glaze, use scotchbrite & WD40. Been there and done it.....:excuseme:

I don't think the YZ450 has ports, and it's a nikasil coated cylinder

I don't think the YZ450 has ports, and it's a nikasil coated cylinder

OK, need a new vision enhancement device (glasses) that 4 looked like a 2. I know i'm irish, but believe it or not, I knew it was nikasil barrel. :busted: To remove material, ie re-size the bore by honing, I still wouldn't use anything other than a rigid hone. :excuseme: PS merry xmas.

OK, need a new vision enhancement device (glasses) that 4 looked like a 2. I know i'm irish, but believe it or not, I knew it was nikasil barrel. :busted: To remove material, ie re-size the bore by honing, I still wouldn't use anything other than a rigid hone. :excuseme: PS merry xmas.

we all make mistakes lol but im not looking to re-size the bore only looking to deglaze it to help the rings seat:thumbsup:

we all make mistakes lol but im not looking to re-size the bore only looking to deglaze it to help the rings seat:thumbsup:

Cheers, Use a scotchbrite and WD. It'll do every bit as good. I'm sure there are other methods, but it has always worked for me since '99 when the FR125 started out.

Compression Check? Ring gaps aligned correctly?

bike has auto decompression so compression check wont work and i have a leak down tester just gotta find an adapter somewhere....and yeah the rings were aligned to how JE says to align them (came with a diagram)

I always use a fine ball hone when I do a top end. Even on a two stroke and have no problems with ports at all. You want to do a quick up and down motion for a few seconds only. The results will be a nice fresh cross-hatch for your new rings to seat in. And yes, leave the cylinder and rings dry. Lightly coat the piston skirt.

I always, always and always use oil on the barrel, pistons and rings of all bike engines I work on.

On 2 strokes I wipe 2 stroke oil on the sleeve and pistons as it burns off quickly and a little richer for a 2T is a good thing.

Smoke could be the valve stem seals leaking oil past them.

I have written volumes on this, and it's an area of great disagreement, even among the best professionals, but I will tell you this much: I always use a ball hone on the cylinder, and I always oil the rings, and not one of my engines that I can remember has ever failed to seat and seal the rings. Not one, not ever.

Regarding honing, use a 320 if you can get it, or a 240, and use the info in this thread as a guide:

http://www.thumpertalk.com/forum/showthread.php?p=4380759#post4380759

As far as oiling goes, I'm not talking about dunking the piston in a bucket of oil, just a smear of oil on each one, and another on the cylinder wall. In my opinion, there is a greater potential to ring failure from damage done on a dry startup than from over oiling.

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