TOPIC:

I am rebuilding my KZ 550 and just about ready to reassemble. I checked all the measurements when I dissembled and am satisfied that everything was within spec. I was planning to bead blast the pistons but was advised by a mechanic friend not to as that could lead to hot spots on the piston. (I was advised by another mechanic friend to bead blast the pistons ) So to be safe I have slowly and painfully scraped the carbon off the top of the pistons. Today I was finishing the last one and discovered that the last really stubborn bit of carbon was covering a spot on the piston that almost looks like a chunk was taken out of the piston. I would guess that the piston is toast. That’s really a bummer as I was hoping to get the pistons in today.

Two questions .1. Should I replace all my pistons? 2. New or used?
I would guess new but am afraid of the cost. But I’m afraid of used too..

Help?

To clean pistons I first spray them with Brake Clean to remove all the oil, then clamp them in my rubber jaw vise ($15 at Harbor Freight), then use a nylon abrasive wheel ($7 at Tractor supply)on a 1/4" drill. It takes about 5 minutes per piston and removes all the carbon.

Generally, if a used piston has no scrapes, scoring, gouges, etc, and no visible cracks, then it's ok to use.

You can certainly replace all the pistons if you like, but I would just replace the bad piston.

Post edited by: steell, at: 2006/04/23 12:23

can you post a picture of it? if it's not bad you can probably get away with running it.

You can also polish them...
I used a wire wheel(fine,and very lightly) on these ones,and then My polishing wheel.These are the factory(original)pistons that I took out when I put in My Wiseco's.They had roughly 28k miles on them.
(they're for sale too)

I had to resize the pic,so there's only 2 pistons in view...

Post edited by: Sandy, at: 2006/04/23 13:26

you can glassbead the tops of pistons,just tape the the skirts and ringlands up real good and clean the pistons really good before you reinstall them. goodluck,happy wrenching!

I did glass bead 2 pistons today. I taped them up on the sides. I figured WTF it's not a race bike and worse comes to worse I do know where there's an 83 motor for a not bad price:ohmy:

I think I may have been just a little overwheimed earlier. I know the theory behind rebuilding a motor I've just not got the experiance. And I'm getting too much conflicting advice from too many people.


Thanks for the replys I'll let you know how it all turns out.

Post edited by: jimyed, at: 2006/04/24 08:28

Thats the problem there are as many ways of doing things as there are people, a lot of them arn't wrong, but some are more right than others.

Personally I wouldn't glass bead anything that is engine related, it's just to easy to not get all the glass beads cleaned off, which usually means game over for your engine.

Make sure you clean the hell out of your pistons after blasting them, use compressed air, and blow untill your compressor is worn out. Especially all the little holes in the oil ring groove.

thats why you mask off the rest off the piston really good.

KL250 wrote:

Thats the problem there are as many ways of doing things as there are people, a lot of them arn't wrong, but some are more right than others.

Personally I wouldn't glass bead anything that is engine related, it's just to easy to not get all the glass beads cleaned off, which usually means game over for your engine.

Make sure you clean the hell out of your pistons after blasting them, use compressed air, and blow untill your compressor is worn out. Especially all the little holes in the oil ring groove.

hahaha then you will end up glass beading the pistons in your compressor when you rebuild it:P