Hi,
I have a Kawasaki Bayou 185 (1985), and today I took the head off to examine the broken off exhaust valve. Well, the cylinder is fine, but I am just going to get a used head instead of putting a new valve in. But, it did some damage to the piston. Will it cause problems with it like this? (sorry, I can't figure out how to post pictures, so you will have to follow the links. The sever I use is slow lately, too) The 2 large gouged out areas are normal; they are so the piston doesn't hit the valves. The piston was loaded with carbon, but I cleaned it.

Pic of piston 1

Pic of piston 2

 

Some people will tell you it will cause a problem, but I can bet that motor will run fine for thousands of miles. The only potential problems would be a hot spot for potential detonation but I think the compression is low enough on that motor not to be a problem. depending on how hard the valve hit the piston you may have caused a rod bearing problem but I doubt it.

I would pop the head on with a new gasket and give it a try

 

I wouldnt go through the trouble of putting the gasket and head on and giong through the whole process again, I would replace the piston. Good luck.

 

I would get a new piston also,and get it honed to de-glaze the bore.

 

For no more than a piston and rings cost, I'd replace it.

 

Well, I don't have a whole lot of money and am trying to keep this cheap. How much would it be to hone the bore, and get a new piston and rings?

 

I would imagine it would be less that $150 for a wiseco kit, I could not find it on the net.

Here are the prices for what you need from www.bikebandit.com for STOCK parts: Standard bore Piston-$54.22, Standard bore rings-$37.42, piston pin-3.47, Circlips (2 required)-$2.40, cylinder base gasket-$8.86, head gasket-$24.94. That is $133.71 not counting shipping. That price should be about the same as your local dealer. www.ronayers.com may have the parts cheaper. If you look around you may be able to get the parts cheaper.

One other alternative that you may try is to get the piston out of the bike that you get the head off of. You will have to buy everything else that I listed above except for the pin, use the same pin from the pison you get. If you remove the circlip, it should be replaced.

You can get a cylinder hone from a local parts store for little money, maybe even rent it for a day. If you don't know how to hone a cylinder, you could probably get an automotive machine shop to do it for $20 or so. If you talk nice to them and tell them you are strapped for cash, you may get it done for $10. You should have them to measure the bore size to see if you need an oversize.

If you want, you could try to use that piston you have. If the valve fractured the piston, it may come apart in the cylinder and wreak havoc and then it will be a whole top end, cylinder, head, piston and all. Been there, done that.

 

The dented areas are not terrible. The indents that are for the valve not to hit the piston are deeper. The broke off edge of the valve is really sharp, and I don't think the piston is cracked. If the camera would have focused in closed, I could have gotten a better picture. How about getting a used piston off Ebay and getting new rings?

 

That would work if the bore is ok.

 

Yes, the bore is fine. No scoring or anything. I don't know. Maybe I will load it up on a trailer and bring it to a couple dealerships and see what they say.