Top end rebuild what do I need?

[1980mcneil]

I don't know what all the top-end entails. I want to buy a new piston and rings as my compression is down a little bit. I've heard a lot of people talk about wossner as the best. Honestly I just like whatever is easiest. I don't have any major mods on my bike and it would be nice if I could just buy a piston set with gaskets. Is that recommended at all? Looks like I can buy a wossner on eBay if those are legitimate? I did a search for wossner kx500 86mm piston and some listings came up for a hundred eighty-five bucks. Then I'd have to buy a gasket set? Not sure what gasket I would need.
It's one of those weisco or Pro-X Pistons any good for a pretty cheap amount and no mods on my motor?

[MMVTwin]

If you haven't got a manual get one of them first

[sandblaster]

Yes... a manual is a must.
Besides the piston and gasket set you will need a wrist pin bearing as most kit's do not come with them.
Before you turn one nut, WASH your engine thoroughly...
Otherwise you will drop who knows what into your crank...
As you are disassembling, take a lot of pics for reference to make reassembly easier.
Once you get the cylinder off... take a good hard look at the area around the exhaust port.
Sometimes it can be hard to spot for a untrained eye.
A dirty cylinder will look something like this



When cleaned can look like this...



The plating is worn off and the rings are wearing into the aluminum.
This cylinder needs a re-plate...

While you have the cylinder off, measure your rod to crank half clearance with a feeler gauge like this..



If you have never measured one, follow these directions..

http://www.oem-cycle.com/forum/viewtopic.php?f=114&t=1284

That will tell you if it's also time for a crank rebuild.

Any questions?
Ask Motorrad 

[1980mcneil]

Thanks a lot for the information guys as always. I'll definitely look into making sure my cylinder coating has a chipped.

My bike is essentially stock. I know everybody on here says go Wossner. But a lot of people are modding and other such things. My bike is a straight trail bike I've never even had the thing wide open and 5th her even close to it. The Wiscos are 120 bucks and come with everything I need. It'd be really nice to just go ahead and pick that up and have confidence that it'll probably work out fine. I know it's sometimes tough for people who want the best for their bike to recommend something less. But do you think for my usage I would be fine with one of those kids? Or the Pro-X kit? I added up the price off Partzilla 4 stock pistons and parts and that was almost as much as a wossner so I might as well get that at that point. What say you?

[big green]

I have used pro x and also oem cast and never had any problems. Currently I am using a wiseco. I think wossner is probably the most durable as they have a little thicker skirt but at the time of my rebuild wossner was having supply issues and my builder also has complete confidence in wiseco so that is the route I went. I think for your application they would all serve you well just make sure all critical measurements are in spec ( ring end gap, bore clearance, etc.) and you should be good to go.

[1980mcneil]

Thank you. That does give me a little more confidence. I'll give the parts a good once over before I install them

[Danger4u2]

The complete beginner's guide to KX500 top-end rebuilds.

KX500 top-end rebuild, version 1.6
http://www.hallbergs.net/kx500/