Which Top End Kit?

I'm going to replace the top end on my 450 , but I don't know which company to go with. Yamaha, Wiseco, and Vertex all make complete rebuild kits for about the same price. I want the one that will be best for the performance and longevity of my bike. Any suggestions or experience with these products?

I've used Wisecos for about 12 years and have had nothing but good luck with them.

It's hard to beat OEM quality. But I've used many Wisecos over the years....and I am using one now. Never used a Vertex, but I think your decision will probably come down to price, cause quality is probably all there.

have you tried JE?? They would be my preference for a piston.

I am sure you wont have a problem w/any of the all of them are quality parts and have been in the business awhile :thumbsup:

When i did the top end on my 426 i put the wiseco 13.5:1 kit in mine...havent had a problem with it and havent looked back!

Bought my kit from Motosport Outlet, good price, Wiseco piston, cometic gaskets, have had no problems. My bike had approx. 350 hrs on it and it really didn't need to be done, everything looked good, just didn't want the piston to fail unexpectedly. Mike

To you gents who have done this before. How/When do you know it's time for a top end if the bike is running OK. On 2 smokes I would do a compression check. But if I understand correctly this on a four stroke may just show some valve leakage. I have a 99 YZ 400 and I do not think it has ever been touched. I'm not trying to steal your post but this seemed an appropriate question.


But if I understand correctly this on a four stroke may just show some valve leakage

do a leakdown test. Anything under about 15% is pretty good. You can hear where the air is coming from. Remove the air filter. You'll hear it in the carby (inlet valves) the exhaust (exhaust valves) or crankcase breather (rings)

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