Maintenance & Technical > KX500 Original
This is why you don't run a CAST piston
Polar-Bus:
--- Quote from: kaw rider on June 10, 2007, 09:31:52 AM ---This is what happen last night.
--- End quote ---
Not to rub salt on your ugly engine failure, but things happen for a reason. I personally can't blame soley the fact that you were running a cast piston caused a failure vs. a forged piston. Cast pistons are incredible strong PROVIDED the tighter tolerences are maintained. Cast pistons expand less than forged so the tolerences can be as little as .002". Forged psitons expand differently and typically need to set up around .005" (hence the common forged piston "knock" when cold. How are the crank bearings?
stewart:
old wise japanese man say....... cast wont last
Albertan:
Other than a bit of extra clearance when the engine is cold, has anyone had any problems with Wiseco forged pistons? I'm puting a Wiseco into my wife's KDX220, because they have a documented problem with stock pistons which seems to be cured by forged pistons.
kaw rider:
my problem was operator error.
quincyman:
--- Quote from: Albertan on June 16, 2007, 05:23:05 AM ---Other than a bit of extra clearance when the engine is cold, has anyone had any problems with Wiseco forged pistons? I'm puting a Wiseco into my wife's KDX220, because they have a documented problem with stock pistons which seems to be cured by forged pistons.
--- End quote ---
I have talked to Dealers and engine re-builders who swear by the stock Kawi pistons. Both for the KDX220 and the KX500. They claim you can ride the same piston for years with no problem, which they say you cannot do with a Wiseco.
The dealer claims the reason the stock 220 pistons break is the motor is not designed to handle the increase rap speeds by adding after market pipes, taking the airbox lid off and replacing the reeds with power reeds. Once these changes have been made the guarantee has been voided and Kawi will not cover it. If left stock he says the bike revs slower and the piston slap does not become an issue. Thus the bikes can run for many years if left in stock configuration. He may have a point but who leaves a bike in stock config? I didn't so I changed out my piston immediately on my 220. Other KDX owners suggest if you ride much at all you need to change the Wiseco out yearly.
When my KX500 cylinder was redone this time around they recommended the stock piston for the tighter tolerances. He made the same basic claims as the dealer. It will last longer. So I went ahead and went that route. And no, he does not sell Kawasaki's but he has been doing these cylinder valves on re-plated KX500's for 30 years.
I will be monitoring this closely. Is there any advice on increasing the longevity of a stock piston and far as breaking them in and engine care procedures?
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