KDX oversize piston kits

[Bikeaholic]

I have an 84 KDX200 that I purchased a while back. On removing the barrel I found it has a 0.5 oversize piston fitted. It needs a rebore and the bike shop hasn't been able to track down a piston kit for it. Does anyone know a supplier that does a 0.75 oversize piston kit for this model. Wiseco don't list one.

[topari]

Interesting problem. AFAIK there was only one size piston.  The bores were plated and could not be overbored. Maybe yours has been sleeved and fitted with a piston off another bike.
Best option maybe to replate and find a standard piston.

[Stevo17]

Would an 86 model piston work? There are plenty of kits available for them...

[topari]

Would an 86 model piston work? There are plenty of kits available for them...

Negative.

[Stevo17]

The later model KX500 pistons with power valves work in the air cooled 500's if you take the bottom ring off.... same bore and stroke. Did they change the KDX from a centre port to a side port or something from 85 to 86?

[topari]

The later model KX500 pistons with power valves work in the air cooled 500's if you take the bottom ring off.... same bore and stroke. Did they change the KDX from a centre port to a side port or something from 85 to 86?

I maybe mistaken. I now recall the 86 pistons were used. I actually have both in my workshop. I will check.

[Bikeaholic]

I maybe mistaken. I now recall the 86 pistons were used. I actually have both in my workshop. I will check.
[/quote]

topari
Did you have any luck checking the 2 pistons.
My cylinder has been resleeved and has a 0.5 ProX piston installed.
Would be nice if the 86 piston and onwards fitted

[GMC]

There are a few changes but I reckon it's a fair chance the pistons are similar.
As per part numbers...
The rings are the same 83 to 86

Pistons are the same 83 to 85
Pistons are the same 86
Pistons are the same 87 to 88

Piston pins are the same 1980 175 to 1985 200
Piston pins are the same 86 to 2000

I have a piston from my 86 model
It measures 67 dia.
Pin is 18 dia.
Approx 28.5 from the top of the pin to the edge of the crown
Dome is approx 4mm