JetMD

iTrader: (1)

Check with Joaquin at: http://www.desotoracing.com/

lil-bump

iTrader: (89)

thanks... He just replied to my email

choisan

iTrader: (6)

can someone kind enough help/tell me that what piston sleeve set(part#) are interchangeable with JP FX R03, many thanks!!!

GMartinez

iTrader: (91)

I would imagine the Kangaroo or the Maxpower xl7 but I would contact www.desotoracing.com to be sure

Brent Davis

The Kangaroo and JP R03 use the same piston/sleeve/rod/crankshaft. I have three R03's and 6 Kangaroos to know this

choisan

iTrader: (6)

so, can i conclude that it is 08513? please help.
Someone told me that the R03 use the piston set of 321. i am little bit confused.

Roelof

Any P/S set from a Novarossi engine with a 14mm crankshaft will fit, at this moment it is the Kangaroo but from older models like the 321, 421, 221 etc will fit, even the set from a N21-5T will work.

You are confused because there are so many choices and most options are based on ports, materials and exhaust port height. Then again, any top level P/S set made for a 14mm crankshaft engine will fit.

But the engine you have must be worn out, a P/S set with rod and bearings brings you on the way for a brandnew engine...

choisan

iTrader: (6)

Actually it was my fault that I did not tun in it properly. It its a brand new machine. The side of the poison was scratched due to the un aware dropped plug wire, the underhead got messed up a bit. So I may look for a brand new set of poison and sleeve.
Thanks for you guys help.

I recall when this engine was out in the market many years ago, there were issues that people easily got the poison scratched even run in by very experienced racers. Some people complained and sent back. I am not looking for any claim. But I might be one of them ending up. Have any of you heard that quality issue before.

Roelof

If you want to you can even use a P/S set from a current 9-porter engine but then you have to get a buttonhead with it (complete packages are sold).

choisan

iTrader: (6)

thanks again for your answer, but does it mean i can plug in any 9porter with its the button head(it is a must as a whole set), i do not have to look for the 7 port piston set, right? any difference in performance of using 9 port but on a 14mm crankshaft?

Roelof

No real large perfomance differences, only large price differences. You are safe with a Kangaroo set.

One hint, always cheack the real head clearance. Just mount the buttonhead with some spacers on the screws (no head) and use a piece of solder in a L-shape through the plug hole and rotate the crankshaft so the solder will be squeezed between head and piston. The flat spot on the solder presents the real head clearance and must be 0.6~0.7mm

choisan

iTrader: (6)

Appreciate your help and info. Thanks again.
Can I say the difference in speed is from the design and timing of crankshaft?

Roelof

Intakes are mostly the same, no issue there.

Take a caliper, set the piston to half height (when removed the head and buttonhead. Set the back end of the caliper on the edge of the sleeve and push down the pin and push the piston to the point you see a glitch of the upper edge of the exhaust port.
Keep the distance in mind or with a digital calper set it to zerro. Then push it way down to BDC en read the caliper, that is the height of the port. With your R03 it will be 7~7.2mm.

Do the same with the new set, I am almost sure it will not differ much, with a higher port you will get a tiny bit more RPM but also loose a tiny bit bottom power and with a lower port otherwise.

michael 1

iTrader: (2)

the ht of the piston as measured from the pin can be different , this will of course change the timing.

choisan

iTrader: (6)

Thanks so much for the explanation. Appreciate that.