Converting kx 85 to 100: what do I need?

[crusty1]

Looking to convert a kx 85 into a 100. I know I need new cylinder, piston, etc. But can I use my Kx 85 head? The manual doesn't say anything about them being different. Guy at the parts place says they have diff. part #s. But I've been told they are the same? Is the squish ban different? What else do I need?

 

[Cr85RaCeR607]

yes, u still use your 85 head. Just send it off to Eric Gorr, he has a 105cc kit for your 85.

 

[gwcrim]

I just did this last fall. Had to get a new jug, piston, head, and requisite gaskets. You can either buy a 100cc power valve or grind/clearance the 85cc one. I chose the grind/clearance method. The combustion chamber is smaller on the 85 head, so it will need replaced or machined.

I wish I'd have sent the parts off to Gorr, but I didn't. He could have set the porting and compression up for even more low end power.

Lemme tell ya, that thing is a SCREAMER now! Scary even for me, and I normally ride a KX500.

 

[crusty1]

Thanks. I have a thrashed cylinder I'd like to do this with for my 14 year old. Next year the bike gets handed down to the 11 year old and I'll probably put the old 85 set up back on until he's ready :aj: :cool: I keep trying to get ahold of Eric but to no avail. Will keep trying or just buy the big bore set up with new everything. Thanks. Dennis

 

[bikepilot]

I think you will find that the 100 is actually easier to controll than the 85, especially if you have it ported for more low end/less top end hit. Even stock for stock the 100 seems to have only slightly more top end, but quite a bit more bottom end power, making the transisition smoother.

good luck:)

ps, if you don't know about the powervalve troubles, look into it (balls fall out of the governor, linkage breaks allowing the pv to hit the piston etc)

 

[Jasle]

call EG early in the morning. about 9am his time. he's busy but sets time aside for the phone in the monring.

 

[gwcrim]

My son is 8 and this is his beast I'm talking about. An 11 yr old with any riding experience would do fine on the 85/100.