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Posted: 08:33 pm Dec 25 2011
by SS109
94_jimmy wrote:the guy i bought it from is the second owner and had only put rings in it a few years ago and no other motor work done. he has owned it since 2001. it has good compression and power so i will probably wait on the wiseco until later.
Sounds like a plan to me!
Deseret Rider wrote:----but I am curious about what the compression reading of a good tight KDX 220 and 200 should be??
E series KDX200 is listed as 119 to 185 psi as usable range. Sorry, I don't know about the 220's.
Deseret Rider wrote:MadMax wrote:I'm under the impression that the stock compression ratio of a 220 is less that of a comparable 200. Send the head to RB. Pronto. Send the carb too.
I'm not following you? What's wrong with my heads and carbs? Why send them---and what will he do with them?
Ron Black mills the head to improve quench (google it!) and to raise the compression. The carbs mods increase power and throttle response. You don't "need" either unless you want the additional power increase.
Posted: 10:34 pm Dec 25 2011
by turtle
There's a whole section on the site here dedicated to the RB mods. You can do a quick search to see what they consist of. You don't need to send anything to RB to have a good running KDX. When you are ready for more power Ron is the man.
My manual says the "usable range" compression is between 95 & 151 psi. I think you are good to go. I'm only guessing but I bet the 220's compression pressure is lower than a 200.
You are smart to change those pistons out. Mine was cracked just like yours. It was only a matter of time to failure. Also, it was clear that mine had eaten a skirt or something prior to that piston! So they do fail.
Edit: SS109 beat me to the punch! And confirmed that the 220 has a little lower compression pressure.
Posted: 07:24 am Mar 23 2014
by C George
MadMax wrote:I'm under the impression that the stock compression ratio of a 220 is less that of a comparable 200. Send the head to RB. Pronto. Send the carb too.
Yes and No , as a tight stock 200 and 220 should both blow 150 PSI when warm. It just seems that the 220 benefits more from
upping the compression.
Compression ratio is hard to measure on a two stroke ,,, pumping pressure is a more accurate way.
195 psi ??? ,,,, Your gauge is way off.
Sorry to wake up such an old thread.