JoeCharge

Member
Mar 13, 2000
86
0
My son is outgrowing his KX60 and I'm looking to move him to an 85. He is a trail rider, not a MX racer but he likes the snap of the 2-stroke. He doesn't want an XR or 4-stroke anything. I was leaning towards the RM85 and KX85 since it is my understanding that they both have power valves. Is that true?

Obviously budget is an issue. I am looking at 2002 and newer models of these bikes but there is no way I'm buying a new one. Anybody have input on one over the other, given the type of riding that my son does. It seems that the mini races are a sea of green.
 

IndyMX

Crash Test Dummy
~SPONSOR~
Jul 18, 2006
5,548
2
Amo, IN
My nephew rides a KX85.. It's got a powervalve. It's not as fast as the YZ85, but it's a pretty capable little bike.
 

Patman

Pantless Wonder
LIFETIME SPONSOR
Dec 26, 1999
19,774
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None of the 85's are great for that type of use out of the box. BUT any of them can be made pretty good or even really good for trail riding given the proper modifications.
We took what was known as one of the most unruly 85's and made it in to a great bike for trail that is easily switched over to a VERY capible track bike. The 2003 CR85R we started with had a crazy hit and I held little hope of it being even reasonable in the trees but my son was insistant he wanted red. So I found a solid used example and we hatched a plan to make it what we wanted. Well some carefully planned modifications from some primo companies and I was amazed. We talked with Eric Gorr and decided on a big bore engine with porting and head modifications combined with a FMF Fatty and Turbine Core 2 (USFS spark arrestor) exhaust and Steahly flywheel weight did wonders!!! Eric sent me a extra capacity Fluidyne radiator to help make sure things stayed cool in the tight stuff which is often overlooked and a big issue with the little screamers. We then had the suspension tuned for him and put it all back together with fresh paint, bearings, seals, plastic, etc... It really is a very good trail bike now that has plenty of power everywhere and is not prone to stalling. Spend 10-15 minutes to pull the flywheel weight and the bike transforms in to a super mini that can run with any of them.

The real bummer is that after 1 season my son had a growth spurt and is now too big for the bike so it needs to go and I have to do it all over again :bang:
 

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Patman

Pantless Wonder
LIFETIME SPONSOR
Dec 26, 1999
19,774
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Shoot me your email or phone number and we'll see what we might be able to work out. Shipping is not too bad and my wife's family lives in Pa. (she's actually there right now). Send it to Pat"at"PitViperMX"dot"com and I'll get in touch.
 

Billinin

Member
Feb 21, 2007
34
0
I have both a 2005 RM85(now a 105) and a 2006 KX85, and I would say without a doubt (when both bikes are bone stock) the KX has more kick than the RM did before it was turned into a 105. The RM has given me some issues with clutches for some reason though..........but both are great little bikes IMO
 

JoeCharge

Member
Mar 13, 2000
86
0
Thanks for all of the info, I appreciate it. One more questions: I have found lowering links for the KX85 but haven't found any for the RM85. Do lowering links exist for the RM85?
 

Jasle

Sponsoring Member
Nov 27, 2001
1,358
0
well the rm is about .5" taller than the kx. the KX seems to have more topend than the RM. KX's at the track seem to eat cranks. Same as the 65's. RM's before 06 were cracking frames up front right near the pipe mount. Probably not an issue for a trail rider but something to look for on a used bike. We cracked 2 ouf our 3 RM's. I had them rewelded from a guy that is a quality welder. Never cracked again...Still running them too. We race...a lot though. Mx and the kid is a jumper.
Its hard to find a flywheel weight for the RM though. R&D has a killer upgrade for the powervalve for the RM. Huge increase in bottom end power output. Kinda spendy though. Really changes power curve. almost 2hp in the lower end. Nothing for topend. just keeps powervalve closed longer. Not exactly a 4 stroke but way better than stock. save the money on the pipe and reeds and you break even with more difference.
 


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