Best 85cc motor for shifter bike??????

[brysn424]

Ok guys. I need y'all's help. What would be my best choice for putting a shifter motor on a cobra roller. Everything is plus 2 jb. Thinking ktm?? Anybody have any opinions?

[nyates450]

The ktm 85 has a crank bearing issue. I'm sure mr dunesberry will chime in.

[djdfairchild]

most are probably going to say cr because of parts price and availability. and its a good motor. i think if you need more torque the rm with the power valve would be a good choice also. but like everyone says look at whats winning and i think you'll see the cr is consitantly on top.

[desratt]

Where do u get em

[bigdaddy77]

We run a CR motor. Why because thats the motor that came with it! We have had good luck with it and no real complaints. I think whats more important than which brand is that you stroke them and get the port timing set right on them. Also dont try to modify the exhaust , this just kills the hp if you start cutting the pipe.
As far as the KTM the performance isnt worth the extra dollars they cost to buy and up keep.
I have given thought about our next build being Suzuki powered. If any of you guys are running the RM motor i would love to hear what you have to say about them.

[brysn424]

I would definately like to take the money out of the question. I need to know hands down the fastest motor thatll last 2 motos haha I don't care if it has to be rebuilt every week. I want the best. I am completely new to mini shifters coming off of the ss 70. Thanks for the responses. Keep em coming

[djdfairchild]

with money no option your probably talking about a hybrid motor. but your in the $5000 range for it. and you may not get to many people chiming in that are running them.

[edwardsp&b]

I'm a rm 85 fan. I think they make more power down low. Be careful about saying money is no object.....your wallet will get hurt quick! Coming off a ss, I would go with stock dirtbike motor. In the bike world the cr is the bottom of the totem pole. I asked this question a year ago and everybody said they were running a cr because everybody else was. Most quad guys don't know this but the 2013 ktm sxs has 6 more horses than every other stock 85 motor. Good luck finding one though!!!

[bigdaddy77]

Contact Terry Varner at Varner Motorsports. Hands down the top guy around. He will steer you in the right direction. We just don't have the need or the money to use him yet. I would give him a call though and see what he has to say. I know he has built multiple national champions 90 mod motors.

[gistmarrs]

An R&D built rm85. Lots of torque and very reliable.

[desratt]

How about a crf 150. Honda hasn't sold a 2 stroke in the u.s. in about a decade.

[bigdaddy77]

You still see a lot of cr 85 in the dirt bike world. Might change if the other 4 big producers made a 150cc four stroke. Look at the supermini dirt bike classes results not to many crf 150 winning.
Now in a quad the crf 150 rules. But if he is wantin to run 90 mod classes they won't allow anything over 125cc FourStroke.
Also the willy mod cobra shifter motor is a proven winner also. Don't know what hp numbers compare to stroked 85 cc dirt bike motors but Macy Davenport won the 90 production class last year and at that time the 85 apex was also legal for that class.

[skyeryder]

Are there certain years of the CR and RM that are better??? Thinking of making one of our Cobras a 85 shifter for local stuff?
What years RM power valved?

[bigdaddy77]

I don't know about the RM's but if you decide to go the Honda route. The 2007 cr has the best stator ,cdi and other electronics. Hard to find used though. And they changed the routing of the pipe in 05. So the older one up to 04 use the same pipe and I believe the 05-07 use the same pipe. Somebody correct me if I'm wrong. I'm sure you will get a answer I have seen a lot of RM builds on here. May want to post the ? At the bottom of the mini section. Seem to get more responses rather than in one specific section like the cobra section.

[edwardsp&b]

The rm's have powervalves from like 03 and up. We always ran 07 or 08 motors. Not sure if there is much difference, usually when I order engine stuff from motosport the parts will interchange with a different couple of years.
Bryan

[#404's Dad]

Originally posted by bigdaddy77
I don't know about the RM's but if you decide to go the Honda route. The 2007 cr has the best stator ,cdi and other electronics. Hard to find used though. And they changed the routing of the pipe in 05. So the older one up to 04 use the same pipe and I believe the 05-07 use the same pipe. Somebody correct me if I'm wrong. I'm sure you will get a answer I have seen a lot of RM builds on here. May want to post the ? At the bottom of the mini section. Seem to get more responses rather than in one specific section like the cobra section.

Not 100% on this or that its all of it but 04 Down seem to be the same, 05-07 Cylinder, Left Case, Stator, Fliywheel and Reed Cage are the same.

I've bought everyone I could get my hands on lately and pulled them all down and thats what I have noticed.

[ontargetracing]

** at least 03 and newer RM's have power valves ;)