cr motor?

[hartwill]

has anyone put a cr250 motor in a trx frame? I was thinking about buying a pv cr250 motor. I know they are more powerful that trx stock but how much more power, how much work/ mods do you need to make, and is it worth it?

[86 Quad R]

do a search grasshopper..... http://www.planetsand.com/forums/images/graemlins/default_dark/horse.gif

[CODY_M11]

Might not be able to do a search with the 3 letter minimum search restriction. But from what I have been told and have read it wouldn't work putting a cr motor in R frame because the motor does not have a counter balancer. So it would vibrate to much. Troybilt had some good ideas though about rebuilding the frame to carry the vibrations through the frame and spread and eliminate them. Would be cool if we could figure out how to make this swap work though cause of the availability of parts for cr motors.

[trx250racer]

Originally posted by hartwill
has anyone put a cr250 motor in a trx frame? I was thinking about buying a pv cr250 motor. I know they are more powerful that trx stock but how much more power, how much work/ mods do you need to make, and is it worth it?

A FRIEND OF MINE BOUGHT AN 88 LAST YEAR WITH A CR250R MOTOR IN IT. RAN IT FOR A COUPLE OF WEEKS, THEN HE BLEW THE TOP END AND ENDED UP BUYING A COMPLETE TRX MOTOR FROM ME. I KEPT ALL THE PARTS INVOLVED IN THE CONVERSION

88-89 SWINGARM (NOTICE THE GAP CUT OUT WHERE THE REAR CR MOTOR MOUNT LINES UP WITH THE SWINGER TO ACCEPT THE PIVOT BOLT.}

MODIFIED KICK STARTER (REVERSE KICK)

THERE IS A SHIFTER THERE NOT SURE IF IT IS MODIFIED OR IF IT EVEN REQUIRES A MODIFIED ONE.

MODIFIED FRONT ENGINE MOUNTS

AND THEY WERE RUNNING A 46 TOOTH REAR SPROCKET.

[CODY_M11]

How were the vibrations of the motor and frame?

[trx250racer]

Originally posted by trx250racer
A FRIEND OF MINE BOUGHT AN 88 LAST YEAR WITH A CR250R MOTOR IN IT. RAN IT FOR A COUPLE OF WEEKS, THEN HE BLEW THE TOP END AND ENDED UP BUYING A COMPLETE TRX MOTOR FROM ME. I KEPT ALL THE PARTS INVOLVED IN THE CONVERSION

88-89 SWINGARM (NOTICE THE GAP CUT OUT WHERE THE REAR CR MOTOR MOUNT LINES UP WITH THE SWINGER TO ACCEPT THE PIVOT BOLT.}

MODIFIED KICK STARTER (REVERSE KICK)

THERE IS A SHIFTER THERE NOT SURE IF IT IS MODIFIED OR IF IT EVEN REQUIRES A MODIFIED ONE.

MODIFIED FRONT ENGINE MOUNTS

AND THEY WERE RUNNING A 46 TOOTH REAR SPROCKET.

pic

[hartwill]

I wonder if you could just use an 86 singer? which I have any way. also with the vibration issue you guys brought up, the crs don't seem to have too much vibration, why is it any different in a quad?

[trx250racer]

OH YEAH... FORGOT TO MENTION THE MODIFIED HEADSTAY MOUNT

AS FAR AS VIBRATIONS IT WASN'T THAT BAD, BUT I ONLY ROAD IT DOWN THE DRIVEWAY AND BACK.

I THINK PEOPLE ASSUME ITS AS BAD AS THE CR500 CONVERSION, BUT I DON'T THINK THE VIBRATIONS ARE AS SEVERE.

[CODY_M11]

I'm not sure. But the cr motor was built for the dirt bike frame and not the quad frame. Honda probably went through all this if they decided to put the cb in the R motors.

[hartwill]

or what about just the cr cylinder on a trx bottom end, I think I read somewhere that it will bolt right up. I would get a power valve cylinder. is this maybe more easily achievable? I'm pretty sure all the power gains are just from the cylinder and ignition anyways. unless I'm missing something.

[Fear250r]

I believe all the CR cylinders on trx bottom ends have the pv blocked off. Not sure how the pv works on the CR, but i thought I read its some type of linkage? Don't quote me on that though.

[troybilt]

Originally posted by Fear250r
I believe all the CR cylinders on trx bottom ends have the pv blocked off. Not sure how the pv works on the CR, but i thought I read its some type of linkage? Don't quote me on that though.

Pre 2002 the PV is controlled by linkage, 2002-2007 they are controlled by servo. Most like the linkage, and the 2001 motors... I like the servo but that's just me. A trx bottom end can be converted to run the PV's does take some work:

http://redrider.embarqspace.com/#

I'm picking up a 450r roller this weekend hopefully, I look forward to trying a CR250r conversion on this beast this summer after my Laeger is finished. I want to build the bike as if it was released by Honda as a 2011 trx250r.... service honda has a kit to convert to forward kick, or at least they do that on the SRX250r that they build with the 400ex chassis.

[Fear250r]

Originally posted by troybilt


I'm picking up a 450r roller this weekend hopefully, I look forward to trying a CR250r conversion on this beast this summer after my Laeger is finished. I want to build the bike as if it was released by Honda as a 2011 trx250r.... service honda has a kit to convert to forward kick, or at least they do that on the SRX250r that they build with the 400ex chassis.


Geez! Another project!? You're only allowed one in the calendar! LOL

[hartwill]

hey troy do you know the power difference? and do you think its worth it or would I be better off going with some sort of aftermarket pv cylinder?

[troybilt]

Originally posted by hartwill
hey troy do you know the power difference? and do you think its worth it or would I be better off going with some sort of aftermarket pv cylinder?

I guess it would depend on how much you want to spend and how much fabbing you want to do. The PV cylinder would be the easiest way to go for sure.

On the CR's there is plenty of information out there and i've read just the other day, they claim somewhere in the 50hp range stock on the 01 CR250's. They were a beast no doubt. I believe the stock CR500 for that year was like ~58hp, just for comparison.

[croat1]

troy: by chance did you contact service honda and ask about the forward kick sonversion (price).

also to all...what pipe problems if any.

[troybilt]

Originally posted by Fear250r
Geez! Another project!? You're only allowed one in the calendar! LOL

I know, dang it.. LOL! ... I'm trading some parts for the chassis, but its going to be awhile before I get started on this one... I don't want to neglect the Laeger build. Which is going to be Sa-weet.

Joe, no I didn't contact Service Honda about the conversion. I'm sure its expensive, though... as with everything-else I want to do with these bikes...

[mxduner]

troy, imho i would try a yz motor personally. I am a die hard honda guy, but the yz motor is just that much better. 99 to 2010 they were the same as far as fitup, with minor porting and pipe changes. by 06 it has been unchanged - a needle change. i had a 06, and a friends 03 was very close to mine, and way more powerful and has more useable power than the cr.

I like the idea of your 2011 trx250r though.

[troybilt]

Originally posted by mxduner
troy, imho i would try a yz motor personally. I am a die hard honda guy, but the yz motor is just that much better. 99 to 2010 they were the same as far as fitup, with minor porting and pipe changes. by 06 it has been unchanged - a needle change. i had a 06, and a friends 03 was very close to mine, and way more powerful and has more useable power than the cr.

I like the idea of your 2011 trx250r though.

I hear what your saying... gosh though, Yamaha makes my blood boil...! I've got a few tricks up my sleeve on the CR, that is if I get around to building this beast. I'll be honest, I'm not expert on the CR's. Only what I've been researching lately. I used to ride 125's back in 93-95... and at that time I was a KX guy... times sure do change!

[mxduner]

Originally posted by troybilt
I hear what your saying... gosh though, Yamaha makes my blood boil...! I've got a few tricks up my sleeve on the CR, that is if I get around to building this beast. I'll be honest, I'm not expert on the CR's. Only what I've been researching lately. I used to ride 125's back in 93-95... and at that time I was a KX guy... times sure do change! lol that is so funny! i went through some changes like yourself. in 01 i decided to get my 1st bike. I was/am a big honda guy. I did not know how well i would like bikes. looking around, i found the cr's going for $5500 +/- new. again i didn't know if i would like bikes. well i came across a new over stock kx and bought it for $3800. Not long later i found out why there was some of these bikes left over. The motor had killer bottom end, and it did well for me,. the rest of the bike stunk lol. I ended up riding it for a couple years, and found a guy that wanted to trade his 06 yz for something tamer for trails. We traded and i threw in $1250 for a bike that had 3 tanks of gas threw it. to get to my point, before i got a bike, yamaha also made my blood boil badly! a friend told me in bike world, to win races you can't be brand loyal. Boy i found out quickly, he was right on. Now i have fallen into the yamaha band wagon a little bit. After all they still make 2 strokes, and that says a lot to a 2 stroke fan.

back on topic. in 00 or 01??? a local racer and a race shop put a yz motor in a aftermarket frame. he did decent with it, and even had a article in cycle news with it. The riders name was cody anderson, and the company i cant think of at the moment. i will try to drum up his name, as he does custom pipes, like the one in that quad. sorry for the autobiography

[slainwarrior]

i would assume with a 250 vibrations cant be as bad as people make them out to be.. i dont know actually how the motor is sitting in the frame but servicehonda.com advertises and sells a 400ex with a cr250 motor in it.. just some food for thought