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cr500 in a 250r frame

325K views 1K replies 114 participants last post by  pokerindi 
#1 ·
i was wondering if anybody has put a cr500 motors in a 250r frame if so what has to be done to make it possible or are there kits for it?
 
#3 ·
Well which frame are you talking? I presume a trx?

It's been done a few times with the 85-86 atc frames.. Also the kx500 in the Tecate 3 frames.

Defiently need some frame notching and custom work to make it fit right. That and also the alighment of the front and rear sprocket so your chain won't be crooked. If you get a complete bike, it easier because then you have the wires and all components you'll need to get the motor fired up.

It is defietly a bad machine, especially for sand dragging.
 
#4 ·
#7 ·
I am doing the conversion right now as matter of fact. Last night I finished my exhaust. I haven't had to cut the frame at all for the engine. All the motor mounts my father and I have made and they are on rubber. So far the exhaust has been the toughest part, we had to cut and twist the pipe quite a bit but it fits nice now. If I can figure out how to post pictures I will.
 
#9 · (Edited)
I have one and it is a beast, the frame was hand made with slightly larger box tubing than a stock R and it is gusseted everywhere, and the body and seat mounts were raised up about an inch for added clearance. It does vibrate some, but not as bad as some make it sound. It is faster than anything I have ridden with.
 
#11 ·
nice job man, no offense or anything, its not showroom perfect but its got the job done. I like it! that pipe looks pretty good. does the bike run pretty good since you cut and twisted the pipe quite a bit? it would look sweet if you could have it chrome or nickle plated. and on your intake setup, you have pretty much the exact same design as me lol. theres a pic of mine.

I been thinkin here lately about building me a trx500r for drag racing. I got an extra 250r frame and im gonna try and get either a cr500 or kx500 motor for it, wichever I find a deal on first. but it actually doesnt look like it will be too hard. I see you made alot of custom mounts for it. when ever I do get started on it im gonna make sure I do it right and try my best to build some good rubber mounts so I wont get so much vibration.
 
#12 ·
#13 ·
It seems to run pretty good to me but a haven't ridden CR500 before so I don't know if it runs differently. From what I have gathered redirecting the pipe doesn't affect too much as long as you don't change the length or volume of the chamber. The pipe that is on it is an FMF and it's pretty beat up, but I have an old power pro pipe that I am going to try and put on it maybe with a straighter flow and if it turns out good I might have a nice finnish put on it.

I see your intake is as custom as mine...nice.
 
#14 ·
Hey, how's it going everybody ? My name is Mike, I'm new to this forum but have been reading quite a bit on here.

I am also in the process of building a TRX 500r for a friend of mine but I am taking a little different approach than many that I have seen. I have been taking pics along the way to document the installation. I have read on other forums that it's a bad idea to build these hybrids because of the non-counterbalanced engine vibrating like crazy.

Well first off the frame needs signifcant amount of extra bracing and gusseting, I also have modified the frame under the engine area so that I have it with a real low center of gravity, I will also be rubber mounting my engine with true isolated rubber mounts. After I finish up making the mounts and strapping the engine in, I am going to be tackling the pipe, which will consist of a LRD big bore pipe. The reason for this is because it doesn't have to be hacked into several pieces or twisted several times to be made to fit, and the stinger diameter will be sufficient for this size engine. It will need the CR 500 sized exhaust flange and a small portion of the head pipe to be modified but will fit all the stock mounting brackets. It also has the adjustable expansion chamber to dial it in to the mighty 500 power plant. Depending on vibration factors after it is up and running, the crank might go to Fallicon to get dynamically balanced to ensure that this will truly be a fun rideable machine.

This quad is not going to be a Drag specific quad but an all around rider friendly quad when finished specifically for Silver Lake.

I will keep everybody posted if there's any interest and I would also be willing to elaborate and share pics of all the details throughout.

Mike
 
#15 ·
yeah some pics would be cool too:blob4:
 
#17 ·
hilpp99 said:
CR500 in its new home. I just finished all the mounts today. Does anyone have a carb they would be willing to part with? I am looking for one so let me know if you have one you can sell.
man, those motor mounts look pretty clean. I really like how that rear one is made up. and is that front lower mount rubberized aswell? it all looks good.

no offense or anything, but no really to fond of the black spraypainted motor
 
#18 ·
Hey thanks, yeah I don't care for the spray paint to much myself but if you had seen what it looked like before you would appreciate it. The engine came from floriday and must have just sat outside for a long time. The outsides of the cases are pretty corroded and beat up. I will do something different when I find some new cases. Everything else has turned out pretty good so far being I am using a vice for a brake, a torch to cut the steel, and a grinder to clean things up. Also all the mounts are on rubber.
 
#19 ·
I have a stock CR500 carb, it's a 38mm PJ with a bunch of extra parts it's old and beat up, but I'm sure it will work until you can get a better one. I use a 38mm PWK that I will be parting with in about 6 or 7 months. I will be having some work done to the motor then and will need a bigger carb.
 
#20 · (Edited)
Go

RZBansheeMan said:
Hey, how's it going everybody ? My name is Mike, I'm new to this forum but have been reading quite a bit on here.

I am also in the process of building a TRX 500r for a friend of mine but I am taking a little different approach than many that I have seen. I have been taking pics along the way to document the installation. I have read on other forums that it's a bad idea to build these hybrids because of the non-counterbalanced engine vibrating like crazy.

Well first off the frame needs signifcant amount of extra bracing and gusseting, I also have modified the frame under the engine area so that I have it with a real low center of gravity, I will also be rubber mounting my engine with true isolated rubber mounts. After I finish up making the mounts and strapping the engine in, I am going to be tackling the pipe, which will consist of a LRD big bore pipe. The reason for this is because it doesn't have to be hacked into several pieces or twisted several times to be made to fit, and the stinger diameter will be sufficient for this size engine. It will need the CR 500 sized exhaust flange and a small portion of the head pipe to be modified but will fit all the stock mounting brackets. It also has the adjustable expansion chamber to dial it in to the mighty 500 power plant. Depending on vibration factors after it is up and running, the crank might go to Fallicon to get dynamically balanced to ensure that this will truly be a fun rideable machine.

This quad is not going to be a Drag specific quad but an all around rider friendly quad when finished specifically for Silver Lake.

I will keep everybody posted if there's any interest and I would also be willing to elaborate and share pics of all the details throughout.

Mike
Are you going to the E2S outing in Aug with it? I also have a TRX 500 that I will have there.
My biggest short fall with my bike has been being able to kick start it. I currently start it with a hand held starter.
No matter how you mount it will vibrate, mine vibrates less than most but it still shakes parts off it.
________
Love quotes dicussion
 
#21 ·
Hell No, I won't be done with it in time.

I've got a Passion 12 port, 4mil, RZ Banshee ( that I have to finish paying for, before I get all the parts back ) that I also need to finish for myself.

As for the 500r, I am going to build a cradle that bolts to both front and lower engine mounts, the frame below the engine is going to be plated in with 3/16, and that will be bolted to 2 GM transmission mounts.

The swing arm pivot on the engine, I reamed out to 25mm and the I put some leaf spring eye busings in ( those had to be reamed out slightly also to pass the swinger bolt thru.

The head stay, I obviously will be making a new one of those, but the neat thing I found to isolate that, comes from a Banshee. The lower torque struts on the Banshee have vulcanized rubber bushings at each end and takes the same bolt diameter as the head stay as well as the rest of the 500 engine mounting bolt holes.

The frame has large expanses of metal in the engine compartment, which needs to be cured and extra tubing put in to close it up a little bit, basically adding a lot more rigidity to the frame around the engine area. The downfall to this is adding wheight to the frame, but We don't give a real big shit about that because it is a play / dune quad.

The intake is going to have to be cut and repositioned to get the carb to clear the frame but no biggie there.

To get the kicker to clear the frame, I am going to try and make a new kicker shaft that will be 1" longer to get the kicker out far enough from the frame, but then there is the pipe issue ( I haven't gotten that far yet to know if the kicker when folded forward will clear the pipe yet ). I will get some pics up and as I progress, I will keep everyone interested up to date.

Sorry for such a long post, this kinda stuff gets me excited.

Mike
 
#22 ·
rsss396 said:
Are you going to the E2S outing in Aug with it? I also have a TRX 500 that I will have there.
My biggest short fall with my bike has been being able to kick start it. I currently start it with a hand held starter.
No matter how you mount it will vibrate, mine vibrates less than most but it still shakes parts off it.
thats what the deal is with our 500 blaster the kickstarter vibrated off and we lost it now it has to be pull started and we can't find a kickstarter anywhere:angry4:
 
#23 · (Edited)
Go

I also did a cradle for the front & mid motor mounts that goes to a single 2" round rubber isolator mounted verticaly, the head stay uses the same style isolator but it is mounted horizontal. The rear motor mount uses the swingarm bolt with a 86 style swingarm.
I have seen at least three motors with broken front motor mounts that were solid mounted, the cradle system should be much more forgiving. I do use a double heim joint to keep the motor straight in line when torque is being applied.


The kick starter I use is from a early to mid eightys honda four stroke that was about 600cc in a enduro bike that had a steel kicker.
It has a good length and can be heated and bent to the shape you need.
I think the biggest problem is the rear brake lever keeps me from getting a nice 180degree kick on the starter.
I also have a compression release on the cylinder and it does help but its still a major pain.
I kind of think the stator on 500's are not as good of a design (single coil) as the later cr250 that is a radial layout. The 85 had a simular radial design then 86 went to a 2 coil design that incorporated a low speed coil but after 87 they went to a single coil design.
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Fix ps3
 
#24 · (Edited)
Hey rsss396, could you post some detailed pics of your set up ?

I have noticed from pics that alot of installations have the motor mounted at some weird ass angles, they are either kicked way up in the front or kicked way up in the rear. I'm trying to go for a real clean install. If you look at how I have my motor sitting you will notice that it is all the way over to the left so that the sprockets line up and the head stay is lined up where the factry one would also ( just the height is different ). The "Honda" lettering on the clutch cover sits damn near paralell to the bottom of the frame justa as it does in the bike and or the 250r engine in the quad

Mike
 
#26 ·
That looks like a pretty clean install.........alot better than most I have seen pics of !

I will try to get a few pics of some of the frame mods I have done so far, but I still have plenty to do for my satisfaction before I can finish mounting the motor.

As for the kicker shaft, I am not for sure how hard they are yet but, I am going to try and get another one, basically cut the 2 shafts and have a chamffer turned on each and try welding them together to make ait an inch longer, then have it finish turned back to the original O.D. If that doesn't work maybe check and see about having a machine shop make a whole new one.

Do you have rubber in the swinger pivot area also ?

Thanks for your pics, if you could get some more I would greatly appreciate it.

Mike
 
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