1978 Suzuki RM250 upgrade

CvMotoKings
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CvMotoKings
Edited Date/Time 3/1/2016 4:34am
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to ask right off is which frame should I use? This will be my first dirtbike build and I just really want to have the same amount of power that it does now, but with a smoother ride cause if you've had a 78, then you know it's not a Cadillac.
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queen of spodes 2/29/2016 4:59pm
2/29/2016 4:59pm
As in a modern Al frame? If so.. please keep posting updates and pictures.
CvMotoKings
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CvMotoKings 2/29/2016 5:07pm
2/29/2016 5:07pm
As modern as I can get. I know the newer style frame wouldn't work, but I need something with adjustable suspension. I'm needing to know which frames will work with the mounts and exhaust.
Harry_Gray
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Harry_Gray 2/29/2016 5:31pm
2/29/2016 5:31pm Edited Date/Time 2/29/2016 5:38pm
Check on off-road.com archives for a similar project. I believe Rick Sieman (AKA Super Hunky) transplanted a 70's era 2 stroke MX motor into a YZ 400/426 chassis. I'd start there for a reference point for your project.
lostboy819
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lostboy819 2/29/2016 5:34pm
2/29/2016 5:34pm
WHY ????????????????

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Harry_Gray
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Harry_Gray 2/29/2016 5:40pm
2/29/2016 5:40pm
lostboy819 wrote:
WHY ????????????????[img]https://p.vitalmx.com/photos/forums/2016/02/29/126147/s1200_AAEAAQAAAAAAAAZ8AAAAJDQ3MjIyOTA0LWY2MjUtNDY0ZS1hNWNlLTE3NDFiNzgzZDY3Ng.jpg[/img]
WHY ????????????????

Why not? If he already has the motor; could be a fun project. Reliable, simple to work on motor in a modern chassis; might be a really fun bike for the trails/desert/woods.
CvMotoKings
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CvMotoKings 2/29/2016 5:42pm
2/29/2016 5:42pm
Because it's such a rough riding bike. It has loads of power, but jumping is horrible on it.
1
scott_nz 2/29/2016 5:47pm
2/29/2016 5:47pm
I would go steel frame, 04/05 KX250F/RMZ250 might be a good option and should be easy to find, , or any of the early YZ-F four strokes,

Steel is much easier to weld, look at some of the horror jobs that are done with alloy frames that are not welded properly, and the breakages that occur,

wont be an easy change over, biggest problem may be the back engine mount/swing arm pivot, as they got beefed up alot to stop flex,

CvMotoKings
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CvMotoKings 2/29/2016 5:49pm
2/29/2016 5:49pm
I really only ride on trails so I need a smoother ride, so im looking for a newer, lighter, adjustable suspension frame. I was thinking about just putting a new swing arm and suspension on the 78 frame, but I figured that would be more work than just swapping chassis's.
scott_nz 2/29/2016 5:51pm
2/29/2016 5:51pm
anything from the mid 90's up would fit what you are looking for, its going to be a huge improvement in handling,

CvMotoKings
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CvMotoKings 2/29/2016 5:53pm
2/29/2016 5:53pm
scott_nz wrote:
I would go steel frame, 04/05 KX250F/RMZ250 might be a good option and should be easy to find, , or any of the early YZ-F four...
I would go steel frame, 04/05 KX250F/RMZ250 might be a good option and should be easy to find, , or any of the early YZ-F four strokes,

Steel is much easier to weld, look at some of the horror jobs that are done with alloy frames that are not welded properly, and the breakages that occur,

wont be an easy change over, biggest problem may be the back engine mount/swing arm pivot, as they got beefed up alot to stop flex,

Any idea of a frame I could use without having to do any welding? Welding isn't a problem, I just can't have it tore down for longer than a day or so and a complete swap with a frame that matches up right would take me no time.
scott_nz 2/29/2016 6:07pm
2/29/2016 6:07pm
scott_nz wrote:
I would go steel frame, 04/05 KX250F/RMZ250 might be a good option and should be easy to find, , or any of the early YZ-F four...
I would go steel frame, 04/05 KX250F/RMZ250 might be a good option and should be easy to find, , or any of the early YZ-F four strokes,

Steel is much easier to weld, look at some of the horror jobs that are done with alloy frames that are not welded properly, and the breakages that occur,

wont be an easy change over, biggest problem may be the back engine mount/swing arm pivot, as they got beefed up alot to stop flex,

CvMotoKings wrote:
Any idea of a frame I could use without having to do any welding? Welding isn't a problem, I just can't have it tore down for...
Any idea of a frame I could use without having to do any welding? Welding isn't a problem, I just can't have it tore down for longer than a day or so and a complete swap with a frame that matches up right would take me no time.
i dont think there see any bike that you will have to do no welding, and tank clearence and the exhaust pipe will have to be delt with as well,

this is a big project, not something that you will do in a day or so,
CvMotoKings
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CvMotoKings 2/29/2016 6:26pm
2/29/2016 6:26pm
Ahh, well in that case the guys are gonna have to ride without me for a few days. Would anyone also know how I could stop it from "basket creeping"? I've read online that all Suzuki's do it from the factory, but it wasn't really clear on which clutch basket to replace the OEM with.
lostboy819
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lostboy819 2/29/2016 6:38pm
2/29/2016 6:38pm Edited Date/Time 2/29/2016 6:40pm
CvMotoKings wrote:
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to...
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to ask right off is which frame should I use? This will be my first dirtbike build and I just really want to have the same amount of power that it does now, but with a smoother ride cause if you've had a 78, then you know it's not a Cadillac.
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do a swap you will more than likely end up with a ill handling nasty look pile of junk that you will have to sell on craigslist and then we will all make fun of you again. Do some upgrades to the RM like a good set of works performance shocks and find a larger diameter fork and you will be just fine.
NHtoWA421
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NHtoWA421 2/29/2016 6:40pm
2/29/2016 6:40pm
No idea where you are, but im in wa and I have a full 98 rm chassis you could use
CvMotoKings
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CvMotoKings 2/29/2016 6:43pm
2/29/2016 6:43pm
That's the thing, we have an awesome cycle junkyard close to my town in AL, that should have something that will have better suspension and everything, but won't take too much work to get running. I basically want a junker that I can put my RM250 engine on. What other brand of bike would be compatible with Suzuki?
motokiwi 2/29/2016 6:48pm
2/29/2016 6:48pm
I would put it in an 04-08 rm250 frame. They are a great handling frame, and you wont need to muck around with suspension valving like you would have to when transplanting a 2stroke into a shitbox, I mean 4stroke frame.
lostboy819
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lostboy819 2/29/2016 7:10pm
2/29/2016 7:10pm
04-08 are center port exhaust 78 rm is a side port exhaust so you would have to cut and weld up the frame and they would be just one of many problems that pop up trust me. It can be done but its not easy or cheap to do it right.
CvMotoKings
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CvMotoKings 2/29/2016 7:11pm
2/29/2016 7:11pm
CvMotoKings wrote:
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to...
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to ask right off is which frame should I use? This will be my first dirtbike build and I just really want to have the same amount of power that it does now, but with a smoother ride cause if you've had a 78, then you know it's not a Cadillac.
lostboy819 wrote:
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do...
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do a swap you will more than likely end up with a ill handling nasty look pile of junk that you will have to sell on craigslist and then we will all make fun of you again. Do some upgrades to the RM like a good set of works performance shocks and find a larger diameter fork and you will be just fine.
Any idea if it'd be easier to put it in an 87 model chassis? I really don't want it to be a newer bike with a big air cooled 2 stroke engine, just want something new enough to have disc brakes and adjustable suspension. I can't find new suspension for the '78 at all.

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lostboy819
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lostboy819 2/29/2016 7:38pm
2/29/2016 7:38pm
CvMotoKings wrote:
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to...
I wanna take my old air cooled rm250 engine and put it on a newer frame with better suspension, my only real question I know to ask right off is which frame should I use? This will be my first dirtbike build and I just really want to have the same amount of power that it does now, but with a smoother ride cause if you've had a 78, then you know it's not a Cadillac.
lostboy819 wrote:
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do...
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do a swap you will more than likely end up with a ill handling nasty look pile of junk that you will have to sell on craigslist and then we will all make fun of you again. Do some upgrades to the RM like a good set of works performance shocks and find a larger diameter fork and you will be just fine.
CvMotoKings wrote:
Any idea if it'd be easier to put it in an 87 model chassis? I really don't want it to be a newer bike with a...
Any idea if it'd be easier to put it in an 87 model chassis? I really don't want it to be a newer bike with a big air cooled 2 stroke engine, just want something new enough to have disc brakes and adjustable suspension. I can't find new suspension for the '78 at all.
Works performance makes shocks and you can get 38 mm forks and clamps on ebay. Go to the vintage MX bikes sites and you will be able to find all the cool set ups. guys still race the 78s but a motor swap to a different year is not worth the trouble. I bet you could trade the 78 RM for something newer because it is worth way more as a vintage racer than a motor swapped Frankenstein bike from hell.

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CvMotoKings
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CvMotoKings 2/29/2016 8:05pm
2/29/2016 8:05pm
lostboy819 wrote:
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do...
For what it will cost and the amount of work you would be able to buy something newer with a better motor and chassis.If you do a swap you will more than likely end up with a ill handling nasty look pile of junk that you will have to sell on craigslist and then we will all make fun of you again. Do some upgrades to the RM like a good set of works performance shocks and find a larger diameter fork and you will be just fine.
CvMotoKings wrote:
Any idea if it'd be easier to put it in an 87 model chassis? I really don't want it to be a newer bike with a...
Any idea if it'd be easier to put it in an 87 model chassis? I really don't want it to be a newer bike with a big air cooled 2 stroke engine, just want something new enough to have disc brakes and adjustable suspension. I can't find new suspension for the '78 at all.
lostboy819 wrote:
Works performance makes shocks and you can get 38 mm forks and clamps on ebay. Go to the vintage MX bikes sites and you will be...
Works performance makes shocks and you can get 38 mm forks and clamps on ebay. Go to the vintage MX bikes sites and you will be able to find all the cool set ups. guys still race the 78s but a motor swap to a different year is not worth the trouble. I bet you could trade the 78 RM for something newer because it is worth way more as a vintage racer than a motor swapped Frankenstein bike from hell.

I'm probly gonna just fix her up back to factory in that case. Put better suspension and brakes on it and ride. The bikes really fun as it is, but it's not a smooth enough ride for the trails that we ride.
Cancerman
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Cancerman 2/29/2016 10:54pm
2/29/2016 10:54pm
Put Ohlins or equiv rear shocks, and go with the latest forks you can put on it. All Balls Racing website has a conversion chart for bearings and such. I would keep the bike as close to Vintage racing standards so your value stays higher. As one poster stated, a Frankenbike is not worth much unless it's really thought out. An aircooled motor is going to take a fair amount of work to put it into anything modern. A steel framed late model RM might be doable, it depends on the rear swingarm pivot is a big deal. So many issues. It will always involve some amount of welding and fabrication. I'd look for a guy who wants an RM for vintage racing, maybe trade for a 90's bike. Or you could go all in, and design something really monsterous, like this...



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Starcrossed 3/1/2016 12:53am
3/1/2016 12:53am
Or this

CvMotoKings
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CvMotoKings 3/1/2016 4:34am
3/1/2016 4:34am
I appreciate the advice guys. I think I'm gonna do just that, fix her up as an updated vintage racer.

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