Anybody tried putting a DR350 engine in a RM250 frame?

I rode a 1999 RM over the weekend, liked the way it handled compared to the DR I have.

Has anybody looked at trying to fit a DR350 engine in a MX frame. It would need a new cradle underneath the engine, and I would think a new airbox.

I did a few internet searches, but didn't see anything. Interested to know if anybody else has done it.

suzuki did it with the 400 and rm in 79 or 80 they ran the 4stroke nats with it it looked pretty good, so I dont see why you couldn,t get your project to work, but the early floater chassis did have a lot of room in it, with the later chassis,s you can run into a lot of headaches with carb clearance problems, but they too can be overcome with a little work, if you decide to go ahead just be sure to post up pics, have fun

It wouldn't be simple or easy. The DR motor is a lot taller than the RM motor. That means significant mods to the frame (and fuel tank) to make room.

suzuki did it with the 400 and rm in 79 or 80 they ran the 4stroke nats with it it looked pretty good, so I dont see why you couldn,t get your project to work, but the early floater chassis did have a lot of room in it, with the later chassis,s you can run into a lot of headaches with carb clearance problems, but they too can be overcome with a little work, if you decide to go ahead just be sure to post up pics, have fun

The 79 and 80 RM's were twin shock rear suspension. Some people even put TT500 engines in those frames, I have a 1978 RM400C bike, and that has plenty of room for a DR350 engine.

I'm looking for a RM with much more modern geometry and suspension

It wouldn't be simple or easy. The DR motor is a lot taller than the RM motor. That means significant mods to the frame (and fuel tank) to make room.

If I have to cut the top frame tube, I will go ahead and do it. I thought of even using the upper part of a spare DR frame I have. If I could use an off-road DR tank, that might have some benefit, as I have a plated DR350, and if it used the DR tank and seat, LEO would likely be none the wiser.

The aim is to get the RM geometry and suspension with the DR engine. May not be worth the effort.

You can swap over RM forks and swingarm to the DR. That might give you something of what your looking for?

I rode a 1999 RM over the weekend, liked the way it handled compared to the DR I have.

Has anybody looked at trying to fit a DR350 engine in a MX frame. It would need a new cradle underneath the engine, and I would think a new airbox.

I did a few internet searches, but didn't see anything. Interested to know if anybody else has done it.

I just can't see a benefit?? Be a heck of a lot easier and perhaps cheaper to just get an older 2 stroke dirt bike. The DR350 is a lump:smirk:

I just can't see a benefit?? Be a heck of a lot easier and perhaps cheaper to just get an older 2 stroke dirt bike. The DR350 is a lump:smirk:

I have a 93 RMX250, so I have a two stroke bike, the benefit is that the DR350, especially is made into a 441 is a really decent engine. It's long lasting, and air cooled so nothong to go wrong. Also I can put the plate on the back, so make it street legal.

I have USD forks on the front, and an Ohlins shock on the back, so I have gone as far as I can in improving the bike. Next step would be a frame swap.

The RM handles better than a DR could likely ever handle, add the reliable torquey DR engine, I think it would be a winner.

You can swap over RM forks and swingarm to the DR. That might give you something of what your looking for?

I have '92 WR250 USD forks on the front, and an Ohlins on the back. Some people have put RMX swingarm and linkage on the back, but the linkage geometry is not correct when the RMX linkage is put on the DR frame, it lowers the back about 1 inch, and apparently isn't the best solution. Some people have put both RM and RMX forks on the front with good results.

I have a 93 RMX250, so I have a two stroke bike, the benefit is that the DR350, especially is made into a 441 is a really decent engine. It's long lasting, and air cooled so nothong to go wrong. Also I can put the plate on the back, so make it street legal.

I have USD forks on the front, and an Ohlins shock on the back, so I have gone as far as I can in improving the bike. Next step would be a frame swap.

The RM handles better than a DR could likely ever handle, add the reliable torquey DR engine, I think it would be a winner.

:smirk::worthy: but not sure how you could get a plate for the RM frame? Surely would turn a head or two.

:smirk::worthy: but not sure how you could get a plate for the RM frame? Surely would turn a head or two.[/quote

Let me worry about that

just curious what does your dr motor weigh, also was wondering how different is the geometry from rm to dr has anyone ever checked?, I changed the steering head angle on an 81 tt250 by raising the rear about 2in it steered a lot better and did not affect the stability too much also changed the tank and seat to later model cr125 I think that affected the handling almost as much as the shock setup,

It's been done! Here's a couple of images of an article from a 1996 Dirt Bike magazine. It's a DR engine in a 1989 RM chassis. There's no shots without the tank, so I'd assume that the upper frame tube has been modified.

Now it's time to find a decent late 90's RM rolling chassis

bikemag003.jpg

bikemag005.jpg

I'm doubting that you will have to "cut" into the top of the frame. I would bet that the sucker will fit right in there.(with the exception of the "brace")

I would think your biggest issue would be with the oil system. The DR is a dry sump system. How do you plan to modify the frame to become an oil tank? Or are you going to make an aftermarket one that sits where the radiators would? That would be my first choice. Double as an oil cooler too.

When you start this I want to see step by step instruction. Maybe I'll resurrect my almost 30,000 mile dr 350 motor?

Anyone have some el-cheapo used dr350 motor parts laying around? I'll gladly take donations lol

i remember that article, notice the external gears for the repositioned kicker? Not my idea of a clean swap at all, having to make sure your external gears are clean b4 you kick, c'mon now!

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