Someone donate a motor ,I'll Try it !
I think maybey we could have a debate...hah..on what would be the best engine for the little KLX250s if we could change the type and size, 2stroke,4stroke, 200-450?

 

I've thought about a 4 stroke engine swap, like a KX250F, isn't that the full on race bike. I've got an old 4 wheeler motor in my garage that I thought long and hard about and another advantage to that is I'd have reverse.

 

I would not put a KDX or KXF motor in a KLX chassis. It would go way to fast for the suspension to handle. I did the easy route to two stroke street legality. Buy your bike in a state like Illinois that issues a title for dirt bikes. Then go back to your state that doesn't issue dirt bikes titles. Go to your friendly DMV and request a title transfer, they will not suspect anything is wrong as it has a title, you will pay your states sales tax and get a plate. I did a 2003 KDX200 this way, hooked up a banjo bolt switch the the rear master and a dual filament socket in the tail light assembly and a LED bulb. Mounted the plate and off to my local dual sport ride. The full knobby KDX with rim locks is really not much fun on the highway. But it is a good 60 lbs lighter than the KLX, and better suspended. Putting a faster motor in a porker of a bike is taking a step backwards in my opinion.

 

I'd rather do the KX250f swap or a KX450f swap. If it wasnt such a pain to make street legal, I almost bought a KLX450r and wouldve done that swap. Pretty much if the title says Offroad on it, they wont let you street legalize it. Which sucks cause I really want a KLX450s dang it! If kawi made one I'd sell my 250s in a heartbeat!

 

Oh man Ive dreamed of this for ever... I think all you would need is a welder and sawsall, mount up the motor and two angle irons to go around the exhaust and a couple of mounts and tabs here and there.. you could prob use most of the klx stuff like keep radiators and etc and get a freakin enduro lighting kit and freakin you got a smoker.. wooo hooo!!! I would buy a husky te511..

 

I had the same thought for a while....doing an engine swap on my KLX. Then I did the best possible thing I could think of........bought a KX125 and turned it into KX144 woods bike and installed a lighting coil. Now I have the best of BOTH worlds. When I feel like doing a dualsport ride I take the KLX, when I want to do a fast paced woods/enduro ride I take the KX. Problem solved.

Just my 2 cents.

 

I miss my good ole 95 KDX200! Damn good bike.

 

Anyone who hasn't done an engine swap involving a frame of one type with an engine from a different bike may not be aware of what a challenge this can be. And when you're talking about bikes with 10-12 inches of travel, you're dealing with some real challenges at the countershaft location to get the engine in the correct relationship to the swingarm pivot. I've seen two of these types of transplants done over the years in a shop I used to work at, and it involved an amazing amount of minutia involving some really fine welding skills, engine placement headaches, and wiring routing wizardry to get everything to work. If someone tells you it's easy, beware.

 

Its easy

 

The MSO for my KLX450R said "MOTORCYCLE" and not "OHV". There was a note at the bottom that said "Not for highway use", but the Vehicle Type box said motorcycle. In PA, that's all that mattered. When I got my title, it said "MC", so I took it to the DMV and got a plate - no questions asked.

It's possible that some MSOs for a KLX450R say OHV, but mine didn't. If you find a leftover KLX450, ask the dealer to see the MSO. If it says "MOTORCYCLE" for vehicle type, you're golden.