2002 380EXC build up

I am building a 380EXC and thought I might take some pictures while I was at it.

If there is anything anybody wants pictures of, put in a request.

I am not a great photographer so suggest anything here you want for me to get better photos.

First up... Big 2-stroke vs little 2-stroke frames comparison:

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Frames upside down.

Hard to see, but the 125/200 frame (rear) has a smaller opening for the motor and the head stay mounts are different.

Otherwise they are identical and weigh the same.

Note the bottom tubes on the 125/200frame (rear) tuck in more than they do on the 250/300/380 frame (front).

Riding both bikes I do notice the 125 clears and slides over things like logs better. Small difference.

Motor mount tabs are not in any where near the same locations. 125 motor will fit in the 250/300/380 chassis but not the other way around.

Motor comparison 2002 380 and 2003 250:

Guess which one is the big boy...

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Edited by sbest

Great idea comparing. Can't wait to see the finished bike.

Ok, just a trial fit of the 380 into the frame.

It came out but it sure doesn't want to go back in.

Even on the 125 I find it is easier to drop the engines in with the cylinder off, at least the spark plug removed.

If I have the engine out for major work I leave the cylinder off and stuff around the piston and rod with rags.

Not an option here, leaving this motor together. If I remove the plug I'll plug the hole with rags or a bung of some sort.

Notice my custom reedbox cover. To keep dirt out of a stored engine.

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That "snout" over the exhaust port has to drop into the space between the frame tubes. It just doesn't want to go. I eventually took it off and managed to get it into place. Then I had another problem. The bottom frame tubes were bent together a couple milimeters and the engine wouldn't drop down between the frame rails and mount tabs. Always better to do this fitting stuff before the paint goes on.

So, I am going to take my homemade "frame spreader tool" and spring the frame tubes back where they should be. Made this tool to get swingarms back in. You are gonna love it.

A guy in our club has built 3 ktm's with 380 conversions. He used 2007 / 2008 250 / 300 frames. rear mount lined up but I believe he said the hole had to be bored out. front mounts had to be relocated, and new top mount plates fab'd. That was it, everything else lined up. My son rode his 2008 and couldnt stop talking about how great it is.

A guy in our club has built 3 ktm's with 380 conversions. He used 2007 / 2008 250 / 300 frames. rear mount lined up but I believe he said the hole had to be bored out. front mounts had to be relocated, and new top mount plates fab'd. That was it, everything else lined up. My son rode his 2008 and couldnt stop talking about how great it is.

Wow! cool idea..you always see CR/KX500AF conversions but you don't see many KTM380 conversions! the 380SX engine in a later model frame would have to be awesome!

I NEVER thought about this. You have put evil ideas in my head. My bro has a 360 that he might want to sell.... hmmmm....

any development? post progress plz :lol::banana:

what sort or bhp do the 380 and 300 exc kickj out?

I got a Rekluse Zstart clutch for your project bike...

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