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2006 frame using a KTM 300 motor

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I have a line on an 06 yz250 rolling shassis, and spare 300 motor in the shop.  Has anyone heard of the

is conversion being done before.  Searches didnt yeild anything for me.

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I have a line on an 06 yz250 rolling shassis, and spare 300 motor in the shop.  Has anyone heard of the

is conversion being done before.  Searches didnt yeild anything for me.

Unless it was a six speed 300 you would be wasting your time.

It is easier to put a WR 3-5 gear and a 300 BB kit on it.

 

I had thought about the 6 speed KTM engine in a YZ chassis, would be cool.

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There was a Dirt Bike article a while ago with a 380 in a yz frame. Claimed it fit easily. Smaller and lighter than yz engine.

I'd choose it over a bored yz.

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Unless it was a six speed 300 you would be wasting your time.

It is easier to put a WR 3-5 gear and a 300 BB kit on it.

 

I had thought about the 6 speed KTM engine in a YZ chassis, would be cool.

Its a W tranny which I like better then a six speed. Its basically the same thing just less shifting. Plus it has lighting, two maps, set up with a Rekluse. The yz  300 kit is 12-1400 bucks and the WR gears if not expensive, is time consuming especially for someone who hasnt done it before.  If I have an engine sitting there with all I need the question is how much bother is it to stab in a superior yz frame and suspension?

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There was a Dirt Bike article a while ago with a 380 in a yz frame. Claimed it fit easily. Smaller and lighter than yz engine.

I'd choose it over a bored yz.

I would choose a 380 as well but its hard to beieve its lighter then a yz motor?  But I have a 300 so that is what I need to go with, plus it is easily lighter then a 380 but I wouldnt care about the weight given that sweet power!

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I would think more work involved fabbing up an engine to fit that to split the cases....but maybe you have better aluminum welding skills than me.

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I would think more work involved fabbing up an engine to fit that to split the cases....but maybe you have better aluminum welding skills than me.

Many builds are pretty easy, for example a cr500 going into a ktm 450 frame.  Some spacers on the swingarm bolt, weld in motor mounts, exhaust, silencer tabs. done.  Need to hear from someone who may have done this conversion.

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Many builds are pretty easy, for example a cr500 going into a ktm 450 frame.  Some spacers on the swingarm bolt, weld in motor mounts, exhaust, silencer tabs. done.  Need to hear from someone who may have done this conversion.

KTM not aluminum frame, so it is a little easier to weld. I had some CR/XR mini conversions years ago that were pretty involved cutting out frame cradle, etc. If the drive train is off one mm it causes lots of issues. Anything CAN be done, just depends on how much you are willing to spend and your amount of expertise on fabrication.

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250/300/380 all use the same cases. Very little weight difference.

The 250/300 cases were changed in 2004, the motors are more compact/less weight than the 380 motor.

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KTM not aluminum frame, so it is a little easier to weld. I had some CR/XR mini conversions years ago that were pretty involved cutting out frame cradle, etc. If the drive train is off one mm it causes lots of issues. Anything CAN be done, just depends on how much you are willing to spend and your amount of expertise on fabrication.

I'd rather have Steel for sure, but the roller is alum and I'd rather have the SSS suspension.  If the conversion is an easy one I'm not seeing where the expense it.  Cutting out cradles an such wouldn't be a place I would go.  Spacers and motor mount hangers should be relatively inexpensive,  especially compared to splitting cases for W gears and a 300 kit.

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The 250/300 cases were changed in 2004, the motors are more compact/less weight than the 380 motor.

yes. Before that though...

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Pete at NOST did a 380 motor swap into an aluminum framed YZ250.  He'd know about those details.

 

When I looked at measurements a while back (was thinking of the same swap when I had my old KTM 380), it would have required some serious machining of the cases, which I believe were narrower than the swingarm spacing. 

 

Why would you choose a YZ250 chassis anyway?

 

I did sort of the opposite - I took my build up YZ325 motor and put it into an RM250.  Super shitty chassis quality, but the handling of the bike is night and day.  There is NO way to get a YZ to handle like that, and there's also NO way to get an RM250 motor to be as bulletproof.

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I saw Pete at Nost's 380 YZ a few times.  When I saw it about a year ago in his shop (he's had it finished for years now) the aluminum frame had cracked from the excessive vibes of the 380 motor he said.  So was waiting on getting it welded back up.

 

We all think the SSS suspension is the bee knees, however Pete at Nost, a suspension genius, always pushing the envelope of suspension improvements had converted the rear suspension over to WP PDS.  I kid you not.  He said the PDS design was more consistent in the stroke without the leverage ratio of a linkage suspension that is not a consistent ratio through it's stroke.  Thoughts to ponder.  Thinking outside of the box can alienate you from some people at times but I love and appreciate the ability to look at things with a critical eye and try new things.  Pete has that ability/

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Its a W tranny which I like better then a six speed. Its basically the same thing just less shifting. Plus it has lighting, two maps, set up with a Rekluse. The yz  300 kit is 12-1400 bucks and the WR gears if not expensive, is time consuming especially for someone who hasnt done it before.  If I have an engine sitting there with all I need the question is how much bother is it to stab in a superior yz frame and suspension?

You could always swap out the ali frame for an earlier steel frame and keep the suspension etc.

Much easier o weld.

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I saw Pete at Nost's 380 YZ a few times.  When I saw it about a year ago in his shop (he's had it finished for years now) the aluminum frame had cracked from the excessive vibes of the 380 motor he said.  So was waiting on getting it welded back up.

 

We all think the SSS suspension is the bee knees, however Pete at Nost, a suspension genius, always pushing the envelope of suspension improvements had converted the rear suspension over to WP PDS.  I kid you not.  He said the PDS design was more consistent in the stroke without the leverage ratio of a linkage suspension that is not a consistent ratio through it's stroke.  Thoughts to ponder.  Thinking outside of the box can alienate you from some people at times but I love and appreciate the ability to look at things with a critical eye and try new things.  Pete has that ability/

I;'ll have to google up "pete from nost".  But it may be for nothing at least for now.  My roller got gobbled up by someone else, rats!

 

I think links are superior in a few areas but they look so ancient compared to PDS.  The levers seem dumb, and it hangs down and smashes on rocks on occassion, although my bud never had much of an issue on his yam, I sure did on my ktm.  The newer PDS is flat out amazing but still not as good as links but its a difference without much distinction, for trail work anyway.

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There was a Dirt Bike article a while ago with a 380 in a yz frame. Claimed it fit easily. Smaller and lighter than yz engine.

I'd choose it over a bored yz.

That's Petes bike over at Nost Suspension. He also has PDS on the bike too...

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