2004 Sf frame mods

[Reddy]

About 4 years ago I did a 250af converaion, it was brilliant until this winter I found 3 cracks in the rails so I've decided to go back to standard. 

I've managed to get hold of  2004 Rolling chassis to go with my 2004 engine. However when I've dropped the engine in only the swinging arm bolt and lover engine mount line up.

So my question is..
Is the front engine mount moved to to fit a 86 500 into a 2004 frame? What else will have been modified to fit this engine.

Cheers in advance.

[yeomans]

I'm not to sure about the 04's , but on the 99-02 frames when using the 86 motor the swing arm and lower mounts line up but you have to re weld the front engine mounts.
I'm sure someone on here thats done a 04 conversion will chime in 

 

[zz3gmc]

I did a 04 conversion using a 02 500 engine. The front mount needs to be moved. I centered the rear headstay with the head. This was for clearance when using a big tank. If using a big tank you need to use the tank from a 05 to 07 KX250. I used a Clarke tank. Use a intake manifold from a 91-94 KDX250, otherwise the carb will hit the shock. I also used a carb top and throttle cable from a 96 KX125 because it angles the cable away from the headstay brackets. Been riding/racing mine for 3 years with no frame issues, cracks etc.

[Reddy]

Cheers for your help again guys!! Front mount has been removed and a new on fabricated.

Now I've just got to try and get everything to fit!

[Reddy]

Just wondering what air box boot would have been used for the 500 conversion?  Would the 2004 KX 250 boot have fitted?

Cheers

[zz3gmc]

I used the 02 500s airboot (this was when using the 02 KX500 engine) with a adaptor plate that I made to fit it to the 04 250 airbox. If I remember right, I didnt have to mod the airbox at all. Everything was done at the adaptor plate.

[Reddy]

Thanks again! This forum is brilliant... Everyone is really helpful.

[zz3gmc]

I believe that the 86 500 used a round slide 40mm mikuni. Will it fit the newer airboot from 88 to 04 500? When I built my 04 hybrid there were not too many people that built one using the 03 up chassis. Tons of info on the older 99-02 chassis and AF builds. It was very similar to any of the steel frame builds with just a few differences. Pretty straight forward, fairly easy build. You wont regret the outcome!