The kx was made for supermoto

[supermotokx]

Hi all

 Hope you've got room for another European. I use my '96 kx for supermoto racing - it's the fastest bike still. It's mods include full FMF system, 290mm front rotor, standard '98 kx 250 caliber. Wheels are 3,5 front and 4,5 rear fitted with cut slicks. On the fast tracks it's the daddy, but on the more slower ones the power comes too hard to control it l?ke the 4 stroke guys do.
 The handling is somewhat bad (compared to fx KTM). 43 mm front forks are not really up for the job and the huge tank prevents you from getting a good load on the front wheel going in to a corner. I'm about to correct this though, as I'm putting my 500 engine into a '98 250 frame/suspension this weekend!! Should be a blast. Has anyone here done this? If so please let me know how it went.

[mikesmith]

Hi Supermotokx,as Paul will tell you theres always room for more!A lot of people ask about the 500/250 swap and Ive seen pictures so it can be done.The swingarm and engine are going to give you the most trouble Ive heard in this swap,and youll have to make a pipe.Let us know how it goes.

[Paul]

Welcome and yes, the more the merrier

You'll need to modify the head on the 500 or the tank will never go back on. There is a mounting tab on the top, backside of the head that will interfere with the tank, have a mchine shop remove that and the tank will mount up fine. As mikesmith says, the swingarm to the engine is going to be your next obsticle. Good luck and let us know how it goes.

[supermotokx]

Yep you guys were right. The engine itself bolts right in the 250 frame, except ofcourse for the swing arm. I've fixed that - no big problem, had to grind a little off the engine block. The top end had to be modified as well (as you said) to make clearance for the tank - not too difficult. Next problem is the carb which is very close to the rear shock and the pipe. The bike allready looks the business . Too be continued.

[mikesmith]

Supermotokx,any news on that 500 into a 125 swap your doing,I want to know how its going?

[supermotokx]

Well I'm back from holiday, and back to the kx. First: I'm not doing a 500 125 swap, I'm putting my '96 500 engine in a '98 250 frame. The first part of removing the 250 engine brackets (exept the bottum one) was done very quickly. While in the removing mood I modified the top end bracket (read: cut off) to allow clearance for the 250 tank. Next was the problem with the 250 swingarm being to wide for the 500 engine and the bolt going through frame-swingarm-engine-swingarm-frame was 15 mm on the 500 and 17 on the 250. After a bit of grinding off both swingarm and engine and boring the bolt hole to 22 mm, inserting a fitting with outer diameter of 22 mm and innner of 17, cutting it all to fit the (again cutted to fit..) swingarm bearings and viola: The engine fits right in.
 Thats where I am now. Next step is to fit the exhaust as I'm not going to make a new one (got a full FMF system). i've checked it out allready, and I don't think I have to mess with the expansion system but only the later part of the pipe. I'll keep you updated.

[John]

I hope you are documenting your progress with loads of pictures to be posted later?

[supermotokx]

You bet...