Advice required on a KDX motor going in a KX frame?

[dave hamilton]

hey guys just been trying to get some headway and no one seems to be able to help so here goes i have a kdx 220 and want to no if i can put in in a kx250 frame with my swingarm forks etc any help would be great as this was a plan after seeing a cr250 frame with a xr 200 motor ar a trial ride as the mx frames are lighter than the beasty frame of the kdx

[mattnzl]

Definately been done before, have a look here: http://kdxrider.net/forums/

Specificaly this forum:KDX-MX Hybrid
Discussion for swapping a KDX motor in a MX frame...

Have to register on the site to get into that area though.
I looked but decided my engineering skills weren't up to it, so just did a KX fork swap onto my kdx which has been great and well worth the effort.

[dave hamilton]

thanks for the help if its a drama i may just swap forks like you did will have a look for kx forks on trade me as i have seen a kx250 frame for sale as just going to swap my swingarm and shock over and go from there

[Rupe]

thanks for the help if its a drama i may just swap forks like you did will have a look for kx forks on trade me as i have seen a kx250 frame for sale as just going to swap my swingarm and shock over and go from there

Grant/Tuna from spectrum motocycles (kawaka dealer) on the Shore in Auckland rides a kdx/kx thing. Give them a call they'd know the buzz

[dave hamilton]

thanks for the info rupe will give them a ring in the morning

[clmintie]

I built a KX/KDX long ago, '91 125 frame with '89 motor. The trick is to find the right year 125 to match the KDX motor so the rear motor mount/swingarm fit is good. Then just carefully remove the front and lower motor mounts, bolt them to the KDX motor and weld them back in their new position. Biggest headache was cutting, repositioning and welding the water pump intake (or outlet, I forget which) to suit. Also on mine the pipe needed a bit of work to fit. I suspect everything might line up better if you use newer models to start with, as my motor came out of a non-perimeter frame. Very nice bike, wish I still had it

[noobi]

Rumour has it this is how the first gasgas was born...

[cheese]

I thought that the first gasgas was born from all the left over shit from all the jap manufacturers?

[gwynfryn]

The weak link in the mighty kdx is the forks. Are you sure that the kx frame is lighter? I think it's the ancillary equipment that accounts for any weight increase ie lights,sidestand,bigger fueltank, heavy stock muffler, steel kickstart and shifter etc. Change some of these parts for alloy,remove lights put some 2003 and newer kx125 forks on and you have a great bike with the advantage of an 18inch rear wheel. The fork swap does require some machining though kdxrider.net is great.
Then again if you have a kdx motor and kx frame mmmm!

[meteor]

This was on dirtrider.net

A wad of cash, messing with triple clamps, matching hubs, brake calipers and steering stops and getting the rear end of the bike up to keep the steering geometry stable. But other than that its simple.... :scream:
IMHO it seems like a lot of money for what you're gonna get. Consider another brand or an MX bike? Another expensive option is to get a KX 125 rolling chassis and bolt the KDX motor in it, thast what Fredette makes


Not being mechanically minded myself it sounds like a bit of effort... and costly.

[ktm84mxc]

Did a similar swap on a 83 kdx250 complete front end from a kx125[ yokes, forks,wheel etc] . Itz easier to swap the whole font end as long as the steering stem is the same size & length. Made a world of difference KDX's have always suffered in the fork department.

[dave hamilton]

thanks for the tips have got a eye on a set of kx forks

[mattnzl]

Get the kx wheel with the forks as well, makes it a simpler swap (different axle diameter and spacers).
You can use either the kx or kdx brake caliper - I stayed with the kdx one, the kx will require the kx brake line.