Anyone replaced 350X engine with a different one? 250x, 300ex, xr600/xr500, ascot 500

[TheRealFatShady]

I am just wondering if anyone has swapped a full engine into a 350X frame. More room than the 200x, seems like it would be cheap to do.

I've heard of 250x engines and 300ex engines being close to bolt it, but I don't like the idea of going down on displacement, and ONLY having electric start on the EX.

What about the old XR500 and XR600 engines? I know the XR200 swaps with the 200x (kicker goes back, though.)

I was looking into the ascot 500 head swap and it seems like a lot of work....could I just drop in a full XR or ascot engine? Anyone done it/results/problems?

Thanks a lot!!!!
PS - Found an old running XR500 for $450 obo, might be worth it as a big bore 400cc kit for the 350X is around that price alone.

[SWIGIN]

Anything can fit with enough work. I'm sure you'll at least have to drop the bottom rails to make room for a 500.

[200x350xtriz250]

You can put a kicker on a 300ex engine and still keep the electric start - that too requires alot of work - split the cases of both a 300ex and 250x engine swap out the needed parts and then machine either the 250x clutch cover to accept an oil line on the 300ex or machine the 300ex cover to allow the kicker shaft through. I believe there are also big bore kits and longer cranks available for the 250x/300ex motors - it is all on what you want, how much you want to spend, what tools you have to utilize and of course your skill level. A stock 300ex or 250x engine is alot of fun as is imho, but again it is all in what you want out of it.

[TheRealFatShady]

You can put a kicker on a 300ex engine and still keep the electric start - that too requires alot of work - split the cases of both a 300ex and 250x engine swap out the needed parts and then machine either the 250x clutch cover to accept an oil line on the 300ex or machine the 300ex cover to allow the kicker shaft through. I believe there are also big bore kits and longer cranks available for the 250x/300ex motors - it is all on what you want, how much you want to spend, what tools you have to utilize and of course your skill level. A stock 300ex or 250x engine is alot of fun as is imho, but again it is all in what you want out of it.

Thanks for the info. I do have a spare 300ex bottom end for parts (taking out some parts for my TRX300 gear reduction) and a spare full? 250x engine. I found another 300ex full engine/wiring/carb for $250 that needs a cam. That may be an option if I can make it have a backup kickstart.

I have seen the big bore kits and stroker cranks, fourstroketech.net does make a 380 and 390 kit, maybe I can do that. If not, maybe a 350X top end will fit??

Has anyone done this/have pictures? Thanks

[Billy Golightly]

I tried the XR500 engine thing. More trouble than its worth by a lot for a 350X frame. Frame has to be extended like everywhere (IE, chop the frame in half and give it 3 inches), engine is freaking huge, crappy kick start shafts, heavy, hard to clearance carb/gas tank height, etc. etc.

[atc500x]

I swapped the ft500 ascot motor with the xr500 kick starter kit ( for back up),without major problem.I only modify the front section of the frame to lower it for about 1 inch and now the cradle is removable for the installation of the motor.No carb clearance problem with the ft500 intake turned for approx 150 degree with a small adaptor plate.I grind 2 find on the cylinder head to clear the petcock.it's now a little bit heavier machine,but alot more torque,it's a perfect machine for high speed trail and winter trail riding,a LOT of torque and a LOT of top speed,never been able to go over 135 km/h,too scary with 4 snow tires. Some of the picture need to be update like the one of the carb,the adaptor plate for the intake been made after the picture,and stock swingarm been installed instaed of the longer one.

[TheRealFatShady]

Thanks for the pics, any more details on how you lowered the frame? And any problem sitting the tank/fenders/seat or anything?

[atc500x]

I just cut the frame to the peg and near the exhaust pipe,this section is now removable.No problem with seat fender and tank since there is no modification to this section of the frame.I can try to get more pics if needed

[200x350xtriz250]

ATC500x I like what you did - and have had no problems with the frame craddle?

[TheRealFatShady]

Thanks for the pictures. I may do that, although I do want reverse....

[shanes1967]

nice bike real well done i know how hard it is to get it to look right but also work well. i did an electric start xr650 but i used the dirt bike frame and suspention anyway nice build.

[TheRealFatShady]

Finally found some 450r pictures, yes they are old, but maybe someone wants to see them.

[torker]

I have not seen it done, but I believe the 400EX engine will fit on the 350X. that engine is very good IMO. It's torquey, somewhat powerful, electric start, huge aftermarket behind it and dead reliable. Could someone confirm if it fits???

TORKER.

[TheRealFatShady]

I haven't heard that it's fits a 300ex, or else more people would have it. Or even the jug would fit, but no info on that either.

But if it does, that'd be newer engines/parts for years to come

[jeddy]

400EX will not easily fit into a 350X frame. The engine will physically fit in the frame. The swingarm is not even close. I started making the swap, then decided it would take a lot more work than I thought. It would be do-able, and make a great trike with a 440 kit (and maybe reverse if you get a new enough one), but would be more entailed than just slapping the motor in. I figured I should get my Ban-Z back together before I tackled this one, and have since sold my spare 400EX.