making my own 400/250r conversion

[bansheeke]

I picked up an 86 250R motor today. bored .20 over, no porting. I got to thinking about what to put this in...i have seen a few people do it, how bout a 400ex? Anyone know anyone who has done it. I would like some more info to see if this is a project i would like to tackle. I know i'm losing reliablitly, but its just not going to be fast with the air cooled 400 in there without a ton of money. so, come on..hit me with some ideas!

ps, i have already seen the atv magazine with one in it, but i'm sure they wouldn't cough up any info.

[Chanman420q]

what would be the point of that?

put it in a 250r frame.....

[markk]

Originally posted by Chanman420q
what would be the point of that?

put it in a 250r frame.....

R frames are weak, and will need alot more maintience than a 400ex frame.
Service Honda Builds some with cr250r motors in them,

I think there is a guy on here ONE FAST PROTO TYPE, thats not how u spell his name, But his real name i think is Jeff B.


I think it would be awsome, But i do agree that a 250r feels better than a 400ex, as far as where u sit!

Get back on and update us on how things are going

[bansheeke]

I prefer the 400 feel. I have ridden plenty of 250r's and just don't like the ergonomics compared to the 400's even though they are failry similar. i know i will need the cdi, coil, and a few other things from the 250R wiring, what else would i need?

[nacs400ex]

Dont waste your time using an R motor, when you can put that motor in a stock or aftermarket frame, WITH 250r T-PIN front and maybe cr500 rear.

If I had a 400ex still, I would deffinetly do the cr250 conversion, as well as the yzf426/crf450.

If you are going through with the 400ex conversion. Your right you would need the cdi, coil, wiring. You might want to get a stock headstay(you would have to modify it to fit the 400ex frame), and front stock R mounts, possibly rear mount for the motor too.

Any ideas how to connect your swingarm to the motor with a swingarm bolt? Or would you use an 88-89 R style setup?

You are going to need a rad for it, little fab to mount it. You are going to need an airbox setup, and an airboot for your airbox to your carb.

[bansheeke]

anyone else have any ideas. still have this motor sitting around. NO I DON"T WANT TO SELL IT( had 50 pms about selling it)

I want to look more into this, but havent' really got any good info

[grabberblue]

If you search the powertrain forum there is a thread on this swap. I am doing it right now and ive had to work out alot of space issues with the radiator and keeping the expansion chamber volume and taper/length. Ive got some great pics i just cant post them yet

[grabberblue]

this might work