RM250 powered 400ex Build

[711streetfighter]

Well I started today, WOO HOO.. First problem is that the 400ex axle pivot bolt (15mm OD) is 2mm smaller then the RM250 swingarm pivot bolt (17mm OD). That means the engine will not stay straight or stay steady on the swingarm bolt. I had to make a bushing. I went to the machine shop and they wouldn't make me one. So darn I thought off to Home Depot and Lowes to figure something out. Well home depot was a no go. Went next door to lowes and found a copper pipe that I eyeballed and it looked close with in a 1mm or so. But darn I forgot my digital calipers. So I bought it anyways and took it home. It was the perfect thickness to take up the space between the 400ex pivot bolt and RM250 cases but it was to 1mm to big in diameter. To easy. Here's the steps.
Video showing play between 400ex pivot and rm cases


Supplies





1. Cut to length needed.


2. Used a square and scribed a straight line down the center. Then I cut a 1mm wide cut along that line with a dremel and filed it until when I squeeze it on the pivot bolt it's snug.


3. Cut into two pieces so that I can split the cases without removing it.


4. Placed it on the 400ex pivot bolt and squeezed it with vise grips then gave it some love with the hammer. Slid in perfectly.


End Result:


Got the motor test fitted and to measure the chain alignment. I'm 8mm off on lining up the sprockets. So tomorrow I will cut the swingarm on the chain side to get it in line then cut the spacers and its on to motor mounts.

[TuckerHardRide]

I'm loving these hybrid threads! Good luck with it and good job with the pivot bolt, I think i'm gonna go make sure my Z's bolt moves freely.

[711streetfighter]

Pivot bolt is fitted perfect now. I have the chain alignment to knock out tomorrow along with engine mounts if I have time.

[richerman]

how can we fit an pivot can i know it or should i go and meet the mechanic?

[chrisroberts916]

That's the best thing you could of done with that Honda, put a Suzuki motor in it!
Looking good

[711streetfighter]

LOL so true. Haven't done much with it since I threw my back out 2 weeks ago but I finished the motor mounts, frame repairs, and electrics. Now its time to fab the pipe up. Here's some pics of what I did today. And I ordered a RMX250 transmission since it has gearing that is relatively close to what you need in a quad.

[woodsrider129]

Your project looks like its coming along pretty good. Other than the mentioned tranny, do you have any other plans for the engine performance-wise?

[jake47]

update pleaseee awesome job so far

[xtremkfx]

I always wanted to do something like this...can't wait to see updates. I wanted to go big though, like CBR, Busa,GSXR........funds just won't allow it as of now.

[711streetfighter]

It's going I haven't had time since I was in NYC all last week. Got home Sat and spent time with the family. The hold up is the pipe, it's a lot of fab work. I didn't like the way it was going so I tore it all apart last night. I'm gonna route it like a 250r pipe. I couldn't get the pipe length right the way I was running it. Then I got a tig welder last week so I practiced a few hours before using it on the pipe.

[711streetfighter]

Na nothing fancy for engine work planned there woods, I just want to see how it works first. After that maybe but I doubt it.

[decentZ89]

thats bad ass though..i love 2 strokes

[mana_z400]

Looking good!!

2 smokers are fun!!

[cassidy 12]

I'm planning on doing something like this wit a z400how many hours of frame work did u need to pit in to get the engine to sit right?

[711streetfighter]

Originally Posted by cassidy 12

I'm planning on doing something like this wit a z400how many hours of frame work did u need to pit in to get the engine to sit right?

Umm about 3 hours time to get the swingarm right and about 4 hours on the mounts, repair frame cracks, and do the gussets. Lots more on the pipe, trying to fab up my own using the rm250 pipe and custom cones to run it similar to the trx250r pipes without changing it to much from the rm250 dimensions. I did lengthen the header of the pipe to increase low end torque but I went over board lol. I need to shorten it and make more cones to get it right. My measurements were off ooops. Here's a pic of where I'm at now with the pipe.



After the pipe the next challenge is to fab up a kick start extension. Basically what I have to do is cut the splined part off the shaft then weld it back together after machining an extension on the lathe. I need to go 2 1/2" to get it to clear everything. Oh and switch to a rm125 kick lever, that way its shorter and less cutting of the plastic to make it work.