converting a 04yz450 to a WR help

[skoke70]

OK, I have a 04yz450 that I have owed since 05, I love the bike but hated the 4 speed for the type of riding I do (tight woods and open roads). Last year I found a great deal on a complete 5 speed transmission out of a 04 wr450 so I had the swap done. It was liking having an all new bike with the wide ratio 5 speed, I love it! I got a 25 good rides on it before the used tranny went out on me. I think a rock slammed into my shift lever causing my shift forks to bend, next thing I know I was popping out of 3rd, 4th and 5th gear.

Well after a long search I found a gut with a complete motor out of a 03 wr450. apparently he tried to put in the wrong size spark plug and striped the hole. Instead of fixing it he found a great deal on an 04 wr and bought it keeping the 03 for spare parts.

I'm going to go and pick up the entire engine from him tomorrow. My plan was to put the top end off of my yz450f onto the wr engine. He also mentioned how he just replaces the starter on the engine which got me thinking, hum electric start and a head light? I knew I would have to have the wiring off of the 03 to make this happen so I called him to ask if he would part with it. Well he said the wiring is still attached to the frame and that I would also need the sub frame for the battery compartment an fuse box, for an extra 100$ I can have them both with the title. I could not pass it up for that price plus he throwing in the front headlight.

Here is my question to you all. Is there anything else besides the top end from my 04 yz engine the I should swap over (crank, piston?) Also how reliable are the electric starts on the 03? should I even bother doing it?

Thanks for the help

[123BigcoopDawg576]

Here is my question to you all. Is there anything else besides the top end from my 04 yz engine the I should swap over (crank, piston?) Also how reliable are the electric starts on the 03? should I even bother doing it?

Thanks for the help

Why even saw heads? its basically the same motor minus the different exhaust cams.

[skoke70]

The threads in the head where the spark plug goes is beyond repair so thats why I'm swaping.

The yz450 exhaust cams are the only change?

[123BigcoopDawg576]

The threads in the head where the spark plug goes is beyond repair so thats why I'm swaping.

The yz450 exhaust cams are the only change?

on the 03-05 yz and the 03-06 wr, the only difference in motor was the exhaust cam, tranny, and fly wheel stuff...other then that its the same:thumbsup:

[ncampion]

The 03 did have a starting problem that you might need to upgrade for reliability.

[grayracer513]

on the 03-05 yz and the 03-06 wr, the only difference in motor was the exhaust cam, tranny, and fly wheel stuff...other then that its the same:thumbsup:

There's more than that. The crankcases are different, as is the left end of the crank, and none of the WR flywheel/stator stuff can be used without changing these two parts.

However, you can if fact put any all or any part of the top of the YZ engine from the piston/cylinder up directly on the WR, and everything on the right side of the engine is identical.

[123BigcoopDawg576]

There's more than that. The crankcases are different, as is the left end of the crank, and none of the WR flywheel/stator stuff can be used without changing these two parts.

thats what i was getting at!

[skoke70]

The 03 did have a starting problem that you might need to upgrade for reliability.

He told me that he did this mod to it

http://www.wr450.com/photos/starter_mod/originals/index.htm

It was supposed to fix a possible issue with the '03.

[SJMC_DON]

The battery / starter relay, etc... is all stored under the WR seat in the subframe.... you would have to find a place to locate all of this stuff unless he was willing to part with the WR sub frame and seat + air box.... hmmmm.

[skoke70]

I got the complete frame, sub frame and all the wiring still attached from him for an extra 100$ with the title. I hoping to get the bike street plated when I get it back together. He had street plates for it in new hamphire but I'm in massachusettes and I don't know their requirements. I will be using his frame and subframe. How is the stock stator output on the 03wr?

I might powder coat the frame black before I put it back together, I did it to my 04 yz frame and it turned out nice with my all black plastics and graphics.

[Birdy426]

I would suggest using the YZ pipe and carb as well. WHile the carbs are pretty much the same, the YZ does not have an air cut valve so keeping up with jetting will be easier.

[grayracer513]

If it works the way it should, the ACV shouldn't affect jetting at all, but it is certainly a completely unnecessary layer of complication that won't ever be anything more beneficial than a potential source of problems. Use the YZ carb.