WR450F engine in YZ frame?
Posted November 03, 2008 - 05:59 PM
I just realized I posted this in the wr/yz250 forum, sorry.
First of all, this is my first post. I just got a 2003 yz450f for a steal, the only thing wrong with it was the engine, seized piston. I was able to pick up a complete '03 wr450f engine. I have a few questions for you experts:
1. will the engine fit? from what I have read, it should. I know there are some differences between the two frames but just rake, trail geometry, not engine mounts. right?
2. can I use the YZ carb? if not why? exhaust?
3. I've read that the yz exhaust cam is a bit more aggresive but if I use it I need to do the 'grey wire' mod. what is that. Should I use the yz electrical system? is it worth using the yz cam?
4. I know there are different wheel sizes, should I use the yz sprockets of wr sprocket sizes?
I'll probably have more questions but these are for now. Any help is greatly appreciated.
Posted November 03, 2008 - 11:36 PM
Posted November 04, 2008 - 03:18 PM
Posted November 04, 2008 - 03:26 PM
You could possibly try to piece together the yz motor with good parts from the wr, like the cylinder, head and piston.
My question about doing that is . whats locked up? I'm not sure if the crankshaft will swap from the one to the other I know it's differant in the later years but I'm not sure about an 03 . if the piston siezed there is a good chance that it could have messed up the crank too. I think what really needs checked here is the stator side of the crank . if they are the same swap the stator and all is good if not then you'll either have to swap the crank or swap out the wiring.If you swap out the wiring you could use the electric starter.
Posted November 04, 2008 - 03:28 PM
Posted November 04, 2008 - 04:35 PM
Posted November 04, 2008 - 06:04 PM
Posted November 05, 2008 - 03:07 PM
I think you have some tough times ahead figuring out the wiring on this thing. I would try and get my hands on a WR CDI and wiring harness if I were you.
Posted November 05, 2008 - 06:36 PM
Thanks for all your help and input. I think Don hit it right on the head. Electrical is going to be the hardest to figure out. The CDI from the YZ is the same as the WR, same part #. I'm not too concerned about not having electric start and I don't have a headlight, not to mention no battery. I had read that to swap out the cams required the grey wire mod or else the hot start system would not work as designed. I have been looking at the generator systems at both. I think I'm going to try just swapping out the entire electrical system from the YZ to the WR. I just got the engine today and was looking it over. This is my gameplan:
YZ frame, everything but the engine.
WR engine with yz cams, electrical system, carb and pipe.
I also figure since I've got the engine on a bench, I'll replace the piston/rings while I can.
My backup plan is to find a wr wiring harness and go from there.
Thanks again for al your help
Posted November 05, 2008 - 07:11 PM
I know the radiators are different on the bikes but you should be fine with YZ rads if you ride desert alot... pack and carry stuff and she'll overheat fast.
Try and download the wiring schematics for both bikes (if you search in this and the YZ forum I bet you'll find them) that way you can see the major differences.
Have fun, can't wait to hear how it works
Posted November 05, 2008 - 07:28 PM
Posted November 06, 2008 - 02:55 PM
I lunched my YZ motor and got a cheap WR to replace i, I assumed at the time that they were the same and only discovered the differences when I stripped it down..hey, I am new to all this.
On the 05 model, the ignitions were totally different, dc and ac, and the YZ stator is inboard and the WR is outboard on the ign case and the flywheels are also different. No idea on cam timings as I am not an expert on the whole YZ/WR intrechangeability thing, but we altered ours anyway by taking off and re-pressing the cam wheels for more top end as I use it for SM racing.
To get the YZ ign on mine, we machined the WR crank taper end and made a plate to mount the YZ stator onto the cases.
Posted November 06, 2008 - 05:17 PM
Posted November 07, 2008 - 11:20 AM
I was afraid of that. Looking more at the parts, th WR has a different crank on the generator side to accomodate the starter clutch.
I think someone makes a starter block off kit for the WR... you should search the forum and see what pops up.
Posted November 08, 2008 - 09:41 AM
Posted November 10, 2008 - 03:08 PM
The 2006 CDI is:
1: C.D.I. UNIT ASSY
The 2003 CDI is:
1: C.D.I. UNIT ASSY
Whole different part number.
Posted November 10, 2008 - 03:13 PM
14: WIRE HARNESS ASSY
1825529-001 Enter 0-99 $107.24
12: WIRE, SUB LEAD
1745409-001 Enter 0-99 $58.92
As best as I can tell from BB.