2003 WRF 450 Build questions and pics.

4 replies to this topic
  • chevy power

Posted March 06, 2010 - 02:45 PM


Im going back to work next week after being laid off for 3 months. This means I can get the 450 put back together. I painted the frame with a midnightblue/black mix of some paint I had left over. It got it street legal and the second day out I lost 5th gear. Polished swing arm and subframe, new plastics.

What I started with, bought it beat up.

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I need some help from someone who has had a 5th gear failure. The yamaha manual list no specs for shift fork wear or any trans specs for that matter. What do I need to look at? My first paychecks going towards the bottom end of this thing. I would like to get a list going this week. Ill post more pics of the bike how it sits later this week.

  • welshmaxxer

Posted March 07, 2010 - 07:23 PM


built quite a few now with various gears gone, if you havent stripped it already, I pretty much guarantee it will be worn dogs on the gears. usually when I build the for customers I fit 4 gears. more commonly I fit 3rd and 5th. the last one I did was slipping/jumping out of 3rd. which required 3rd and 5th on the one shaft (as the 2 engage each other to drive) and I recomended 3rd and fifth on the other shaft also. if doing this on a budget you will probably only need 2 gears, however the last bike I did had serious money spent on the engine. (which makes you wonder why a top engine builder put all that effort into building an extremely powerfull engine and didnt look at the gearbox when fitting the crank???????)

even if you have no experience in this, when you pull it apart it should be pretty obvious which bits you need.

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  • chevy power

Posted March 16, 2010 - 04:56 PM


I have the motor apart have since soon after it happened. I ordered a crankshaft (wiseco) ended up being a tooth broken on second gear. I am close with the guys at my local dealer ship, the service manager gave me some tips and the dogs and forks looked fine to him. I dont understand why it locked up in fifth, but I am going to get a clutch basket out of the quad. Have the machine work done on the cylinder and ride the hell out of it. Total cost with the gears, crank, and timing chain was about 375. Piston, rings wrist pin and head gasket is going to be about 150. Getting 20% over cost is saving me. It is ridiculous how much the mark up is on this stuff.

I am going to start the build this weekend if all the parts show. I will be taking pics and posting them up. Fingers crossed the parts come in.

  • chevy power

Posted March 21, 2010 - 04:01 PM


Found out that the second gear was seized to the main drive shaft. Took a lot for the 12 ton press to take it off I was also heating with a torch. Looks like a lack of oil probably from riding on the street at high speed with stock gearing. Here is some pictures of whats going on.

Main Shaft.
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Second gear that seized to the main shaft.
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The color that came about mixing some paints I had left over. Midnight blue with some black. Was hoping for a bluer look but it should hold up, I have some clear grip tape I will put on the frame to help with wear from my boots.
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Working on polishing the swing arm.
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  • crazylikeafox

Posted March 21, 2010 - 04:35 PM


lookin good...........keep us posted.


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