YZ-F 5sp conversion

[SFO]

We finally finished installing the '02 yz 5sp in our '03 yz 450 motard bike.

This is a HUGE PITA.

Both cases must be machined to accept the 5sp shift drum, both cases need the shift shaft holes deepened on one of the shift shaft bungs, one gear must be clearance ground to get proper axial freeplay on the main shaft, custom shimming for proper operation, the clutch has to be clearanced in relationship to its axial offset on the mainshaft this was done by surface grinding the washers under the clutch basket, and you will also need a complete 5sp box w/shift shafts, shift forks, shift drum and main shaft and pinion shaft assemblies complete w/ gears.

10 hours in a machine shop plus parts, (thanks Rich), BTW, it works great!

 

[Rich Rohrich]

Nice work Bill.
You guys are definitely living up to the Team Rocket Scientist name. ;)

 

[PeteN]

Bill, I assume this means that the WR450 gearbox is not a "bolt in" either?

Good Luck in VA,
Pete

 

[SFO]

I can't tell you positively, but I don't believe a 5sp shift drum is going into a set of 4sp cases w/o machining.
I would have to had used the '03 wr stuff to know for sure.
The ratios of the yz suited our goals better so that is what we used.
Rich, was this Thumps gearbox?
If so, tell him who is going to be riding our bike, I think he'll get a kick out of it.

 

[Rich Rohrich]

Originally posted by SFO
Rich, was this Thumps gearbox?

Yep it's the gearbox from his '99 417 motor :thumb:

 

[SFO]

Do you have the factory ratios from the service manual for a 99?
I believe what we have is not the smae as what I thought an '01 gearbox was supposed to be.

 

[Rich Rohrich]

I'll get you that info when I get home tonight.