Why are Yamaha Gearboxes so crappy?

[Oring]

Just an observation. Mine, pulled down had metal fragments everywhere. The KTM box had heaps more Kms and very little damage. The YZ was rooted
These boxes are in the 450,s too! Alot of common gear that just can't handle the grunt increase.
It seems to be Ride one week, rebuild the gearbox everyother!
Its time Yamaha had a closer look at whats inside the Box!
Anyone got ideas as how to beef it up?

[Satch0922]

2 1/2 years of abuse on my 426 and no problems....sounds pretty solid to me.

[Dell30rb]

I think either you are putting it back together wrong, or there is a manufacturing defect with your cases... mabye causing a bind somewhere. I know many people with yz450's and none have had any transmission problems.

[psyklone393]

i see you're in australia. you know how water going down a drain spins the opposite direction down there? maybe the gears are trying to spin the wrong way in the gear box ...



-Z

[Oring]

Psyklone that is a Cool answer, No its not that I'm putting them back together rong I think it something in the way I ride, possibly slipping clutch way too much. No I think there is some basic loading issues with the yami boxes. It may be that the motor has slower been getting more powerfull and that they haven't caught up to it yet. Satch are you planning to rebuild the bike soon. Also what sort of maintenance are you doing? which oils are you running, etc I would like to know how you have done so well because I'm rebuilding mine now and I want it to last!
I'm betting when you look inside the 426 you wont like it!
I liked the 426 I had. Awesome bike!
How long are you guys warming them up before you get going?
You must be doing something right and I'm doing it rong!

[Satch0922]

I have been into my bike several times. Had the clutch basket out to install a 98' actuator arm, recently had the clutch cover off to replace the gasket.....VERY clean inside. Also check the valve clearances last month. THe head is spotless.

I use Mobil 1 15w-50 red cap and change the oil every third ride and clean the filter every other oil change. That is really about 3 hours per oil change give or take an hour. I also use a UNI air filter and clean it every other ride. Othere than that the top end has been off once to install a new piston (not because it needed it but just a preventive maint.)


I also use a magnetic drain plug and it usually has some small shavings but that is normal.

PS. I am still on my stock clutch!!!!!

[twoofeach]

2000 YZ426, I took mine apart in February when I installed the 450 cam I learned right here on ATM. Since everything was exposed, I went ahead and checked everything. Also, some Yamaha techs said it wouldn't work and tried to deter me from doing the swap. In March, I opened up the cases again. Everything looked good. Four years of wide open desert freeriding hasn't ruined my case. I too am pretty much stock. Hey, if you need more power than factory, you are a living legend. Even the factory Yamaha riders wanted to tune the bike down.

[MotoMan]

I would have to say that something isn't together quite right if you are having those kinds of issues. I have rode Yamaha's for the last 12 years or so, and the last issue I had was with a 88 yz250.

In fact most YZ's are known for excellent trannies......