4th Gear Slipping

4th gear is slipping. All other gears work fine. Any ideas?

Yeah pull the motor split the cases replace 3rd and 4th pinion gears (these gears are meshed to each other through matching dog's the dog's get rounded, probably due to a bent shift fork and it starts popping in and out of gear) I would go ahead and replace all three shift forks and check for wear on the drive gears as well, that will be a min. I know cause I am doing the same thing to my 426. Good luck :applause:

The cause of bent forks and/or rounded dogs is like the chicken/egg question. Bent forks will round off gear dogs by incompletely engaging them. Rounded gear dogs will bend a shift fork by making the gears force their way out of engagement against the fork. Ultimately, the cause is usually "lazy" shifting, crashing on the gear lever, or just a lot of time on gears not quite hard enough for the job. Either way, Cheese is correct.

Be sure to inspect the tooth faces as well as look for wear at the dogs, as 426's have been subject to flaking and spalling in that area. A good shift fork will show wear only at the fork ends, and not in the center of the 'C'. A fork that shows no center wear, and is not excessively worn on the thrust surfaces can be reused, but if there's any doubt, just replace them. It's too big a job to do twice, and, because of the layout, transmission problems are a threat to your engine.

Is it bad gear season? I've sure seen (and experienced) a lot of this lately.

My 2000 has some bunk gears that I found upon disassembly. They were not giving me problems, but they surely would have soon.

Cheese, you get that bike back together yet?

I'm still waiting on some damn parts to ship before I can finish reassembly. All I've managed so far is replace bearings.


I am close to getting it back together, I too am waiting on parts. I went ahead and ordered a high comp piston to throw in as well. Trans it back together, I just went ahead and replaced all 3 shift forks, 3rd & 4th pinion, 4th gear, 5th gear, oil seals, head bolts, clips, and other various shit. How is it going with you. :applause::eek:

I'm still waiting for the damn oil pump from the mail order guys. I did get my gears in the other day, so I can put the trans back together I suppose. I'm SOL without that oil pump though.

Plus I'm still having second thoughts about my crank. This is the second rebuild with this crank and I have a funny feeling the rod bearing is gonna crap out on me (even though it feels great). The wife is gonna kill me if I spend any more money on this thing......

The wife is gonna kill me if I spend any more money on this thing......

Second that my wife is hitting the limit on my spending craze too. :applause:

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