'01 426 Gearbox issues

[Max Factor]

My brothers just bought a second hand 2001 YZ426 and it seems to "jump out" of 5th gear. It happens anytime after shifting into top, it jumps out of gear resonably violently, the motor instantly free revs and then it re-engages. It continues this cycle till down shifting.

Has anyone else had / heard of this problem with the 426?

It seems to me like an issue with the selector dog or pawl not holding engagement?

 

[skthom2320]

Do a search on www.thumpertalk.com. There have been some 4th gear problems on '01 bikes. I have 100 hours on mine and it is still fine ...


Here is a link to one of the threads:

http://www.thumpertalk.com/bike/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=6&t=003829&p=

 

[SFO]

The '02 yz-f's have different part #'s for some of the gears and the shift forks.
My wr does it too.
I will be putting the new stuff in it soon.

 

[gonads]

Whilst this problem occurs ocasionally, it is not a common problem.
It certainly sounds like the pawl may be bent.
I suggest a complete gearbox rebuild. Whilst rebuilding the box, perhaps you may want to utilise the rest of the bike.
May I suggest keeping the bike as spare parts for any friends you may have that ride similar models, or maybe considering a similar purchase
Gonads "Hans" Off ma KTM520

 

[Max Factor]

It turned out to be worn / rounded dogs between gears. Needed 3, 4, 5th gear sets. One shift pawl was slightly bent and quite grooved. All new parts coming. (piston also was up for a change)

The dealer said 426 gearboxes were becoming 'suprinsingly regular'. He just re-built an '02 model that was 3 months old.