4th gear questions

First off this really is for the people that's lost gears in their 426's

The last time I raced my 426, when I went into 4th under power is seemed to jump out of gear just for a split second, it gave the same feeling as if the engine misfired but I know it came from the tranny. Well I got my 02-250F and I haven't ridden the 426 in about 3 months. I planned on taking the 426 to the desert tomarrow so I gave it an oil change today since it's been sitting and took it for a spin, soon as I hit 4th it started the ? ? ? I can't really say its jumping out of gear, ever put you bike on a stand in top gear and let it spin away, it gets a chain slap and the rear wheel jumps and lurches, kinda the same thing but under power in 4th? ? gezzz I feel stupid not being able to describe it, I'm wondering if I dont have a lost tooth on 4th gear. Anyone out there thats lost gears what did your do.

Originally posted by MXOldtimer:

First off this really is for the people that's lost gears in their 426's

The last time I raced my 426, when I went into 4th under power is seemed to jump out of gear just for a split second…

That is exactly the sensation I got when the tranny on my ’00 up-chucked. Technically I did not lose either fourth gear completely, but due to the excessive carnage it was difficult to determine the sequence of events. Both fourth gear wheels were missing some pieces, it could be that one such piece got lodged between third pinion dogs and fourth, or something. But I ended up with a shift fork lodged under the crank, a broken case, intact but severely damaged fourth gears and a third pinion wheel in about forty pieces.

So, hard to say exactly what happened. But in your case it sounds like you have worn dogs or a bent fork, or both. If a fork is bent, not fully engaging the dogs, they will skip in and out of gear, and this will of course only serve to wear the dogs and exacerbate the problem. Eventually one wheel may come apart under the pressure of such an abrupt engagement, or spit off a few pieces which may wreak havoc elsewhere (as appears to have happened in my case).

I’m no metallurgist, but looking at the fourth gear wheels on my ’00 made me think they had a casting problem with these parts. Except for the grenaded third pinion every other gear-tooth face in the tranny looked perfect, while every load bearing face on both fourth gears was pitted, some to the point that a good portion of the tooth had chunked off.

I would think that if your gear teeth were damaged enough to actually let engagement skip you would have experienced other problems by now. But if I were you I would dive in there to see what is what before something similar to what happened to my ’00 happens to yours.

A few shift forks and gears won’t set you back much, but I spent over a grand, just in parts, because the tranny explosion ruined the cases and crank.

Hope this helps.

Thanks Hick

I just wanted another opinion before I started my exploratory surgery :)

"Nurse a #8 please"

Hey Doug- I was looking at the archives and here is a copy of one of Eric's posts that has some stuff in it you should read:



Originally posted by Taffy:

thanks Hick

tell us how you broke your cases please Hick?



Not sure, but it looks like:

1) several teeth on 4th wheel and pinion gear chunked off

2) then collar/dogs on 3rd pinion gear, where 1st shift fork rides, broke

3) then fork got in a bind with broken 3rd pinion gear and broke the case where the fork shaft rides

4) then the fork got tangled in the crank and gouged and bent it. But it didn’t stay there and the bike was running (I pulled in the clutch when the tranny did lock up) until I killed it (I was already hysterically mashing on the kill button before I came to a complete stop).

I was going pretty hard and had just upshifted into fourth when it happened. All I felt was a little hesitation/false neutral sensation when I shifted, I clutched/let off the gas and CLUNK.

Wouldn’t you know it this was the ONLY ride I’ve ever been on w/out a phone. So, in order to prevent long walks in the desert, always carry your phone (even if it doesn’t work), your bike is sure to break otherwise as my experience has proven.

Anyone who reads this that has R&Red a crank from a case half I would appreciate some pointers. As I mentioned, the local motorcycle brain trust advised I use a hammer

Hopefully the “bearings in freezer” trick will suffice…

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