My son returned from the dunes yesterday & said his 2002 400ex was slipping 2nd gear only? He said, "It shifts fine, works fine in all other gears, but when going in 2nd it slips (jerks) & makes a noise like shifting but it didn't".

This is about his 6th ride on a rebuilt topend & reworked bottom end. When we rebuilt the topend we had to split the case halves to replace the crank & rod & found that a shift fork was broken (can't remember which one) & 3rd gear had a chiped tooth so I bought a used transmission & we replaced the fork & gear, everything else seemed ok, looked just like the other transmission.

Our Clymers doesn't mention anything about where to start, any ideas?

More importantly, is it mechanically safe for him to ride like that or should we tear it down before riding again?

Thx, Del

 

Further riding will probably do further damage. It is either the fork or the gears for second. I would say split it back open and look for wear.

 

We pulled the engine this morning, pulled the right crankcase cover off & were suprised we didn't see a piece of a shift fork lying on the bottom of the crankcase halves, a good thing, but now the cause of our problem is still unknown.

Before we went any further I had my son work the gearshift & I watched what was going on, not sure what I'm looking for but what I did notice is that at certain times the drum stopper (sping loaded piece that fits in the "V" of the gearshift cam plate, the star, when in gear) would not always stop in a "V" of the cam plate, it would stop on a tip of the cam plate. As you rotated the chain sprocket the drum stopper would drop into gear (the "V" on the cam plate) as it should.

Is this normal?

Does it tell us more about the problem?

Thx,
Del

 

i would think that is normal. just think about it this way. if the quad is not running and you shift from neutral to 1st it will sometimes roll then you hear a click and the quad will stop as it catches the gear. this is normal and most likly what you are seeing.