Cutting out in 5th gear only

Hello all,

I have a 2001 YZ426 engine in a roadracing (Tigcraft) frame. It's been bored, stroked, hot cams, ported. My problem is the engine cuts out horribly in 5th. But 5th only. The cutting out seems in no way related to rpm. It cuts out instantly when I shift into fifth and will cut out no matter the rpm. It does not cut out in any other gear. I've disconnected the neutral switch and the other wires with it, I put in a new stator, checked all the wiring and connections; the carb seems fine except I have to use a 135 main jet. (I tried re-jetting from 135 to 165 but nothing helps the 5th gear problem.)

I don't see how since I diconnected the wire at the neutral switch, but could it be the CDI?

Any knowledge, insight, hunches, best guesses would be greatly appreciated.

I'm leaving for the track early Friday morning, Aug. 19, so I won't be able to respond until Monday, but thanks in advance for any help.

Steve

Grayracer, there seems to be quite a lot of these 5th gear problems. Is this a manufacturing fault or is it simply a case of the gears being abused? My 02 426 runs fine but obviously if there is something that can be done to avoid these problems then that's better than fixing it.

Prevention is better than cure...

I think it's a mix of things. First, I don't think the gears were as hard at the locking dogs as they should have been. Beyond that, slow, lazy, imprecise shifting that allows the dogs to "grind" over each other won't help matters.

I know people with really old 426's that have never had this problem, so the rider probably has something to do with it. Shift crisply and positively. Should help the gears live longer.

Thanks a lot for the reply. (I didn't make it to the track.)

I thought about a transmission problem, but if

it were that wouldn't I hear/feel grinding or something? What I hear is the engine stumbling. I'll be going down the straight (roadrace track) in 5th and the engine just

never clears up.

I had the bike on a dyno. I can rev it up in 4th and it's

smooth as silk up to 11,000, but in 5th the engine cuts-

out no matter the rpm.

Thanks again,

Steve

Thats dead on for a tranny. Mine did the same in 3rd. messed around with it until 4th went too. Take a look down stairs, see whats up

Mine did the same thing.. In fifth it would almost be like the rev limiter would come on too early or the clutch was jumping in and out but in fact it was the tranny. It ran fine in all the other gears so I knew then it wasnt the engine. I needed to replace 3rd, 5th and the shift fork.

Happened to me twice... 5th gear cracked.. No wonder they went to a 4 speed.. :D

Thanks to everyone for the advise. I certainly wasn't

thinking seriously about it being the transmission. I'm

going to check it out.

Thanks again,

Steve

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