Thanks for that tip, I will give it a go first before asking the dealer.

I had a similar problem on an older bike and it turned out to be a pinched diagphram(sp) over the jet needle. May want to look into that. This would make sense, as the area that you are talking about is in the mid-range, which just happens to be the area afftected by the needle.

I'll fess up. I did this before. Talk about puzzled.

I think the reason lots of people have done it but they are just to shy to admit it.

Well, finally got it in and out of the shop. They tested it for several things and broke into the clutch and adjusted a couple of things they said weren't in correctly, but to no solution. It is still doing the same thing. The service manager said the only place left it could be is in the transmission itself. They said that could run around $950 and that they would put the labor charge I paid for the clutch work toward that service. That is still around $800 and I dont think I want to put that much more into the bike.

So, new question. Has anyone rebuilt their transmission on the GZ250? If so, how difficult is it and do you need all the special tools that the service manual shows? I may try it myself.

I sure would like to know why they think its the transmission. I can't imagine a transmission problem that would do this without some hard shifting or crunching and grinding.

Ignition system problems can cause surging. I had a bad connection in a connector that would do this at almost exactly the same speed. The vibration was causing the connection to break and shunting down the ignition system. When the vibration subsided the ignition would come back on. I got home by riding slow to keep the vibration down.

I think they came to the conclusion by process of elimination.

I did discover a potential source of the problem on my own last night riding. My foot was close to the shifter lever and I felt it bump my foot right before the engine skipped in fifth gear. I started monitoring the shift lever and it would slowly creep downward until the engine skipped, it would then pop back up into place. It is still only happening in fifth around 48mph and up but found if I kept firm upward pressure consistently with my foot it didn't happen. It wore my leg out pretty quick but it didn't skip once when I did that. I don't know where the origination of the problem is stemming from, but it is the closest I have come to a symptom besides the skipping.

Any ideas anyone. The dealership's mechanics don't seem to be helping any. I have been through 3 of them now.

Sounds like some type of return spring or the like has given up. Obviously internal but could be an easy cheaper fix than the whole tranny. Of course what do I know, but do keep optimistic.

Re: Power loss
 

I realize this is very old thread, but, did you ever discover the source of this problem ? This is what my bike is doing. Runs fine at 50 mph in 4th gear but in 5th it surges and stumbles like it is popping out of gear or starved for fuel as I go from 45-55 mph. used berrymans carb cleaner, checked air filter, checked exhaust. otherwise runs fine. just on the high way as i shift to 5th and accelerate it stumbles and surges. very annoying. my bike is a 2007 with 1000 miles on it with 600 miles over the past two months.