TZR 125 problem. Please help!

[weasel]

Ok, you may have read my other post about my TZR dying at about 70, well now the problem has developed.
I opened the powervalve today, so i could really test the bike, and it was all going fine, other than the flat spot you get before 7,000revs, it was fine.
I Came across a nice stretch of road, so opened it up in 2nd, and it was clocking 50mph at the redline in 2nd, which i thought was pretty good for a 125, then kept it going all the way up to about 65, when the same problem occurred, the bike lunged, and started to die, but now its doing it more often, it wont run properly at 55mph in 6th.

Basically, it will red line in the first 3 gears , no problem, but as you approach about 60 - 65, the revs begin to die, and when this happens, if you pull in the clutch to try and blip the engine, it bogs, just like it does when you are running out of petrol. Then after a few pumps of the throttle, it revs up again, so you go down a couple of gears and its fine. Ive come to the conclusion that the problem is lack of fuel, because of the way the engine bogs, but theres plenty of fuel in the tank. Ive got an in-line filter, could this be blocked, and thats whats causing it, also, should i check the filter that sticks up in the fuel tank?
The engine has been bored out 2 mil, and its got a gianelli exhaust, but i havent re-jetted it yet, is this small jet likely to cause a big enough shortage of fuel to cause this sort of problem.

Any help would be gratefully recieved!?
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Its still restricted officer.... Honest!

[Gazdaman]

My MZ used to do something similar, thing it was a slightly bunged up main yet, when did you last clean the carbs out?

A bunged fuel filter definately wouldn't help!

Gaz

[quik_d]

hey sorry if i sound like dumbass but could ur problem be cos ur pushing ur bike over 50 in 2nd gear? i mean ur asking for it to blow up its only a 125 hasn't it got 6 gears? generally 2nd gear should take upto 30ish most i would say. Am probably wrong tho
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LOOK AT DAT M8 WELL LUSH A PARROT INT IT

[quik_d]

hey sorry if i sound like dumbass but could ur problem be cos ur pushing ur bike over 50 in 2nd gear? i mean ur asking for it to blow up its only a 125 hasn't it got 6 gears? generally 2nd gear should take upto 30ish most i would say. Am probably wrong tho
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LOOK AT DAT M8 WELL LUSH A PARROT INT IT

[stevo as b4]

first id check for crap in the tank and flush it out. Then strip and clean the carb and blow out every jet and passageway with an airline. It would be worth getting a new fuel filter they are only a pound or so! if it still plays up after this, and none of the jets were blocked or the needle/slide worn etc, then it must be a jetting problem. If you have a 2mm overbore, and a different exhaust then thats easily enough to effect the jetting.

[weasel]

Ive never done much on the carb side, so i this will all be part of the learning curve, so when i blow it out with an air line, do i have to totally dismantle it, or can i just take the carb off, take out the main throttle/needle bit and fire an air line down there, or do you have to do each jet individually?

And as for the guy saying that i shouldnt do 50 in second... calm down dear! I dont normally do 50 in second, this was just to demonstrate how it will red-line in the first few guys, but die at about 7,000rpm higher up the gears. and besides, the redline isnt a warning line... ITS A TARGET!!

Chears guys.
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Its still restricted officer.... Honest!

[Gazdaman]

You need to unscrew two screws on the top of the carbs, the slide with just slide out, with the needle on the end.

Loosen off the circlips around the carb rubber, I never remember if the TZR125 is a single or a twin, I'll assume a single.

Then once the carb is free (might require you taking the choke mech with you) you need to unscrew the float bowls then the jet is a brass nut looking thing with a hole in it near the middle of the float bowl.

Unscrew it, and blow it through, and remove any other crap you find.

Gaz