Major Revving Problems

[mrbluesbox]

OK. Bad things happened last nite with my Derbi GPR 125.
Drove home from work fine and stopped at a amates house on the way home. left the bike standing for a hour, then went to go home.
Started the bike up of, gave it a rev and it just went absolutely nuts - redlining at 13k revs.
Turned it off, tried again, the second it fired up 13k revs again. Arse. Its like the throttle is stuck on open.
Called out the AA and after a week or two the guy turned up. general thoughts were possible a snapped throttle cable, so half dismatled the bike enough to get to the carb, but without taking the entire bike apart it was impossible to get the cables off, but by feeling the cables and playing with the throttle it seems like the cables are still in once piece and doing something (have to check this at weekend). Best guess by the AA guy was that the piston is jammed in the carb, but he wouldnt be able to do anything about it there, so packed up and dissapeared and i pushed the piece o crap home which is where it remains.
So the opinion of the AA guy was a little bit vague and he really didnt tell me exactly what the problem was and didnt exactly sound very confident when he told me. The jammed piston thing seems a reasonable possability though.
Anyone got any other ideas before i take it to bits?
Also the bike is still covered by the manufacturers warranty, do ya reckon this would be covered? id have to hire a van n get it down to blackburn though to the closest dealer which is gonna cost a few quid so do you reckon id be better trying this or trying to get it fixed locally or have a craack myself?

Any input would be greatly appreciated.

Cheers.

Gaz.
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I seem to have misplaced my pants...................

[irving]

[mrbluesbox]

No probs - thanks for the quick reply - im also in work and am researching what to do for when when i get in
The throttle seems to work ok. It feels normal and is snappng back to the closed postition after opening. Af far as i can tell i can feel the cables moving in the cable holders when the throttle is turned, but i havnt managed to remove the cables yet to check 100%.

[edit] if it helps with the ideas the model of the carb is a Mikuni TM 28-92 [/edit]
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I seem to have misplaced my pants...................

[Finglonga]

[XR125]

Don't think it could be the throttle otherwise your engine would of been flooded and never have started in the first place.

[mrbluesbox]

Didnt really seem to have a problem starting it, although it is quite a reliable starter. Havent tried it today though, but i will when i get home.
If i try to take a look at the carb to see if the pistons sticking, will it invalidate my warranty?
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I seem to have misplaced my pants...................

[mrbluesbox]

Okay quick update.

Just been speaking to Derbi on the phone and they've recomended that i dont start playing with things myself as if i accidentally manage to break something then ill invalidate my warranty
Luckily i managed to get in touch with Philip Youles (blackburn only unfortunately) who said that the work should really be repairable under warranty so im gonna leave all this well alone just incase i make things worse.
Youles said gonna pick the bike up on tuesday, fix it and drop it back off for £47 provided that they find the engine hasnt been tampered with - which it hasnt - well at least not that i know of

Hopefully ill be back in action next week sometime but thanks for the suggestions anyway.

Gaz.
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I seem to have misplaced my pants...................

[Pete.]

[feef]

[irving]

[Pete.]

Fuel injected bikes certainly won't flood by cranking with a wide-open throttle.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[mrbluesbox]

The only time i managed to flood it is by having the choke wide open on it when it wasnt entirely necessary (when i first picked up the bike )
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[Marci]

Had similar issues on the Mito... turned out throttle cable was snagging on ignition barrel. Started bike with handlebars turned to left and started fine. Soon as straightened out the bars, it'd rev to redline. I'd replaced throttle cable and not tied it off to it's usual spot. During the process of the snag, also pulled at the other end and pulled adjuster out of carb so it was snagging on the cable guide atop the carb... clicked that back into position, cable tied the throttle cable along a sensible path... all probs solved.

So, first things first, check cable doesn't snag when you straighten up the front wheel, then check both ends to ensure adjusters aren't caught on anything - ie: do a basic idiot-test before taking it to a mechanic and being appointed an idiot.
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FAB-Racing MiniMotoSidecars - Back with a vengeance - F1 Class 2011...
CBR170 engine, custom chassis - www.minimotoscene.co.uk

[mrbluesbox]

lol sounds like good advice
probably better check that before it gets sent off
Ill have a look when i get in later.
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I seem to have misplaced my pants...................

[ddracer]

This could also be a leak in the inlet manifold or the reed block if it has one, as this will allow extra air into the system and lean it out hence the redlining.

DD

[ddracer]

Added note to above check the 2 stroke oil feed line it may have come off or have a split in it that would be the same as a split intake rubber.