Txt280 Over Revving

[notfallenyet]

Have already posted this in the Gas Gas section and have had some responses but hope to get more coverage here!!

I've already read several posts about this problem but hav not come across the definitive answer.

Some people have had the same occur on Sherco's also.

Any help would be greatly appreciated.

Hi Folks,

Well the story goes like this, up at 7am have some porridge (need the strength) load the 2 bikes. Drive 15 minutes and meet my pal. Take the 2 bikes out, 1999 TXT270 and 2002 TXT280. Jump on my old 270 starts first kick!! Turn around and look at my pal who normally takes 3-4 kicks to start the 280 and he's bent over the bike. What's wrong now?? Seems that when he started the bike which happened to start first kick, it over revved uncontrollably. We started it again twice and the same thing happened.

The engine kill switch did not seem to perform it's function as efficiently as I would have liked during this over revving. It took quite a while for the engine to stop.

Load the bikes up again and home to the dungeon.

Cleaned the carb which was not dirty.

Air filter is clean.

Petrol is fresh.

Carb / throttle function is correct. Bike has a Delorto PHBL 26 carb fitted.

Spark plug was slightly creamy in colour but dry and clean with a good spark.

The bike is in very good condition overall and has not been abused. We're not talking about a bag of bolts here!!

The last time the bike was used was a week ago and then it did not want to idle, it settled down after about 20 minutes so we passed no heed of that.

So anyway people, what do ye think is the reason for this over revving.

Thank you in advance.

Edited January 12, 2009 by Notfallenyet

[jools]

Had this a few times on Gas Gas's in the past. Try;

1) Lubing the throttle cable. You need to do this regularly on Gas Gas bike or the throttles can randomly stick

or

2) There may be an air leek in the inlet (rubber bell mouth from carb to reeds). Regular removel of the carb can do this or if you run a Keihin in the original inlet, as its a larger bore and stretches it.

You said he runs the standard dellorto so could just be a hole or rip that developed over time.

3) The actual Inlet/reedblock unit maybe loose or gasket could have broke and air is finding a way in.

his is what i've experienced in the past. A few things to go on anyway!

Goodluck!!