GasGas TXT80 Won't Start

[Dillypoop]

I just picked up this GasGas txt80 yesterday for cheap ($600 US). It's a 2001 model, from what I can gather. The PO said the bike was "hard to start and running poorly."

Well, I got it home and tore into it to figure out what it is. First thing I noticed was fuel EVERYWHERE! They just cleaned it off when they brought it to sell, but fuel had filled up to the expansion chamber and all the way back into the carburetor. Weird, but okay. I noticed the carb fuel vent line was missing so I added that. Maybe the float got stuck and couldn't flow out fuel because it couldn't build up head on the vent being as high as it is?

Second thing I noticed:

"Well taken care of." Ha, right!

Then, I noticed this: 

I guess that'd cause it to be hard to start, huh? Gas was squirting out of it and the head pipe while trying to kick it..

Anything else y'all can think of to check first before ordering parts? Spark is good, it's wanting to start. Compression is 165psi. Seems high for a head problem. Rings, piston and cylinder look fine but I haven't measured ring end gap yet; just a quick look through the exhaust port. 

[jfc]

Have you turned the bike upside down with the plug out to remove the excess fuel from the crank, turn it over by hand with the kickstart pushing out the fuel through the plug hole. (Make sure the spark plug is well away from the fuel!)

check carb float and needle are working as it sounds like the fuel is just over filling the carb!

[section swept]

You’ll need to remove the exhaust and allow it to drain out too! Check the carb vent pipe routing from the workshop manual to make sure you don’t create problems. If you turn the bike upside down to empty the crankcase be aware that the gearbox oil may leak out through its breather. 

[Dillypoop]

6 hours ago, jfc said:

Have you turned the bike upside down with the plug out to remove the excess fuel from the crank, turn it over by hand with the kickstart pushing out the fuel through the plug hole. (Make sure the spark plug is well away from the fuel!)

check carb float and needle are working as it sounds like the fuel is just over filling the carb!

I picked it up on the front tire and pushed the kickstarter getting most of it out. Really kicking it got more to shoot out of it during a compression test... That was fun. The plug is soaked and probably needs to be replaced. I noticed the NGK the PO replaced it with looked new and it seemed like it was a cooler plug than needed. If I recall, it was a BR9EIX. I'd figure a hotter plug would be needed with the time spent at idle in trials? The BR9EIX is a plug we generally used in high-compression dirtbikes. He most likely just threw that in there since that's what he had.

 

I checked and they seemed fine. I'll throw the carb in the ultrasonic cleaner and get everything else really clean. Do these Delorto (sp?) carbs only have vents and no over-flow lines? What about a set float height?

I thought it was pulling in gas from the intake vacuum. Maybe not?

1 hour ago, section swept said:

You’ll need to remove the exhaust and allow it to drain out too! Check the carb vent pipe routing from the workshop manual to make sure you don’t create problems. If you turn the bike upside down to empty the crankcase be aware that the gearbox oil may leak out through its breather. 

I've done that also. It was full of it... I do like how easy they are to remove on this bike!

I've not been able to find a workshop manual for this bike. Does it even exist?

Thank you for the pointers. I'll most likely be draining all fluids and pulling the engine to tear the top end down.

[copemech]

if it is a standard dellorto phbl the things on either side are bowl vents only and not an overflow. no hoses are required but short ones act as mud  deflectors. the float arm should be Level with the bowl surface w/ inverted. be sure the floats are not floded and float properly.

[Dillypoop]

16 hours ago, copemech said:

if it is a standard dellorto phbl the things on either side are bowl vents only and not an overflow. no hoses are required but short ones act as mud  deflectors. the float arm should be Level with the bowl surface w/ inverted. be sure the floats are not floded and float properly.

Thank you. It's a PHBG21DS and it looks like a single vent.

I was talking to Jim Snell and he said he bets the fuel was left on and it'll drain from the tank and into the cylinder over time when transported on a trailer (or truck). Weird but okay. 

Ordered the head gasket, some other miscellaneous gaskets, and a new rear brake MC. The old one's piston is seized in the bore. 

I did also notice the boot coming from the airbox into the carb is full of holes. Has anyone been able to make up a replacement for this? Apparently the manufacturer "lost" the mold. 

[Dillypoop]

GasGas TXT80 Info.PDF

GasGas TXT80 Info (2).PDF

GasGas TXT80 Info (3).doc

Here's some info Jim sent me about the TXT80 models if it will help anyone else. It's a general spec sheet (.doc), a slide mod diagram and a clutch cover tutorial.

[copemech]

good deal, as I was going to point you toward Jim anyway, as he is the knowledge bank. parts too!

you may have to make up an inlet hose.