Issue with CG?

[TygerTung]

I've got this problem with my CG being if you hold the throttle wide open for too long it will just cut out on you for about 10 seconds.

So I'm caining down the motorway, lying on the tank, feet on back footpegs, creeping up to the 110kph mark, then it just cuts out on me, slowing down, going down through the gears, then it comes back to life.

Also can happen when caining up the hills.

What could cause this?

Cheers,

Sam

[beyond]

Check you have enough fuel in the tank.
Check that the carbeurater float needle hasn't got some crap in it.
Sounds like you are sucking fuel out of the float chamber faster than it's going in??

[k14]

Yeah I'd say its running too lean. You have to be careful running those smaller bikes are wide open throttle for too long, can sieze them if you're not careful.

[FROSTY]

bro tis simple--check the badge on the tank --remove it all all will be good
But seriously I agree with the above posts --but also check that the fuel line is big enough and unscrew the bottom of your fuel tap off--Its a square headed bolt,--in there is a fuel filter--make sure that is clean and unclogged
DONT just eyeball the jets etc--blow em out with compressed air -blow in the direction of fuel flow

[T.W.R]

possibly it could be an issue with spark aswell seeing its only happening at full noise! the coil could be breaking down :yes:

had an old XR250 that used to do the same thing

[TygerTung]

It's only if you're wide open continously for about 2 or 3 minutes.

I'm going down the motorway soon so I'll try it out and see if it does it again.

[MSTRS]

Then you definitely have a fuel 'blockage' ie the fuel in the bowl is being used quicker than it is being replaced. Remove fuel tap from the tank and strip/clean all parts. Replace the hose to the carby with a larger bore. Carby sounds like it is fine, so leave it alone.

[TygerTung]

Went out for a ride today and didn't do it at all, in fact was running real mint!

I'll do what you said though and clean everything out in any case.

[F5 Dave]

Do you have an in-line filter? These constantly are the cause of the fuel hose kinking. Sometimes just re-running the hose will fix or cause a problem.

Also check the tank cap vent it not partially blocked.

[TygerTung]

Nah no inline filter.

The tank doesn't vent at all, in fact it's sealed as. Does it need to be vented?

It's fully airtight.

[Motu]

Just because it's a tight fit doesn't mean it's sealed,loosen the cap and try again - just don't lose it! Like everyone says you have a fuel supply issue,if it's good some days and not others then something is blocking and unblocking the supply - you are going to have to do a strip of the whole system and clean out everything as you go....start with the carb and work backwards.

[MSTRS]

....start with the carb and work backwards.
Or start at the tank end. Murphy's Law will still ensure that the problem will be the last thing that you check.....:killingme

[F5 Dave]

Maybe he’s already applied that idiom.:shifty:

The tank has to be vented for petrol to get out, just like anything struggles to get out of a vessel but like the old T Sauce can if you make a vent hole in the other side they flow much better. If you take the cap apart you will see how it vents. People get caught out on this often when a tank sealant is used.

On my GS tank there was another vent in the top of the tank filler (when cap is off the pipe extends into the tank.) that helped bleed the air from above the filler so you could squeeze another litre in. I’ve got to admit, that one caught me.

[TygerTung]

It's not the original cap, and it builds up pressure in the tank if it's am hot day.

Looks like this may be the problem, do I just drill a hole in the cap and put a tube, like on some other motorcross bikes or somthing?

[F5 Dave]

Thank you, thank you. Send the cheque to the usual address.

Depends on the cap if it can be modified so it doesn't squirt out petrol, or just find another cap. Have made tank breathers, but really hard if you can't get into the tank to push a stem up & bolt it.

You could use a tyre stem through the cap & a tube with one of those MX one way flow tubes.