GPX 250 won't idle warm

My GPX has a problem where it will start and idle (without needing to
use the choke to start) but then after a minute or so the idle speed
will slow and then the motor will die. I suspect that there is some
blockage but then why does it start at all?

Any suggestions appreciated. Thanks.

 

Is this if you just sit it there and don't blip, or give it a bit of
throttle, or it will do it when it's hot as well, ie, after a 20 minute ride
or something?

Most carby bikes take a bit of warming up in winter, so even though they
might start, they won't idle when they are cold without a bit of help.

Cam

 

Hi,

Thanks for the reply.

On the morning it happened I noticed something wierd in the idling and
suspiciously just rode around near home, for a long enough that normally
the bike will go without a choke. I ended up having to push it home. I
would get to the roundabout at the bottom of the hill and it would die.
I normally don't need to use the choke.

 

I've seen that happen when the battery has little fluid left
in it. It will start cold, but as the charging system tries
to charge the battery, the lack of fluid can make it boil the
remaining fluid, and current just stops flowing and it comes
to a stop. Impossible to start again. Leave it an hour or
two, and away it goes again.

Topping up the battery at least let the person get home.

I never heard of what caused the low battery fluid,
but it could have been a dud charging system that boiled
the battery, or just poor maintenance.

Rob.

 

If it's a fuel blockage, there would have been enough fuel in the float
bowls to go a few hunderd meters.

(you *didn't* have the fuel tap turned off.. did you?)

If your fuel tap is vacuum operated, then a blocked, broken or displaced
vacuum hose would do it. In which case using the 'prime' setting would
get you going again temporarily.

Did the bike go again later or has it stopped altogether?

A partial blockage in the fuel system might let the float bowl refill
slowly, then make the motor cut out when it is empty.



Moike

 

The bike is still rideable sort of, it's just that if you let the revs
drop to idle then it is prone to stopping and even if you catch it it is
very slow to build up revs again and very rough. However once you are
at 80k for example it seems fine. I think it is a fuel blockage of some
sort, not certain. I did note that a pipe to one carby was not
correctly pushed on and missing a pipe clamp.. Had to put a cable tie
on it. This seemed to work for a bit since it would then idle, but
after going for a ride the problem came back.

 

What kind of pipe? Fuel line? Vacuum line?

If there's a vacuum leak and a vacuum operated tap, the tap could be
closing at idle.

-----sharks