Hyosung GT250r Cutout problem...

[justin777]

Hi All,
New to this forum, but thought it would be a good community for advice...
I have had my Hyo for a few months, without any real problems.
Lately, I have noticed it has backfired through the carbys on start a few times...
Yesterday, I was coming home from a mates house, and coming onto the freeway I dropped it back a gear and booted it to redline to merge, then changed to 6th and the motor backfired and cutout altogether for about 3-5 seconds, then came back on after I twisted the throttle off and then back on a bit....
In the next few minutes of cruising at 7000rmp (100kmh) it did the same thing 2 more times..
I pulled over, and stopped the bike to look for any obvious problems, but couldn't see anything. I babied it home just taking it easy without incident, but its got me freaked that Its gonna leave me stuck on the side of the road somewhere...

Anyone got any Idea what this could be?

Cheers in advance
Justin

[antoineperth]

clean out carbies????

[killswitch54923]

bike may be running a little rich if it's constantly backfiring like that, not to sure as to why it is stalling tho.

[burlyoaf]

you got 6 gears?

[Aussasin]

What year is it? How many K's has it done?

[jasle]

Im going by car (because i play with carbies) it sounds like it is just running to rich not catching a spark... or the spark plug could be iffy just go through the ignition system make sure you are getting the right voltage everywhere

[justin777]

Its a 2008 model, done about 8000km's.
Yes, its a 5 speed... sorry.. just used to the 6 in my car... never really counted the gears i guess!
Thanks for your suggestions... clean out fuel system, check spark and voltages...
Will post if I find anything suspicious!

[justin777]

ALso, been reading a bit, and it seems that this bike has a problem with ventilation in the tank... so when you boot it to hard for too long, the suction gets too great on the tank, and effectively stops the fuel flow for a bit... then when you back off the throttle, it allows the air in the tank to equalise, and thats why it cuts back in... sound plausible?
Someone even said the vacuum was so great, it used to pop part of their tank in, and on release, it would pop back out...
Any thoughts on this?

[Aussasin]

ALso, been reading a bit, and it seems that this bike has a problem with ventilation in the tank... so when you boot it to hard for too long, the suction gets too great on the tank, and effectively stops the fuel flow for a bit... then when you back off the throttle, it allows the air in the tank to equalise, and thats why it cuts back in... sound plausible?
Someone even said the vacuum was so great, it used to pop part of their tank in, and on release, it would pop back out...
Any thoughts on this?

I've heard of this prob before, but never experienced it myself. From what I've read it seemed to be more of a prob with the earlier models.

[Aussasin]

But still doesn't explain the backfiring through the carbs. Have you rang your dealer about this problem?

[Decoy]

I have a 2008 model and sometimes after a hard squirt on the highway and rolling off and back on again it will lose power (feels like fueling issue) and then surge back on again and go as normal. I guess it's just that tank vacuum thingy

Once it lost power altogether and I had it towed to the dealership and we thought it was a carby issue. Turns out it was a spark plug lead came loose

[chuppathinggy]

hey, ive got a 2010 model and had trouble with stalling when changing down gears and revving high up to 3-4 mins of starting the bike. happened about 4 times. when i took it in for a service they said there was something wrong with the throttle computer. not sure of the technical terms... they replaced something in there for 80bucks, but the warranty paid for it. hasnt happened since and ive put another 5000k's on it since then.