Suzuki GN250 '94 bogging out at higher RPM, speed?

[Suture]

is there nobody in Denmark that can help?

Not anyone trustworthy. The mechanics here are overpriced to the point where diagnosing this issue alone would cost more than the actual bike did. As a benchmark, cleaning and adjusting the carb, changing clutch plates, checking the breaks and changing oil+filter as well as airfilter would cost 900$ here as a package deal.

[Suture]

Fuel flow with a blocked or partially blocked air intake on the filler cap (breather ) is intermittent normally runs fine for 5-10 minutes then the symptoms start and magically disappear (when the cap is opened to check the fuel level (for a while.)
The filter on the petcock intake (if it has one buried in the tank) is dependant on a number of factors including fuel head (level) and the amount sloshing happening In the tank.

Ah, so if I do what haydes55 suggested and drive around with the fuel cap slightly opened, this would diagnose the above? If it works it's the air intake and if it still an issue it's the fuel delivery (petcock, hoses, filter) or possibly the ignition system?

I'll have to check it tomorrow morning because for some reason the evening gets colder and the problem doesn't really present itself as much then, if at all. I suppose it does point to your suggestion as cold generally means less expanding of parts which could cause a blockage?

[husaberg]

Ah, so if I do what haydes55 suggested and drive around with the fuel cap slightly opened, this would diagnose the above? If it works it's the air intake and if it still an issue it's the fuel delivery (petcock, hoses, filter) or possibly the ignition system?

I'll have to check it tomorrow morning because for some reason the evening gets colder and the problem doesn't really present itself as much then, if at all. I suppose it does point to your suggestion as cold generally means less expanding of parts which could cause a blockage?

yes it could. A decent mechanic should be able to sort what the likely cause is in a few minutes
Not really anything to do with expanding parts, the bits are blocked or not
Note the colder weather =better running, maybe points to the mixture being overly rich at the moment , so check the air filter and the carb flat level as well.

[sidecar bob]

Not anyone trustworthy. The mechanics here are overpriced to the point where diagnosing this issue alone would cost more than the actual bike did. As a benchmark, cleaning and adjusting the carb, changing clutch plates, checking the breaks and changing oil+filter as well as airfilter would cost 900$ here as a package deal.

Sounds like I need to move to Denmark. Are there many BMW cars over there?

[husaberg]

Sounds like I need to move to Denmark. Are there many BMW cars over there?

That's rotten, I always suspected something was rotten in Denmark.................

[Laava]

That's rotten, I always suspected something was rotten in Denmark.................

Just the state. The rest of it should be sweet.

[husaberg]

Just the state. The rest of it should be sweet.

Alas I knew you so well, (that I knew you were going to say that)

[Jamesdsm]

It's bloody cold in Denmark at times, I'd adjust the idle to sit around 1500, see if that works for ya. As for the power loss, there's a bunch of things it could be, mostly been covered by previous posters

[Suture]

Sounds like I need to move to Denmark. Are there many BMW cars over there?

I suppose there are a few, but their drivers don't exactly have the greatest reputation :P

[Suture]

yes it could. A decent mechanic should be able to sort what the likely cause is in a few minutes
Not really anything to do with expanding parts, the bits are blocked or not
Note the colder weather =better running, maybe points to the mixture being overly rich at the moment , so check the air filter and the carb flat level as well.

Unfortunately the weather has been around -3 to 5 degrees. After I checked the cables the issue hasn't occurred at all so can't really say what helped and what didn't. I'm hoping you were spot on, and it was just a blockage that released

[Suture]

It's bloody cold in Denmark at times, I'd adjust the idle to sit around 1500, see if that works for ya. As for the power loss, there's a bunch of things it could be, mostly been covered by previous posters

The idle is set to 13-1400 from the visit to the mechanic. It doesn't start 100% as it used to (required throttle) , but when it's warm it idles perfectly. I'm hoping the previous posters were right in that it was a blockage, because I haven't experienced the issue again. And yeah, it's friggin cold :P I have heated handles and heated gloves and my fingers still get a bit chilly if I drive above the speed limit :P