Highway troubles (tried a lot!) -fixed!!-

[Krav]

Hello!

Im experiencing the following problem

Problem
When travelling the highway (100-120km/h) in less then 3 KM's my bike will
- start losing power
- starts stuttering
- starts responding poorly to the throttle
- have trouble keeping it running and will idle really low by the side of the road
- When i wait 3-5 minutes, it will start and idle normally, and i can drive on a bit for less then 3KM's before it starts all over again.

Note
- When the symptoms start appearing, and i open my throttle fully, it will still pull. As symptoms get worse, even this will not work anymore.
- The problem only happens when in 6th gear as it seems. Today i drove to my work in 2nd, 3rd (a lot of 6-7000 rpm) and it didnt show any signs of trouble at all.



Here's what i've allready done.

Tried possible solutions (in this order)
- Octane 100
- new spark plugs
- Oil change
- Oilfilter change (to K&N)
- Valve clearance changed (on the low end, but in spec.)
- Removed frame petcock. RES directly connected to carb's. normal fuel capped off
- Installed 2 podfilters (main jet's 148) (a small checkup revealed that its not really dirty in there)
- Cleaned fuelcap (it didnt seem to do Pssssshhh when i opened it in the first place though.)

this i haven't highway tested yet.
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- Connected frame and engine block to the - on the battery, to make sure of grounding of frame and block
- New fuel line and new fuel filter
- Adjusted Sparkplugwire's not to touch the beltcover/engine anymore.
- Cleaned off bobine connections a bit, not really well though.

I noticed that spilled fuel leaves a reddish residue btw. Seems like rust in the tank. but if that was the cause, it shouldn't only show this problem at the highway, should it?

I'm out of idea's what can it be?!

[bmf]

I am thinking fuel supply, try to run it on prime to see if there is a vacuum problem. Double check the tank cap?

[Krav]

Thats what i read on the forum aswell. There is no petcock now only the one on my tank. There CAN not be a vacuum problem, or clogged route from tank to carb.

A colleague of mine suggested that i would clean out my tank. especially since its now hooked up to the RES on my tank petcock. im going to do that when i get home. Other ideas are most welcome though!

[Malfruen]

- New fuel line and new fuel filter

New fuel filter? Have you got one installed at the moment?

If so, get rid of it and see if that helps at all. I had one on my GS when I bought it and had the same issues as you're describing until I chucked it.

Edit: If you're worried about rust getting into the line, there is a mesh screen at the base of the tank which should hold back any big nasty bits of what used to be a fuel tank from getting out.

[HPP8140]

check float height

[Krav]

I had one installed. I replaced it now, and the fuelline aswell.

The rust isnt really visible in the fuel, but you can see that the fuel in the line isnt really that clear.
The reason i saw the rust in the first place was because i spilled some fuel , and when it dried, it left a red/brown residue.

How do i check the float heigth? how do i know how high to set it?

[The Buddha]

Vacuum lock in the tank.
Or you pinched a hose that lets air equalisation - the top T of the carbs.
Or Pinched a fuel line.

Did it suddenly start doing this ?
What did you do recently ?

You start taking a nice big tank bag ? - Yea it closes off the tank vent.
You move things around under the seat - you pinched a hose ... etc etc.

Cool.
Buddha.

[Krav]

Hi Buddha,

I took apart the tank cap, and cleaned it all. especially the vents.
The hose on the T piece is in a nice straight line till between my accu and my frame, not pinched. (do it like this, because of the absence of an airbox)
fuel line is not pinched.

I think, and i think of it just now that i had this problem when i put my bike on RES before. so maybe i should clean out the tank, or connect to my FUEL instead of my RES.

What i did recently is in the list in the first post.
i don't have a tank bag. and im sure that all the hoses are free and unpinched.

[Krav]

  managed to resolve the problem! I connected up to fuel insted of res on the tank, and the problem was fixed.

I gyess i have to clean the tank petcock now.
My overal performance has dropped a bit though. I guess im going to need to finetune a bit.

Thanks for the help anyways!