'91 gsx1100f low power problem

[gratz]

Hi, Just a question re: my bike..

It's a 1991 suzi gsx1100f powerscreen with 44000 miles on the clock. The problem is that it runs out of steam above 80mph. Seems to accelerate fine through the gears (although not as fast as it should) and in top will cruise at 90 all day. If I crack open the throttle it takes ages to get to 100 and runs out of steam - it feels as though it has been restricted somehow...

I plan on changing the plugs/oil/filters to see if that makes a difference. Just wondered if anyone had any thoughts. This should be a 136 bhp bike and much faster. I used to have a gpz1100 & that was ballistic in a straight line, and was hoping for a similar riding experience...

[Tango]

Yeah....I'd start with replacing plugs, air filter, oil and filter etc. There's nothing blocking the air inlet to the airbox is there?......sounds like the engine is being strangled. Megawatt is the man for these bikes.....He used to race it's predecessors at Santa Pod and elsewhere.......

[gratz]

Nothing blocking air intake as far as I can see - plan on taking it out in the morning (weather permitting...) and giving it a good old hoovering to see if that makes any difference as a temporary measure. It's very frustrating as it starts on the button, doesn't smoke or anything, runs smoothly other than the top end issue and is otherwise everything I was looking for in a bike having foolishly sold my '96 GPZ1100 a couple of years ago...

[Stu]

sounds like the diaphragms aren't working as they should to me this is a known problem with them

[ThePhatomfart]

Yes agree with whats already been said, top speed problems like this I always look at valves(adjustment) spark (good strong one) and carbs (good function) and maybe float height too low

[gratz]

Cool, thanks guys

Will check air filter first & hope it's an easy fix (when does that ever happen haha? ), failing that will check carb diaphragms & see what happens...

[megawatt]

The oil cooled GSX1100F has more in common with GSXRs than air cooled GSX1100ET Bob.

Lack of top end power points towards a main jet problem, a restriction in air or fuel flow or a power problem related to a throttle position sensor or ignition timing. Did you do anything to the bike immediately before the problem occurred?

[Tango]

The oil cooled GSX1100F has more in common with GSXRs than air cooled GSX1100ET Bob.

Ah....fair enough Alan......

[gratz]

Thanks for all the replies guys

I have recently bought the bike, so have done nothing to it as yet other than to patch a couple of holes in the exhaust- it seemed fine on the test ride and riding it home (when I was taking it easy), but it wasn't until I started using it for my daily commute that I noticed the top end power is lacking... Dont know if it's relevant, but it also seems to be very frugal on fuel for an 1100 - I am getting around 200 miles per tank

[Tango]

Yeah....deffo sounds like a carb issue. Pull the plugs and check their colour........also, I'm assuming that the throttle cable is adjusted ok?.....and the carbs are balanced?