Exup valve needs adjusting?

[slappy]

If I accelerate hard once I hit about 9000 revs the engine misfires really badly and I have to back off, its ls very pronounced misfire.
I have changed the fuel filter but it made no difference. If I accelerate normally there is no misfire.
Am I right in thinking that my exup valve needs adjusting?

[PaulSmith]

No. Exup is fully open at 7k. More likely to be something partially blocking your airbox.

[Tmation]

Ah the old waterproofs or spare gloves under the seat trick 

[slappy]

I just checked under seat and the airbox inlet is clear of any obstruction.

[Falcon 269]

When was it last serviced?  Plugs checked/changed?  Air filter cleaned/replaced?

What's the mileage?  Any mods? 

You're saying you can get it to the redline with gradual throttle but not full throttle?

[slappy]

Plugs and filter were changed six months ago. No mods done except for Akrapovic end can which has been on for 18 months.
With gradual throttle I can redline in first three gears, not tried other gears as I would need a nice quiet road for that. 

[Falcon 269]

OK, thanks - more questions.

Has the bike been laid up over the winter?  More precisely, how much has it been ridden in the last few months?  Were these symptoms present before?   Mileage would still be helpful to know. 

In the meantime, I would check the EXUP operation and adjustment just to eliminate that from the list of possible contributors.

[slappy]

It has been used at least once every two weeks over winter doing about 60 miles each run out.
The symptoms have only appeared on the last two rides, this Sunday and a week  ago.
The mileage is just over 22000 miles.
I will check the exup this coming weekend.
Thanks for the feedback. [size=78%] [/size]
 

[Falcon 269]

I'd drain the float bowls, too, in case you've picked up some water in your fuel.  Be careful you don't overtighten the drain screws because that will crack a float bowl.

You could also remove the plug caps and trim 1/2" off the wire to get a good contact between cap and cable core. 

These two steps are intended to eliminate simpler possibilities before going further into the diagnostics.

[unfazed]

I agree with Falcon269 comments although water is more inclined to be a slow starting issues than a high end rev issue unless you have a lot of it, but it could be an accumulation of dirt in the bowl which is being sucked up under hard acceleration, so draining as he said may solve the issue but for a different reason. If it improves after draining you may have to remove the carbs and clean out the bowls.
also check to ensure the fuel pipes are all ok, no kinks check both the one from the tank to the filter and the pump to the carburettors.
Just because the air box inlet is clear is not enough to check, you will have to lift off the air filter cover to ensure nothing was sucked in.
Would not be the first time a little furry friend made a nest in there.

[PaulSmith]

Check the condition of your airfilter aswell.

[slappy]

Thanks for all  the info, I have got Thursday off work so it looks like a long day in the garage.

[Slaninar]

Just a wild guess. Does the 1000 have a fuel pressure regulator? I know that some GSXR 1000 have that, apart from the fuel pump. It has a tiny fuel filter inside that can get stuck - so it has to be changed (100 euros), or cut open, cleaned, then welded. 

[slappy]

Problem now sorted, though I am still unsure of exact cause.
I trimmed half inch off ht leads, adjusted exup valve as there was a little bit of slack in both cables and drained the float bowls.
The only thing that I could see wrong was a bit of corrosion on one ht lead where it screwed into the cap.
Took it out for a test run and it ran fine , in fact it felt smoother at all revs.
Thanks for the tips and help. 

[Falcon 269]

Simple fix.  Good.  Love it when a plan comes together.