GSXR1100 fix

[kerryg]

I bought a GSXR1100M as an insurance wreck. I bought it off a a guy who was using it as a commuter and it was running well until his minor prang (which involved some mainly minor and cosmetic damage...the engine was not affected). Bike sat around for a month or two before I got it. Whren I tried to run it it roared straight to 6000rpm and coughed and spluttered and backfired. So I've drained, cleaned and refilled the tank with fresh gas, pulled off the carbs and given them a good once over and clean (although actually didn't find any crap in them but anyway pulled them to bits and blew air through jets etc), serviced air filter (UNI filter, so it was washed and re-oiled), fresh plugs. Started her up and went straight to 6000rpm. Rough as buggery and the odd backfire to boot. So after checking throttle cable adjustment and idle screw setting I tried again...same thing but this time to 3000 rpm and then dying. Still running rough. Re-start ..same thing. Straight to 3000...then dies.

I'm puzzled. Any ideas??

[750Y]

butterflies/throttle cables operating freely? vacuum attached correctly?
choke working properly?

[vifferman]

butterflies/throttle cables operating freely? vacuum attached correctly?
choke working properly?

Hydrocillator primed with Uranium 232? Pilot light lit? Operator lubed with beer? Mmmmm..... beeeeerrrr......

WTF?!? Why don't we have a drooling Homer Simpson smiley?

[kerryg]

butterflies/throttle cables operating freely? vacuum attached correctly?
choke working properly?

Butterflies/throttle cables/choke seemed to be working fine when off the bike. Now (to reveal my ignorance here...) the vacuum. Are you talking about the vacuum tube from the fuelcock to the carb inlet manifold?

[kerryg]

Hydrocillator primed with Uranium 232? Pilot light lit? Operator lubed with beer? Mmmmm..... beeeeerrrr......

WTF?!? Why don't we have a drooling Homer Simpson smiley?

I am thinking it will be something blindingly stupid (somewhat like the response above... ). The bike was (according to the previous owner, who I believe) running well before it was pranged and the engine was not implicated in the prang...so it's something related to sitting around unused perhaps, or it's something has been bumped in the prang...or someone has messed with it since the prang .......

[vifferman]

I am thinking it will be something blindingly stupid (somewhat like the response above... ). The bike was (according to the previous owner, who I believe) running well before it was pranged and the engine was not implicated in the prang...so it's something related to sitting around unused perhaps, or it's something has been bumped in the prang...or someone has messed with it since the prang .......

The irritating thing (apart from my last post) is that I've read this exact same description countless times on various forums:
"Yeah, I bought this (insert name of mouldering 3547 year-old museum piece here) and when I started it it revved to a bazillion revs, backfired through the carbs, burnt my eyebrows and hairpiece off, then stopped".
But I'm pharked if I can remember what the usual cause was, except it was usually summat to do with crap in the carbs, and you said you've already cleaned those. Are you sure everything was hunky AND dory? What about the carb sliders and diaphragms?

[gav]

Maybe some sort of air leak? throttle slides definately closing properly? guess you've checked for a kinked cable somewhere? stuck choke cable?

[kerryg]

Are you sure everything was hunky AND dory? What about the carb sliders and diaphragms?

Always keeping in mind my amateurish mechanicking skills......I didn't find anything awry in the aforementioned areas including the aforesaid prophylactic devices and slidy things

[Blakamin]

tried the inlet manifolds for cracks? timing cover? electrical problems? (my cbr backfired and flamed the exhaust when i had a loose connection)

[Mr Skid]

(my cbr backfired and flamed the exhaust when i had a loose connection)

Have you considered setting up a new thread for all the stuff that's gone wrong with your cbr? I'm having trouble keeping track of it through all these other threads..

[aff-man]

i gots a problem with the manafold rubbers that is causing the exact problems you described. Make sure they are sealing properly.

[Sensei]

As above check that the diaphragm on top of carb slides are sealed & have not hole's & are in the right way round / Check that all the vacuum cap's for tunning are on the nozzle's Check that your butterflys are closing & cables are on the right linkage for opening & closing > back firing is a sign of unburnt gas or lead's on the wrong plug SENSEI

[kerryg]

Well here's the weird thing. I took the carbs off (that makes 4 times now) and rechecked everything. Nothing obviously wrong apart from a decent sort of a leak from the drain plug on one float which I thought I had already remedied..but this time fixed real good. Re-assembled it. Fired it up and it ran fine. So, go figure. Maybe I had a cable twisted or something, to account for the over-revving, and/or an air leak at the inlet manifolds that was fixed when I reinstalled the carbs and tightened everything up real well and/or fuel starvation on one carb due to the leak which accounted for the rough running.... or all of those..or none....I'm none the wiser really. Anyway it's all good until....

I was off the get a dyno done on it today and it starts coughing and spluttering and I limp to the bike ship running on 2 or 3 cylinders where it is now being looked at by *proper* mechanics but interesting thing the service manager said to me was "what gas are you using" and I said 96 and he said that's pobably the problem, a fouled plug due to using the crap 96 gas we get here.....so I hope that's the reason but I'm using 96 in mty other bikes too and NOW I'M VERY CONFUSED