Running Rough when warmed up.

[Seifer]

Don't want to get to broken record with you guys but I thought I'd chase some advice. Bike starts and idles fine when cold on all cylinders. However after going for a short ride, say 3 mins cylinders 1 and two struggle, cylinder 1 runs ok but doesnt seem as hot as the others, but cylinder 2 shuts down altogether. I still need to balance the carbs properly but what is causing the change once it warms up. 1 and 2 run off the same fuel line but the filter seems ok. This continues on idle once warmed up.
The factory pro tuning tips suggest its running rich but plugs are fine, not fouled but how long do u need to ride till you see soot. Any case I dropped the needle right down to the second slot. Ive also dropped the mains to 147s from 152.5.
I get the feeling its running fairly hot but I havent taken a proper temperature yet (is a thermometer down the oil filler ok?).
Im also concerned I may not have given enough gap on the piston rings but im not sure what the symptoms of that are, Im prettyu sure i did it correct.
Bike is a GSXR 1100, 1216cc, 5 degree yoshi advance.
Exhaust is 4 into 1, ceramic coated.
Muffler is a shorty coming out from under rear sets.
Carbs are 36mm, factory pro, as i said needle clip at second highest slot, main jet 147, pilot is whichever they gave in the kit, 2.5 on the screw.
Running 2 pod filters

I know there are a lot of questions but there has to be something im missing. Id rather get rid of anything obvious before i take it to the mechanic/dyno.

[Seifer]

Oh and I aboslutely suck at setting the float heights, like for me near enough is good enough, so has anyone got any tips, i swear when I bend the tangs it barely moves. and i have no clue how to hold it steady and know when the float is just depressing the needle. IM pretty sure they are right but that probably means shit,

[pommie02]

what happens if you come back from the ride and let the bike idle for a while ?
if the fuel height was too low, this should sort its self out at idle.
running too rich....remove the air filters to let in more air
too weak...pull on the choke to richen up the mixture.
i assume the engine has been pulled down ? do you have a compression gauge.
it could be leaking valves

[Seifer]

Ok its definately a carb balance problem, I had a fiddle with the balance screws and got it to run pretty well both warm and cool. Only problem is the suction on one of the carbs is very low, so i have three balanced (1,2,3) but 4 is useless. When I raise it up to meet the carb next to it the revs increase up to about 4k. What would cause this? Intake leak? ( I sprayed wd40 but there was no noticeable change). WHat else.

Also where should aGSXR1100 idle, it dies anywhere below 1200 revs.

[pommie02]

are you using vacuum gauges.
if its not sucking the fuel wont be sucked into the cylinder.
swop a couple of intakes over to see if the problem moves.
where abouts are you ?

[Seifer]

I'm in the inner west Sydney, i'll try a swap over tomorrow. Problem really is that once they are balanced i cant drop those revs, so what is the last cylinder doing to cause that. I'll let you know what happens tomorrow.

[pommie02]

balancing is easy with the right tools, i have never managed to do it without vacuum gauges.
you could have closed off one butterfly, thats why you have no suction.
i always set the carbies up on the bench first, using a small feeler gauge in each butterfly and get an equal gap
that gives a good starting point
is the bike causing black smoke at idle

[Seifer]

No smoke, im using a proper set of gauges so no issue there.
What is a a butterfly exactly?
As long as its not the valve clearances then im fine, i cant take the rocker cover off as all 7/11 owners will be familiar with,
Im pretty surethey are correct tho.

[oldskool]

Too lean.

[Gix11]

quote:Originally posted by Seifer


What is a a butterfly exactly?


Butterfly Valve to be correct. Here's four of them (the gold things):

http://www.asfphotos.com/upload/1265159006.jpg

[Seifer]

Right...Gotcha,
Well ive figured it out, 3 things have caused it. 1, one of the carb rubbers was missing a bolt so prob letting a bit of air in. 2. The exhaust valve was to tight on the number 4 cylinder. And 3, the main culprit, the vacuum cap on the carb was cracked where the hose hooked in for the guages. Hence the false reading. She still doesnt have asmooth idle but she is getting thre.
Where should the 1100 idle and how smooth should i expect it to be.
Thanks for the help,

[Seifer]

Oh one last question, what would cause the revs to jump 2k revs as soon as u tap the throttle, it idles between 1000-1300 but as soon as you turn the throttle a fraction it jumps to 3500 revs plus. Any ideas?

[grindella]

carby balance is out

[Gix11]

The balance will make all the difference mate. Get all seals sorted right the way through and make sure nothing is catching or rubbing (in other words make sure they are clean) and then do the balance. Will make a world of difference.

[oldskool]

air screws need to come out a turn.

[Seifer]

Ive richened it all out and its running much much sweeter, one last question...
Can I measure the enginge temperature by placing a thermometer between the fins on the cylinder block?
Or will this be hotter than it should be?

[BANDITROD]

oil cooled motors always seem hotter than what they actualy are dude chances are its fine

[Seifer]

Ill take ur word for it, shes at around 115 on the case. Its on you tho Rod, on you.

[oldskool]

Your welcome.

[Seifer]

Was that sarcasm? I said thanks a few posts up and I havent finished yet.
Thanks for your help thus far though, mate.

[BANDITROD]

quote:Originally posted by Seifer

Ill take ur word for it, shes at around 115 on the case. Its on you tho Rod, on you.
how is it going mate have you got it sorted

[oldskool]

No sarcasm here, If you take Rodders word for anything you are welcome to it.LOL
Me sarcastic fuck no Im black an us niggas us guns not sarcasm.

[Seifer]

I think so rod, I rode to work yesterday and the temp was at 130, thats at 11pm, no traffic.
I rode it home with the choke on and it registered the nasty heat of 80 degs so i'll up the mains by a bit.
So yes, sorted.

[BANDITROD]

good to hear

[Supercharger_Mark]

Hi Seifer
Before I had a set of vacuum gauges (which is the wright way to do it) I took the carbs off and got a ½ or 1mm diameter drill bit, wound the idle screw in until the smooth end of the bit just slipped under the lowest point of the butterfly, on the carb that houses the throttle cable. Then adjust the next carb to each side so that you just feel drag as you pull the bit out.
This will get your butterflies pretty close to the same opening.
And, spend time getting the float height Wright it is that critical.
The next thing is: Worm the bike up and with a short screwdriver(I cut an old one down) adjust the idle mixture screw starting at about 2.25 turns out on all in half turn increments one carb at a time.

Hope this helps
Mark.

[Seifer]

Ok here is an interesting one for you, what would cause two of the carbs not to fill up properly. If i leave the tap on prime, carbs 3&4 fill up completely but 1&2 only a tiny but.
First off its not the tap or the filter, they are flowing fine.
Second its not the floats, when I blow through the fuel hoses 3&4 can't blow through cause the floats have closed but 1&2 flow though.
Third its not the balance as this happens when the bike is off.
Fourth its sporadic, sometimes it fills up, other times it doesnt, my ride to work this morning it didn't and leaned out badly as a result.
Any thoughts, thanks guys,

[oldskool]

some GSXR carbs had 2 fuel lines has yours been converted to a single line?

[Seifer]

No I have 2 Lines, how do you convert to one?
Ive richened up the mixture a fair bit, at the screws, pilots and needle and its running still at 120+ degrees. Im taking it to get tuned next week. Anything else to check overheating wise, its got a five deg advancer so i doubt the timing is retarded enough to cause it. I think my spark plugs burn a bit hotter than the J9A's they normally have in it. Will this be enough to do it.
Is there a difference between case temp and oil temp, cause im just measuring the temp from the fins on the block.