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ral

GSX 1100 ET

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Having loads of aggro with this, carbs have been completely stripped and all jets and airways thoroughly cleaned but still refuses to run from cold on cylinders 3 and 4, complete nut and bolt engine rebuild so reluctant to rev it too hard but both cylinders kick in above 5000rpm,driving me bloody nuts, Ignitor unit/transistor unit checks out ok, spark is good on all four pots, is it just going to be pilot jets or am I missing something?...

Carbs are standard Mikuni BS34

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Welcome to OSS,

Three things it maybe, 

1. Float height.

2. Pilot jets.

3. Air leak in intake carb rubbers, use chain oil or similar and spray over and around carb rubbers.

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Thanks for the reply Wraith, will be pulling carbs off AGAIN this Sunday to double check, forgot to add that air box and filter is also standard.

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Check the little jet in the float bowl that feeds the choke.

Often missed and difficult to properly clean.

Do those 2 cylinders run ok when warm, or are they always off below 5k?

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When the bike is warm does it run OK? If so, I had the same on my efe engined bike. It's the very fine drillings for the cold-start circuit that get blocked with varnish. These are in the float bowls and in the main carb bodies. It is fairly striaghtforward to clear the float bowl holes as you can see if they are blocked or not by squirting carb cleaner. For this I used wonder wheels wheel cleaner applied with a syringe (it's fairly acidic). For the main bodies, it took several attempts using various methods to get it all cleaned out. First, I soaked the carb bodies overnight in a mixture of acetone and cellulose thinners (it's probably not a good idea to smoke when mixing this solution......).  Make sure all rubber and plastic parts are removed as the solution will destroy them, and if the carb bodies are painted, they won't be afterwards. Then it took three attempts with ultrasonic cleaners, first with a mild citric acid solution, then the usual carb cleaning solution. Take care if using acid as if you leave it too long it will remove your zinc plating from the steel parts. Eventually, this worked after I also realised I had a weak spark due to a faulty CDI unit (thanks to Sheep on this site for selling me his spare to get me out of a hole:)).

Edited by Dezza
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Thanks for the replies folks, to answer some points made

Even when warm cylinders 3 & 4 appear to not be running below 4/5000rpm they kick in above that so still leads me to think it’s pilot jets or like Dezza said the cold start circuit

i will update when I’ve taken the buggers off again and refitted, COULD BE A LITTLE WHILE THEN :mr711:

 

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Ok carbs three and four stripped all jets inc choke removed and recleaned,crap in pilot jets and some residue on choke pin, carbs rebuilt checked for leaks then back on with high expectations, how the held did they build these things on a production line as the air box is a bastard to fit !!! Yes I know it needs to be on prior to carb fit, been there done that, Had plenty practice now so found that removing all engine mounts except the bottom two and tilting the engine forward gives extra room when getting carbs in and out, anyway hooked up the remote fuel tank wire up battery press button BUGGER won’t turn over,tries but solenoid sticking at least that’s what I think or could be battery, whip out plugs to see if it will spin over without compression, press go get showered with fuel out pot one, quick look with torch confirms fuel in pot one so quickly suck it out with tube before it can contaminate oil, drop float bowl off number one check float is shutting off all ok, spin motor over to clear any left over fuel, plugs back in and it fires straight up no choke needed and pick up is good revs nice and smooth no popping , get the strobe out and check timing some adjustment needed to get it bang on, SWEET always nice when you’ve done a complete nut and bolt rebuild from  a box of bits out a shed.

One and two are running a lot hotter than three and four but done enough today and with the workshop door wide open so I could get some fresh air it was getting a bit fresh so will have a look at plugs tomorrow to see if it’s running lean.

Will try to see I can get pics on here as well.

Thanks for the welcome messages folks, great forum with loads of info.

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Pics of current status, list of still to do

Finish sorting wiring, left switch mackerel me thinks

Paint, near two grand at Dream Machine so looks like I will be doing it

Seat

Tyres /chain/sprockets, sure theres more, as always time is biggest issue.

Edited by ral
Missed a point

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Engine was blasted first then painted with high temp silver then cooked on the barbie, can’t remember exact name of paint but will see if I’ve any left next time I’m in the workshop, it’s a Matt finish as didn’t want to go all glossy

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You might try syncing the carbs. If u dont have the vaccuum gauges u can set the butterflies to a piece of wire. Set the idle control carb to "slight drag" on a small chunk of solid wire n make the others match. Reset ur idle b4 u start it tho.

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Done prior to refitting, now running as it should thanks.

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