running on two cylinders :( please help!!!!

[airz1988]

1993 gsx600f firing on cylinder 1 and 2 only!!! 3 and 4 are stone cold!!!

the problem started THURSDAY (4 days ago), i was at work and all this horrible rain covered my bike which is running on k and n air filters (there is only 2 filters as they supply 2 carbs each) i think rain may have been sucked into the carbs or may have made its way in while the bike was stood? either way, on my way home i lost power completely, pulled up at the side of the road and discovered ONE of the cyclinders (number 3) was cold. i got on the bike and somehow made my way home with the bike making a right noise. i installed a new spark plug without checking the spark and replaced the leads and it seemed to have sorted the problem.

i finished work FRIDAY and started the bike with the choke on and started to warm her up and realised the problem had come back. i had no choice but to ride it home and set off on my way. the problem seemed to have cleared itself and continued to use it through the day and everything was fine, no problem at all.

SATURDAY (yesterday) i started the bike again to nip out and pick up something from town and discovered it had come back, the cylinder was cold again. i took the ht leads off and checked the spark for each lead and they were all fine. i swapped them around too see if they would make cylinder number 3 fire again but no joy. the leads worked fine on each of the other 3 cylinders, making me realise it wasnt an ignition issue, so i started the bike again and realised cylinder number 4 was down too, meaning the bike is only starting and running on cylinder 1 and 2. 3 and 4 are cold.

i removed the fuel tank completely and checked the fuel tap and checked the fuel filter and appears to be fine.

i re-fitted the tank, fuel lines and vacuum pipe.

i checked the fuel lines and none are split or blocked so i know fuel is reaching the carbs. there is one hose going to the center of the left pair of carbs and there is another hose supplying the right pair of carbs.

i removed the tank again, took the air filters off and checked inside the filters and boots to the carbs and all is ok.

i refitted the filters to prevent anything getting into the carbs.

i removed the carbs and drained the fuel, opened the tops up, checked the insides and all is nice and clean, so i put the tops back on.

i removed the bottoms and cleaned the pilot jets, checked the needles, checked the float assembly and cleaned the float chamber, then put the bottoms back on.

i put the carbs back on the bike and put the fuel tank back on and set the tap to prime to put fuel back in the carbs, then set the fuel tap to the "on" position.

i opened the drain screw on each of the carbs one after the other and each hole is letting sufficient fuel drain out, meaning fuel is reaching the carbs.

i turned the bike over and it is still happening. cylinder 3 and 4 is cold. it obviously runs terrible and backfires really loud and cuts out when on idle. i now wont be able to make it into work tomorrow because of this. i really need it sorting asap. next thing to try is to spray wd40 into the carb throats to see if it will help the cylinders fire up

i am not mechanically minded and really need advice on where i should have started and what to check first and what i do next? i thought it would be a simple fix as it happened then seemed to have sorted itself out and was running full power and everything was ok. then it went wrong again over night. it was fine when i parked up. next day, probe was back again. here again is what i did in order.

checked sparks-all ok
checked and swapped leads to rule out faulty leads-all ok (lead positions are ok)
visually checked coil packs and lead positions-all ok
checked fuel lines and vacuum line-all ok
removed fuel tap and checked fuel filter and tap mechanism-all ok
removed and checked air filters-all ok
removed carbs, took to pieces, found dirt build up in float chamber, cleaned chamber and cleaned jets-all ok
replaced everything in its correct place, fired it up and still no change.
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Airz

[Nobby the Bastard]

Please define 1 2 3 and 4.

By most people's understanding of which cylinder is which, it's almost impossible to lose one of 1 and 4 and one of 2 and 3 at the same time with no prior warning.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Triumph Sprint ST 1050

[airz1988]

when sitting on the bike faceing forward, cylinder 1 is the far left and cylinder 4 is the far right. i lost cylinder 3 first (center right/3rd from left) but then it started working again, then parked up over night and found the two right cylinders had stopped firing and only the left side of the engine was working?? which makes me believe it isnt anything to do with the leads, coil packs or plugs?? as isaid i a not mechanically minded but know enough to do basic troubleshooting.
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Airz

[bamt]

You haven't said that you've checked the plugs.

Check that the recesses they are in haven't filled with water (IIRC these have a drain hole above the exhaust on each cylinder, like the Bandit).

It's possible that the spark plug recesses have filled with water (heavy rain, bike on it's side stand so the right hand side is exposed) that hasn't drained because the holes are blocked. That'll cause the spark to go to ground outside the cylinder rather than the plug.

[airz1988]

Third paragraph down says I checked the Sparks, meaning I took the plugs out in turn, connected them back to the leads and started the engine with the plugs against the head and the Sparks were jumping across fine. Also, the leads have caps on them, when I took the leads and plus out there was no water in the recesses or around the plugs
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Airz

[ThatDippyTwat]

He explained why even with a working spark, you may have problems. I don't own one, and I understood perfectly what he means.

Good luck getting any more help with your condescending attitude and sarcastic response.

[tom_e]

[bamt]

To be fair to OP, I missed the line about pulling the plug and I didn't take offence. It is odd, there's not a lot common between 3 and 4.

Tried running for a short time without the air filter (should be OK in a clean garage) or swapping the filters over? You say you've examined them, but there could be something going on there as I assume they are on cylinders 1&2 and 3&4.

Plug caps in good nick? Is there enough length of HT cable to swap 2&4 to check that it's not a water ingress issue on the number 4 lead? I think it's possibly a bit tight to do that unless you can move the coil.

[doggone]

Usually if two cylinder are out it's one of the two the ignition coils - relatively easy home fix to replace.
You can diagnose by swapping them over with most bikes.

With a bike from that era it was a common fault when they were almost new.

There's always a chance of more amusing causes such as *friends* swapping leads over.

[airz1988]

hi i didnt mean any sarcasm from my reply and i believe it doesnt loook like a sarcastic reply either, especially as i put a sad face at the end of it, its causing me great stress, luckily somoeone has offered to take e into work for the next 2 weeks until he goes on holiday so might be putting it into agarage if i cant sort it myself

yes bamt you are right i have a filter on 1 and 2 and a filter on 3 and 4, il try running with the filter off as i have been advised to spray wd40 into the carb while it is running to see if that starts the cylinders firing? yeah the plug caps are fine but will try swapping the all around again see what happens? it could possibly be water that has affected the lead but sparks seem to be jumoing across fine?

doggone i dont think it will be coils as its 3 and 4 and they are powered by different coils, i believe the left coil powers 1 and 4 and the right coil powers 2 and 3? if not i think its left coil for 1 and 3 and right coil for 2 and 4? im not sure without checking the manual again but im pretty sure theyre in the right place as they have numbered leads? ill try all this tomorrow after work tomorrow.

i really appreciaate any advice, as i said earlier to a friend, i dont think its going to be somewthing too big a proble as 2 cylinders have gone at once, if it were just the one i would probably think it were piston rings or something like that. fingers crossed i dont have to get it to a garage.

thanks guys keep your suggestions coming.
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Airz

[Nobby the Bastard]

[airz1988]

yeah thought it was i just couldnt remember, thats whats making me rule out coil packs but i will deffo try swapping them all around again tomorrow to see if any of the cold cylinders fire and any of the hot cylinders stay cold
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Airz

[airz1988]

BOOOM LEADS 3 AND 4 WERE THE WRONG WAY ROUND!!! BEEN OUT ON IT FOR AN HOUR AND A HALF NOW!!! WHAT AN IDIOT SO HAPPY THANKS EVERYONE FOR YOUR INPUT AND YOUR CONCERN
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Airz