running on three cylinders

[el_oso]

still having trouble with the divvy. still only firing on three.
i have checked the spark. it is good and strong.
swapped the plug for one that i know is working just to be sure.
there is also compression. not tested with a meter, just thumb over the hole. i can't hold my thumb over the hole to keep it sealed as there is too much air pressure.
how would i check that there is fuel getting into the cylinder? i tried putting a few drops directly into the cylinder but this still didn't help.
i have also already cleaned the carbs twice. once just blowing through compressed air and another time with a full strip, clean and then blown through with compressed air.
mixture screws have also been reset.
only got a few more days to sort this bike out before i move out of my parents house so need to get the bike running as soon as possible as i am pretty sure they are getting extremely pissed off with it, now that it has been sitting on the front drive for about 9 months
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[radical]

When you remove the plug from the offending cylinder is it wet or dry after trying to start the bike ?

[Pussy Magnet]

He is right above chek the spark plug if its wet , if it is dry it off 4 an hour or 2 then bung it back it

[Frost]

You first need to determine if its electrical or not. New plug would be useful, as would swapping the coils over and seeing if the problem follows the coil or stays on the same cylinder.

It would take about 30psi to move your finger off the plug hole, so testing like that is of no help. Compression is unlikely to be an issue, it is at least worth trying everything else first before attempting to check rings etc.

Most likely it is due to flooding, or a mixture that is too rich. Check the mixture screws are as the manual says they should be, and that the carb is sat properly in the rubbers. When you say you blew the carbs through with and air line, did you actually get the jets out and visually check them? Or did you just stick an air line into the carb mouth?
Check the carb sync isn't miles out by seeing if the slides / butterflies move in synchronous and close at the same time visually.

[el_oso]

the plug is wet when i take it out which indicates it is not firing. i did clean it and even swap the plug over with one that i know is working. it is therefore not a fault with the plug. as already said there is a spark from the plug. i will however swap the coils over.

when i cleaned the carbs thoroughly i did completely strip the carbs including taking all the jets out and then blowing through with compressed air. so there should be no blockages.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[loply]

Not that I really know what I'm talking about, but is it worth having a quick gander at the valves?

Check the clearances are vaguely right and try to ascertain if one is sticking?
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[radical]

check that the choke flap on the carb is not stuck in the closed postion on the non firing cylinder, also is there any way that you can check the slide operation by looking in through the airbox as the bike is running, does the bike have normal cable operated slides in the carbs or are the carbs of the CV type?

[el_oso]

no idea what type of carbs i have. know nothing at all about the things.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[radical]

check your carbs are operating properly by veiwing the slides via the airbox with the filter removed , if the carbs of of the CV type it is possible that the diaphram on top of the carb which fuels the non firing cylinder is damaged, punctured or torn as this will cause the problems that you are having, but do try to check the slides by veiwing first before you strip the carb.

[Kickstart]

Hi

They are CV carbs. However I wouldn't expect a punctured diaphragm to stop it idling (at idle the slide is going to be pretty much closed).

Would agree to check the valve clearances, although that could also show up with a proper compression check.

Which cylinder is it? My Divvy had a habit of occasionally dumping a load of petrol into the left hand cylinder when parked on the side stand.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[radical]

[Ichy]

How do you know its only firing on three? How do you know which cylinder isn't working?

I'm sure someone will correct me but its a four cylinder with two coils so it works on a wasted spark. Probably 1 & 3 and 2 & 4 share the same coil. You should swap the plugs leads over to the other cylinder that shares the coil. if the problem moves then its electrical. If the problem stays with the same cylinder then its spark plug, fuel or cylinder.

Swap the plugs around. If the problem moves then its the plug.

Next open up the airbox, remove the filter and spray easystart or similar (some use WD40) into the inlet on the affected cylinder. If it starts to fire then its likely to be a fuel issue, if it doesn't then there may be a problem with the cylinder.

[el_oso]

swapped the coils over today. still nothing. swapped them back. firing on all four and running sweetly. went inside, grabbed my helmet, jacket and boots to take it round the block. halfway round, the engine stopped. restarted again. relatively easily but with three cylinders again. swapped coils round again. played around a bit, still nothing. swapped coils back. still firing on three.
the cylinder that isn't working is number three. as viewed counted sitting on the bike from the left to right hand side.

i know that it is only firing on three because the downpipes are not hot on the third cylinder. this problem also seems to result in the problems i have been having earlier with this same bike. (if anyone has read them threads.) been having trouble with the bike sticking at 3k rpm. when it was running on all four cylinders earlier this problem did not happen so my guess is that these problems are related.
have swapped plugs over with ones that i know are working and with new plugs aswell. HT leads have also been swapped with the coils.
will get the tank and airbox off tomorrow and spray some easy start in there to see if that solves the problem. if not i will then check the valve clearances.
____________________
Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[temeluchus]

Might be worth swapping the coils over (ie 1+4 over to 2+3).

Although just once cylinder does imply its not ignition as mentioned by others.
____________________
Some shite cruiser. Now with guns and FREEDOM!

[Phoenix]

When you did all this coil and lead swapping is it the same cylinder every time that cuts out? Has it at any point been one of the other cylinders? If it's just the one cylinder then I can't see it being electrical. Are you sure there isn't a big air leak leak between the carb and intake on that cylinder, not a lose or missing vacuum port screw or unblanked vacuum hose.

[el_oso]

yes. same cylinder each time that cuts out. swapped plugs, coils, HT leads. directly checked the spark coming from the plug and it seems good and strong. can clearly see a blue spark in daylight
also the same cylinder that doesn't fire each time.
i have had the other cylinder running briefly again. had the bike on choke and the other cylinder fired up. the lumpiness went and the header pipe got almost instantly scorching hot. after turning the choke off the cylinder stopped working again as the pipe cooled down.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[radical]

You have a carb or fuel problem, if there is a drain screw on the float bowl of the carb loosen it to make sure the carb is getting enough petrol and check the float height and float needle on the carb

[el_oso]

yep. the fourth cyclinder started when i sprayed easy start in there. c_dug is coming round soon to give me a hand with stripping the carbs once more. he has a bit more experience than me at carb trouble. hopefully will have this sorted by the end of today.
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[Ichy]

before you strip the carb do what Radical said, undo the drain plug on the bottom of carb four. It will tell you if the float and needle valve are working.

Get yourself a little inline fuel filter. easy to fit and will save hassle in the future.

[el_oso]

already have inline fuel filter.
all four cylinders are working again. loose bolt causing poor sealing on the jet holder in the carb.
still not running right. when warmed up the throttle is sticking again.
____________________
Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[el_oso]

after leaving the bike to cool down overnight, i started it up this morning. it idled well at about 1k rpm. after sitting on idle for a few minutes the revs climbed gradually higher and higher until they sat at 3k rpm. what would cause this. it is a late registered 95 model diversion.
the fact that i have removed the carb heating system should not cause the revs to go high when the engine warms up should it? it is the only thing i can think of that has changed since this problem started
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L

[Kickstart]

Hi

Sounds a bit like an air leak. Inlet rubbers cracked or not done up tightly?

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[c_dug]

Should have thought of checking that the other day, I had the same with my TDR.
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I am a bellend, I am a man of constant sorrow, I am a gummy bear, I am a rock.

[loply]

Revs rising like that is the classic air leak sign.

If you've had the carbs on and off a few times they might just be seated wrongly. If the rubbers are stiff or mis-shapen try heating them before installation (hair dryer works well).... Then they slide on like a... Well, you get the idea.
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Yamaha SZR660 Caution to the wind, the throttle pinned!

[el_oso]

i have checked for air leaks numerous times. really can't find any. any good methods besides spitting on your hand or covering the thing in soapy water and looking for bubbles
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Duke 390
Previous: '05 XR125L | '96 XJ600S Diversion |'05 Suzuki GSXR1000 | '05 Honda CBR125-R | '97 YZF 600R Thundercat | '11 Honda CBR250
Car: Jeep Wrangler 4.0L