3XV running issues

[peteholt]

Hoping someone can help me with an issue with my 1991 3xv. Have had the bike about 8 months and it has run beautifully until last weekend when I got caught in the rain. I took shelter in a local café for about 45 minutes until the rain had passed then set off for home, but after about 2 miles the bike started to splutter as if running out of petrol so switched to reserve, and it seemed to clear for a mile or so and then it started doing it again. When trying to accelerate it would cut onto 1 cylinder and that cylinder would then start to smoke badly until the throttle was rolled off again. The bike is by no means standard and was running premix and had pod filters fitted when I got it, but was running well up until last weekend.
I have removed the carbs individually to check for blocked jets etc and after reassembly it starts and ticks over fine but when taken up the road, as soon as you try to accelerate, it holds back and feels all choked up and cuts onto 1 cylinder again. It is the top cylinder, (left hand exhaust) that appears to have the problem.
Has anyone every had a similar experience, or could it perhaps be an electrical issue?
Any assistance to resolve this problem would be gratefully received as I am out of ideas now.

Regards Pete

[Paul]

At cafe
Someone shove something down your tail pipe?
Tried to remove spark plug cap?
Else
Remove rhs plug and with kickstart feel the compression left side
Check all pipes to air jets

[scooble]

check that the fuel tap runs sufficient fuel, it may be partially blocked and just dribbling out, enough for small loads and tickover.
Also swap the coils over, and check again and see if the problem remains on the same cylinder or not

[peteholt]

Thanks for the replies, unfortunately have been at work all day today so unable to get back out in the garage to take another look. Just can't understand how it could be running fine one minute, then 45 minutes later after a rain stop running like a bag of crap, which originally made me think it might be water related.
Will try to find time to check it over this week and report back. Thanks again for your replies !

[peterbike]

Is your tank vent clear ?  You might have a vacuum forming. 
Or have you cleaned the filters in the inlet to the carbs ?

[jools]

Water in somewhere ?

[Crank]

Water in somewhere ?

I agree, the rain seems to be a defining factor. I would check the coils, ht leads and caps carefully.

Also, use some contact cleaner or some compressed air through the connectors on the cdi in the tail, water may have found its way in there from the back wheel.

[peteholt]

Quick update, I have checked the tank breather and that is all clear, fitted 2 new spark plugs and checked the filter in the carb inlets and they were both clean, the fuel tap seems to have a good unhindered flow of fuel but still it is not running right. I have checked all electrical connections and all seem ok, so will swap the coils tomorrow to see if the problem changes to the other cylinder. The bike starts and revs cleanly when on the stand but as soon as you try to take it up the road, it seems to be all choked up and cuts onto 1 cylinder under acceleration. Starting to lose patience with this bike and the neighbours are getting pi**ed off with all the noise I am making, so out of courtesy to them, I only work on it for an hour or so at a time. Hopefully I might make a breakthrough this weekend, but only have tomorrow as doing the London to Brighton Bike ride on Sunday so that's another day lost.
Any further advise would be greatly received and thanks for all the suggestions to date.

[eyrey1]

see if any water has got into the flywheel
or to the cdi unplug conectors and clean then spray with wd40 and wipe again
there is some propper electrical spray you can get for doing this job
cdi is above the rear mudguard and under the tool box storage bit
mine is plumbed into the box itself now and i use some velcro and it never moves or rattles
and i get to it in 3 seconds not half an hour ,and then the same putting it back together
if you have some spray [electrical] id do every junction box i could find , sounds like water is in somewhere

[jools]

Crank seal ?

had something similar to that on an old RD400 as soon it was under load, the worn bearing would allow the crank to twist slightly breaking the crank seal

[eyrey1]

my crank seal went 18months ago on the 3xv it was ok one day the next it was crap
wouldnt tick over ,rev on its own ,no power

[peteholt]

Have tried a 2nd carb today on the troublesome side and it was no different so suspect its not carb related now. I did notice that it was smoking more on the affected cylinder side. I still feel that it is an electrical problem, but was unable to swap the coils over due to the length of the wiring, although there is a spark from the coil on the affected side. Am giving up now as made far too much noise again according to her indoors! Could be having a bonfire with it at this rate 
Any more valued advise would be gratefully accepted

Pete

[horse 1]

got the same trouble, I hope it`s not crank seals, but you can bet your life it is.

[Warwick]

Once you've checked all the obvious stuff re: fuel and spark, it can be useful to pop the pipe off the offending cylinder and shine a torch up the exhaust port to check for any issues there. Or just pop the cyl off if it's easier, or you want to check things out more fully.

[horse 1]

Will do warwick, thanks.