Only running on right cylinder..... well sometimes

[davidtilton]

Hi all,

I'm hoping someone out there has had a similar problem and unlike me managed to solve it!!

I have a 1990 Super Tenere with an 850 TDM engine.
I have recently ridden it to west Africa , 6000km of trouble free riding until the last 2 days.Anyway it made it and was shipped back.
Now it's home I am trying to fathom why it starts quite happily but will only run on the right cylinder, and then after perhaps a few hours of fiddling it starts and runs fine on both...... until I take it for a ride and then it intermittently runs rough as if it has a poor fuel feed on left (?) side.
It has a great spark, I fitted a new coil and leads. tried swapping plug caps.
Fuel pump, besides not strictly required, works.
I can blow through the vacuum hose, it does run on gravity only, if I disconnect it.
Fuel feed seems ok, as far as carbs. slides move when I rev it so presume diaphragm ok
Airbox on or off makes no difference to it running on one, so not filters full of sand/dust.

So my thoughts are that something is amiss in the left carb, have sprayed carb cleaner, checked inside the bowl for debris, unscrewed and reseated jets etc
Ran fine this morning but only for a couple of miles, annoying that it is intermittent .

So running out of ideas other than hand over the carbs for a complete refurb???

Help / ideas please!!

Many thanks in advance

Dave T

[donnybach]

Could just be shite in a passageway. Or a loose connection in the ignition circuit. Is it failing at random or when it’s hot?
I’d give the carbs a good clean with solvent anyway as you’ve been in shit conditions. Check all the connections in the ignition. Clean all the terminals with electrolube and make sure they’re tight. Was the good spark there when it wasn’t firing?

[davidtilton]

Hi,
Thanks for your thoughts.
It is random
Usually the bike starts easily and ticks over on choke but only on the right cylinder! left exhaust stays cold.
If I pull the left plug it is sparking, indeed jumps a big gap,
All the new electrics, coil, leads etc have been remounted.

Today after much head scratching it decided to run on both but was soon rough on a ride

Think I need to take the carbs out, not sure on disconnecting the throttle cable, and perhaps pay a company such as Coln Engineering to give them a good reconditioning with new seals and jets etc as I am reaching the edges of my abilities and knowledge of carbs

Dave

[donnybach]

Definitely worth doing. If you have a manual though you’d be ok doing it yourself. They’re pretty detailed. A good soaking and a blow through with an airline works wonders.
I think a thorough clean up will do it judging by the dusty use. Just remember to use the 850cc set up. Sounds like a great bike. I always wanted an 850 super ten.

[davidtilton]

So I'm hoping I made a school boy error......
I never checked the 'new' spark plugs......

Put an old one in the left side and ever since the engine has not missed a beat!!!

mind you it will take a good few miles for me to relax riding it.

[donnybach]

That’s good news.