Bike runs fine at high RPM but dies at Idle

[lazydays]

I want to check my 'theory' of what is wrong with my engine before I clean the carbs (yet again)

1) Engine is quite hard to start, especially when warm
2) Idle is poor and will die after a while
3) If i pull RHS spark plg from engine while idling it cuts out completely
4) If I pull LHS spark plug from engine it carries on idling (no drop in RPM)

From this I assume I have a problem with either LHS ignition or LHS carb and the RHS cylinder is keeping the idle running

5) I checked points and spark - all seems good on both sides
6) Occasionally the RPM while idling will jump crazy fast after i blip the throttle (ie not drop down) , when this happens if I pull lhs plug the RPM drops , if i reconnect the plug RPM rises back again.
7) While the engine is revving fast if I pull RHS plug the engine keeps running (RPM drops)

On the road the bike is fine and feels as though both cylinders are working fine and the bike pulls away no problem, the problem is only at idle and has also died while running downhill.

I think I must still have a blockage in the idle circuit on the LHS carb - any suggestions or ideas ? I already checked carb balance and that seems to be right, idle screws are 3 turns out each, but they dont seem to have a big effect on smooth idle

 

[arfstrom]

3) If i pull RHS spark plg from engine while idling it cuts out completely
4) If I pull LHS spark plug from engine it carries on idling (no drop in RPM)

I am assuming you are only pulling the boot? off the spark plug? You can do the header pipe test too. after initial running the engine, you can feel the header pipes before they get hot. (don't burn your self)

Of course I dont know how you cleaned your carbs, so a Ultra sonic be #1 choice, boiling #2 with a light acid (vinegar or lemon juice) , and only using a carb cleaner would be my last choice. (i have never done the ultra sonic, but I would If I can get one.)

You are in it, as deep as you can be, print out the carb section from the manual, Do the float level check, do the boiling option. Do anything it suggests! Read the fine print.

With out having the engine HOT, pull the plugs, after running it for upto a minute, and see what the spark plug is doing? perhaps its isn't the Carb. I know the wires tend to go into a (I am not passing a spark day) Since these ends just twist onto a spike or a screw, freshen up the bit on to the wire. I usually recommend a .5 inch cut off both sides of the wire. Spark plug side, and the coil side.

I suspect the bike will seem to work at higher speeds, with out firing on both sides. based on the amount of varnish, I have found on certain fuel bowls, With out a laser thermometer to take your header pipes temps after trip, it will be hard to tell.