Hi i got some nice new HEL brake lines but unfortunately the wrong size banjo bolts, so i decide im in here i might as well do a carb balance and clean out. I took the carbs off (no kidding about the effort required) cleaned them out 1 by 1. all passages clear anyway so move onto the carb balance using the drill bit method. Only tiny amount of adjustment needed. Any way now once all fitted up, tank on etc, The bike runs only on 3 cylinders, with no4 (front right) not firing.

What are my possible causes?

Bad air seal? i checked these and as far as i can tell they are on like normal (hard to see with the water pipes etc in the way for this cylinder). Is there a way to check this using something flammable apart from engine starter aerosols?

Electrical system? the bike was running perfectly 2 hours before (this is my punishment for being inquisitive)

There are probably more things to check So add to the list please!

Thanks in advance 400gb

OOh more info.

Spark plug is good, went fine when swapped into other cylinder.

carb slide behaves normally when looking down and revving lightly.

How do i check if the coil has miraculously managed to shit itself just as i was fiddling with other stuff?

Coil is good too. A big healthy blue spark

Where does this leave me?

Air leak?

Fuel supply isuues?

Got it warm and took it for a spin with just the tank on. Seems to be fine now??? Maybe it just needed to be warmed up.

Lol did i just make a thread to talk to myself???

Harvd wrote: Lol did i just make a thread to talk to myself???

Maybe, whatever floats your boat!

You could do a compression test if the problem persists, otherwise possibly when cleaning no.4 carb somthing didnt go back together properly

Possibly a loose connection to the coil, might be worth crushing the crimp slightly if they are a bit loose.

took it out for a thourogh 50km ride and it went better than it used to. it idles much better too.

Could a non sealing carb rubber have caused this? then as the bike heated up the rubber it sealed itself better and problem dissapears?

Electrical system was fine so must have been air/fuel.

Any way its gone now thankfully

Did you clean the carbs with carb cleaner? Id be inclined to say the prob was with a carb, the rubbers are pretty tightly on, & an air leak is likely to hang around. Electrical, unless theres a bad connection in which case it will return. The plug may have been slightly fouled and it flooded when you started up. Anyway a good ride cleans the plugs of carbon build up so should be fine

MexicanGringo wrote:The plug may have been slightly fouled and it flooded when you started up

^^ What he said!