Carb question

[fredp]

Running a dual set of mikuni vm30's on a cb360 stock headers, free flow silencers. The question is can one cylinder run rich while the other is showing a pretty good plug chop? I've got no air leaks, timing is dead on, spark is strong, the bike starts first kick. With the stock carbs and stock jetting the plug chops showed even results (a hair lean). Any insight is greatly appreciated.

 

[Tim]

Sure thing they can - each carb / cylinder is working on its own regarding mix. Imbalanced running can cause racing / stuck idle etc. but the bike can run.

I presume you've synced the carbs, made sure the slides are moving at 'exactly' the same time etc? I'm nearing the tail end of setting up my VM34's on my XS650.

Needles at the same position? All the jetting is the same? Mains, pilot, air, needle jet, needle, slide cutaway etc.? Float heights set?

 

[fredp]

Everything is sync'd, but i've got no stuck idle or racing, it actually idles smoothly at 1100 and excelerates just as smooth. Right now everything is set exactly the same, slides, jets, needles, floats set, everything identical.

So it is okay to tune each cylinder independently?

 

[Rocan]

Everything is sync'd, but i've got no stuck idle or racing, it actually idles smoothly at 1100 and excelerates just as smooth. Right now everything is set exactly the same, slides, jets, needles, floats set, everything identical.

So it is okay to tune each cylinder independently?

yes. often times the carbs adjustment screws dont give the exact same mixture at the same settings. tune to each cylinder.

 

[fredp]

Will do, thanks guys.

 

[boingk]

Are you running new plugs of the correct type and heat range? One could simply be a semi-dud that fails under cylinder pressure.

If they're new, just tune to each cylinders requirements. They shouldn't be drastically out, start tuning with the needle. Jet changes of more than one size may indicative of something going wrong...worn rings dud carby gaskets etc.

Cheers - boingk

 

[fredp]

thanks guys, i totally got it ironed out, just waiting on new pilot jet's and i'm good to go. I actually swapped in some new plugs and found the tiniest air leak at the carb gasket. So with that done, the plugs are reading right on, now just need those pilots and i'm good to go for summer.

 

[Greenbush]

Running a dual set of mikuni vm30's on a cb360 stock headers, free flow silencers. The question is can one cylinder run rich while the other is showing a pretty good plug chop? I've got no air leaks, timing is dead on, spark is strong, the bike starts first kick. With the stock carbs and stock jetting the plug chops showed even results (a hair lean). Any insight is greatly appreciated.

Hey, when you put the VM30s on did they just mount right up with the stock Carb insulators boots?