Ypvs 31k

[sherman]

Hi 
Iv took on a build finish for my nephew 
it’s a Cagiva mito with a 31k engine with fitting kit 
Iv got it running 
it will only run on the right cylinder unless choke is on then left cylinder starts up
if you push choke in it drops onto 1 cylinder again ( the right ) but not instantly 
so you pull the choke out and the cylinder starts again
carbs are cleaned and blown through including emulsion tube
slides and float bowels on correct carbs plugs checked and ht leads swopped over
the fuel line splits by plastic y piece as mito tank has only one outlet 
the vacuum line on right carb is blocked off
the power valve is locked in open position 
any thoughts 
thanks 

[shaunthe2nd]

Did you remove the brass balls and clean the air correction passageway when you did the carbs?
Choke balance pipe securely fitted?
Carbs balanced correctly?

[dougw]

As above, and pilot jet could be partialy blocked, old fuel residue is next to impossible to clean out properly, new pilot of same size has cured problems a few times for me , despite my best attempts at cleaning (including ultrasonic)

[sherman]

Brass balls out 
not really mucky and passage way clear 
choke link pipe air tight 
swopped coils and plugs from my 350lc ( no difference)

[shaunthe2nd]

Did you check carb balance? I'd look at using lollipop stick method and also the pips on sliders in the view glass on carb at WOT.

Other thoughts:
Can you hook it up to an auxiliary petrol tank to eliminate the Cagiva tank and fuel tap causing flow restrictions?

Are you using genuine mikuni pilot and main jets? Some of the aftermarket ones can be troublesome.
I'm assuming its jetted correctly for your set-up (exhausts, air box etc)

[midlifecrisisrd]

See if it is possible to swap the carbs over

Will need longer tubing to link the choke

Steve

[muttsnuts]

sounds like a blocked pilot jet, check you can see through it and the 4 side holes are clear, just because they have been ultrasonic lceaned does not mean they aren't blocked, I've had some jets so blocked I've had to replace them - even my jet drills wouldn't clear the blockage (and they are very small drills e.g. 0.5mm in size !)

Also check your air screw setting, if its out, try screwing it fully in, if it starts to splutter/try to run then its the pilot circuit for sure that's blocked

[sherman]

Hi 
I put my 4lo carbs on it jetted by mutts nutts with Nikkon pipes
and it runs 
The bike has mesh pod filters and allspeeds and was running 22.5 pilot and 270 mains ( I’m sure pilots are to small for pods )
I haven’t opened my carbs to see what it’s jetted ( I don’t like disturbing when set up for my lc)
so 31k carbs running premix with 22.5 and 270 with allspeeds and mesh filters 
were do you suggest I start 
and also do I blank of the vacuum line and oil nipples 
thanks 

[midlifecrisisrd]

When you say mesh filters are you talking about k&n style with the metal backs

If so they ain't too good, you'd be better with foam filters

Also 22.5 is standard pilot. If you have ditched the airbox you will be way too weak

Would think mains would need to be over 300

Steve