stage 3 kit fine tuning on B12

[VJ]

after a fair bit of pissing around with jetting on my bandit 12 engined fighter im almost done but Ive got a slight issue.

Running DJ150 mains, Dynojet needles on 2nd clip down, pilot air screws 3 turns out. K+N dual filters, gsxr k1 ti headers and a shorty exhaust. Ive slotted the ignition backplate so I can dial in advance rather than fit an advancer but its currently set to stock. Recently serviced including valve clearances, carbs are spotless and have been static balanced with feeler gauges (will be doing a vac sync in the next few days)

It runs like a beauty after 5k and pulls hard all the way to redline, Idles fine but Its got a flat spot between 3-4.5k most noticably when under 1/4 throttle. I cant seem to work out of I should adjust float height or mixture screws more. The issue is not noticeable at all when out on the open road as its rarely below 4.5k but when I get into traffic/stop start riding its a pain in the ass and I have to give it a fistful to get past the flatspot.

Ive tried lifting the needle a notch and it ran over rich and lost midrange so Im pretty sure the needle height is about as good as its going to get. 

 

 

Cheers

VJ

[Oilyspanner]

 

That initial bit of throttle and lower revs is controlled by the pilot jet, you normally have to upsize the pilot fuel jet with pods. The fuel level in the float bowls has a fair effect in this region too. If you've already turned the mixture fuel screws out 3 turns, you could try another turn to see if this enriches the mixture enough - the pilot will need to be changed though I reckon - if you've changed that, then the fuel level will need to change. If you've not altered the fuel level/altered float heights, it shouldn't be them - unless you've knocked them.

[clivegto]

If it were me I would lift the needles to top and turn air screws 2 1/2 turns out.

[boilerdude]

The needle And the pilot circuit do have some overlap. When you raise your needles or at least when I do I notice my idle goes up slightly as well.

 

My 1st gen bandit 1200 seemed happiest on smaller pilots. 35 or 32.5. And the needle around middle setting. There are 6 slots if I'm not mistaken. One of the 2 middle ones. 

[Rossco(Iceman Josros)]

I have a similar issue with my 1100 Slabby running BS34 carbs with a stage 3 kit - will be dropping the needles a notch this afternoon to see if any improvement so will report back 

[Guest YoshiJohnny]

That range is usually the needles, it could be the emulsification tubes (main jet holders) are a bit oval and it's running a bit rich at part throttle. It could be an awful lot of things, they were designed to run with an airbox and sometimes no amount of messing around will get them spot on (even with a dyno). If you have pods junk them for some bellmouths and socks to get more venturi...