Running lean after removing restrictors

[Herr Tod]

I have removed the 34 HP restrictors and should have 50 HP now. However it ran very lean at half throttle, where the needles are the most important. I have the (33 mm) carburators stock, according to my service manual.

I have just finished working on the bike. I have set the needles one setting higher than they should be and now it runs much better, but not completely flawless yet. I suppose this is also because of the end can, in my case at the moment a Micron. When I slip my Yoshimura RS-3 on it should be better.

Any ideas why it runs so lean at stock settings, except for the exhaust? I find it a bit strange...

[Spacey86]

Hi there.

I had the exact same problem with mine( running a standard exhaust) on my B4 VVC, was told, by the guys at my local dyno that that was just how it was set up at the factory. It runs lean after you put an after market exhaust, cos you get better flow throught the engine, this is the only reason that i know for it running lean. I just had mine Dynoed and set up, took 10 dyno runs but is now running sweet as phuck!!!

[Herr Tod]

I am very interested in your carb settings However if I am not mistaken the 400VV has 32 mm carbs with; #90 mainjet, #30 pilot jet, #95 throttle valve and 5DF17 needles. I have 33 mm carbs with; #100 MJ, #32.5 PJ, #130 ThV and 5EZ67 needles. But maybe I can compare your info to the original settings.