Author Topic: Jap B400 VC carb jetting question  (Read 234 times)

Offline Ivandit

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Jap B400 VC carb jetting question
« on: July 01, 2019, 04:59:33 AM »
Hi there!

So last year I got a 6Sigma jet kit for my '94 VC, installed and running (apparently) well with a K&n air filter and stock exhaust.

The fitting instructions tell you to replace the stock jets with 105 on #2 and #3 and 102,5 on 1# and #4, which kinda made sense to me after reading about how that difference compensates the different cooling conditions on inner and outer cylinders, adding a bit of extra fuel to help #2 and #3 cooling:

But then...last week I was reading the japanese service manual prior to a valve clearance check and got a bit shocked when reading the carb specs:

So, apart from them being the same size (what's the point with the kit then??)...they are supposed to be fitted completely the other way around!! That is 105 on #1 and #4, 102,5 on #2 and #3.

Any thoughts/experience on this?

So far I've had different opinions, from "stick to the manual" (why the outer cylinders are set to be richer then??) to "the manual info is wrong" (hard to believe IMO...).

I just want to go back to stock jets, but I just don't know which is the right way...any help is much appreciated!! :beers: