Topic: Carb Jetting Help for a not so stock engine

[Dolomite]

Bikes all finished, running on the lean side. Was wondering if you guys had any jet size recommendations based on the engine setup. It's a 76 750K engine with 78 750K PD carbs.. The engine has a cyclex CX1 cam shaft, 836cc big bore, open exhaust and 60mm velocity stacks. Mechanic wants me to see if i can get a recommended size because he wants to do the jetting to be sure that's the problem and not anything else. Thanks!

[Dolomite]

Whoops, current size is 110, I'm thinking at least 120? But because of the upgraded cam and over bore I'm not certain.

[Dolomite]

Ordered a full set from 110 to 147.5, which oddly has every size but jumps from 127.5 to 140, so I got an additional set of 135 incase it seems to want to fall in that range.

[TwoTired]

Don't expect the main to be a cure all.  It provides the dominant mixture for 3/4 to WOT.  The slide needle controls between 1/4 and 3/4.  So, if you need more fuel in that operating range, you must raise the tapered slide needle out of its orifice, relative to the position of slide opening.

I don't think, 78K slide needles have any more than one groove.  So, shimming the clip to raise the needle might get you to where you need to be. Otherwise, find some needles for the 77F model, as they should have multiple grooves to allow adjustment of throttle valve mixtures.

Cheers,

[Dolomite]

Awesome, thanks for the advice! This is the past thing left before the mechanic is done with the bike, he wants to make sure it's running perfect. Oh and settling the bill 

[Dolomite]

Turns out 127.5 was the magic number. So I have a LOT of other jets if anyone needs any. Or may just throw them all on fleabay.