44mm mikuni

[Zach_x2]

Ski is a stock 650 with a Coffman pipe. I installed a 44mm and the ski runs good on top but loads up on bottom and only likes to start with the throttle wide open. Been trying to tune it out but haven't really got anywhere. Wondering if anyone has any base settings for a similar set up like this. Pop off, jet sizeing, high low turns in/out. Im at a pretty low elevation in WA. 100-500ft most of the time. Thanks!

 

[OtherDonnieGuy]

What are your current jetting specs and pop off, and where are your fuel screws set at?

 

[Zach_x2]

Jets are really stripped but I got them out. Hard to read but I believe the low is a 115 and the high is a 135 is what it looks like. Not sure on pop off yet and the high is 4 turns out. Low is 3 turns out

 

[mn_reeds]

The general starting point for 44 sbns on a kawi 650 are 120p, 140M, 2.0 N/S and an 80 gram black spring which is 21psi pop off. Start about 1.5 turns each and start tuning via the mikuni manual.

FWIW look at the base of your carb and the specific model should be stamped there. Depending on the model you'll have 3 or 4 holes in the venturi which will affect jetting to some extent too.

 

[OtherDonnieGuy]

Jets are really stripped but I got them out. Hard to read but I believe the low is a 115 and the high is a 135 is what it looks like. Not sure on pop off yet and the high is 4 turns out. Low is 3 turns out

Pull out the low speed screw and see if it has coarse or fine thread.
If it's fine thread, start with 2 turns out.
If it's course thread, start with 1 1/4 turns out.
Also you could have a leaking needle and seat, or a leaking o-ring on the seat itself, and that will cause it to run rich down low.
By Checking pop off, you are able to check for leaks.

If you cant (or won't) check pop off, and carb has an aged needle/seat, at least replace the o-ring on the seat if you don't do anything else. That's where I see the majority of issues with used carbs.

 

[TL91]

What @mn_reeds said. I've got an X2 with a SBN 44 (retail type) and a B-Pipe and am running 115 Low, 145 High, 2.0 N/S, 80g spring and that seems to work pretty well for me at about 900 feet elevation. Not sure where my high and low speed screws are at, but those settings ought to get ya a decent starting point.