Yamaha Ss440 Low Speed Bog [Archive] - Snowmobile World : Your #1 Snowmobile Forum

: Yamaha Ss440 Low Speed Bog

01-07-2005, 03:16 PM
I am having trouble. The motor was rebuilt, I put an aftermarket airfilter on to make carb mods easier. I have a bog at low to mid throttle positions. Seems that it runs lean in the low spoeed circuit. It is a keihin carb, I have a 172 main jet (up from the factory 165). The plug color is great after 20 miles at that jet#. It has an #80 pilot. I decided late at night to drill out 2 of the 8 metering holes. It did not seem to get rid of the bog. I noted that the 1985 ss440 came with a #92 pilot jet. Or is therere something I am missing? Air screw is 1.5 and the bog does not occur if I give it a little "choke" as I go along.

Help is need as it is a pain for my daughter to "putt" around the yard...Thanks...Joel

01-08-2005, 05:36 PM
my ss433 had somewhat the same problem it was the fuel pump just make sure it is working proper

01-24-2005, 11:10 AM
Sounds like you need to fatten up the pilot jet.. Those butterfly carbs are kinda finicky. Unlike a slide valve carb, you need enough pilot jet to make the transition to mid throttle position. Try a #85 pilot first. If it gets better, play with the air screw a little. I think stock setting is 2 turns out on the SS, so try that. if you need to go more than 2 turns out, you need to go fatter, like say the 92. My SRV is at about 1.5 turns out.