Blaster Carb Tuning Help 93' WB1 Single Carb

[Adam E.]

I read Group K's page and feel like I'm doing everything right, but the results are not evident.

Background: Rebuilt carb with OEM Mikuni kit. Fresh fuel lines, filter, plugs installed. Ski is completely stock and has been switched to premix. I did not change N/S as the old one looked O.K.

Situation: After starting it briefly the idle doesn't sound completely right. I don't have a tachometer, but thought I could tweak it slightly. However after giving it just a little throttle it begins revving very high and doesn't come back down. This freaked me out as for awhile I couldn't cut the power. I am a newb when it comes to carb tuning and have no idea where to go from here.

Specs:
Single SBN 44 Carb
Running Premix @ 40:1
Compression: 160/160
High Speed Jet: 135
Low Speed Jet: 115
Needle/Seat: 1.5
High Speed Screw: 1 5/8 out
Low Speed Screw: 1 7/8 out

Your input is appreciated.

 

[tor*p*do]

Sounds like an air leak to me

 

[Dartman]

do you have stock air cleaner?
if not
put in a 95 gram spring and 120 pilot 2 1/8 turn
132.5 main 1 turn

 

[Adam E.]

Air cleaner is the stock one. I re-used my old carb spring because the one they sent was wrong. My pop-off pressure was spot on at 55psi.

After reading another post I'm thinking I have a "runaway ski" from a lean condition. It seems that I have an air leak. I believe I may know the culprit. I used gasket material to make a carb base gasket. This may be causing the issue. I will buy new carb base and air intake gaskets to stop the leak.

 

[Dartman]

you still may want to jet it like i suggested as your on premix now
premix causes lean fuel issues
oil injected carbs will run richer than the same carb on premix
try running the low adjuster to 2 1/2 turns out and recheck idle screw so your not too high on idle opening
all new mikuni sbn rebuild kits come with one each in the kit, 115 gr and 65 gr

 

[Quinc]

PM @Rdrttoy for the best deals on gaskets.