stage 2..dropped to 7400 rpm

[RXPNJ]

ski runs and pulls like a rapped ape....but only goes to 7400. I changed the plugs. Oil is fine. Supercharger is chugging along. I don't have a boost gage. The old plugs that I pulled were lite(running lean). Full stage 2. Stock ecu...I believe it is a boost leak. Anything else to check. Thanks

Peter

[The Bandit]

Its a boost leak.

[JFizzleJR]

I have to disagree. That could be the case, BUT, have you checked the supercharger slip before you mentioned the S/C is 'chugging along' ??

I had the same problem this week (still isn't fixed). RPMS went from 7750 to 7450. Changed to a prop that is 2mm less aggressive AND changed from 81 to 83mm ring. I thought that would put me into the ballpark of 8000-8100. Boost is 5.9 lbs at 7450 STILL. I am SURE there are no significant leaks because I just went through all that BS for the longest time and a week ago was running 9 psi+ at 7950. Supercharger was BRAND NEW less than 10 hours ago. Spring washers, metal washers, ceramic bearings, green wheel..

My point is, the only thing I can think of is the slip moment is extremely low (probably from breaking in the S/C in my case).
My advice is to thoroughly inspect your supercharger health (atleast do a slip test) and THEN go hunting for all the wonderful boost leaks if the slip moment is in spec..

[RXP-REX]

I didn't think a ski pulled "like a raped ape" if it had a boost leak?

[The Bandit]

I have to disagree. That could be the case, BUT, have you checked the supercharger slip before you mentioned the S/C is 'chugging along' ??

I had the same problem this week (still isn't fixed). RPMS went from 7750 to 7450. Changed to a prop that is 2mm less aggressive AND changed from 81 to 83mm ring. I thought that would put me into the ballpark of 8000-8100. Boost is 5.9 lbs at 7450 STILL. I am SURE there are no significant leaks because I just went through all that BS for the longest time and a week ago was running 9 psi+ at 7950. Supercharger was BRAND NEW less than 10 hours ago. Spring washers, metal washers, ceramic bearings, green wheel..

My point is, the only thing I can think of is the slip moment is extremely low (probably from breaking in the S/C in my case).
My advice is to thoroughly inspect your supercharger health (atleast do a slip test) and THEN go hunting for all the wonderful boost leaks if the slip moment is in spec..

You have a boost leak AND a slipping S/C

[Vman]

First thing I would do is get under the ski and check out the intake to make sure nothing is wrapped around the shaft... then the prop, wear ring, all that good stuff you can check just by looking.

I've seen plastic bags and such tightly wrapped around driveshafts- that'll rob you some rpm big time... simple stuff first.

[The Bandit]

You have a boost leak AND a slipping S/C AND a plastic bag.

[Vman]

Or a rope...

[JFizzleJR]

I know I don't ..

Maybe he does though.

[The Bandit]

You have a boost leak AND a slipping S/C AND a plastic bag with a rope inside.