Hello All!
Longtime lurker, first time poster. I'm hoping to get some more direct advice from the experts on this site. A few things first:
1) Compression = 85 psi on each cylinder
2) Correct plugs shooting a 7/16" gap on all cylinders
3) Rebuilt carbs and fuel filter/pump 2 years ago
4) Primer bulb gets firm and works properly, fresh and flexible fuel hoses
5) Static WOT timing set at 13 degrees (manual calls for 17 degrees running WOT in water)
6) Timer base moves fully and freely
7) Current prop = 13X19 (13.25X17 is on the way)
8) Decarb procedure performed this year
9) Link and Sync performed (butterflies fully open and close in unison as designed)
10) No tach on the dash, I use a phototach in the driveway
I have observed the following symptoms and I'm not sure if they are related to each other or not:
1) Bottom plug is slightly darker than the other 2
2) Idle rpm fluctuates between 900 and 1200 in a barrel
3) When I first shift the motor, the engine will slowly stall (15-20 sec) unless I give it extra throttle
4) Sometimes, shifting from WOT to neutral too quickly will make the motor stall
5) Sometimes, advancing the throttle too quickly will make the motor stall
6) Sometimes, the motor will only start on the lake with the warm up lever up
7) Warm-up lever usage increases rpms by a ton! (1000-1500 rpm)
8) Running in barrel with the air silencer off, I hear some slight air movement
9) Idle air passage screws were quite a bit off from each other (I lightly seated them and then backed out 2 full turns)
10) After running in a barrel, the impeller housing (and everything else inside the LU) was covered in black gunk
A few questions for the experts:
1) Is a change of 300 rpm in idle normal in a barrel?
2) Can a lower pitch prop increase rpms outside of just WOT?
3) How can I even out the idle rpm and forward gear idle rpm to be more similar in speed?
4) Would an exhaust leak, too long in the barrel, or unburned fuel cause the coating of black inside the LU?
5) What are the specific steps (in sequence) to correctly check and set:
Let me know if I left out any important information. I appreciate the help in advance and I look forward to getting these things resolved!
Longtime lurker, first time poster. I'm hoping to get some more direct advice from the experts on this site. A few things first:
1) Compression = 85 psi on each cylinder
2) Correct plugs shooting a 7/16" gap on all cylinders
3) Rebuilt carbs and fuel filter/pump 2 years ago
4) Primer bulb gets firm and works properly, fresh and flexible fuel hoses
5) Static WOT timing set at 13 degrees (manual calls for 17 degrees running WOT in water)
6) Timer base moves fully and freely
7) Current prop = 13X19 (13.25X17 is on the way)
8) Decarb procedure performed this year
9) Link and Sync performed (butterflies fully open and close in unison as designed)
10) No tach on the dash, I use a phototach in the driveway
I have observed the following symptoms and I'm not sure if they are related to each other or not:
1) Bottom plug is slightly darker than the other 2
2) Idle rpm fluctuates between 900 and 1200 in a barrel
3) When I first shift the motor, the engine will slowly stall (15-20 sec) unless I give it extra throttle
4) Sometimes, shifting from WOT to neutral too quickly will make the motor stall
5) Sometimes, advancing the throttle too quickly will make the motor stall
6) Sometimes, the motor will only start on the lake with the warm up lever up
7) Warm-up lever usage increases rpms by a ton! (1000-1500 rpm)
8) Running in barrel with the air silencer off, I hear some slight air movement
9) Idle air passage screws were quite a bit off from each other (I lightly seated them and then backed out 2 full turns)
10) After running in a barrel, the impeller housing (and everything else inside the LU) was covered in black gunk
A few questions for the experts:
1) Is a change of 300 rpm in idle normal in a barrel?
2) Can a lower pitch prop increase rpms outside of just WOT?
3) How can I even out the idle rpm and forward gear idle rpm to be more similar in speed?
4) Would an exhaust leak, too long in the barrel, or unburned fuel cause the coating of black inside the LU?
5) What are the specific steps (in sequence) to correctly check and set:
- idle air screws on each carb
- idle stop screw on throttle arm
- WOT stop screw on throttle arm
- throttle cable trunnion from control box
- cam and roller to ensure spark advances just before butterflies open
- shifting cable trunnion from control box
- warm-up lever positioning and functioning
Let me know if I left out any important information. I appreciate the help in advance and I look forward to getting these things resolved!
