112 SPL has rough mid range running. Otherwise runs good. Opinions?

[havoc_squad]

Hmm... couldn't find, or didn't look at all possible causes

See how it runs, they may have corrected it with replacing the cam follower, it will affect the Pickup Timing as it changes the Snyc between the Carb and Timing Advance and less than smooth performance can happen

I'm suprised there wasn't some signs of pre-ignition/detonation going on due to the ignition timing advance much more than the fuel/air supply did from the transition from idle to intermediate.

I would also guess that your carb throttle arm was not fully open due to the outter roller missing, hence why WOT fuel was not achieved.

I do know that whether two stroke or four stroke, you can identify hesitation issues by dropping the hammer in idle to safe WOT speed run under load. Then compare the behavior from idle at load with a slow progression of the throttle.

It helps to identify the behavior/symptoms of each stage of fuel/ignition.

If you have an issue with intermediate stage of throttle, what affects it?

Ignition timing, whether all spark on all cylinders not missing, intermediate fuel jet.

 

[racerone]

Yes , ----Post on the outcome.

 

[JLesko]

Took the boat out for a ride after the work. The roughness is down a bit. The best way to describe it is that the rpm range where is it rough has shrunk. Maybe it is between 2200 and 3000 now. The idle is smoother and it just runs better overall. The impeller had a chunk taken out of one of the blades and was 5 years old, so that has been replaced. Additionally, the overheat warning alarm was not working so I had that fixed as well. The lower unit had a bad shaft seal. There was some minor pitting on the shaft, but they said it was not a big deal. They changed the seal, pressure tested it and changed the oil. I think I am at a point where I am just going to go with it until it doesn’t run anymore. I mean, how much money do you spend on a 23 year old outboard.... Ran at a steady 4800 rpm / 24 mph across the bay and back with no issues. I asked about the 17 pitch prop taking forever to plane and not going above 4300 and the consensus was that the boat is probably underpowered. With 50 gallons of fuel, 2 adults and 2 kids plus the boat, I am at close to 3000 pounds total. Having the 112 when the boat is rated for up to 150, may be a bit too small of an engine. No big deal for what we use it for. It uses about 10 gallons of gas when we go out for the day and that is fine. I am going to leave the 14 x 13 pitch prop on it and just use the boat like it is. Thanks for the help from everyone.