Re: 70hp idling characteristics?

[johnyrude200]

I’ll pull the flywheel and investigate. Compression on the motor after sitting since last fall was 102-107 even on all 3 cylinders prior to me running it, so I suspect the internals are still OK. I can retest compression now that it was run for a few hours continuously and surely everything is well oiled and wet. Might do a good de-carb too.

Thank you both for throwing so much good information at me, it will be a learning curve, and I’ll need to go through your questions/recommendations 1 step at a time.

To start, this motor is running cold. I have not seen it rise above 123° yet, even after running it at near WOT for a few minutes. Any recommendations on how to improve this? Water in the river is still quite warm up here (70° or better).

I don’t have a 1993 service manual; I’m using a 1994 copy. What is the default carb settings…1.5 turns? ’94 calls for this, BUT ’95 calls for 2.75 turns. I am assuming 1995 motors and newer have a lot of revisions? Also is the synchronization process the same? Could explain what I did wrong if I used the wrong manual.

Don I followed the service manual using the piston stop to establish the reference arrow at the top of the manifold is in the correct position. The rest of the manual basically says to run the motor at idle with timing light and use the adjustment screw located under the flywheel, behind the starter, to adjust timing. But when I changed this screw setting, it didn’t help anything and the timing light showed no change to when cylinder 1 was firing. What did I miss here?

I ended up playing with the carbs, trim setting, and throttle cable trunion to get a idle where the motor didn’t stall out anymore at ‘lower’ idle. I don’t think it’s set correct, because anything below 700-750 and it’s stalling out. It’s also somewhat pulsating at idle back and forth between 700-900 RPM, not steady. Runs rough up through 2000RPM than clears out and acts normal. If I trim UP at idle, the motor starts breathing more easily and may actually sneeze/miss running a little lean and RPMs go up noticeably, as much as 1100RPM.

What does the large high speed jets do to help this motor?