Re: Cold Running Motor…Revisited

[johnyrude200]

I’ll go through the motor again in the next little bit and report back. I do have a set of new coils to swap out, and will double check the flywheel woodruff key.

Frank – I read your post from yesteryear about the recirculating hose, however since the blue boards are now gone I have a question. Do I just reroute the hose by drilling a small hole in the pan, then the exhaust, and running it into there? Of course plug up the orifice on the intake bypass (temporarily with a toothpick, and permanently with the crankcase seal).

I have been toying with starting to do these conversions since I have been working on a lot of the post 1968 18-20-25’s, and they all idle like crap and blubber like hell until they clear out…plus a ton more smoke. I’d like to think it isn’t something obvious I’ve been missing on 4-5 different motors, as I’ve checked the low-speed bearing (packing), cleaned carbs, gone through the usual timing of the ignition, etc. These seem to be the only motors I have been working on that run this way so after reading what everyone has said, I guess it’s just the way they run

I have observed that on pretty much all of the 18-20-25’s from that ’68-76 period, the initial setting of 1 turn out for the low-speed needle doesn’t work. It will make it run, but they cough (lean), and generally about 1 & 3/4 turns to 2 turns seems to be what fixes this. At the very most, 2 &1/4 to 2 & 1/2 turns.

If it’s not coils, timing, or a lean setting, I’ll pull the powerhead to check the water restrictor.

Jerry – even with sustained 1/2 throttle, temperature wasn’t coming up. What has me scratching my head is it didn’t run like this when I put it away last fall. What is alarming/red flagging to me is that 3/4 throttle it is misfiring badly. The only thing I’ve changed since I put it away was I re-calibrated using the timing fixture last night. Previously, it was using a feeler gauge with the point rub bars on the ‘set’ mark on the crank cam. They are new points (well, used all last summer new). I also want to note I use test props in my 275 gallon tank; so hopefully that helps negate some of the ‘non-load calibration’ issues.

Frank – I set timing using the timing fixtures and a continuity meter and have it right on for 1/2 between the 2 timing marks on the magneto. When I put the motor away last fall, timing was set placing the rub bars on the the ‘set’ mark on the crank timing cam and a feeler gauge. Am I missing something here? I can go back and forth between the two settings if necessary for some trial and error before pulling the powerhead to investigate the water restrictor.