HI,
Inherited a 1978 2hp Mate. Not too many hours. Read many posts, similar but not the same as my symptoms. I have a Service Manual and parts list. I used a timing light with external battery to check timing.
I rebuilt carb (new kit, with new float, needles, float needle, cleaned it at least 4 times (I restore old multi-carbed motorcycles, so know my way around carbs). I was meticulous about checking passages and broken needle tips.
Float height set parallel.
New Plug
New Plug Cap
Cleaned tank and tank filter
New fuel line
Good gas flow
Vent not closed (always check)
New points (gap set per service manual, then adjusted a little to get timing marks right)
New condenser
Adjusted gap and checked timing (was a little advanced, so adjusted gap a little to get timing mark into correct spot.
Adjusted carb to open at marks on timing / throttle plate
Water pump replaced, mists water out just fine. Temp check at head while running OK
New fuel and oil mix (I usually use ethanol free premium)
Motor starts fine with light choke. Idles great. Runs good after warmup, up to the "start" mark on throttle plate. If I accelerate up to full speed from slow, engine speeds up nicely, then immediately starts to 4-stroke and slows down about 20%. Slow jet around 1.25 turns. Rinse, Lather, Repeat. I can slow down, let it settle, then speed up again, same symptom: accelerates smoothly, the starts to 4-stroke, and slows down 20%.
Here's the kicker. I get the best high RPM with the high speed needle CLOSED to 1/16 a turn open. Any richer, and the motor slows down and 4-strokes worse. BTW, I did think that the little washer/seal that connects the float bowl tube above the high speed jet to the carb body wasn't sealing. I put a bigger one in to make sure it sealed when the float bowl screws were tightened. Didn't seem to matter. Seems to be too rich at high speed (4-stroking).
The only things I haven't checked or changed are the reed valves, the coil, and the shaft seals. I just ordered reed valves and will try and replace them this weekend. I seem to have great blue spark. Engine starts easily, even with a rope on the flywheel.
On the 3rd and 4th carb cleanings, I checked really carefully for blocked passages and broken needle tips anywhere. I'm going to pull the carb and clean it again, since I have to pull it to change the reeds.
Any other ideas? My brother says I should go for one of those $99 rebuilt carbs on Ebay. I might try it. I've gotten lots of old outboards running, including 3 British Seagulls this summer.
This little Evinrude has me stumped. Oh, I'm at 6500 feet altitude, so I know about jetting and altitude effects. The slow and high speed jets should compensate (but you never get the horsepower back).
Any ideas to check would be appreciated. I guess bad reeds or leaky seals could cause my symptoms. Running out of things to check.
Stu
Los Alamos, NM
Inherited a 1978 2hp Mate. Not too many hours. Read many posts, similar but not the same as my symptoms. I have a Service Manual and parts list. I used a timing light with external battery to check timing.
I rebuilt carb (new kit, with new float, needles, float needle, cleaned it at least 4 times (I restore old multi-carbed motorcycles, so know my way around carbs). I was meticulous about checking passages and broken needle tips.
Float height set parallel.
New Plug
New Plug Cap
Cleaned tank and tank filter
New fuel line
Good gas flow
Vent not closed (always check)
New points (gap set per service manual, then adjusted a little to get timing marks right)
New condenser
Adjusted gap and checked timing (was a little advanced, so adjusted gap a little to get timing mark into correct spot.
Adjusted carb to open at marks on timing / throttle plate
Water pump replaced, mists water out just fine. Temp check at head while running OK
New fuel and oil mix (I usually use ethanol free premium)
Motor starts fine with light choke. Idles great. Runs good after warmup, up to the "start" mark on throttle plate. If I accelerate up to full speed from slow, engine speeds up nicely, then immediately starts to 4-stroke and slows down about 20%. Slow jet around 1.25 turns. Rinse, Lather, Repeat. I can slow down, let it settle, then speed up again, same symptom: accelerates smoothly, the starts to 4-stroke, and slows down 20%.
Here's the kicker. I get the best high RPM with the high speed needle CLOSED to 1/16 a turn open. Any richer, and the motor slows down and 4-strokes worse. BTW, I did think that the little washer/seal that connects the float bowl tube above the high speed jet to the carb body wasn't sealing. I put a bigger one in to make sure it sealed when the float bowl screws were tightened. Didn't seem to matter. Seems to be too rich at high speed (4-stroking).
The only things I haven't checked or changed are the reed valves, the coil, and the shaft seals. I just ordered reed valves and will try and replace them this weekend. I seem to have great blue spark. Engine starts easily, even with a rope on the flywheel.
On the 3rd and 4th carb cleanings, I checked really carefully for blocked passages and broken needle tips anywhere. I'm going to pull the carb and clean it again, since I have to pull it to change the reeds.
Any other ideas? My brother says I should go for one of those $99 rebuilt carbs on Ebay. I might try it. I've gotten lots of old outboards running, including 3 British Seagulls this summer.
This little Evinrude has me stumped. Oh, I'm at 6500 feet altitude, so I know about jetting and altitude effects. The slow and high speed jets should compensate (but you never get the horsepower back).
Any ideas to check would be appreciated. I guess bad reeds or leaky seals could cause my symptoms. Running out of things to check.
Stu
Los Alamos, NM
