HELP! Yahama PRO50LG (1987)

[mike_fishing]

I'm really getting SICK of working on this damn thing! Can someone please give me some advise/direction ? I bought an old Monark just to get this motor to put on another boat. I've cleaned the carbs like 3-4 times already. It runs for a minute , then cuts off. Sometimes It stalls when I put it in gear. But if I "feather" the electric choke I can get it going for a ways, then cuts off. It wont start right back up , but if you give it a few seconds it will. It seems like some kinda fuel issue. Though the filter is new.The pump is strong, gas is fresh and like I said, I've gone through the carbs 3-4 times. I've blasted carb cleaner through every jet! I'm not an "outboard guy" but I'm learning. I'll rebuild this damn motor if I have to. I have too much money/time in it to get another. Plus it really is in pretty good shape for it's age. Please can someone help me fix this damn thing?!! I've always liked Yahama products. I know this is just an old motor and not a POS.
Mike

[99yam40]

have you checked compression and spark to make sure all is good?

Have you checked fuel delivery with a pressure/vacuum gauge and looked for air leaks with a piece of clear tubing in the fuel line after the pump?

Timing is something else to make sure is where it is suppose to be at start,idle, and open throttle.

If all is good then you probably need to pull carbs disassemble completely and soak in a carb cleaner, blow out all passages and jets with compressed air and reassemble.
Do not forget to do the link and sync like the manuals says any time the carbs come off and are put back on. it is all part of the adjustments.
you are probably needing a service/repair manual. I use the one from Yamaha but there are others out there

[mike_fishing]

No I haven't done any of those things , other then checked the spark. Thank's for giving me some direction!I'll try those things. Stay tuned for an update. Thank you very much !

Mike

[mike_fishing]

Very Bummed out

I did a compression check yesterday. The #2 cyl. has only 30 lbs. of compression. I've built several V8 car engines , but never a 2 stroke motor. Much less and outboard engine. Does anyone know a good place to get rebuild kits for a fair price ?

Mike

[boats.net]

Need to tear it down and find out how much damage you have and if crank and rods are ok.