old school seahorse stalls at low rpm help

Hello, I'm new to this forum but have bought stuff recently to tune up my first ever boat/motor purchase. Anyways, the motor is a 57-59 model year Super SeaHorse 35 RDS-20. I recently changed spark plugs, bought a carb kit, but couldn't find a new float. The old float which I am still using has paint peeling from it just an fyi, but still seems to work... I think. Problem is, I got it running and have adjusted the high speed but am having problems with the low speed. I think I have it set right as it idles fine but will eventually stall when I stay at low speed. WOT and neutral are just fine and motor stays running. Again I have taken it out fishing a few times already and when I slow troll or slow from fast speeds, it will seem as if it is starving for gas and when I adjust the needle, it will react in a good way but then go back to the same routine of wanting to stall and then eventually stall. It takes a big toll on my starter battery if I were to stay out for a long time on the water. I adjusted the slow speed as stated from almost everywhere I've read up which is from the manual and it won't stay idling good. Please help.

I also bought an ignition tune kit with new points etc... but haven't installed yet. Would this help? Thanks for any help.

Re: old school seahorse stalls at low rpm help

Welcome to the iboats.com forum. The experts here, which I am not, can help you with any question about your boat, motor and trailer. I previously owned an RDS-21 and had similar problems with the idle speed. After three carb tear-downs with soaking and rebuild, I still found some hard "crud" in the low-speed passage that had to be removed with a pick. After that, it was smooth at idle. Good luck with that great old motor!

Re: old school seahorse stalls at low rpm help

If shellac is coming off the old float, it is just clogging up the carb. Take the carb back off and replace the float (available from any Johnnyrude dealer) and thoroughly re-clean the carb and all the tiny openings, especially the idle circuit. Remove the welsh plug on top of the carb and clean that that out thoroughly, and make sure the little holes in there are clear. Any small speck of foreign matter will cause problems you describe.

Re: old school seahorse stalls at low rpm help

Well when I rebuilt the carb, the kit came with a new welsh plug in which I took off the old one and believe it or not, the dang thing fell off after installing it, atm, I am using a plastic disc that I made to the right diameter and sealed it with thread lock sealant. Has held up for 3 weeks now.... but have only been in the water 4 times since. Where can I get a new welsh plug without having to buy a whole new kit? I will have to call my local johnson dealer to get a new float as Iboats didn't carry any for me. Also there is a roller type thing that leans on the cam plate and connects to the throttle plate inside the carb, I was reading an online manual and adjusted it by setting my speed lever to slow first, haven't ran the motor yet as I am repainting the boat. Thanks for the replies and advice.

Re: old school seahorse stalls at low rpm help

You have to tap it almost flat with a ball-peen hammer. I also apply a few drops of epoxy just to make sure it seals good. Let me know the exact diameter of the welch plug - I probably have one around here.

Re: old school seahorse stalls at low rpm help

sumo82 said:

Also there is a roller type thing that leans on the cam plate and connects to the throttle plate inside the carb, I was reading an online manual and adjusted it by setting my speed lever to slow first, haven't ran the motor yet as I am repainting the boat.

Click to expand...

It sounds like you are describing the "cam follower" and it is part of the link&sync to make the throttle open at the correct timing mark. The high and low-speed adjustments cannot be made until the motor is at normal operating temperature AND in the water, under load. FYI, if you go to a dealer for parts, it really helps to have the original P/N for them to look-up. The link below is to the OEM parts catalog for your RDS-20. Good luck!

http://www.marineengine.com/parts/v...ntage-evinrude-johnson/377518/37751800001.htm