Home › Forum › Ask A Member › 1972 Johnson 2hp – low speed and idle problem › Re: 1972 Johnson 2hp – low speed and idle problem
July 19, 2015 at 10:24 pm
#20416
quote fleetwin:
Just want to make sure I understand. You ran the engine before replacing the seals, and it did not idle correctly then either. Am I correct?
I have never done a compression test on one of these 2hps, but others have reported much higher compression readings, like 115PSI. Any signs of overheating? Have you had the cylinder head/exhaust cover off? Please don’t rip it apart based on my questioning though, hopefully the problem is a much simpler one like others have described.
I will just emphasize what others have said so far. Make sure the carb butterfly is closing fully, and the throttle shaft is not jammed/corroded. The only way to do this is to remove the carb and look at the butterfly while manually opening the butterfly slightly, then releasing it. The butterfly should snap closed on its own, without having to “help it”. Have a look at the throttle plate as well, does it look like someone has been at the screw/removed it before?
I have never done a compression test on one of these 2hps, but others have reported much higher compression readings, like 115PSI. Any signs of overheating? Have you had the cylinder head/exhaust cover off? Please don’t rip it apart based on my questioning though, hopefully the problem is a much simpler one like others have described.
I will just emphasize what others have said so far. Make sure the carb butterfly is closing fully, and the throttle shaft is not jammed/corroded. The only way to do this is to remove the carb and look at the butterfly while manually opening the butterfly slightly, then releasing it. The butterfly should snap closed on its own, without having to “help it”. Have a look at the throttle plate as well, does it look like someone has been at the screw/removed it before?
Yes, it ran before and after seal replacement, but still only at high speed.
No signs of overheating.
I’ve gone over every detail of the carb…all components appear to be in good shape and operating well. Good suggestion about the throttle plate… it doesn’t look like it’s ever been removed, but I’ll check it out the alignment mark.
You got me thinking about the compression. Before I take the cylinder head off I’m going to try another compression test. But I won’t be able to do it for a couple of days now.
Thanks again…stay tuned.