1972 50hp model 50273c engine trouble

[rnfor.jesus]

Was out on a check out run (this motor is new to me) after I had just replaced the throttle cable and I am having an issue I hope you gents can help me with. I noticed today that it has a top speed of about 20mph at full throttle. I am having an intermittant problem that occurs after I have been running a while. I give it full throttle and the rpms seem to go up only about half and I can obtain about 7.4mph! (per my gps) If I take it out of gear the rpms will rev through the roof but not when in gear. Sometimes it works if I shut it off and wait a few minutes and other times if I shut is off it will work right away. Then engine in not running hot because I can keep my hand on the engine without problems. Any Ideas out there? Brian

 

[tashasdaddy]

Re: 1972 50hp model 50273c engine trouble

dirty carbs. but first, has it been sitting up for a while? have you check spark on both cylinders, and compression. post findings. are you using new fuel?

 

[F_R]

Re: 1972 50hp model 50273c engine trouble

It's running on one cylinder. And quit revving it like that in neutral. Good way to blow a piston. Um...that'll make it run on one cylinder for sure!

 

[R.Johnson]

Re: 1972 50hp model 50273c engine trouble

That 50 HP twin was not the last word in reliability. Check compression, if low, don't spend any more money.

 

[rnfor.jesus]

Re: 1972 50hp model 50273c engine trouble

Yes I think the engine has sat for a while. Currently I have no access to check cylinder compression. (unless autozone rents/loans them out?!?) I looked at the spark issue and I am sure this is it. The bottom cylinder has no/intermittant spark. I removed the ignition coil and found the wire kind of corroded but the coil casing itself has a large crack. The top coil fires strong. I switched the wires from the top cylinder inside the "power pack" to the lower cylinders position and again got great spark. I think replacing the coil should rectify the situation, right? Oh, I will not be revving the engine in neutral anymore!!!! Brian