1975 Johnson lean pop?

[guest]

I have a 1975 Johnson 85 the compresion is good, spark is good, thoroughly cleaned both carbs, yet still I have a pop through the carbs (only occurs at idle) that is hard enough to kill the engine. It restarts immediatly untill the next sneeze or pop. There is a high speed and low speed fuel jet but no adjustments for air mixtures. All gaskets, fuel pump and hose connections seem fine what could I be missing. Carbs look to be opening together. Is there ay low speed timin changes I could do? Please Help.

 

[guest]

Re: 1975 Johnson lean pop?

Just thought I would add I believe dirty carbs are definetly not the problem I did a thorough job inluding removing and cleaning all jets. Could this be reeds? Can they go bad if they are not broken?

 

[iwombat]

Re: 1975 Johnson lean pop?

Did you remove the plug over the idle jets and clean those out with compressed air?

 

[guest]

Re: 1975 Johnson lean pop?

Yes, the carbs were completely disasembled and cleaned there is also no excesive play in the choke or throttle shafts>

 

[guest]

Re: 1975 Johnson lean pop?

I am no mechanic by any means, but is there anything else I can look for?

 

[HighTrim]

Re: 1975 Johnson lean pop?

Just thought I would add I believe dirty carbs are definetly not the problem I did a thorough job inluding removing and cleaning all jets. Could this be reeds? Can they go bad if they are not broken?

Is it spitting back at you, sounding like a mild backfire? If so that would indicates a carb slow speed restricted jet..... something causing a lean carb scenario.

Blowing fuel out the carb throat with each downward thrust of the piston would indicate a reed problem if you had one.