carb kit didn't fix-- what next?

[martinphantom]

86 johnson 25 hp-- I get poor perfomance(maybe a miss??) in low speeds, idles fine and runs great at WOT. Once the butterfly starts opening its ok. Link & sink next? Did a search and could't bring it up.

 

[martinphantom]

Re: carb kit didn't fix-- what next?

Plugs are new-along with all but one fuel line. Got good spark. There is some carbon on top of the pistons though. Compression is outstanding-125(if gauge is correct).

 

[HappyHillbilly]

Re: carb kit didn't fix-- what next?

Fella,<br />I'm not a mechanic, by far, but I've read in these forums about the plug gap making a difference in low/high speed performance. <br /><br />The posts I've seen were concerning plugs with gap settings of .030 - .040. A gap of .030 improved low speed and idle in some motors. A gap of .040 improved high speed. It may not apply to your motor, though. Maybe do a search for gap settings for your plug. <br /><br />I'm just trying to be helpful. If nothing else, I gave your post a bump.<br /><br />Best wishes!<br />HH

 

[fireman57]

Re: carb kit didn't fix-- what next?

Sounds like you may have missed some junk in the low speed jet when you did the carb. Possibly an air leak or a weak fuel pump.

 

[martinphantom]

Re: carb kit didn't fix-- what next?

Pulled welch plugs when I did carb-am fairly certain it's not carb related(was awful clean inside). Runs exactly as it did before. Manual says gap setting is 40-thats what I went with.

 

[fireman57]

Re: carb kit didn't fix-- what next?

link n sync might do it. If your butterflies aren't opening at the exact time you will have a stutter on take off. Usually your plugs are gapped at .30. .40 seems to work better for long periods of idling or slow trolling. Hope you are using Champions.

 

[martinphantom]

Re: carb kit didn't fix-- what next?

Butterfly-single barrel. Champion plugs. Doing a decarb right now.

 

[OBJ]

Re: carb kit didn't fix-- what next?

Check your cam follower roller Martin. Look on the cam for a reference mark. When this mark is dead center on the roller, the throttle plate should just start to open. There's a screw on the starboard side of the carb to make any adjustments needed.

 

[martinphantom]

Re: carb kit didn't fix-- what next?

Two marks about 1/4 inch apart--center them?

 

[martinphantom]

Re: carb kit didn't fix-- what next?

Also-did a decarb using sea foam and a squirt bottle-seemed to help some but still some carbon on top of the pistons. Think I'll buy another can and give it another treatment.

 

[martinphantom]

Re: carb kit didn't fix-- what next?

Cam follower roller is passing first mark and opening on the second mark-is this correct?

 

[martinphantom]

Re: carb kit didn't fix-- what next?

One other question? Is the "low speed adjustment" for idle? Or is it a "lean/rich adjustment? Or should it affect engine performance in low speeds? Currently it only seems to affect idle. But it seems to work backwards-turning clockwise increases idle speed(after initially setting it all the way in and backed out one turn).