25 Johnson Bogg with cover on

[EddiePetty]

A 85 year old fellow down the road asked me to get a 25 Johnson (25R73A) running for him that has sat for the last 21 years!!

Long story short, after new mag, coils, plugs, impeller, thermostat and carb re-build...it runs and starts like a scaled monkey: until the cover (hood) is latched down!!! Engine will bog down and run rich with excessive smoke at any speed above fast idle (in gear or neutral).

I have examined the cover for contact with anything.....Nuthin'. There is no cover insulation and the cover fits properly.

The only air intake I can find is a square-ish opening beneath the carb and just above the transom clamp area.

As an experiment, I paddle-bladed two 1-1/4" holes in the cover just beneath the aft hood hand grasp area...much improvement with engine speed.

Anyone with ideas how the intake air is restricted or am I chasing the wrong idea??

 

[Haffiman]

Re: 25 Johnson Bogg with cover on

Somewhere you have an exhaust leak into the cowling.
Might be the base gasket (off with powerhead), might be an exhaust cover gasket??

 

[freddyray21]

Re: 25 Johnson Bogg with cover on

agree exhaust leak and the carb is choking on it's own exhaust. best to fix it but some have drilled holes in the cover to vent it, but I would fix it right.

 

[Steve A W]

Re: 25 Johnson Bogg with cover on

Are You barrel running it or is it on the boat?
If it's in the barrel it will pick up exhaust gasses from in the barrel.
Put a fan to blow exhaust out and see what happens.
Good Luck .
Steve A W

 

[EddiePetty]

Re: 25 Johnson Bogg with cover on

Are You barrel running it ......?
If it's in the barrel it will pick up exhaust gasses from in the barrel.
Put a fan to blow exhaust out and see what happens.
Good Luck .
Steve A W

Sorry for the delayed response folks. We were out slayin' the Spot most of yesterday !!

Re-checked myself on the exhaust leaks.....notta one.

Set up the floor fan this morning and B-I-N-G-O !!!!!!!!!!!

Sometimes the simple is Soooo obvious that it escapes me !!!!

Thank each of ya'll for the suggestions.

See... after six plus decades there is still knowledge to be absorbed !!!

Thanks!!!