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bf25a rough idle

roscoe69

roscoe69

New member
purchased a bf25a a year ago and used it a couple of times before winter set in. I used good gas while running it and a great amount of seafoam in the fuel. I drained the carbs and refilled with the high saturated seafoam gas for the winter. this spring I drained the carbs and refilled with seafoam gas. first couple of boat trips everything worked good. we probably used three tanks of seafoam fuel, but now have a idle problem. checked plugs and lower plug is white . adjusting the fuel screws doesn't seem to change the engine speed until all the way in. on all three carbs. the motor runs great at high speed. do I have a air leak? should I just pull all three and do the clean thing.. I don't want to hurt the engine if this problem would hurt it.
 
How much Sea Foam did you put in that fuel?

Generally, Sea Foam should be used to decarb the engine and kill varnish that builds up on carb parts. I don't think it should be used as a routine gas treatment. If it is, it should be used very sparingly. It is primarily alcohol.
 
thanks for the reply's, I probably used a bottle to a tank full, the purpose was to make sure that the varnish if any would go away.
 
Storing with Seafoam probably not a good practice. As chawk_man says, it's mostly alcohol and alcohol absorbs water.

Your white plug indicates lean burn so that cylinder might not be getting enough fuel for some reason.

You are correct to consider air intake leak although that SHOULD have all cylinders burning lean. But if the leak is at the carb gasket for a specific cylinder then that could cause the one cylinder to be lean.

With all that Seafoam maybe it DID cause a little chunk of something to get knocked off and into a carb passage. With Honda you can't rule out a good carb cleaning.

Do you know if the valves have ever been adjusted on this older engine? A tight exhaust valve could cause elevated cylinder temperature and that might look like a lean condition at the plug. I would check valve clearances if not done already.

You are also right about a lean condition hurting the engine. I wouldn't run it that way, especially at high speed.

Good luck.
 
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thanks guys, will check the valves but I do believe something got dislodged and ended up in a passage. will have to make plans for a good carb cleaning. I do have a spare engine for fishing.
 
hi guys, here is a update, cleaned every little hole in jets one new gasket and put her back together. balanced carbs. idles and runs great now.
 
Good job, when you drain the carbs, you should just leave them dry, don't fill with gas and let it sit. If anything you should fog them if you want to put anything in them during storage.
 
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