Small Engines (Lawn Mowers, etc.): honda 7.5hp engine, little boat, spark plugs

Question
Hi there

I have a honda 7.5hp engine on my new little boat.

The engine starts (eventually) but when you go to low revs it stalls. It also stalls if you rapidly put up the accelorator.

I have repalced the spark plugs and also cleaned the carb. I am unsure of what to set the mixture screw or whether this could caucse this issue?

I also notice there seems to be a screw to adjust air? this seems to be something you are meant to do with your fingers as it has no place to insert a screwdriver. When I got the the engine this was done up tight. I dont know if this is anything.

when the engine is running it seems to work fine. It is only in the low revs although when i was on the water you couldnt put the accelorator to maximum as it would start to choke if that is the right word!

Thanks a lot

Answer
Hi Olly,

Try adjusting the screw.  If it IS a mixture adjustment it should not be screwed in all the way.  Although both are not always present on a particular engine, the larger high speed mixture screw is usually set at about 1&1/2 turns out, while the low speed screw is set at 3/4 turn out.

Let me know how you make out.
Michael