Engine Bog

[zenoahphobic]

Geez, I dunno guys. Every single carb'd engine I've ever had... cars... boats (4-stroke and 2-stroke)... etc, etc. Has always had some type of bog on a cold engine and quick acceleration. I've owned quite a few boats, but I've run literally hundreds with my job. On smooth, con*****ed acceleration - no bog. But on quicker acceleration, yes.

I agree there is some consequence when rapping the throttle on too fast. It may not be noticeable in some engines, but it was a way of testing the limit bore diameter when choosing a carburettor size. With fuel injection fuel gets in quicker and thus the temporary lean situation is less so than with Carey's, however the tendency to make new motors leaner, this stall, bog or backfire is making a comeback.

[TownsendsFJR1300]

Geez, I dunno guys. Every single carb'd engine I've ever had... cars... boats (4-stroke and 2-stroke)... etc, etc. Has always had some type of bog on a cold engine and quick acceleration. I've owned quite a few boats, but I've run literally hundreds with my job. On smooth, con*****ed acceleration - no bog. But on quicker acceleration, yes.

Bone cold engine, cold water, start and nail it, I agree, you can get some bog (especially with the choke fully off)

Jasons in west Florida, water temp is about 80F, air temp even warmer.

Between the water temp, air temp, engine is still semi warm, it shouldn't bog.

[99yam40]

There is only 1 screw per carb that will effect the idle mix (lean/rich) that can be adjusted...the air adjustment screw.

that screw adjusts the amount of air and fuel mixture that gets thru during idle.
there are air jets and fuel jets and passages that can plug or restrict proper flow.
I do not think that motor has a screw that just adjusts the amount of air

there are main jets that can be restricted also

also make sure the timing is advancing as it should and hit spec

[DennisG01]

Bone cold engine, cold water, start and nail it, I agree, you can get some bog (especially with the choke fully off)

Jasons in west Florida, water temp is about 80F, air temp even warmer.

Between the water temp, air temp, engine is still semi warm, it shouldn't bog.

Well, for sure, the Florida "variable" is one that I have no experience with! BUT... in his first post he stated he ONLY gets the bog on a cold engine. Once it's somewhat warm, he doesn't get the bog. This is the key piece of info I've been focusing on - but certainly I could be missing something. On the other hand, without being the person who is actually running the engine I certainly can't say if it's the "normal" amount of bog for a cold, carb'd engine - just that it is not abnormal for a bog to be happening and possibly he's looking for an issue that doesn't exist. But, on the "other" other hand, none of this is to say that the engine can't be tuned a little better - but again, hard to say without being the person actually running it. And, as I mentioned, I "know about" tuning an engine/carb's, but I do not have near enough experience or knowledge in this area to get into the nitty gritty of it - it's much better left to those of you with the experience.

[Jason2tpa]

Now the worst of the weather has passed I was able to drop boat in water and make carb adjustment. All it took was a 1/4 turn out each of the air adjustment screws, and I brought the idle speed up 100 rpms to the higher end of spec. Definitely made a difference.