side bowl, back drag carb ??

[free boat rides 4 sale]

I have wmk-18 carbs. They are side bowl, back drag. There are two nipples sticking up from both places on each carb in bowl side and main carb body. I asked the two people who adjusted the idle on my motor about them and they said, "don't worry about it." However, from what I am reading and the postings I read here and info I have found on the net, I am thinking they are needed. I understand they help control the air/fuel mixture, which, my motor is running rich.
So, how does this kind of carb actually work ? And, do I need to worry about it?

Also, I am hearing the ethanol that is in gas is not good for 2 cycles all at. mine is a 1978 1500 inline 6 2 cycle.

Input please, be greatly appreciated.

Thank you. Mr. M

 

[green4themoney]

Re: side bowl, back drag carb ??

the back drag carburator has an additional circuit which lowers the atmospheric pressure in the float bowl to increase fuel economy at mid-range

 

[Chris1956]

Re: side bowl, back drag carb ??

There is supposed to be a small rubber hose that connects the two nipples together. If this is missing, you could run lean at idle. Alternatively, you can plug the nipple on the carb body, if you want.

 

[free boat rides 4 sale]

Re: side bowl, back drag carb ??

I read your replies and want to thank you for doing so. I am going to attach the tube because I do believe there is good reason for putting it there. If it is suppose to give fuel economy, then I am going to do it. However, this motor is HARD to get started (cold blooded) and when I do get it started, it has a lot of unburned fuel in the exhaust, even after I have run a cross the lake for about 15 minutes. I wonder if the carbs and/or the distributor is set correctly ? I have noticed that when the throttle lever is in the "off, or idle" position, the stops on the carb linkage is not resting against the "stops" on the carb itself. This leads me to believe that the butterflies in the carb are not closed per say and instead, open, making it hard to start because the carbs are letting in too much air, meaning, that the carbs are open 3 tenths of the way instead of just bearing being open, or a tenth of the way open.

I hope that is understandable.

I have heard the carbs run differently in the water at a lake compared to the water hose hookup. Do you think or know if this is true ?

Have a great day. Mr. M.

 

[free boat rides 4 sale]

Re: side bowl, back drag carb ??

I read your replies and want to thank you for doing so. I am going to attach the tube because I do believe there is good reason for putting it there. If it is suppose to give fuel economy, then I am going to do it. However, this motor is HARD to get started (cold blooded) and when I do get it started, it has a lot of unburned fuel in the exhaust, even after I have run a cross the lake for about 15 minutes. I wonder if the carbs and/or the distributor is set correctly ? I have noticed that when the throttle lever is in the "off, or idle" position, the stops on the carb linkage is not resting against the "stops" on the carb itself. This leads me to believe that the butterflies in the carb are not closed per say and instead, open, making it hard to start because the carbs are letting in too much air, meaning, that the carbs are open 3 tenths of the way instead of just bearing being open, or a tenth of the way open.

I hope that is understandable.

I have heard the carbs run differently in the water at a lake compared to the water hose hookup. Do you think or know if this is true ?

Have a great day. Mr. M.

 

[Chris1956]

Re: side bowl, back drag carb ??

There is a link and synch procedure for that motor. You might buy a service manual, but here is the verbiage w/o pictures.

Idle timing is 4-6* BTDC That is you want the timing to be in that range, just as the carbs start to open. There is an adjustable brass collar on the dissy (loosen the two 5/16" bolts) that you need to slide to contact the carb lever at that timing.

Max timing is 21*BTDC, and is set with the max spark set screw. Max carb opening is set with the throttle stop set screw. Idle speed is set with the idle set screw.

There is an inline Link and sync post in the FAQ forum. It is not specific to your dissy motor, but it is very good.

Personally I would check compression and spark on all cylinders first to see where the unburned fuel is coming from. You might inspect the fuel pump as well.