50HP spitting back irradic RPM's

[rockytopp]

I have a fifty HP. Model... 507L8B. Serial 1048 this is all I can read. not sure if its all there or not.
This unit starts fine with choke assist. how ever it spits back like a lean runner.
I feel that the carb is the culprit I have not cleaned it yet and the whole rig has set for several months. started first time today in about six months. and even then it was not run, as it died when put in gear,but would idle if not engaged in forward or reverse.
Now I have it and will go through the carburetor, not sure if it needs a kit as it starts and runs fine but I don't like the spitting back , Could this be a gasket or perhaps a vacuum leak ? I have not found any thing that could cause this by inspection. course I know this does not cut any thing when there is a bug that gives you fits.
Are there any tips to be aware of when taking the carb apart??? It looks simple and I will probably do this small job my self. I do not have a book but its just a small carb. what can go wrong? Thanks guys for any help. Paul.

 

[roscoe]

Re: 50HP spitting back irradic RPM's

Go ahead and get the carb kit.
Get the factory kit from Mercury. Well worth the few extra $.

Make sure you soak it well, over night, and then blow it out with high pressure compressed air.

 

[rockytopp]

Re: 50HP spitting back irradic RPM's

thanks I got the kit, now how ever I see on the top of and just off center where
you would normally see a air screw adjustment there is a jet out of a carb. screwed in to it, I took it out and can't tell if it had an air screw or if the jet belongs in the hole. in all my doings I have not seen this before, Is it right or has some one done this that did not know what was the right way to fix it?. I just can't believe that a jet takes the place of the old style screw.
Help on this please. thanks Paul

 

[Frank Acampora]

Re: 50HP spitting back irradic RPM's

If it's a Tillotsen carb--the name will be cast onto the body--then they are all over the place. Some had a white plastic plug in the top front and if you unscrewed that you would see a jet screwed in where you would expect a needle. Some had an air bleed jet screwed into the side of the main body casting. So, I would not be surprised to see an air bleed jet where you described. However, I would expect to see somewhere else an idle mixture adjusting screw--although it is not an absolute. Some Evinrude carbs had fixed idle jets.