18hp Fast Twin starting/running troubles

[geekomatic]

I've rebuilt the carb with a new float as well.New points (checked the gap several times),new coils,new condensors. I actually manager to get it all back together.Plugs get great spark.The gas mixture is right,and the it's pumping gas like crazy.It will crank and run for appr. 5-15 seconds and then die.I started fiddling with the high and low speed needle valves just to see if I could get it to even out and idle for awhile.It always dies.There is gas puking out of the carb intake where the choke butterfly is located.After it starts running, the leaking appears to stop. New electric choke works like a charm, by the way.<br />The needle valves look brand new and I did replace the packing on both.I adjusted the new float as best I could.One screwy thing:The low-speed needle valve packing nut was missing when I got the motor.Impossible to find a replacement, so I went to ACE and got the closest thing possible and screwed it in there. Not the best fit! Bad Idea? <br />I can't seem to find any proper starting instructions for the motor.They were on a printed sheet on the inside of the cowl, but they've disintegrated to the point where I can no longer read them.Is there a standard starting procedure?<br />On a side note: I also replaced the lower unit fluid when I swapped the impeller.It pumps water fine.I get a nice spray when it's running.At this point, I'm just glad to get the thing back together, but I would love to put it to work.

 

[Joe Reeves]

Re: 18hp Fast Twin starting/running troubles

Fuel spraying out of the carburetor indicates the float level isn't correct.<br /><br />(Carburetor Float Setting)<br />(J. Reeves)<br /> <br />With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.<br /><br />(Carburetor Adjustments - Two Adjustable N/Vs) <br />(J. Reeves)<br /><br />Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns. <br /><br />Setting the high and low needle valves properly:<br /><br />NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle va /lve adjustment.<br /><br />(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting. <br /><br />(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting. <br /><br />When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[OBJ]

Re: 18hp Fast Twin starting/running troubles

Geek...the idea of the packing follower nut is to compress the packing around the needle so air won't leak in around it. Is your make-shift nut doing that....when you tighten up the nut, does it make the needle harder to turn? If so, then the nut will work...but, if the needle stays very lose, consider replacing it with the correct nut. Is that a home made gasket on the bowl?

 

[geekomatic]

Re: 18hp Fast Twin starting/running troubles

Great advise from Capt. Reeves as always.I'll take the carb apart again and see what's going on with the float.<br />Admiral OBJ,The ACE nut is not cutting it at all.I've ordered a stock unit from Laing's outboard.2 bucks.I think I can handle that.These folks seem to have everything.The needle is VERY loose regardless of where I turn it.Really should have known better.<br />That gasket on the bowl actually came with the rebuild kit.Does it look a little weird?