[Bill Schwab]

Ok guys...I need some help. I have a MAX 6 wheel drive amphibious ATV powered by a twin cylinder Rockwell JLO engine made in WEST, thats right an oldie, WEST Germany.

It has a Walbro diaphram carburetor and the fuel pump is also in the same metering block as the carb diaphram.

Heres the scoop. It runs and starts well, then, it starts flooding badly. I rebuilt the carb, and in it there is a needle and seat that opens and shuts as the diaphram works. If it pumps too much fuel, there is a return line that pushes fuel right back into the fuel tank and there is a crankcase vaccum line that gives suction to run the fuel pump/diaphram. After the engine warms up, it begins to loose power, and dumps raw fuel into the crankcase to the point where the engine drowns itself and eventually dies.

I have been told by various sources the needle and seat sound like the problem, and there is this little curved bracket that opens ands shuts the thing as the carb works. Assuming there is a bendable adjustment on this thing similar to how a float adjusts, does anyone have experience with these carburetors? This engien was also used on Scorpion snowmobiles, and the engine is still being made under the Cuyuna name, part for part. it's an oldie and a greatie, but I need help.

I have taken it apart, and apart again and it's still, doing the same crap.

Any takers for help?

[Pelican]

The carbs on my Stihl equipment are Walbro and work in a very similar manner.

Have you checked that the return line is clear?

Also, on my equipment, the diaphram can be installed upside down and the engine will still run, though poorly like you describe. If your diaphram is like mine, it has a steel disc on one side with a tab in the center, this should be towards the inside of the carb vand contacting the needle lever. The plain side goes toward the outer cover. My dealer put one in backwards once and it ran crappy like you describe.

[Bill Schwab]

That just might be Pelican....I got the thing used, and, the old owner may have put it in backwards. I'll let you know tomorrow after I play with it again. You're right about that return line too. and i wondered if that line has to be higher than the fuel pick up as well, like as in the position of it inside the fuel tank....It seems to me that the return should be well above where the fuel level is.

[Rex Mann]

Bill,

A guy I know from snowmobiling, that's right snowmobiling in Arizona, actually has a Scorpion he has rebuilt. I could hook you up with him if you need more ideas.

Peace,

Rex

PaversInstalled.Com

[Bill Schwab]

Rex:

I'm open to all help. I have been swamped lately and have not had my head under the hood, b ut by Satruday, I want to go take that thing through Mission bay and around the beach.

Scorpion sleds were big on drag racing. They put roller wheels on the skiis and drag race them in sand and in the grass.

[PSUscaper]

Try this guy...he's a local that nows a few things....

http://www.snowmobilebarn.com

[Bill Schwab]

I wanted to thank those who helped guide me. In the mayhem of the weeks, I worked on this ATV after hours. I rebuilt the carb and completely skipped over the part where it specifically tells you how to adjust the needle and seat. So, I took the carb off, yanked out the diaphram and metering block, set the needle rocker and the machine runs great. Now I am fabricating an alumiminum throttle bracket so the weekend is going to play time in the bay, or maybe I'll take it over to Lake Hodges and see what it does.

[tractornewbie]

I always wanted to try one of those things.

Make sure you bring life preservers.

DT.

Originally posted by Bill Schwab
I wanted to thank those who helped guide me. In the mayhem of the weeks, I worked on this ATV after hours. I rebuilt the carb and completely skipped over the part where it specifically tells you how to adjust the needle and seat. So, I took the carb off, yanked out the diaphram and metering block, set the needle rocker and the machine runs great. Now I am fabricating an alumiminum throttle bracket so the weekend is going to play time in the bay, or maybe I'll take it over to Lake Hodges and see what it does.

[Bill Schwab]

My family manufactured them in the 60's and early 70's. We did the Sidewinder with a 292 cc Rockwell engine.

They were a riot then, and still are. Out in the dessert, this thing steals the show and it's beat silly.....