Rockwell JLO engines

[Deleted User]

Hi all. It's been years since I have been in snow country, originally from Illinois.

I have an late 60's/early 70's Max 6 wheel drive ATV. It has a 340cc Rockwell JLO engine that was also used on Scorpion snowmoblies in the 70's.

My question is this. It has a Walbro diaphram carb on it. the engine runs strong, but, the carb I thought, needed work. It was dumping lots of gas into the throat, to the point where the engine was bogging down and would flood so badly the crankcase would fill with unburned gas. I got a kit and rebuilt the carb, and it still is doing the same thing. Today, fired it up, reved it, warmed the engine, and it began dumping fuel again. I took off the return line to the tank and watched it fill a coke can in not much time at all. I'm about at wits end on this thing, and am not going to give up.

Is there anyone who knows a little something about th JLO engine or Walbro carb that could help me? We used to own a marina in the 60's, dealt Evinrude motors and snowmobiles and my mechanical knowledge is better than most. I'm obviously missing something on this one.

Thanks in advance for any help you can provide.

Bill Schwab
Naturescape Landscape Co.
Encinitas, Ca. 92024

[X's&O's]

Just a quick reminder did you get the RIGHT carb. kit for it? The JLO Motor was from 66-68' for the Scorpion. Then came back from 72'-73' But never made a 340. The ROCKWELL 340 came in 74' ended 75'. Now if JLO made rockwell (not sure) well then thats fine. If its from a Scorpion they used Tillotson carb's (round plates) from 66'- 72' then walbro (square plates) from 72' till 78' sorry my book only goes till 78', and in 76' they used the mikuni on the Sorpion Brut 340 & 400 Brooten motor. But Note the walbro & tillotson both have the same looking throttle body.

WALBRO Carb. Model's with the rockwell 340cc motor from 74'-75':

WRA
WDA
*WF10

The WD,WDA and WR are very much alike (diaphagm style) but the *WF have a float style bowl like the MIKUNI carbs.


OK now to the fuel prob. Its filling the crankcase with gas. Do you have drain plugs on the bottom of the crankcase?

Is it had to pull over when it sits over night?

Do you have a metal gas tank or plastic with a "PLASTIC" gas cap?

Does your impulse line to the carb. fill with gas?

Let me know if there anyother things.

[Rodimus Prime]

what exactly do you mean by fuel dumping down throat.. also when you rebuilt the walbro did you put BOTH gaskets AND the reed valve diaphram it the circuit plate?

if you only put one gasket under that circuit plate it will flood your engine quite nicely.