742B CARB FIX

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tlaskey

Member
Joined
Oct 10, 2018
Messages
8
OK, This is the first time posting but have read I have had carb issues on my 742B with the Mitsubishi 4G32 forever....
Rebuilt it over and over, gets better and worse. Finally had it!

Bought a carb for a Mitsubishi lancer, Installed with some modifications and
IT RUNS BETTER THAN IT EVER HAS! Right now I still have the secondaries plugged and running off only the single barrel like the original carb.
The last picture kinda shows wher I removed the linkage for the cars cable and added the lever for the original bobcat linkage. all worked great.

Carb MD-081100, MD-006219 for a Lancer AND before you say that doesn't have a fuel shut off solenoid......I added a fuel tank transfer solenoid
set up to flow fuel when the key is on......done.

When warm the machine starts with the throttle at idle with NO CHOKE and just purrs. I've been fighting this forever.
I made a half inch aluminum spacer and used the plastic spacer from the original carb to get hight to keep linkage from interfering with manifold. Made longer control rod from governor, and will open up the air cleaner adapter to fit the new carb, (it's a little bigger than original)

Just saying a few hours of work and less than $150 bucks and this is running the best it ever has. I will update once I really work the machine but it sure seams like this is fixed.
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Kalbiking

Member
Joined
Sep 21, 2022
Messages
21
Nice .how you make the spacer? You have a mill?
Does your machine have some contraption that runs off of engine belt that has linkages to carburertor? Looks like a mini smog pump but its not. Weird thing i dont think its a governor
 

Kalbiking

Member
Joined
Sep 21, 2022
Messages
21
A car carb doesnt have accelerator pump does it? Does it have the governor like in photo? If it does is it still operational?
 

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dfb

Well-known member
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Sep 11, 2017
Messages
55
Nice fix! What year Lancer did you get a carb for? I need to add a shut off solenoid to mine also.

 

Kalbiking

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Joined
Sep 21, 2022
Messages
21
Nice fix! What year Lancer did you get a carb for? I need to add a shut off solenoid to mine also.

Just got to ebay and search for 4g32 carburetor but they dont have accelerator pumps .dont know if it matters much. He doesnt use a solenoid .he running an electric fuel pump wired up to ignition switch. I dont know why it needs a fuel shut off solenoid anyway if it has an ignition coil shut off with the key.​

 
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tlaskey

Member
Joined
Oct 10, 2018
Messages
8
Yes, I have the same govenor and the carb I bought does have an accelerator pump internal. Made the spacer on my mill but could be done on a drill press. 1/2 inch aluminum and I used holes saws for bores. Used the pastic spacer for a templet.
 

Kalbiking

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Joined
Sep 21, 2022
Messages
21
Good deal. They got those carbs on ebay for as low as $85. Are the bottom flanges different or its just a height issue? You couldnt get your old one rebuilt right? I read there little check balls people overlook.

 

Kalbiking

Member
Joined
Sep 21, 2022
Messages
21
Yes, I have the same govenor and the carb I bought does have an accelerator pump internal. Made the spacer on my mill but could be done on a drill press. 1/2 inch aluminum and I used holes saws for bores. Used the pastic spacer for a templet.
I never saw a carb with internal accelerator pump since they all need a lever attached to throttle somehow. Even on little dirt bikes theyre external. Maybe its the plunger thingy
 

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tlaskey

Member
Joined
Oct 10, 2018
Messages
8
Yep that is the same accelerator pump. Should have said integral not internal. I know how people like to slam.

All good! I'm done
 

dfb

Well-known member
Joined
Sep 11, 2017
Messages
55
The electric fuel shut off is helpful in preventing fuel from the higher level in the tank from flowing into the carb when the machine is off. The needle and seat in the carb does shut it off but as the fuel evaporates in the carb the tank keeps filling it. The electric cut off prevents this.
 

Kalbiking

Member
Joined
Sep 21, 2022
Messages
21
The electric fuel shut off is helpful in preventing fuel from the higher level in the tank from flowing into the carb when the machine is off. The needle and seat in the carb does shut it off but as the fuel evaporates in the carb the tank keeps filling it. The electric cut off prevents this.
Ha just put an inline shutoff valve easy peezy. I guess . hey tlaskey can you text me i got some questions and pics to show you. Email or text me please. [email protected] or 740 738 3001
 

Kalbiking

Member
Joined
Sep 21, 2022
Messages
21
Yes, I have the same govenor and the carb I bought does have an accelerator pump internal. Made the spacer on my mill but could be done on a drill press. 1/2 inch aluminum and I used holes saws for bores. Used the pastic spacer for a templet.
Got a pic of it on the engine? What about the factory spacer plate? What does that large vacuum nipple go to?
 

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dfb

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Sep 11, 2017
Messages
55
My 742B has no vacuum under any throttle positions at that large vacuum nipple. It appears to be blocked off. I would call it a dummy that is not used in this application.
 

Kalbiking

Member
Joined
Sep 21, 2022
Messages
21
The big vacuum port on mine is open. Do you have the part# on your carb mine is in photo.maybe mine off something else.?

28-32DID SA27
 

dfb

Well-known member
Joined
Sep 11, 2017
Messages
55
If there is not a hose in need of a vacuum source that is not hooked up, I would just cap the nipple off. Being that yours is now an automotive carb, that port could have been used for something like power brakes.....that I am guessing you don't have. Cap it off, you will be fine.
 

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