Main Jet replacement

[High Hopes]

Is it possible to install an adjustable main jet on the carburetor without dropping it off the manifold? The electric fuel pump is close to were the jet is installed.

Also, how does one adjust for proper fuel /air mixture once the jet is installed? Is there an instrument for this?

Steve

[Don Moyer]

Steve,

You could install an adjustable main jet with the carburetor installed if (in the unlikely event) you have space to get a screwdriver in place to remove the fixed main jet and install the new fixed part of the adjustable main jet assembly.

Adjustment is the easy part; you simply turn the adjustable needle in until it seats in the fixed jet and then back it out approximately 2 turns. From there you adjust the jet for best RPM with the engine fully warmed up and at your favorite cruising RPM.

Don

[High Hopes]

Hi Don,

FYI, I dropped the fuel pump and had access to the jet port. BTW, much less smoke with the fuel leaned out.

Thnx -Steve

[zanchi]

I have an adjustable main jet needle valve that leaks. It appears that the 'stuffing' has been removed. How do I seal it?

[roadnsky]

I have an adjustable main jet needle valve that leaks. It appears that the 'stuffing' has been removed...

When you say "stuffing"... do you mean the WASHER?

[thatch]

I have a feeling that he may be talking about the internal shaft seal. Think of it as a seal on a faucet shaft or a really small stuffing box packing. While trying to find a replacement, a good place to start might be a lawnmower shop.
Tom

[zanchi]

roadnsky, I wish it were that simple! The needle valve leaks from the stem. When I removed the needle valve and the top nut, I found nothing where I would expect to find packing (stuffing). Maybe this valve does not need packing, and is just worn out?

[ndutton]

Yeah, it has shaft packing. You'll have to find a replacement somewhere (carburetor shop?) or replace the jet. Some old outboard engines, the Evinrude Fisherman 6 for example, had the same thing on their mixture adjustment.

[thatch]

"Pixels?"

As a footnote to this thread, Jerry's photos sometime seem to be on almost a "molecular" level. Nice work and keep 'em coming.
Tom

[roadnsky]

The needle valve leaks from the stem....Maybe this valve does not need packing, and is just worn out?

I'm curious... how old is your Adjustable Main Jet?
I know it's not my money but $40 is an easy fix.


@ Tom - Thanks