Usually just for a few seconds after I shut it off it likes to sputter a bit. . Any ideas why or how to fix?

Called run-on. Caused by carbon build up that acts like glow plugs to unburnt fuel. You can up your octane, or clean the valves. May also be caused by rich fuel. Start by ckeaning carb and tune.

Mine does this a little as well.  I have the carb rebuild kit in my shed but am scared to pull my carb off.

It's called dieseling here in Idaho haha. All ya gotta do is either, like they already said, up the octane for a bit, OR you can hold the throttle open to rev it up and pour a LITTLE bit of water down the intake. Not too much cause it'll hydrolock, but a little tiny bit at a time will clean it out

What's the idle at? Too high of an idle can cause it too

Are you running the stock hitachi? If so, there should be an Anti-Dieseling solenoid on the side of it to prevent this. Dieseling is sometimes common with the Weber swap because there is no solenoid. What you can do also besides water, is rev the motor up, remove the air filter cover and pour about 1/2 can of Seafoam down the carb, and then either stall it with the Seafoam, or shut it off quick. Let it sit about 15/20min then fire it back up (May take a little bit depending how good your plugs are) it will smoke like hell for a few, but rev the hell out of it, and once it stops smoking so much, take it for a spirited drive and give it a good running to blow out the carbon.

 

Seafoam will do the same thing as water, but is petroleum based. And personally a better solution. I've done it to ever vehicle so far, Carb or FI.

 

Here is a good video showing you how to use it correctly.

 

Edited April 28, 201510 yr by TheLoyale

Idles at 1000

 

I'v got a Weber carb. Where would be the best intake/vacuum valve to get the seafoam into the crank shaft?

 

I put better gas in her today but I'v been meaning to do a seafoam anyways..

It's called dieseling here in Idaho haha. All ya gotta do is either, like they already said, up the octane for a bit, OR you can hold the throttle open to rev it up and pour a LITTLE bit of water down the intake. Not too much cause it'll hydrolock, but a little tiny bit at a time will clean it out

Use a spray bottle, that way the water is already atomized, and is much easier for the engine to "digest"

The Brake booster hose or straight down the carb. Either way it'll work its way around the intake system cleaning it out. DO NOT, stick it in the crank case. There are other options to clean deposits out of the oil system.

Idle could be brought down a bit, 700-800rpm would be best.

Idle could be brought down a bit, 700-800rpm would be best.

I thought you waned it up, so the chance of hydrolock was decreased because the amount of water per cycle would be decreased

Sounds good! Ill dump the Seafoam 1/3 in the gas tank, 1/3 in oil and 1/3 down the carb.. Thanks gents!

I thought you waned it up, so the chance of hydrolock was decreased because the amount of water per cycle would be decreased

 

If you are gonna be dumping Seaform down the carb, yes you want to rev it so it'll suck it thru the system and not just bog it out.

 

For normal running idle, 1000rpm is too high, 700-800rpm is best for normal idle running, this will reduce the likelihood of it dieseling when the ignition is cut off.

Sounds good! Ill dump the Seafoam 1/3 in the gas tank, 1/3 in oil and 1/3 down the carb.. Thanks gents!

 

Do not use any in the oil unless you have an extremely dirty motor. Just putting it thru the carb and in the fuel will be fine to clean out the air and fuel passages.

Use a spray bottle, that way the water is already atomized, and is much easier for the engine to "digest"

Touché haha that probably does work better.

Do not use any in the oil unless you have an extremely dirty motor. Just putting it thru the carb and in the fuel will be fine to clean out the air and fuel passages.

And if you do, make sure to change your oil within 100 miles

If you want a better product, which you can leave in the oil to help clean and add some protection, try using Marvel Mystery Oil. It is an additive which works with all oil types (You can put some of this in your Petrol as well) After you change you oil, I would add about half qt to the fresh oil (DO NOT OVER FILL OIL) and it will help clean out deposits and sludge from short trip driving.