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Burnt Valve ? '78 620


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there's a sight glass on the carb??? lol
front you say? should i be able to see it with the carb hat on it? im guessing some of the california emissions junk could be blocking it

the fuel pump works GREAT, i turned it over standing outside and watching it pump gas into an empty water bottle. pumps in strong bursts

coming from a motorcycle background, imo it sounds like a stuck float or a partially clogged jet

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Stock carburetors have a window (older ones) or a small round glass with a white dot on it. Gas should be showing at half way point.

 

If no gas, float may be jammed it the up or valve closed position OR the brass screen on the banjo inlet fitting is plugged.

 

If gas then the idle circuit may be plugged. Or idle cut solenoid not working.

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57 minutes ago, banzai510(hainz) said:

when cold runs fine?

whats the choke doing?

 

get a timing light

When cold it did run fine 

 

Tried to fire back up maybe an hour ago, now cold, and it's doing the same thing... few seconds and dies

 

I'll see if I can find the window 

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35 minutes ago, 420n620 said:

yes, you have to remove the air cleaner to see the gas site glass. 

Got 'er ! 

 

About 1/4 full 

Pic of from above angled down 

20210530_112921.jpg

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36 minutes ago, datzenmike said:

That's more than enough to run and idle on.

 

Can you keep it running long enough to get the engine warmed up???

Does it stall cold or hot or both???

It's now stalling hot and cold

I can keep it running by giving it gas but it's a delayed throttle response

She wants to stall under load

Won't run on her own at all

 

So all that changed was I put maybe 1/2 mile driving on it in the community after it was idling for 3-4 mins without issue

Starting to warm up and it started missing under load 

I limped it back 

Seems like it isn't getting fuel? 

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20210530_112921.jpg

 

This says it is getting fuel.

 

Do you know where the idle mixture screw is? it's on the base of the carburetor on the valve cover side.

Do you know where the idle cut solenoid is? It's a hexagonal shaped thing on rear passenger side with a RED wire going to it.

 

Unscrew the idle mix screw but keep track of the turns so it can be put back the same.

Unscrew the idle cut solenoid but have a care, there is a loose part inside with a spring so be ready for this and don't loose it.

 

With both removed, get a can of carb cleaner that comes with a straw. Stick the straw in the idle mixture screw hole and spray the shit out of it. It should likely blow out the idle cut solenoid hole, so don't get it in your eyes. Now spray the idle cut hole and it should spray out the idle mix hole. Install the idle mix screw and spray into the idle cut solenoid hole. This will back flush any dirt into the float chamber.

 

Put the idle cut solenoid back in and give it a try.

 

Once warmed up, set the best idle mix buy doing the following...

Turn idle down as low as will keep running. This will make changes to idle quality easier to notice. Turn idle mix screw in or out back and forth and find the smoothest fastest position. There may be up to one turn where there is no change so just guess and set in the middle. Idle speed will have improved so turn it back down. Repeat the idle mix adjustment again and again until you cannot improve the idle quality and the idle speed is 700 to 800 RPMs.

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So my a/f screw was clogged and the solinoid was hand tight 

She was 5.5 turns out 

Blew it out 

Runs. 

Timing was at 20° ish, set it back 

Played with a/f and idle screw - but my idle guy is all bent -___- sigh man this is one thing after another 

I slightly bent the bracket to counter the bent adjustable idle screw/diaphragm piece 

Pulling the throttle open and closed while adjusting the idle and playing with the bracket /screw must have flooded it lol she wouldn't fire back up

Will go back it at it tomorrow, but we're real close

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