1980 Special 650. Left side cylinder won't fire, carb leaks on Primary

Anyone else have a similar problem?

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Pyrobooster

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Hello all,

I'm new to this forum and to my 650, but I'm starting to love both!

Here's my problem, any help would be much appreciated.

1980 Special 650, 3500 miles, sat in a non heated or cooled garage for twenty years,
also may have laid on its side for several weeks/months when it was newish.

I cleaned the carbs all out, got a new battery, and have spark in both cylinders.
When I set the petcock to "PR" fuel leaks from the left side air box out of the carb, but not in "ON" position.

It will start with almost no problem, but will not keep running unless I keep giving it gas by holding the throttle. The right left cylinder will not run reliably), and seems to only kick in if spray starting fluid in the left side air box. I have not compression tested it yet, as I do not think I that is the issue, as the miles are so low and all the internals that I have seen are pratically flawless.

Here's one more piece of info, the exhaust pipes are blued from the engine heat differently, the right side, the side that fires (a medium blue color) is noticeably darker than the left side the side that does not fire (a reddish gold color).

Does anyone have any ideas? This is my father's old bike and I went through hell to get the title, and would love to ride it before winter.

Thanks in advance,
Pyrobooster
 
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www.amckayltd.com/carbguide.pdf
The petcock has three positions. PRI/ON/RES. The PRI is a prime position, this is used when you need to get fuel too the carbs with out the engine running. As in had the carbs off for cleaning, the tank off for cleaning.
The on position is the normal position. As the engine starts the vaccum turns on the fuel. In the RES or reserve position is for when you run the main tank dry, switching to RES gives you another 3/4 gallons of fuel. It works with vaccum too.
Thats why fuel leaks in the PRI position. Your carbs need to be cleaned. You have a float or float valve sticking.
Leo
 
www.amckayltd.com/carbguide.pdf
The petcock has three positions. PRI/ON/RES. The PRI is a prime position, this is used when you need to get fuel too the carbs with out the engine running. As in had the carbs off for cleaning, the tank off for cleaning.
The on position is the normal position. As the engine starts the vaccum turns on the fuel. In the RES or reserve position is for when you run the main tank dry, switching to RES gives you another 3/4 gallons of fuel. It works with vaccum too.
Thats why fuel leaks in the PRI position. Your carbs need to be cleaned. You have a float or float valve sticking.
Leo

I'm testing this in a few minutes. Carbs cleaned as well, had leaking but now I don't. Even have fire on right side. I currently have the updated aftermarket OEM petcock on the tank and both air valve tubes on my carb boots capped off. I know the original petcock had a hose going from the left side intake to the petcock, so will it make any difference if I have it set up without that tube? I tried it with the tube and it just pours gas straight into the boot/ intake lol. I'm going to try swapping the plug wires, what happens if it doesn't fix it? I even hear fuel going in the carbs when I open the petcock.
 
I'm testing this in a few minutes. Carbs cleaned as well, had leaking but now I don't. Even have fire on right side. I currently have the updated aftermarket OEM petcock on the tank and both air valve tubes on my carb boots capped off. I know the original petcock had a hose going from the left side intake to the petcock, so will it make any difference if I have it set up without that tube? I tried it with the tube and it just pours gas straight into the boot/ intake lol. I'm going to try swapping the plug wires, what happens if it doesn't fix it? I even hear fuel going in the carbs when I open the petcock.
You KNOW what you will have to do, stop beating around the bush!
 
+1! The holes at 3:00 and 9:00 in your intake bells vent the float chamber, and when for any reason fuel level in uncontrolled, fuel pours out those holes, into the air filter, into the intake port, past a valve, and into the crankcase, thinning the oil. In addition to a dirty float valve, you may have a float that has taken in fuel or float level that's set too low (=fuel level too high). There are numerous fine threads on diagnosing and correcting all of these problems. Tip: the Tech button will take you to lots of good stuff, and the search function on this forum actually works.Seek and you will find.
 
You're not making much sense here. There's aftermarket and there's OEM. They're not the same thing. OEM is Original Equipment Manufacturer, an original part right from the factory. Aftermarket is some other company making copies of original parts.
 
+1. Using anything besides genuine Mikuni brass is a crapshoot. Chiwanese repops look cheaper, but may cost you more in the long run. You can't get something for nothing, but it's easy to get nothing for something if you buy cheap enough.
 
You're not making much sense here. There's aftermarket and there's OEM. They're not the same thing. OEM is Original Equipment Manufacturer, an original part right from the factory. Aftermarket is some other company making copies of original parts.
Mikesxs.com said that they don't really make the petcock anymore that would be the "original" so they have this replacement one lol I wasn't sure what to call it.
 
When gas overflows the carb and runs out the float valve has issues.
You need to pull the carbs and check the float height and the cleanliness of the needle and seat. Have you read this? www.amckayltd.com/carbguide.pdf
This will help you work on your carbs.
I think a lot of the 80 up bikes have more blue on the pipes than the older models. I think this is due to the carbs being set uo too lean at the factory. They did this as part of the pollution controls. Being leaner things run hotter. This excess heat blues the pipes. Or current flavor of gas runs even leaner than the gas back then.
Even with stock air boxes and exhaust they often need bigger jets. I usually go up one on the pilots and one or two on the mains. Adjust the mix screws as needed for proper mix.
Leo
 
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