bike fires but won"t stay running

[Beast]

I need a little help guys.
I have a 99 1500 Nomad. The air intake has been modified, Baron mixture needle installed, new jets. The bike worked great Monday and Tuesday. Wednesday morning it fired but would not stay running. If I give it some gas and hold the throttle open a little bit it stays running. The boot from air to carb is tight. I did notice my idle adjustment cable had come loose and the knob het the muffler and partially melted. I can still turn it. Any thoughts would be appreciated. Thanks, Mike

[macmac]

I have never had a chance to work on a carbed Nomad yet, but I would find and follow ALL the smaller vac lines behind the throttle plate that come from anything, to the backside of the carb and to intake manifold, and check both ends of any tubings there for being cracked brittle split loose, and look for anything caps that may be there as well for the same and or just missing. I am betting there is a air leak called vacuum leak in the industry.

This would lean out fuel mix wicked bad, to the point the engine won't idle. While you do this cold if you fond anything and 'fix; it, then start the engine with the carb still wide open to SEE. Watch the piston move in the carb body, and slowly turn the throttle grip for more rpm making sure the piston seems to rise evenly in the carb bore. ALL CV carbs like this use a black rubber diaphragm that in heat time and etc can pin hole or split. These are ALL indexed too, usually with a rubber lug on the part that sits in a place to align it to the piston and to the carb body.

IF the engine coughed or back fired caps and tubing can be blown off their ports.

[redjay]

Do the carbed models have a choke ? Maybe it needed more choke this morning as it was cooler ?

[minst7877]

They have the enricher just like the other bikes. CV carbs do not have a choke as we normally think of them. They add fuel to the mixture rather than eliminating the air flow to create a richer mixture.

DC

[redjay]

How does carb sense that the motor needs more fuel when the engine is cold ?

[minst7877]

It's a manual knob just like on the injected bikes.

Running OK one day and not the next check all carb boot connections and also all the vac lines like Mac suggested. Check the boots for cracks.

DC

[ringadingh]

I'd give it a real close look at the carb boots to make sure they are not cracked, if they check out good perhaps a good carb cleaning would help, as there may be a passage plugged with dirt.
You do have good gas in it don't you, and a clean fuel tank?

[rolfe]

Originally Posted by Beast

I need a little help guys.
I have a 99 1500 Nomad. The air intake has been modified, Baron mixture needle installed, new jets. The bike worked great Monday and Tuesday. Wednesday morning it fired but would not stay running. If I give it some gas and hold the throttle open a little bit it stays running. The boot from air to carb is tight. I did notice my idle adjustment cable had come loose and the knob het the muffler and partially melted. I can still turn it. Any thoughts would be appreciated. Thanks, Mike

After I rebuilt reds carburetor few years back. All of a sudden red starting lacking power from the carburetor. Just no power, yours sounds a bit different.

I could not locate the problem , so removing the gas tank to check all the rubber lines going to the carburetor. I did see that there was a damaged line. Replaced it No problem.

Try checking Top Side of Carburetor.

My neighbor just rebuilt his twin carbs. The jets did get some blockage

[macmac]

Originally Posted by minst7877

They have the enricher just like the other bikes. CV carbs do not have a choke as we normally think of them. They add fuel to the mixture rather than eliminating the air flow to create a richer mixture.

DC

This is correct, and the enrichment valve in the carb is cable or linkage controlled. This is all manual operation, and does more than just set the throttle plate open more which is all it does on injected bikes which has a resistor on the throttle shaft.