Anyone familiar with CV carbs?

[Asshat]

Been having this problem with the carb on a 2000 Softail…


Had the battery tender on it all night, since it was dead again last night.

It starts up just fine with the choke, push the choke back in and start to ride, starts out ok – 1st gear. Shift into 2nd and it starts to hesitate, like it has no power, or no fuel. Shift back down to 1st and still, try to accelerate bringing the rpm up and it just wants to bog and die. Almost seems like fuel starvation.

I checked the float, everything measured out ok. Cleaned everything up, needle jet is in the correct way.

[Rickysnickers]

I have a KLR650, which uses the same carb. How long has the bike been sitting? If it's been a while, then you may need to clean the carb out. For some reason, they do not like sitting for very long. The KLR guys report finding the main jet has a blockage in from the gasoline sitting in it. You could try using some Seafoam and see if that helps.

[Ziegelsteinfaust]

CV carbs are more dependent on air flow for the signal the carb runs off of.

Try spraying some carb cleaner in the throttle body, pour some cleaner in the tank. Then go get it hot, and drive in a lower gear to get more fuel flow through the carb


On my bike this helped get it back to normal fast. Otherwise you may need a rebuild to clean out the garbage.

Another thing I do with cars, but can be a bit of a trouble on bikes. Is rev the engine up, and put a rag over the carb. Do it a few times. This can pull out the garbage in the carbs small orifices, and I do this regularly on my carb cars at oil change time.

[Asshat]

Here’s another update.

I switched the spring in the fuel valve, confirmed I have constant fuel flow. I was able to ride down the street. Going from 1st to 2nd to 3rd. Not too bad.
I’m cruising along in 3rd and let off the throttle, then roll the throttle back on - it sputters, hesitates, does a pop-pop-pop-pop as I am trying to roll the throttle on. It does this for a few seconds like it has no power and finally starts to recover and power through, getting the rpm back up. It keeps doing this, but from a stop I can go through the gears.

So, I think it’s better, but just a little. Not sure what the hell is going on. I plugged the ports that went to the fuel canister and fuel valve.

[Dead Parrot]

If your fuel shutoff valve has a vacuum connected safety shutoff valve, those, at least on Kawasaki Vulcans are a known fuel flow problem. Motor will go from running fine to acting like it is out of gas, even with a full tank. Look for a small vacuum hose running from one of the carbs to the fuel shutoff. Fix is to replace the fuel valve with one that doesn't have the little vacuum valve.

If you are in a Ethanol gas only area, could be your problem. Especially if you have high humidity. The booze likes water and will pull it out of the air if the bike sits for a few days. If it sits long enough for all the gas to evaporate, the water is left to corrode the carb guts. Seems to depend on the carbs. Had an 80s era Yamaha 650 twin that never needed carb work over 20 years even with using ethanol gas. A newer Vulcan has needed a couple before I lost confidence in it and parked it.

[Asshat]

Figured it out. I installed the needle jet from the top instead of the bottom with the main jet.
Dumb, huh?

[Rickysnickers]

Originally Posted by Asshat

Figured it out. I installed the needle jet from the top instead of the bottom with the main jet.
Dumb, huh?

HAHAHAHA!!!! At least you found it! Ride safe

[Ol Blue K20]

Enjoy it, and keep the rubber side down and watch out for the yahoos