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Discussion Starter #1
Hey everyone,

Hope all is well. I’ve got my old 440 LTD that’s been putting up a fight recently. I got her fired up after a complete tear down and rebuild. The issue is that I have idle issues once I get on the throttle. I’ll do my best to explain the problem. When starting the bike, with the choke on or off, the bike idles perfectly, around 1300 RPM and can hold the idle well. The issue starts when I get on the throttle. I give it some gas and the bike revs to around 4 grand and won’t come back down. After about 30 seconds I’ll shut it off, try again with the same results. The issue only starts when I give the bike some gas. I’ve looked into the following with no avail.

1.) Stuck throttle – I thought maybe the throttle butterflies were sticking open. I checked the throttle linkage, no sticking, no binding, nothing. I’ve lubricated the mechanism and everything seems fine here. Throttle is not sticking open.

2.) Vacuum leak – I thought maybe I had a vacuum leak. When the bike was idling, I sprayed starting fluid all over the carburetor to see if idle spiked to indicate a leak. Nothing. I then fogged propane gas all over the carburetor while idling; hoping to see if that spiked the RPM’s but again, nothing.

I don’t have the stock air-box installed. In fact, I’ve got some air filter pods on order from the Kawasaki dealership but for right now, I don’t even have air filters of any kind on the bike. Just open carburetors but the mechanic at the dealership said that shouldn’t affect idle or throttle response. I have no idea why the bike idles fine with the choke on or off, but when I rev the engine, it just shoots to 4 grand and won’t come back down. If anyone has any thoughts/idea/suggestions, please let me know because I’d love to get this bike out on the road after all the work I put into it! Thanks so much.

Kirk
 

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Look at your carb holders or "manifolds" they are the rubber things that hold the carb to the head. If they are original, they leak. That can cause the problems you are talking about and more. I fixed mine with gasket sealer but buying new is a better solution.
 

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My guess is that your air slides might not be falling after you let them off. As you twist the thorttle the vaccuum pulls those slides up and lets gas come around the needle jet, so the fuel can be mixed at a different rate. stick your finger in the rear of the carb and lift up on one of the slides, it should slide up with virtually no effort and fall immediately after you let your finger off with a resounding "thud".
 

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sounds lean. crank the idle mixture screws out about a full turn each and see what that does for you.
 
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