No throttle response, slides not moving

Hi guys,

I got a 440 LTD two months ago. Was running decent, but the air box was cracked. I switched to pods and rejetted with a 6 sigma kit. It ran much better after that. I then took the bike apart to paint the frame and the engine. Put the carb back on to ride it and no throttle response at all. After being puzzled for a week I brought it to the local motorcycle shop, they cleaned the carbs in their ultrasonic cleaner and noticed a small tear in one of the diaphragms. I ordered an installed brand new diaphragms, floats, etc, the carb is now pretty much brand new yet still no throttle response. The throttle cable is fine, it activates the butterfly valves and snaps back when throttle is released. It idles great with choke on or off but just won't throttle at all.

What does, "won't take throttle" mean? Does it die when apply throttle, does it idle ok, does it only run with choke on, ect. Give us a little more info here.

It idles as it should with choke on and off. When I give it throttle, it continues to idle at the same RPM, the slides won't move up to allow more fuel into the combustion chamber. It won't die out at all, it's pretty much when I give it throttle nothing at all happens and it will continue to idle.

Do you still have the old diaphragms? I used a small patch of nitrile glove and a TINY bit of gurilla glue to patch 3 holes in mine, and it worked like a dream! Maybe your new diaphragms are too solid a material to allow the vacuum to move them? Try spraying condensed air into your intake passages. This should allow you to actually witness what the slides are doing when they get some air.

The new ones did look stiff at first, but I blew into the passages (red arrow in the attached picture) and the slides moved up fine with the new diaphragms. I did shim the jet needle because the jet kit provided the shims and told me to do so. I thought that maybe the spring was putting too much tension on the slide and preventing it to move up with the shims on the needle, so I took the springs out and tried to throttle without the springs (thinking that the bike would stall out due to too much air when it was throttled). But when throttled still nothing, the bike will just idle. I blew into the "intake" passages and the slide moved up, but I do not know If 7 and 8 were getting air through them.

What kind of pods do you have on the carbs? 650ed says that emego pods can actually restrict airflow to certian parts of the carbs. If that isn't an issue, try rejetting back to the original jets. My '81 440 doesn't have the filter or filter holder, and it's actually running a bit on the lean side.

This sounds way more fundamental than the carbs being out of sync or the pods not working. It sounds like something is missing from the rebuild and that the carbs aren't even seeing the throttle cable move. I've got a set of CVs off the bike that I can try to get some pictures of, but no response to the throttle cable moving sounds like the carbs are just sitting there waiting for the fun to start.

Some of the pods will cover the air jet locations in the carb intake bell. Not saying this is what is going on, but it the pods do cover the air vent for the top of the carbs (where you blew in air to see if the slides move) it would certainly create the issue you are having.

So I just did a compression test and found the right cylinder to be 130 psi, and the left was 100 psi. I'm assuming this is definitely contributing to the problem due to the engine not pulling enough vacuum to the carbs which won't allow the slides to be pulled up.

Do you have the slides orientated correctly? The small hole at the base of the slide, must be on the engine side. If you replaced the diaphragms, did you get them back in correctly?
Also as posted already, some "Pod's" block the vent port at the rear/ bell mouth/ airhorn area. the slide will not lift correctly if either is wrong. Did the rebuild kits come with new jet needles? Same # as the stock ones? What about the other jets? With No Air filters it may be SO lean that they won't lift. What happens if you add some choke?
Also the needle must sit into the slide correctly for the correct mixture. The slide should lift just fine with 100psi. by the way, did you check that compression with a warm engine and the throttle held wide open?

I just checked to make sure that the slides are oriented correctly. Jet needles did not change, the only thing that changed were the main jets, but it ran after after I changed those jets. I'm not sure if the carbs are out of sync, but could the carbs being out of sync be another cause of this problem?

A bench sync is what you do till you get it fired and warm. That's just setting the slides or butterflies even, mix screws even, and the All Important Wet Fuel height in the bowls. This is with a clear tube test. Do a search and you will find Pattons tutorial, or maybe he'll post it in this thread,
Fuel height is critical and needs to be set for the carbs to work correctly.