TOPIC:

I have been working on a 1982 KZ750 LTD for about a year now and I finally have the bike running well enough that it doesn't leak any gas or air and but there is still something not right about it...

I had the carburetors cleaned and synced by a mechanic in April. I have put on maybe 200 miles since then. I have always noticed that when I start the bike up (in neutral) it idles fine and I ride away. After about 10 minutes of riding, if I come to a stop sign while holding in the clutch in first, the RPMs will drop really low (not sure, don't have a tach) and the bike dies. If I shift into neutral before coming to a complete stop, it usually will idle and I don't have to keep revving the engine to keep it alive.

I noticed that when I shift from neutral to first, the RPMs drop significantly. I have the idle adjustment screw set so that it can start fine when cold, but once the bike warms up, the RPMs will stay high after I let go of the throttle. If I adjust the idle screw so that the RPMs drop at a normal rate, the bike will die at idle even when warmed up, because the idle is too low. I checked all of the jets and they all look clear and clean. I sprayed some carb cleaner in them just in case but I still have the problem.

Is this a carburetor problem or something else? Is it maybe a clutch problem? I was thinking that my clutch may not be disengaging all the way when I pull on the lever...

Loosen up your clutch cable a little.


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Does the bike seem like it wants to go forward at a light with the clutch pulled in? Do you have a centerstand?

Did he check the carb float levels? Did he set the idle with a tech of some sort?

I did that but I don't have much left to loosen. It didn't seem to make much difference, but I will try again.

Does the bike seem like it wants to go forward at a light with the clutch pulled in? Do you have a centerstand?

The bike does not want to move with the clutch pulled in.

Did he check the carb float levels? Did he set the idle with a tech of some sort?

I'm not sure exactly what he did, but I checked the float levels today when I had them apart. They were at the same measured height.

Does the bike have a history of drag racing? It sounds like it's not perfect even when in neutral. Check vacuum lines and carb boots for leaks if you haven't already. Choke circuit too, check the plug condition.

dpivas7 wrote:

Does the bike seem like it wants to go forward at a light with the clutch pulled in? Do you have a centerstand?

The bike does not want to move with the clutch pulled in.

Did he check the carb float levels? Did he set the idle with a tech of some sort?

I'm not sure exactly what he did, but I checked the float levels today when I had them apart. They were at the same measured height.

Clear tube method and adjust. Reset the mixture screws to best idle.
Steve

I'll do the clear tube method and see where that's at. I ordered a carb sync tool last night so I can save $150 and do it myself to make sure they're actually balanced. I'm hoping it's only a sync issue.

I adjusted the clutch cable again last night and it didn't seem to make a difference. To my surprise, I actually had a harder time getting the bike to idle in neutral...

Togoster wrote: Does the bike have a history of drag racing? It sounds like it's not perfect even when in neutral. Check vacuum lines and carb boots for leaks if you haven't already. Choke circuit too, check the plug condition.

Not to my knowledge. It sat for 4 years before I bought it. It was in seriously rough condition, but I was able to ride it 50miles home after buying it.

I actually replaced the vacuum lines, carb boots, and spark plugs in April/May . I'm not sure what the choke circuit is, but I'll look into it.

The tool will come in handy. In no time at all you'll be syncing carbs for others. 150 sounds a bit steep by about double but hey, whatever the market will bear I guess. Tachometer and feeler gauges are nice tools too.

Keep up the fight, you'll solve this.

One thing before i start my busy day. The dynamic sync with carb sticks or gauges is the last thing on my tune up list. It is dependent on the overall health of the motor (ie: compression, valve adjustment clearances, etc) proper jetting, a bench sync, a good tune up and well, you get the idea. It's not a magical tool. I know that in every Craigslist ad the panacea for every poor running bike is it needs good carb sync and I don't believe it for a second. That's likely the last thing it needs...literally!