Don't know where to start

Ok, So I bought a 1982 KZ650 (650 CSR H2) and when I got it it was in great shape cosmetically but the carbs were clogged up and there were vacuum leaks.

My roommate and I cleaned the carbs up and then I chased down the vacuum leaks (all the hoses have been replaced) and removed the "smog pump" system completely.

The bike has been having issues with its idle, when the bike is cold it wont do it, and when it gets all warmed up it still likes to die. But if I turn the idle up it jumps from 1500 RPM to like 6000 RPM in almost no turn of the idle screw. Also when I pull out the choke it jumps to around the same 5000-6000 RPM within 45 seconds of the bike starting. (I kinda wonder if this is related to an air leak on the carb boots...)

So the other day we were doing a clutch cable change and did the oil. I know the oil was overfilled (discovered it but had to go get a siphon to move some back out) So the bike sat for a couple of days until night before last i siphoned out the rest. When I tried to start it it didnt want to run without choke at all. It also feels like it has a miss when in first gear, the bike shudders a bit and then rather then a clean pull the power surges up and down. (at WOT it takes about 4-5 seconds or more to get through 5000 RPM in first which is where the problem clears its self up and the bike runs fine through 5th without issue)

Pulled the plugs last night and they had a bit of carbon on them but they seemed fine (they only have 300 miles on them)

So I would appreciate any help on my issues. Thanks guys!

Would:
Check valve clearances;
Assure timing advancer isn't sticking;
Check for leaking carb holders;
Adjust pilot air screws;
If necessary, re-address carb pilot circuits.




Good Fortune!

Ok you mentioned adjusting the pilot air screws... when the carbs were cleaned a lot of the settings like the air/fuel screws were changed, I have been looking for a good starting place for them (I know they need individual tuning)
I checked my factory service and clymer manuals and have not found a good starting place.
Also I think I need to do a mechanical sync on the carbs, but the clymer manual says the 82 doesn't require that service.

Also one last question, I know many of the KZ's have dual throttle cables, and during a previous post someone told me to be sure they are in good shape... I can only find one throttle cable though... is that normal?

derekthemajestic wrote: Ok you mentioned adjusting the pilot air screws... when the carbs were cleaned a lot of the settings like the air/fuel screws were changed, I have been looking for a good starting place for them (I know they need individual tuning)
I checked my factory service and clymer manuals and have not found a good starting place.
Also I think I need to do a mechanical sync on the carbs, but the clymer manual says the 82 doesn't require that service.
Also one last question, I know many of the KZ's have dual throttle cables, and during a previous post someone told me to be sure they are in good shape... I can only find one throttle cable though... is that normal?

Absent FSM specs for guidance, would guess beginning with 1.5 turns out from lightly seated on all carbs.

Am thinking desired "sync" with the CV carbs at hand would be to match the slight openings of the butterfly valves at zero throttle.

Some carb designs require only one cable.

Good Fortune!

Am presupposing the carbs at hand are CV style, and not manual slide carbs.




Manual slide




Good Fortune!

They are the CV carbs. Mikuni VM24SS I think

If the reported issues persist after the following items have been addressed:
Valve clearances within specs;
Proper functioning timing advancer (not sticking);
Correct fuel levels (using clear tube test);
No air leaks in carb holders or elsewhere;
Throttle butterfly valves synced;
Pilot screws set at 1.5 turns out, and thereafter tuned for best idle (where turning doesn't affect rpm, indicates something wrong inside the carb);

Would then consider possible problem with the carb pilot circuits.

Good Fortune!

If not already done, would install a good after-market in-line fuel filter.
Available at most bike shops and suppliers.

www.z1enterprises.com/detail.aspx?ID=293

Good Fortune!

derekthemajestic wrote: But if I turn the idle up it jumps from 1500 RPM to like 6000 RPM in almost no turn of the idle screw.

classic symptom of a vacuum leak

Thats what I thought but it seems to appear at a certain RPM range... could it be it is the carb holders and they only leak under higher pressure?

Yep, it sounds like the classic leaky boots / bad vacuum synch combo.
The scenario: The bike ages and the rubber starts to deteriorate to the point where leaks form. the owner will start to fiddle with the carbs to try and get the bike running properly and the problem just gets worse until you get the condition you have. No amount of adjustment is going to fix this.

Yes, they will sometimes leak only under certain circumstances. Sounds like you have some good sized leaks, though. Correct that FIRST. If you are not sure how, there are threads that discuss this or we can help.

Once you get the leaks sorted out, then you get to synch the carbs and set the mixture and idle. I do them simultaneously. That is, I leave the synch tool on after the synch is done and I set mixture and idle while keeping an eye on the synch. Careful when you start the synch, it sounds like you may be out far enough now to suck the fluid out of the tube on the tool.

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