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SO FRUSTRATED - Run away idle
- WBPDX
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- 1983 KZ750 H3
I've been through a whole bunch of drama with this turd. Bad wiring, tight valves, and then a sheered-off timing advancer pin, and a destroyed advancer.
I've now fixed everything that I've discovered wrong. The valves are adjusted, the advancer is new, the pin has been replaced, the cams re-timed and correct, the carbs cleaned for the 4th or 5th time, spark re-checked on every cylinder, checked float levels using clear tube, compression 120psi or better, checked boots carefully. In addition, I replaced a questionable main jet in the #1 carb.
The bike STILL isn't really running on all four cylinders. It seems to be running hot on 1 and 3, cool on 2, and not at all on 4 (still.)
The good news is it no longer back fires out the carbs, and no longer requires riding the starter to start. It fires up pretty much right away.
The bad news is it will not rev up (it used to) except when it is sitting there idling and all the sudden it runs away to redline and has to be shut down.
I'm about to part the bike out. Not because I don't think it can be fixed, but just out of sheer frustration!!!
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- WBPDX
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- 1983 KZ750 H3
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So I started it up and started spraying water and looking carefully, trying to find a air leak.
I was unable to identify any air leaks, but, it was smoking a bit like it was sucking the water in, and, oddly, after letting it run for a few minutes, all four pipes were hot. So the water must have plugged the leak enough for it to fire on all four?
I'm thinking it is the engine-side boots; one does look very questionable (happens to be the non running cylinder, #4)
Any other thoughts? I will probably clean, polish and check all the slides one last time before I order anything.
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- MFolks
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Have you thought about doing the "Wired George" relay modification to the ignition system? This bypasses the aged wirng in these older bikes. His website is www.wgcarbs.com it covers the parts and how to wire in the relay.
More than a few guys here have done this modification to their bikes.
1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
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- bill_wilcox100
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Sounds as if you have found the next layer. I changed my carb mounts and it solved one of my symptoms. Not the cheapest fix but what can you do.
You will not know how many layers you have until they are all solved.
Best of success.
1977 KZ650-B1 (Stock)
Upgrades:
- Dyna S Electronic Ignition (DS2-2)
- Dyna 3 Ohm Coils (DC1-1)
- Coil Repowering Mod
- Progressive Springs Front & Rear
- Saddlemen Seat Cover
- New Metallic Red Re-Paint & Repro Badges.
Montreal, Canada
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- 650ed
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1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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- ironyankee
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- WBPDX
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- 1983 KZ750 H3
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I tried putting some gasket maker on the cracks in the carb holders, it didn't really make any difference.
I did discover two slightly sticky slides. I cleaned them and put a drop of 2 stroke oil on them...
I think what that did was let them not stick DOWN, as the bike now pretty much fires up and idles at 5-8k, if reved, it will go higher and stay there. Seems like a major vac leak, but where it is coming from is completely NOT obvious.
I think I am going to get new carb holders, and also replace the float needles for the heck of it. Maybe the little plugs that hide the idle-meter jets as well. If there is no improvement, I am going to part it out or sell it as a parts bike.
Also, I would consider rejetting for pods, just because it is SUCH a chore to get the carbs off! But I'd like to get a baseline where it actually runs first!
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- Kawickrice
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- After Monday & Tuesday, even the calendar says WTF
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73 Kawasaki Z1
07 HD CVO Ultra Classic
82 Suzuki GS 1100
74 Yamaha RD 350 (My two stroke toy)
77 Kawasaki KZ 650B-1 (My putt around bike)
80 Indian Moped (My American Iron)
1
Long Gone
75 Suzuki GT550
74 GT 380
79 RD 400 Daytona Special
72 Honda CL 175
74 Honda QA 50
Tampa FL
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- Patton
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When you check for vacum leaks use carb cleaner or something flamable and spray suspected areas, if leaking the idle will rise. I dont think water is what you should use, but I have never tried it.
Would concur about not using water spray.
Could try WD40 or propane gas sprayed about the carb holders and vacuum caps to help determine whether outside air is being sucked into the fuel mixture. Listen for changes in rpm and look for extra smoke from the exhaust, as indications that fuel mixture going into the combustion chamber is being affected by air drawn in through cracks or leaks in the carb holders or vacuum caps.
Good Luck!
1973 Z1
KZ900 LTD
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- ironyankee
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- ironyankee
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- ironyankee
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