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TOPIC: hanging rpms

hanging rpms 4 years 10 months ago #522102

  • bromz
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I know this has been discussed many times but im stuck. Bike was running great then my petcock started leaking. I replaced it with a pingle on off res got rid of the vacuum. everything is the same except i plugged number 2 carb where the vacuum line was going to the petcock. (i have tried every combo there is even completly removin the epa clean air system. Bottom line bike idles great blip throttle rpm go to 4k and stay. blip it one or two times they return. replaced carb holder boots. They had cracks new boots from airbox to carbs. checked for vac leaks with wd 40 no leaks. checked all spark plugs and they are all firing. throttle isnt sticking visually watching it return. I have a little bit of backfiring through carbs and when i shut the bike down out the exauhst pipe once. carbs have been cleaned twice this spring and synced. please dont tell me i have to clean them again. im just missing something. help please
1981 kz1000 csr

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hanging rpms 4 years 10 months ago #522106

  • peter1958
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Only thing I can think of would be the throttle grip hitting controls. Sounds like you have coverd everything

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hanging rpms 4 years 10 months ago #522126

  • vintagebiker
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There is one thing you haven't checked. The mechanical advance under the ignition cover. Make sure the springs and advance cam aren't sticking or broken.

If the exhaust is popping you have an air leak or lean mixture some where.Plugged idle circit jet.
Carbs not synced properly will do this as well. But sounds like you have checked all those things.

Make sure you have free play at throttle when grip is at rest at least an 1/8 of an inch movement.

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If all else fails, JUMP!

hanging rpms 4 years 10 months ago #522139

  • MFolks
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Tried the UNLIT propane torch? The gas will make leak finding much cleaner than giving the carb holders & boots a bath in WD-40.

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1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)

hanging rpms 4 years 10 months ago #522179

  • bromz
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so i lubed the throttle itself and was gonna adjust the free play. what does free play mean? the throttle rolls 1/8th inch before the butterflys react? my throttle doesnt roll at all with out the linkage moving. then gonna work on greasing the advancer as soon as i can get it apart

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hanging rpms 4 years 10 months ago #522183

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MFolks wrote: Tried the UNLIT propane torch? The gas will make leak finding much cleaner than giving the carb holders & boots a bath in WD-40.


Carb cleaner works great too. No oily mess. Ed

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1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

hanging rpms 4 years 10 months ago #522216

  • elfmagic17
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bromz wrote: so i lubed the throttle itself and was gonna adjust the free play. what does free play mean? the throttle rolls 1/8th inch before the butterflys react? my throttle doesnt roll at all with out the linkage moving. then gonna work on greasing the advancer as soon as i can get it apart


Ya sounds l;ike you need to loosen yout throttle cables a little.

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Kenny Hicks
74 Honda CB550
75 Honda CB360 (runs and rides good but not a show bike)
77 KZ650B1 (Runs Great, but needs painted and a little work.)

hanging rpms 4 years 10 months ago #522427

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Well guys it was a simple one. I had the gas tank on and off a dozen time not paying attention the throttle cable was pinched under the tank! Thats the reason i couldnt get any free play also. So all is good and back to normal! (FOR NOW) Thanks for all your help

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hanging rpms 4 years 19 hours ago #578771

  • donthaveakawman
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sync the carbs? idle adjuster screw also. carb work basically is my best guess.

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