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jetting question
- murr50
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19 Mar 2010 21:00 #354733
by murr50
1977 kz650 C
jetting question was created by murr50
currently i have a 1977 kz650C. Im thinking of ordering a V&H 4-1 exhaust system, but want to order new jets at the same time.. this is assuming they are needed corrrect? Anyways i was wondering if anyone else had this same setup on their bike. If so what size jets do you have? I am just looking to save some time tinkering with different sizes. thanks!
1977 kz650 C
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- bountyhunter
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19 Mar 2010 22:06 - 19 Mar 2010 22:08 #354756
by bountyhunter
1979 KZ-750 Twin
Replied by bountyhunter on topic jetting question
If all you are changing is the exhaust, and you are using a street legal baffle (not a straight pipe), my silly wild ass guess would be that you could probably run the stock pilot jets or MAYBE go one size up and go one or two sizes up on the mains. That's my best guess.
1979 KZ-750 Twin
Last edit: 19 Mar 2010 22:08 by bountyhunter.
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- 650ed
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20 Mar 2010 04:54 #354802
by 650ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
Replied by 650ed on topic jetting question
What exhaust system is on it now? BTW, if it's a stock system in good condition it's worth $$$. Pics would be nice. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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- otakar
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20 Mar 2010 06:43 #354812
by otakar
74 Z1-A stock
76 KZ-900 Totaly stock vice MAC pipe
77 KZ-1000A stock
78 Z1-R 100%MINT 500 original Mi.
78 Z1-R Yoshi 1103 kit stage 1 cams Yoshi pipe. Etc
79 KZ-1300 (1400)
80 KZ-1300
81 Scratch built GPz1150R
82 KZ1000
Replied by otakar on topic jetting question
No matter what modifications I have ever done to my bikes I have never had to change the Pilot jets. Only the main jets and needles or needle positions, and do some pilot screw adjustments. If you are changing to a pipe and say putting on pod filters, than you can go up by two or as much as four main jet sizes, richen up the pilot screws by one-half turn and raise the needle positions by 2 notches. This should put you in a good running position.
74 Z1-A stock
76 KZ-900 Totaly stock vice MAC pipe
77 KZ-1000A stock
78 Z1-R 100%MINT 500 original Mi.
78 Z1-R Yoshi 1103 kit stage 1 cams Yoshi pipe. Etc
79 KZ-1300 (1400)
80 KZ-1300
81 Scratch built GPz1150R
82 KZ1000
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- TeK9iNe
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20 Mar 2010 07:48 #354832
by TeK9iNe
Motorcycle Shop Owner/Operator
79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors
Replied by TeK9iNe on topic jetting question
In this case you will likely not have to change pilots.
With a V&H exhaust, I would increase the mains by 1 step, but thats it. Most stuff comes jetted fairly rich from the factory, even though they kept leaning shit out for emitions.
Put the exhaust and mains on there and properly tune the pilot circuit, then ride and enjoy.
Properly tuning the pilot circuits involves using a very accurate tachometer/vacuum guages to find the absolute highest power for each cylinder. There will be no exact number of turns out, they will all differ slightly at max power.
Your carbs will also need to be vac synced afterwards.
Good luck!
With a V&H exhaust, I would increase the mains by 1 step, but thats it. Most stuff comes jetted fairly rich from the factory, even though they kept leaning shit out for emitions.
Put the exhaust and mains on there and properly tune the pilot circuit, then ride and enjoy.
Properly tuning the pilot circuits involves using a very accurate tachometer/vacuum guages to find the absolute highest power for each cylinder. There will be no exact number of turns out, they will all differ slightly at max power.
Your carbs will also need to be vac synced afterwards.
Good luck!
Motorcycle Shop Owner/Operator
79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors
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- nads.com
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20 Mar 2010 20:30 #355051
by nads.com
Replied by nads.com on topic jetting question
If you run it lean it'll have torque through the roof. They are so lean already, I,d say jet it up just to keep it running cool for hot weather, (and some extra grunt at higher r's.
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- murr50
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22 Mar 2010 16:10 #355486
by murr50
1977 kz650 C
Replied by murr50 on topic jetting question
yea the stock exhaust is in great shape. I'm still not sure if i want to buy the V&H just yet. I want to make sure i know exactly what I am doing so i can just install in a day, rather than tinkering around for a week while i could be riding. As for pictures i don't have any yet but i will definately post when i get my hands on one of those fancy digital ones. Any additional information would be a great help.
Thanks a lot guys
Thanks a lot guys
1977 kz650 C
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