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KZ750 High Speed Problem
- Mutz
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I have 135 main jets in now and stk idle jets. The bike came with a alphabet header. The bike runs great!all day long at 60 mph or less. Once i get on the highway. and get up past 65 mph. she starts to bog down like she needs more fuel or bowls are empty. does the same with stk 125 jets.
I have the needle jet clip second from the bottom. no leaks, air or fuel.
I checked timing and its advancing. new points & condesor. B7ES plugs. Float bowls are full.
I'm going to check coil and wires next. As per shop manual. I think it is some how fuel related.
I pulled plugs after test, seem kinda lean. Idle mixture is out 1 1/2 turns. Did anyone have this problem? and how did you fix it?
Thanks for any help.
Lawrence
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- bountyhunter
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Make sure the air vent in the gas cap isn't restricted.
Is there an inline fuel filter? May need replacing.
Make sure to clean the fuel system top down. Rinse the tank, clean the petcock assembly, install new inline filter. Make sure the fuel filters allow enough flow.
Not sure about an alphabet header. If it's a straight pipe, you are probably running way lean.
BTW: the twins use the B6ES plugs, not B7ES. Probably not the source of the problem, but just FYI.
1979 KZ-750 Twin
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- stardon
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- bountyhunter
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1979 KZ-750 Twin
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- WildBill86
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Ride it, Like you stole it
~Wild Bill~
1983 Kawasaki GPz750
1975 Kawasaki S3A 400
Certified Harley Davidson technician who came to the dark side
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- Patton
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Mutz wrote: ... Once i get on the highway. and get up past 65 mph. she starts to bog down like she needs more fuel or bowls are empty....
May test ride with the fuel cap ajar, to assure adequate tank venting.
If issue persists with cap ajar, it's not being caused by an obstructed cap vent.
If issue disappears with cap ajar, it's likely caused by an obstructed cap vent.
Good Fortune!
1973 Z1
KZ900 LTD
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- Mutz
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Ran propane tank around boots while running.
Didn't notice any differance. I looked at the holders didn't see
Signs of cracking. I will check again. As they are old.
Thanks again.
Larry
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- 650ed
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1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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- martin_csr
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Check the coil, especially if it's stock. A simple test is to ride the bike at highway speeds, then stop & check to see if it's getting hot - press firmly w your fingers. Mine tested fine w a multimeter but they were getting real hot, so I installed Dyna coils.
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- Mutz
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- Mutz
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I ordered a coil and wires yesterday. 35 years old.
piece of mind. and one thing to eliminate.
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- leitz
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