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Mikuni BS34 Has Me STUMPED!
- KZ1000P1995
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I've been working on this easy, basic, and fairly simple KZ1000P for over 2 years now and am feeling like a first-grader. I have a new head, pistons and rings, exhaust pipes, and have rebuilt the carbs (9-10 times now!) and still can't get the thing to idle. Cylinder 1 and 2 simply won't fire.
They are connected to the correct coils and have perfect blue/purple spark
The valve clearances are perfect with compression of 150 all around
The carb vacuum lines are all plugged
There are no air leaks at the carb mounts - when I spray starting fluid around the carb mounts nothing happens. When I spray into 1 or 2 they fire. Also, I have sealed the carb mounts to the head with liquid gasket and I tighten the clamps onto the carbs as tight as possible.
Something to note: when I start with full choke only cyl. 3 & 4 run. After a minute of warm up I can close the choke and start to lightly rev the motor. At that point cyl 1 & 2 exhaust pipes start to heat up, so they seem to run when "on the needle" but not on the pilot jet.
Here's the BIG CLUE that I can't figure out: When I place my hand over the intake of carb #1 or #2 they start to fire (idle speed increases) and when I pull my hand away it's soaked in gas. Also, when I turn the pilot screws in or out on carb 1 or 2 nothing changes. I keep them all at 2 1/2 turns and they have new O-rings.
HELP!!!!!!!!!!!!! and thanks in advance.
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- Nessism
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zeus.mtsac.edu/~cliff/storage/gs/Mikuni_...Rebuild_Tutorial.pdf
The link it to a carb rebuild tutorial. If you haven't done all the steps as detailed then you probably still have dirty carbs.
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- KZ1000P1995
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Yeah, I used to put the carb to airbox boots back on with stock filter before I would try and start, but its a real pain and it didn't make a difference, cyl 1 & 2 still would not run.
BTW, I loved that tutorial and followed it to the letter when I did the 1st, 2nd, 3rd, etc. rebuild to these carbs. I practically have it memorized now.
I have used carb cleaner in a can and high pressure air many times to confirm that all the interior passages are open. Also, I have soaked and used the air to ensure all the jets are open as well. Those carbs look like new inside and out!
The only thing that seems to make sense is a major air leak somewhere between the carbs and head, but none to be found. These carbs have no vent tubes either and all four vacuum lines are capped.
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- Patton
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Indicates failure of mixture getting into the carb bore via the pilot circuit.
If applicable carbs ---
Good Fortune!
1973 Z1
KZ900 LTD
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- jdvorchak
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Don't fix it until it's broken.
John
83 KZ550M1
83 KZ1100LTD
Also own:
2010 Harley Ultra Classic Limited, 2008 Harley low rider 71 CB350/sidecar
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- ThatGPzGuy
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Good luck,
Jim
Jim
North GA
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 KZ1000P
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1965 Mustang
1967 Triumph GT6
1976 Bronco
"If you didn't build it, it's not really yours"
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- Nessism
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Be sure to remove the pilot jet and hold them up to a light to be sure the orifice is open.
Some people try to clean the carbs by spraying carb cleaner through the body instead of soaking in carb dip but that doesn't always get the internal passages clean. You gotta make sure the pilot circuits are clean or the bike won't run at low speed.
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- KZ1000P1995
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- martin_csr
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I compared the ingredients to a can of the good stuff that I have.
When cleaning your carburetors, did you remove the pilot plugs & air screw plugs and install new o-rings afterwards?
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- jdvorchak
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Honestly I rarely dip the carbs. I can un-gang them and with a fresh bottle of brake cleaner and a guitar string I can do an entire rack in just a few hours. But that is me and I do lots of carbs every month. I like to say to my friends, after the first couple of dozen carb racks it gets easier.
Don't fix it until it's broken.
John
83 KZ550M1
83 KZ1100LTD
Also own:
2010 Harley Ultra Classic Limited, 2008 Harley low rider 71 CB350/sidecar
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- Nessism
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martin_csr wrote: The Berryman's professional chem dip is very similar to their old formula.
I compared the ingredients to a can of the good stuff that I have.
When cleaning your carburetors, did you remove the pilot plugs & air screw plugs and install new o-rings afterwards?
I've heard good things about this formula - 0905.
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- martin_csr
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Methylene chloride is toxic & easily absorbed into the skin. It's also volatile, so don't breathe the fumes. Wikipedia says there have been 14 deaths of bathtub refinishers in the past 15 years because of poor ventilation & improper protective gear.
The other ingredients in Berrymans may reduce the volatility. not sure.
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