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29 smootbores
- willemZ900
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Could it be that there is at that speed a vacuum in the petroltank? Otherwise the carbs run really great and are completely rebuild, the very thin gasgets under the jetblocks are also new. Any suggestions?
Willem
The Netherlands
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- wiredgeorge
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wiredgeorge Motorcycle Carburetors
Mico TX
www.wgcarbs.com
Too many bikes to list!
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- willemZ900
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- Patton
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Insufficient flow through petcock allows floatbowls to get dry and "run out of gas." Sit there for a few moments (fuel slowly drizzles down into and fills the bowls) and then engine cranks right back up as if nothing was wrong, only to repeat the problem shortly thereafter by again "running out of gas."
Imo, an accessory in-line filter should always be used, particularly with smoothbores having no floatbowl overflows and therefore especially succeptible to obstructed float needle/seat interface allowing excess fuel to escape up into carb bores and into crankcase.
Would also discontinue using the "S" shaped hose between airbox and crankcase breather, and route another breather hose around swingarm to underneath bike. Avoids possibility of excess fuel (which has risen into carb throat and flowed into airbox) from draining through the S shaped hose down into the crankcase.
An example is shown below.
Good Luck!
[Click on image to enlarge view]
1973 Z1
KZ900 LTD
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- willemZ900
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- Patton
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While doing this, can also check for proper functioning of the fuel tank cap vent.
If fuel keeps freely flowing, when thereafter reconnected to carbs, fuel would logically keep pouring on into the floatbowls.
As known, possible clogged cap vent and/or impurities clogging the petcock pick-up tubes may cause fuel starvation symptoms regardless of perfect petcocks and perfect carbs (which depend on a vented clean fuel source).
Have also seen it happen on new bikes with freshly re-painted tanks where some paint fragments got inside the tank and migrated down to huddle around the pick-up tubes. Sucked up tight against the pick-up tubes, especially under acceleration or higher speeds where more fuel supply is needed to maintain required levels in the float bowls.
Feels just like "running out of gas" because the float bowls are indeed "running out of gas".
Good Luck!
1973 Z1
KZ900 LTD
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- Russ Jackson
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1976 KZ 900 B1 29 smoothbores, Kerker, Lester Mags
2008 Kawasaki Concours 14 abs
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- gane
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[img][/img] 1977 KZ1000A1
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- Russ Jackson
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1976 KZ 900 B1 29 smoothbores, Kerker, Lester Mags
2008 Kawasaki Concours 14 abs
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- Patton
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... ran it without a filter it ran correct. However without the filter float bowl #1 stuck twice causing gas to trickle out of the pod...
Red Flag Alert -- where gas trickled out of the pod, it may well have also flowed the opposite direction into the combustion chamber and down around the pistons/rings into the combustion chamber.
If not already done, would sniff-test oil for any fuel odor and examine condition of oil for any fuel dilution.
Good Luck!
1973 Z1
KZ900 LTD
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- Patton
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Have never experianced w/ 29's, but once w/ 26's could out-run the float valves w prolonged wfo. went from 2.0 to 2.5's & cleared prob. G
went from 2.0 to 2.5's -- what do these sizes refer to?
1973 Z1
KZ900 LTD
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- gane
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[img][/img] 1977 KZ1000A1
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