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Old 05-29-2011, 04:55 PM   #1
allanworks
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Default 1978 kawasaki kz750 twin help

hi im new to motorcycles and forums .but i used to be a ase certafied machanic.i was thinking about removing my air box and switching to direct clamp on air filters.you know the ones that clamp directly to the carb.well if i do that will i have to adjust the carb because of the extra air flow. also i have a pet**** stuck on reserve and my left carb is leaking gas out the drain tube at about a drop a minute does that mean i need to rebuild the carb/pet**** or both.also later down the road i was thinking about doing a full restore would it be worth it or sell it after fixing the problems and buy a newer bike.
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Old 05-29-2011, 08:17 PM   #2
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hi im new to motorcycles and forums.

but i used to be a ase certafied machanic.

i was thinking about removing my air box and switching to direct clamp on air filters.

does that mean i need to rebuild the carb/pet**** or both.
Gee, Allan, those questions don't give me a warm and fuzzy feeling about ASE certification !!

1) The bike you got is probably too big for a total rookie (ref. the other thread you started) unless you are a pretty big guy.

2) Do NOT mess with the stock equipment as long as the bike isn't running right.......that is, carb leak. On a bike that old, messing with the "tune" of the mixture probably isn't a good idea at all......on a bike that you intend to ride any time soon.

3) A certified mechanic should know what the likely causes are for fuel overflowing a carb: sunk float or stuck or leaking needle valve..........OR the drain screw is loose. A healthy dose of carb cleaner might help but the bowl will probably have to be pulled. If you are lucky, you can do that without taking the carb all the way off.

4) Some gas valves come apart easily but most don't; you're probably gonna have to live with that or at least leave it for last.

Do I need to say that you should NOT ride the bike with gas dripping out ??
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Old 05-29-2011, 08:31 PM   #3
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yes im 250lb im ase certafied for cars and trucks dont know any thing about motorcycles. yes i figured it was the float or stuck needle but thought there might be a diffrence between auto carbs and motorcycle carbs bieng the diffrence in size and all.as for the shut off valve i bought a rebuild kit but it only came with o rings shouldent there be more to the kit .funny enough it runs like a champ and doesnt leak when running
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Old 05-29-2011, 10:00 PM   #4
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O-rings for a petschlong (this site hates the word "pet****") renewal-kit are about right; there's not really much to one of those valves. Don't forget to lubricate the non-fuel-contact sliding-surfaces of plug with an EP grease a bit before re-assembly. Makes switching from "run" to "reserve" easier on-the-fly.

You'll find moto-carbs are built essentially "upside-down" to a typical auto-carb, not to mention the difference between the "variable-venturi effect" of a constant-velocity carb as opposed to the fixed-venturi of your typical auto-carb.
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Old 05-29-2011, 10:33 PM   #5
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thanks for the reply. ill have to pick up some grease then.i thought the carb would at least have some difrences . i just bought 2 rebuild kits and a kawasaki machanic manual on ebay spent less than $65.hope i dont need new floats cant find them for my bike.would filling crack in floats with lead work on motorcycles. used to do that with riding lawnmower carb.would cover crack with lead then sand it down.or maby a gas resestant resin would work
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Old 05-30-2011, 06:23 AM   #6
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but thought there might be a diffrence between auto carbs and motorcycle carbs

funny enough it runs like a champ and doesnt leak when running
There are, of course, some physical differences but the principal and most of the parts have the same functions.

Having your fuel valve stuck at REServe really isn't a big problem......except you don't have a reserve to fall back on.
Riding it on RES only means that if you run out, you are OUT.....and have to walk for gas.

The fact that it doesn't leak enough for you to NOTICE when it's running means that the leak is probably VERY small and likely is caused by a leaking needle valve and not a float problem. It could also mean that the excess fuel is being sucked into the engine.

You should not worry about the floats ahead of time......as they might be plastic anyway.

Before you go tearing the carb apart, you DID check the drain screw.......didn't you ???
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Old 05-30-2011, 06:35 AM   #7
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I'm no pro with carbs but also a loose fuel line may be leaking. Try to find where the leak is exiting the bike, not where it is driping from. Easy trick is to use paper towels , and see where they get wet first. Good luck.
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Old 05-31-2011, 06:45 PM   #8
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ok i figured something out.the choke was stuck slightly above off i oiled it now its free and the carb stoped leaking.i drove it around town today with some sea foam to clean carb. back roads of coarce.im getting used to it going around curves are fine.gotta get used to throutle stalled at stop sign a couple times.not giving it enough throutle i guess.now down shifting to slow down is that mandatory i would rather just use the brakes.
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Old 05-31-2011, 10:17 PM   #9
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I don't see how the enricher (or even a "real" choke) can cause the carb fuel-bowl(s) to overfill.

You still have the problem, OR you got lucky and the crud managed to dislodge itself from the float-needle seat.

(am I the only one to notice that, this Spring we have probably the worst outbreak of float-needle-itis EVAR on MO?)
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Old 05-31-2011, 11:11 PM   #10
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yea i dont get it eather .the petkok is my next adventure.
come to think about it my carb on my truck had problems two months ago
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