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-   -   1978 kawasaki kz750 twin help (http://www.motorcycle.com/forum/motorcycle-general-discussion/18680-1978-kawasaki-kz750-twin-help.html)

allanworks 05-29-2011 04:55 PM

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.

Easy Rider 2 05-29-2011 08:17 PM

Quote:

Originally Posted by allanworks (Post 260722)
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 !! :rolleyes:

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 ?? ;)

allanworks 05-29-2011 08:31 PM

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

The_AirHawk 05-29-2011 10:00 PM

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.

allanworks 05-29-2011 10:33 PM

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

Easy Rider 2 05-30-2011 06:23 AM

Quote:

Originally Posted by allanworks (Post 260729)
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 ???

A Star Ride 05-30-2011 06:35 AM

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.

allanworks 05-31-2011 06:45 PM

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.

The_AirHawk 05-31-2011 10:17 PM

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?)

allanworks 05-31-2011 11:11 PM

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

pushrod 06-01-2011 06:32 AM

allan,

The newer formulations of fuel, especially with the corn squeezin's in them, are causing all sorts of problems. Especially with older vehicles. The rubber used in the fuel systems is probably not ethanol-compatible.

So, if you must buy E-whatever fuel, make sure you also treat the fuel with an Ethanol-treatment, like from Sta-bil.

Regarding the airbox mods. Don't do it. Unless you are going to race the bike, putting 'pods' on the carbs is usually a major PITA.

Regarding the leak, I'd also recommend you check the bowl screws. They may need to be tightened. Just a bit.

You don't mention how old the tires are. If they are dry-rotted (that is, they show cracking in the sidewalls), you need to 'spoon on some new buns.'

A Star Ride 06-01-2011 06:35 AM

One thing to check (and you'll feel stupid if I'm right, lol) is your pet peter in the "ON" position not the "PRIME" position?

allanworks 06-01-2011 07:00 AM

petkok is on reserve and doesnt leak any more. tire is about 3 years old still got good tread.

Easy Rider 2 06-01-2011 07:03 AM

Quote:

Originally Posted by allanworks (Post 260831)
drove it around town today with some sea foam to clean carb.

not giving it enough throutle i guess.

now down shifting to slow down is that mandatory i would rather just use the brakes.

I agree you need to keep an eye on that fuel leak.......and before you ride it too much more, change the oil.....if you are sure the leak has stopped.

Part of your stalling problem might be that your idle speed is too low......or if the engine is still cold, you aren't leaving the choke on long enough.

Stopping with the brakes ONLY is a bad habit to get into. You don't have to actually let the engine slow you down but you NEED to shift down one gear at t a time as your speed decreases. That puts you in the right gear if you want to take off again.....AND.....bikes are really hard to shift more than one gear at a time, sometimes almost impossible when standing still.

P.S. Seafoam is not a really good carb cleaner. After that is run through, get a can of Berrymans B12 Chemtool. It cleans better and is about 1/3 the price.

allanworks 06-01-2011 07:51 AM

ok good thats what i thought about down shifting. ive used chemtool before but sea foam to me seamed to be the better stuff run it threw pcv valve and all the carbon build up in your engine is gone.planed on changing the oil to day

Easy Rider 2 06-01-2011 10:55 AM

Quote:

Originally Posted by allanworks (Post 260861)
sea foam to me seamed to be the better stuff run it threw pcv valve and all the carbon build up in your engine is gone.

1) There is no good evidence that "normal" carbon buildup is really bad for an engine. It is, in fact, self-limiting under normal circumstances.

2) That is quite different than cleaning varnish and other deposits from inside a carb.

allanworks 06-01-2011 11:35 AM

i do know that just a few drops can strip the clear coat paint and primer off a car.if it can do that i think varnish shouldent be a problem .of cource cheam tool and sea foam could be the same thing in two diffrent cans.and as for the carbon issue i had a geo prizem once it ran like **** ran some sea foam threw it and she perred like a kittian see what happens is carbon builds up on valves causing them not to seat right allowing blow back causing the engine to run bad.carbon on the pistons its self is realy know problem.i use the stuff because of exsperiance and what i was trained to use.firestone use to use it for the fuel system tune up and thats what i was trained to use

Easy Rider 2 06-01-2011 02:43 PM

Quote:

Originally Posted by allanworks (Post 260873)
if it can do that i think varnish shouldent be a problem .of cource cheam tool and sea foam could be the same thing in two diffrent cans.

Trust me, it isn't the same.

But I am not going to argue with you.
You obviously know everything about everything......or at least think you do.

I'm done.

The_AirHawk 06-01-2011 03:14 PM

Quote:

Originally Posted by allanworks (Post 260873)
i do know that just a few drops can strip the clear coat paint and primer off a car.if it can do that i think varnish shouldent be a problem .of cource cheam tool and sea foam could be the same thing in two diffrent cans.and as for the carbon issue i had a geo prizem once it ran like **** ran some sea foam threw it and she perred like a kittian see what happens is carbon builds up on valves causing them not to seat right allowing blow back causing the engine to run bad.carbon on the pistons its self is realy know problem.i use the stuff because of exsperiance and what i was trained to use.firestone use to use it for the fuel system tune up and thats what i was trained to use

They don't even smell the same. Seafoam smells like jet fuel or kero, Berryman's B12 smells like Tolulol (Toluene).

I've never seen either of them strip catalysed auto-grade paint, but they WILL take spray-grenade paint right the hell down to bare metal.

allanworks 06-01-2011 07:33 PM

well im sorry that your getting frustrated with me its just i speak my mind.and it gets me in trouble some times .im not saing that chem tool is bad or anything ive just not used it that much and i like to stick with what ive found to work.ok maby it was more than a few drops.if you wipe it off emediatly no problem.i poured it in the tank spilt some on truck went up stairs to get a towl to wipe it off and forgot what i was doing found it the next morning the paint all bubled up picked at it and the paint chiped off.
never smelled it:) so i wouldent know havent been a machanic sence the late 90s

allanworks 06-01-2011 07:44 PM

a way to under stand it is lets say i have a tapping noise in my engine the first thing that comes to mind is marvel mystery oil there might be better stuff out there but ive learned to trust the stuff .just like lucas,slick 50,engine restore,wd 40,liquid wrench and so on these are things ive come to trust if they dont fix problem then ill try something else.good i love liquid wrench that stuff has saved me a ton of broken nuckels


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