kz750 ltd h2 1981 - will crank wont start fully?

Take a look at Joe's video in this link (skip down just a little past the picture of the clear plastic bowl):

kzrider.com/forum/3-carburetor/500682-clear-float-bowls#503278

steelhorseangel wrote: ...the internal
tank filter, connected to the petcock.
inside the tank filter, there is a tube inside the filter.
this central tube fits in the base of petcock. this
is one tube, next to this tube is another hole.
does a second tube (smaller) fit into this
second hole?....

The second hole doesn't have a tube, as the second hole accepts fuel until the tank runs dry.

But the second hole might have its own separate filter.

The petcock's so-called "filters" are just screens which help prevent some of the larger grit from passing on to the carbs.

This is why aftermarket in-line fuel filters are necessary.




Good Fortune!

q)

when i unscrew the nipple bowl drain screws
fuel only drains out of two tubes only?
on unscrewing the other two drain screws,
the fuel comes out of the screw holes and not
the nipples?

blockage somewhere?

NIPPLE BOWLS
on draining the nipple bowls (for carb inspection) by using clear drain tubes, connected to the nipples. i unscrewed each screw in turn. i expected the fuel to come out of the nipples, yet in two cases the fuel came out of the screw holes? two were like this, no nipples drainage!.

If fuel fails to discharge through the drain nipples from bottom of the float bowl, would suspect that the overflow circuit is clogged.

As to performing the clear tube test with carbs on the work bench, I simply hold or prop the carbs upright and level while performing the clear tube test, and don't bother with any separate rigging or clamping the carbs to a board, etc. Chalk it up to laziness. :lol:

Good Fortune!

thank you patton!

i laughed out loud!

how do i unblock the overflow system please?

such a big learning curve, nearly there!...

kind regards mr guru

Angel

when i unscrew the nipple bowl drain screws
fuel only drains out of two tubes only?
on unscrewing the other two drain screws,
the fuel comes out of the screw holes and not
the nipples?
blockage somewhere?

Please wear eye protection while spraying carb cleaner, because it always backfires.

Am thinking (not positive) that these are Keihin CV carbs with a dual function drain screw.

With the screw tightened, the overflow circuit is supposed to function.
This means if excess incoming fuel is getting past the float valve (for whatever reason) and rising up too high inside the float bowl, the rising fuel is supposed to only get as high as top of the overflow tube.

Upon reaching height of the overflow tube, the excess fuel is supposed to then escape down through the overflow tube and exit through the nipple.

With the drain screw loosened, the float bowl is allowed to drain completely.

Must be careful when attempting to clear the overflow passageway so as not to break off, crack, crimp or otherwise damage the rather thin fragile overflow tube.

The following could be done with the float bowl removed and in hand.

With the drain screw tightened (whereby overflow circuit is operational), could try to clear the overflow passageway by blasting through it, by spraying carb spray into the nipple, and hoping to see the spray exit from top of the overflow tube.

Could also try spray blasting the opposite direction, starting at tip of the overflow tube, and hoping to see the spray exit from the overflow nipple.

Could also remove the drain screw, and try spraying into the drain screw hole while blocking the nipple hole with a finger, and hoping to see the spray exit from top of the overflow tube.

Could also remove the drain screw, and try spraying into the drain screw hole while gently blocking top of the overflow tube with a finger, and hoping to see the spray exit from the overflow nipple.

Also, the drain screw is supposed to have an o'ring, which I believe may prevent or minimize fuel leakage when the screw is loosened.

Good Fortune!

a big thank you!

i've some eye protection, for the overflow
job tomorrow. i will make sure that i don't
spray any rubber etc. i greatly appreciate
your help and advice!

it's better to do a complete job from start
to finish. i like this situation, a conundrum
that is a learning curve as well.
the last owner made a message of one
of the carbs internal fittings, it was stuck
and partly broken. i bought an easy out, knew
it would come in handy. bought two spare
keihin carb shells, my doner supplies!

thank you!

Angel

Yeah, the carbs are right side up (normal/onbike) position. As in Pattons pictures...

Bowls on. Perform clear tube test on one bowl/carb at a time - setting it correctly, then move on to the next. With a rig like i described, it shouldnt take more than 30 minutes to set all fuel heights correctly and move on to the next thing. (we dont have alot of time in the shop to screw around) :laugh:
If you have to set the floats very high (pushing float needle spring up hard) to get the fuel level correct - use some metal/brass polish and some cotton swabs to polish the float valve seat to shiney like new state.

If you have metal float needles, good idea to put them in a drill and spin polish them too.
If rubber, make sure they are clean/no cracks, and shouldnt have any severe indentations.

Good luck!

hi tek

thanks for your help!

i actual have two spare carbs sets here.
i bought them from ebay com.
sadly the all the brass idle screws have
been chewed by the last owners.
is there any simple way to extract the screws.
any mechanics tricks of the trade?

i had a look at the spare carbs and measured
the float heights. i was seeing what was the
average resting height of my spare carbs.
they all seemed to be 2cms. i will
be making the rig tomorrow for the clear
tube method. when my engine was last
running, this time last week. the new standard
spark plugs ended up sooty dry black.
this is too rich. the workshop advises
float height too high, creates sooty dry plugs.
looking forward to setting up the carb rig,
working methodically through each carb setting.
i've got all day to do this!....

having to do the fuel levels under a time
restraint must be stressful tek!

i will let you know how i get on, something
new to learn!

many thanks

Angel

steelhorseangel wrote: sadly the all the brass idle screws have
been chewed by the last owners.
is there any simple way to extract the screws.
any mechanics tricks of the trade?

You can carefully drill into them just enough, then use a stripped screw extractor to remove them. Best to spray some penetrating oil in there first and let it sit a couple hours before hand.

the new standard spark plugs ended up sooty dry black.
this is too rich. the workshop advises
float height too high, creates sooty dry plugs.

Not necessarily! Plugs should only be read for condition when the engine has been put under load, with the choke not in use at all. With small throttle openings/near idle, it can take several miles to color a plug for a good reading. I prefer to stay away from plug reading all together when setting upa bike (readings are really only good for WOT or cruise position after long rides).
Get the fuel heghts set. Bench sync the throttle butterflies/slides. Put air/mix screws to default. Install. Fire up the bike, get it off choke, and set the idle. Then adjust air/mix screws (which will tell u if there are any other problems ), then take a ride! - Provided everything else is safe! :laugh:

having to do the fuel levels under a time
restraint must be stressful tek!

Not too stressful when your getting paid to do it. But takes time away from other projects when things dont go as planned :pinch:

Wish I had all day to do stuff! :silly:

steelhorseangel wrote: ...all the brass idle screws have
been chewed by the last owners.
is there any simple way to extract the screws.
any mechanics tricks of the trade?....

If speaking about heads of the #1 screws being chewed or rounded out, which prevents grip with a screw-driver, there's a special screw-driver type tool with an extraction tip that might enable sufficient grip or bite to remove the screw. The tool tip looks similar to the cutting tip of a reverse drill bit.



community.craftsman.com/Taps-Dies?page=3

www.directindustry.com/prod/recoil/bolt-...rs-19519-428407.html


Then there's the easy-out method by drilling a hole into the screw and using an extractor tool.




But when dealing with these very small screws, the above methods may prove unsuccessful.

Would suggest obtaining if possible a small reverse-cut (left-hand) drill bit slightly smaller than the screw body without threads, so as not to damage the female threads in the carb. Such reverse drill bits are sometimes difficult to find.
(Could try: Sears, Lowes, Home Depot, Harbor Freight, NAPA, ebay, Snap-On, Mac, etc.)

This method requires some careful slow gentle drilling so as not to break off the drill bit inside the screw.

Often when using the reverse (left-hand) drilling technique, the screw will self-extract.

Good Fortune!

"i actual have two spare carbs sets here.
i bought them from ebay com.
sadly the all the brass idle screws have
been chewed by the last owners.
is there any simple way to extract the screws.
any mechanics tricks of the trade?"

The advice of the left hand drill bit, then a extractor is what I used before. But also soaking them with penetration oil, and then using a Butane Micro Torch to heat just around the Screw Boss casting area of the carb. Of course all Petrol has been removed and the carb is dry, float bowl off, etc. The only other thing besides being on center when drilling is to be careful with the penetrating oil, it may burn a bit at first. But you can heat spray, heat spray. It'll smoke and burn a bit, but will help loosen the grip on those old threads.
Your Carb re-builders of course should have done this already. Sorry to hear your having so much trouble. You'll get it though and once set up that bike should be sweet.