kz750 ltd h2 1981 - will crank wont start fully?

hi everyone!

thank you very much for your really informative messages.

i think i've confused you here. the carb builders are JRS of Swansea, Wales, UK!
the £300 restored set of my original carbs are on my bike now.

i also bought 2 other sets of carbs and another set with spares on from the US!
being in the uk, i can't get spares for these carbs, so hey i bought a job lot!
the brass idle screws 3 x 4 = 12 screws, 5 are ok, 7 need to be removed.
i knew they were like this and i should be able to remove them.
Anyone heard of 'freeze and release' this is cool stuff that chills out metal
to help remove any stuck bolts, studs etc. just shake well and it's very effective.

*** GOOD NEWS - THE CARBS ARE NOW SET UP USING THE CLEAR TUBES METHOD!.. ****

i've now set up my own carbs in the vice, on my bench, i even used a spirit level,
for precision! i simply used my own clamping idea. a coil bracket, metal strip and a g clamp and aligned the carbs up. i filled the fuel inlet with a small funnel and did each carb as instructed.
once i understood what i'd to see and do, it all worked out perfect.






FAULTS FOUND WORK DONE BY THE PREVIOUS MECHANICE

1) the butterflies wouldn't open up by the twisting the throttle, resulting in a
too fast an idle. this is now correct. why would he set a throttle too tight,
which wouldn't open the butterfies. he was here a few hours, couldn't the carbs
correct. he only manually tried to set the float heights, using the haynes manual,
not the oem one.

2) the original float bowls, were indeed blocked, i simply changed them
for 4 matching bowls, where i tested each bowl for fuel drainage for the clear tubes
test. all cleaned and work perfectly now.

the bike started up on the key, no throttle needed, YIPPEE!
purred like a bike cat!...., slight burp in running, sounds a bit lumpy.
however i sprung a leak bewteen the new tygon fuel line
inside diameter is 5/16" and the sintered brass inline filter is 1/4". the tygon
fuel is jelly like and i would like to change the filter to a 5/16" one to make a
better seal.

PROBLEM, NOT FIRING ON 4 CYLINDERS? 3 PIPES HOT, ONE COLD?

the dynamic timing is not yet done. could this be causing the cylinder not to get hot?

i did try to test the dynamic timing. I connected the induction to cylinder #1, the cold pipe
and to the positive and ground. i put the light at the hole in the stator plate
and can see the timing marks. however, the timing plates is vibrate and i don't know what to here.
i contacted boyer bransden and they said that the dynamic timing is 40 degrees TDC.
i wanted to do this final timing and yet i don't understand what i'm seeing. i can do a movie
tomorrow?

many thanks

Angel

steelhorseangel wrote: PROBLEM, NOT FIRING ON 4 CYLINDERS? 3 PIPES HOT, ONE COLD?

the dynamic timing is not yet done. could this be causing the cylinder not to get hot?

i did try to test the dynamic timing. I connected the induction to cylinder #1, the cold pipe
and to the positive and ground. i put the light at the hole in the stator plate
and can see the timing marks. however, the timing plates is vibrate and i don't know what to here.
i contacted boyer bransden and they said that the dynamic timing is 40 degrees TDC.
i wanted to do this final timing and yet i don't understand what i'm seeing. i can do a movie
tomorrow?

many thanks

Angel

OK Angel, good to here its starting up now/better, at least. NICE JIG

1 Cylinder not firing...

Did you bench sync the throttle flaps/butterflys?
Did you set the pilot mixture/air screws?
Did you visually verify that cleaner sprays thru all jets and passage ways in carbs? (Making sure pilot passages are clear in the castings)?

Do those things...

If 3 pipes get scalding hot, one cold - NOT an ignition issue (unless plug gap has been mashed closed for some reason). It is a fuel/air issue (most likely), or compression/valve issue (less likely).

40 Degrees TDC would be at full advance. When idling correctly, it should be 10 degrees I believe. If the "F" mark is bouncing around, it may be you have very loose advancer springs, allowing the advancer to snap open/closed at idle - advancing and retarding the timing erratically. Could be something loose?

Make the correct adjustment to the carbs. Then start the bike up. get it hot/off choke, and drop the idle down low as it will go and stay reletively smooth. Now try your tiing light on all four plug wires noting any difference. The timing light should fire rapidly, repeatedly without EVER missing a flash. If it misses flashes, there is a problem/incorrect setting with the ignition.

Good luck!

I agree with TeK9iNe that it's not an ignition issue. If you want to be 100% absotively positive you could swap the spark plugs between cylinder #1 and #4, and attach the #4 spark plug wire & cap to cylinder #1 and the #1 wire & cap to #4. This will result in everything ignition wise being swapped between #1 and #4. Then start the engine. If the problem moves to cylinder #4 (very unlikely) the problem is in the wire, cap, or plug. If cylinder #1 still is the cold one you have positively ruled out any ignition cause.

hi tek!

did my tubes in 29 mins! not!

i did sync the throttle to the butterflies.
everthing opened and closed.

i've not checked the air/fuel mix, since
master mechanic had a go at adjustment
last week.
this is something that i've not done before.

the advancer plate, springs and bob weights
were dissected. boyer's electronic ignition
doesn't use them parts. when i hooked up
the inductive connection, i did this to #1,
however i didn't get a light at all?
it may of been a bad croc clip i thought,
so i repositioned the clips. i got a light. i
shone it onto the timing marks, too much
vibration to see what is actually there?

the engine i've, has only done 6,600 miles
from new. it's an 81 (4).

ed has suggested that it might be the ht
lead, cap or plug, all new. i'm using iridium's
ok?

i will swop the leads from #4 to #1 and see what
happens.

the dynamic timing hasn't been done.
boyers notes advise 40 degree's tdc.
please see their websitem.

the carb balancing was attempted last
week, again the mechanic, had the carb
flooding to contend with also.

the guy that i bought the engine off,
said that the engine has great compression
in all cyl's. i hope the leads, cap or plug
is the problem of not getting hot.
i did check #1 for a spark, it's there!

i don't know about valves etc.

i need to read up on the air/fuel mix.
i'm lost with this adjustment, need to research
the service manual tek!

thanks for guiding me, what a bud you're!

Angel
x

thanks ed!

i will change the #1 and #4 leads tomorrow,
fingers crossed!

i will let you know!

how many years have you been a mechanic?

i paint animals, i'm a wildlife artist!

regards

Angel

Personally, I wouldn't use NGK iridium plugs in a KZ750-H2. This is because NGK doesn't list an iridium plug for that model bike, they list the standard B8ES plug. Consequently, there is no way of knowing if the iridium plug is of the correct heat range and possibly even the length. Maybe NGK's European site shows different plugs? How did you select the plugs you are using?

Oh, I'm not a mechanic (just ask anyone on this site); I just like playing in grease. Ed

The cylinder that is not firing, maybe a vacuum leak or a Idle circuit in the carb plugged. Does the pipe get hot at a larger throttle opening? The Idle adjustment mixture screws you said were stuck, you now have them working? How many turns out from lightly seated, about 1-1/2 to 2 turns?
Maybe the cylinder is still not getting fuel, so what does that spark plug look like?

hi ed you're a Guru to me!

thank you for your help!

in the uk we've a company called wemoto
do a search on this company for
the two kinds of plugs.
i asked boyer bransden about
the plugs, they said upgraded
ignition could use ngk iridium
for a better spark. however they
cost over 3 times as much, but
are they any better? they say longer
lasting, more efficient spark etc
which is the best? electronically wise
things have moved on.

q) would a modern electronic ignition
system be better with a standard b8 plug
or a modern alternative the iridium?

regards

Angel

I believe Bransden is giving you a bunch of hype regarding their ignition system (keep in mind; they want to stay in business). You may not know it, but your bike already had an excellent Kawasaki electronic ignition the day it was built. So your ignition has not been upgraded; it has simply been swapped out for a different brand (which frankly may or may not be inferior to the original). Most folks who switch from points to electronic use Dyna ignition and coils; although in some cases they are able to find a Kawasaki electronic ignition to fit their bike which draws less current than the Dyna. I don’t know what the current draw difference is between the Bransden and the original.

Assuming you are using NGK BR8EIX plugs, they should work ok. I found a cross reference that says they are equivalent to the NGK B8ES, so the heat range and plug length should be the same. Whether or not they provide any advantage that makes them worth 3 times the price of a normal plug remains to be seen. Perhaps someone else on this site with hands-on experience using iridium plugs will chime in. Personally I use ND Hot-U plugs in my bike, but NGK make a quality plug too.

The only difference that you would be able to tell in those expensive IR plugs, is a lighter feel to your wallet/ purse. Unless you feel that you would get 100,000mi of riding on a set of plugs. Better to get the B8ES, or equivalent.
Is your cylinder firing now? Was it just that the plug was fouled with black wet carbon?

hi ed

thanks for your reply!

when i bought my bike, they're like hens teeth in the uk!
i've never seen another one. the whole bike looked ok, but frozen in time
with rust and decay. lots of parts missing, or the wrong parts fitted.
my clocks were 1980, the harness matched the bike. the harness didn't
match the bike. this became my quest to find parts to complete the bike.
i'd an oem ignition system fitted from factory, the coils had gone bad.
the cost over here for suitable coils were a lot. it was cheaper
to change the whole system over to one that they use on racing bikes here.
i understand what you mean about the oem parts. it's my location in the
world. no oem parts, you never see a kz here at all.

here is what boyer wrote to me:-

*************
Hi Angela,

Top dead centre (TDC) is the (0 deg) position when the piston right at the top of its stroke in the cylinder bore.
With your machine, the 4 pistons are arranged on a 180 degree crankshaft, therefore 2 of the pistons will be 180 degrees out of phase with the other 2 (for reasons of balance).
TDC of any piston can easily be found by carefully inserting a wooden dowl (pencil?) through the plughole of the cylinder concerned. The engine can be turned over more easily from the back wheel if all the plugs are loosened or removed to reduce compression in the cylinders.Using a dial gauge indicator is a more accurate method of determining the top of the stroke than a pencil. With any cylinder in its TDC position, the degree wheels 0 degree position can be referenced with a mark on a suitable part of the crankcase. If the engine is then rotated in the normal direction of rotation for 360-40 deg = 320deg (to reduce the effect of backlash), the MAX ADVANCE position (40 Degrees Before Top Dead Centre) can be marked. This will be the max advance strobe timing mark for 2 of the cylinders. The timing mark for the other 2 cylinders should be made 180 degrees around on the crankshaft.

Regards,
Kevin - techl.

**********

i've not set the dynamic timing as i don't know how to do it correct for 1 & 4,
2 & 3. It's strange that 1 & 4 are warm pipes, yet 2 & 3 are hot.

i need to research the use of a strobe and to hopefully set the 2 pairs of cylinders.

Also pilot idle, air/fuel mixes, never ending, but a constant challenge!...

many thanks

Angel


Boyer Bransden Electronics Ltd
Frindsbury House
Cox Street
Detling
Maidstone
Kent
ME14 3HE

Tel: 0044 (0)1622 730939
Fax: 0044 (0)1622 730930
Website: www.BoyerBransden.com

hi motorhead

not had a chance to do anything today, some friends have called around!

back in the garage tomorrow. 2 pipes 2 & 3 are hot, 1 & 4 are warm?

i need to look at air/fuel mixture and pilot adjustments.
it's a voyage of discovery motor!..

i know that the bikes, starts and stops, sounds ok!..
i will post a movie as and when i work out why the other two cylinders are not
firing properly.

i personally think it's my lack of knowledge about all things mechanical!
the strobe hasn't been done. i tried to do this and i don't understand
about time setting for 1 $ 4, then 2 & 3. it's coincidental that
the cylinders that i'm having a problem with are 1 & 4, so is this a timing
problem?

ed disagree's with boyer about the timing degrees etc

thanks for your help, as always!

kind regards

Angel & 'Eric'