Can't start 83' KZ750

You have to lube the advancer pivots.

Check for proper functioning by using a timing light to watch the advancer arms quickly open and close as rpm is varied by blipping the throttle.

It's sometimes possible to dispense a drop of oil on each pivot by doing so through the timing window (without removing the advancer).

The advancer should NOT look like this:




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karoliens wrote: Can't start my KZ750. Plugs are new, carbs cleaned, spark is good, starter rotates. Pilot screws 3 turns out, choke on. Battery is good. It shows sign of starting but there is no running. Is the ignition timing is controlled automatically on these bikes? I also changed chain tensioner at some point. Could it be something with the chain itself? Thanks.

Did it run before? If so, you mentioned that the plugs are new. Did you properly gap them. No offence meant by my comment, we all forget steps and make little mistakes sometimes. Just had that very situation on another forum I frequent. Guy changed his plugs at the same time he did an oil change and it wouldn't start. I had suggested the starting fluid test to see if it was fuel or not. And of course that didn't work. It turned out to be the spark plugs not being gaped before he installed them. Good luck.

But do you need to gap new spark plugs before puting them in? I thought they are pre-gaped already. The spark plugs are NGK BR8ES.

karoliens wrote: But do you need to gap new spark plugs before puting them in? I thought they are pre-gaped already. The spark plugs are NGK BR8ES.

In my experience, the gap on brand new NGKB8ES spark plugs is usually correct out of the box, but it's best to check the gap before installing.

Why the "R" plug?
Which should be run, if at all, only with (1) solid metal core -- not suppression type -- plug wires, and (2) non-resistor plug caps.

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But manual says NGK BR8ES, the gap is 0.7mm.

karoliens wrote: But manual says NGK BR8ES, the gap is 0.7mm.

IMO, when the FSM specifies an "R" spark plug, it's likely intended for using with non-resistant plug wires and non-resistant plug caps.
Otherwise, with more that a single resistance element in the three components (i.e., plug, wire and/or cap) the spark may be unnecessarily weak.

Is it for sure that valve clearances are within specs?

What are compression test results?

Will the engine run momentarily when starting fluid is sprayed into the air intake while attempting to start the engine?

One basic thing would be to not touch the throttle when attempting to start a cold engine using full choke.

Where included in the carb design, an "enrichener system" is designed to function with all the throttle slides fully closed, and an "enrichener system" functions less efficiently when the throttle is partly opened during the process of starting a cold engine.

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I think Patton's on to something...
5000 ohm plugs + 5000 ohm wires + 5000 ohm spark plug boots = 15000 ohms in coil secondary circuit! Just speculation... but that would sure make it hard to start! :blink:

karoliens wrote: But manual says NGK BR8ES, the gap is 0.7mm.

My manual also says BR8ES - Canadian spec model and I'm sure that is what was on the bike when it was new but plug caps have been changed many times since then and so I dropped the resistor plugs and just use straight B8ES now.
Having said that I think the bike should still start with those BR8ES plugs. Patton did mention something that I take for granted and is really important and that is No Throttle.
Absolutely hands off the throttle when starting.

Thank you guys. Will try everything you said and I will inform how it goes.

Valve clearances:
IN #1-0.10 #2-0.10 #3-0.10 #4-0.05
EX #1-0.10 #2-0.05 #3-0.10 #4-0.15

Bare in mind I have feeler gauge 0.05-0.10 measurements. No 0.06, 0.07... Manual says 0.08-0.18.

Again checked the manual for correct spark plugs and it says NGK BR8ES or NGK B8ES. And in front of the NGK BR8ES there is "E" symbol in circle. My plugs are without caps and wires are for such type plugs also. Lubed the timing advancer, turn pilot screw two turns out. Now making new valve cover gasket. By the way previous spark plugs were yttrium lr15yc. I googled and think them are no good for this engine at all?

With regard only to heat range -- and not the other physical dimensions -- if the Brisk conversion chart is accurate, an NGK 8 would be replaced with Brisk 12 and not Brisk 15 which is way too hot and apt to burn a hole in the piston.




What did you say about the compression test? :whistle:

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