TOPIC:

Some very interesting inputs re the problem re coils and fuel problems. Myself have no spark? Bike was running fine after restoration, but left for a week and tried to fire up no spark. Shall be going for the Coil replacement and discount the ballast resister. Fitted new plug caps standard. But fitted NGK BP6ES plugs. Its a learning curve re the Z1300 and one day would like to ride the bike.

LareNurminen wrote: Hi,

I have had issues with hot starting on my -79 and -82 bikes. One idea that has been bounced around and has logic to it is:
Our carbs feed fuel due to the vacuum created by the pistons.
If the vacuum is not created, the fuel will not flow.
Therefore, having the idle adjustment screw set too high prevents the creation of sufficient vacuum and therefore starting.
When you start the bike cold, you use choke = add fuel to the system. When starting hot, you do not use choke = no start.
As written in the earlier comments, bump starting a bike which refuses to start hot works every time.

I have adjusted the idle screw to minimum to gain maximum vacuum.

I believe the hot starting problems are due to the insufficient vacuum, battery voltage going low due to starting and causing weaker spark.


Lauri

I'd like to respectfully challenge this statement.

This particular carburetor has 3 fuel delivery circuits, the Main circuit, the Idle circuit and the choke circuit.

The main circuit feeds fuel on or above the 2000 rpm range. Reason being as the butterfly valves open air being drawn through the venturi in the carb causes a low pressure area near the main jet which is also the location of the port which takes that vacuum and applies it to the diaphragm raising the carb piston which then meters the fuel through the carb.

the choke circuit is in fact a miniature carb within the carb with a jet that is very rich compared to the 14 to 1 ratio of the main jet circuit. When you open the choke circuit you're supplying air not through the main venturi like most automotive carbs but through a separate port.

The idle circuit is also a carb within a carb. It gets air supplied via a port in the front of the carb and draws fuel in as the air passes the idle circuit jet and this also is unlike the setup in an automotive style carb. it also is jetted rich compared to the main circuit @ 14:1 ratio.

Depending on how you've set up your butterfly plates (more open or less) will affect how far open you've set your idle air bleed screws. By design, Kawasaki has suggested that the throttle butterflies be set at 1-1/2 turns open from fully closed to set the baseline position of the butterflies. Adjusting the air bleeds after that point will richen or lean out the mixture and also affect marginally the idle rpm.

Bottom line, when starting the Kaws you shouldn't be opening the throttle at all which would apply a high vacuum to the idle circuit and or the choke circuit if it's been opened. There will not be any vacuum inside the main body of the carb at all since the butterflies are virtually closed.

Starting problems pre-dated any starting fluid use, and I never squirted it directly into the carbs -- only into the bottom of the air box. Wouldn't I be seeing some smoke if I had piston/rings problems?

Well, thanks for all your thoughts, guys. I was hoping for some consensus, but your ideas are all over the place, and I don't have the time or patience to test/eliminate them all. With my luck, the last thing I tried would be the right one, anyhow!

I hate to spend money on a 35-year-old bike, but I have a good local bike shop. I've never regretted a dime that I've spent there, and I've spent thousands on fixes and tune-ups for an assortment of vintage street and dirt bikes. I'll let you know what I find out.

Don't take it to a shop just yet.

Are you still running on the stock floats? When was the last time you removed and inspected the float-valve body O-ring? Are you 100% certain the fuel-shut off AND the float needles shut off completely? What is your sync'd vacuum reading?

Your problem is a classic example of flooding. And I assure you "Flooding" doesn't have to mean "ounces" in the intake. These engines will not tolerate too rich a starting mixture and it takes very little fuel leaking into the carbs via the main-jet to create an over-rich situation. This can only happen when the bowls over-fill. The Over-Flow modification prevents this and remember it is merely an over-flow and has no affect on the "carb-tuning".

Even one carb. (2 clyinders) with a fuel "leak" on a set of carbs that aren't set-up correctly can create hard starting. Add to the equation other minor issues and the problem is further complicated and exhaserbated. The at-idle throttle-plate gap as pointed out is very critical and sensitive. Too much (thousanths) and your buggered. Whether by "turns" or by the "paper-strip" method they need to be sync'd precisely and when starting from scratch I have found the "paper" setting to be best starting point, personally speaking. Keep in mind: As little as 1/12th of a turn (either way) on the sync-adjustment will have a dramatic effect on the Vacuum reading.

Tuning and adjusting must be logical, accurate and progressive in the correct sequence. It becomes a "Catch-22". If the ignition timing is "off" the starting already has a liability. And if the carbs aren't adjusted correctly allowing the engine to run smoothly, then it's difficult to get the ignition timing accurate. This is an over simplification but the point I believe is made.

Re: Tank insulation. It can do no harm. I would however suggest an "automotive" grade "felt" product (with the foil covering). Foam may heat-disintegrate relatively quickly and as unlikey as it may be - I'd prefer the more flame resistent Felt type between my legs.

Re the "coil" comments. I had an ignition trigger that would let me ride for 50 to 100 K and quit. As little as 60 seconds on the side of the road was all it required and the engine would start and run on all 6 again. This was a PITA on my cross Canada trip! The Big problem if a coil is in question of "opening" when hot: How quickly can the defective one be diagnosed with a meter while hot enough to still be "open" and before it cools.

It is easy to pay someone to fix your problems but unless "your Guy" has worked on 1300s (and by that I mean OWNS one and understands it ) it's just as likely the problem won't be found and the carbs and ignition will come back even more outta whack. Even the "old timer" former Kaw. shop mechanics will be very hard pressed to remember anything about these bikes other then they were practically impossable to tune and at best were difficult.

The above mentioned ideas are something a bike owner can check-out quite easily.

Hi Scotch,
Thanks for bringing us back to an issue that many of us have struggled with our selves.

TouringGuy: what do your plugs look like? Are one or two or more black? Perhaps wet or sooty?

Surely you've got time to check the plugs.

Bill