TOPIC:

This is a supplement to the 1979 Carb Tear-Down and Rebuild.

Despite being able to strip the carbs down to the core to facilitate a cleaning process, there are three tiny jets per bore which can resist cleaning due to their size and location. With many complaints of poor running after hydrosonic and various forms of chemical cleaning it stands to reason that regardless of the cleaning method it is often not thorough enough; hence unsuccessful.

My take on this is as follows:

The three jets that I believe give us the off-idle transition to mid-range are inaccessable, parse. They are located behind the closed throttle-plate (air filter side) and are staggered very specificaly to give a progressive increase in fuel/air as the throttle is opened. They sequentially supplement the single idle-air delivery until the RPM increases sufficiently to draw the fuel through the main-jet. If these three jets are clear then transition from off-idle should be smooth and linear. If any one of them is plugged then the sequential addition of fuel is interupted giving a flat spot in the throttle repsonse. If all three are blocked then the engine will likely stumble and perhaps quit at this point of throttle input.
To check the 3 jets for fuel delivery turn the idle-air screw all the way in.(off) With a thumb over the end of the corresponding jet tower and the index finger inside the venturi covering the opposite end, fluid (alcohol in this case) can be injected at minimal pressure into the idle circuit using a syringe pushed into the idle-jet tower.
(The main-jet tower is blocked to prevent the fluid from travelling backwards, into it.)
The fluid is forced out of the three jets if they are clear and unobstructed. If any or all do not discharge with a strong and identical stream then the carb requires additional cleaning attention. Similarily the tiny holes in the emmulsion-tube are sized and placed in a specific pattern to give the appropriate atomized fuel/air ratio proportionate to the throttle position and fuel level in the bowl. Any blockage of the ports in the emmulsion-tube will affect performance also but at least they can be cleaned easily.
In both cases the smallest particles of debris can obstruct these jets/holes causing endless hours of grief and frustration. A quality fuel filter is mandatory and because the carb jetting requires air to be mixed with the fuel internally (remember the emmulsion-tube?) prior to reaching the venturi it is equally critical that the air filter system be perfectly sealed and the air filter be in good condition.
To check the three throttle bore holes a .025" spark-plug gap guage should pass through each jet. (1979 Carb) If it doesn't: that jet is blocked. Rust particles, mineral build-up from moisture, dislodged scale etc will block these easily. A previous picture in the "1979 carb tear-down" (Carbs and Fuel Injection thread)shows a "stalactite" formation around one set of transition jets which would have rendered this throttle-bore useless. Hope this informs and helps !

Technical corrections by anyone better versed on this topic are welcomed.










Once the 3 transition ports have been determined to be clear the idle-air screw can now be opened the typical 3+ turns and the fluid discharge from it can be useful in determining whether it is clear.

Scotch:

A great write up on one of the most troublesome ares of this carburetor. Thanks for taking the time to document this idle circuit.

T.

Your contributions to this forum are always so detailed and interesting, Scotch. Thanks for taking so much trouble to share your wisdom.
A couple of questions:
I have not seen you mention ultrasonic cleaners in connection with carb cleaning. Have you tried one of these?
Are you currently restoring a 1979 1300? I just wondered what you were planning to fit the carbs to.
What got you interested in the Kawasaki 1300? What aspects of its character do you most like?

Thanks for comments and Q's.

#1 Ultra-Sonic cleaners: I have never owned, borrowed or used one. Primarily because I have never had access to one nor could justify the cost of a quality device. I have also read in this forum and many other forums of a high degree of those who commented that after using an Ultra-sonic cleaner the carb. conditions did not improve satisfactorily. There are many reasons this technique could be unsuccessful at the home level. Having experienced dirty carbs at their worst with the 1979 rebuild and understanding the principles of U/S cleaning I haven't been convinced that a single U/S cleaning is going to do the job adequately on carbs this gummed-up. This opinion is primarily due to the high number of those who undertook having their carbs U/S cleaned "professionally" and also without any apparent success. Knowing what I know (personally speaking) I'll take the lemon-juice, glass-bead and Lacquer thinner/Syringe method any time.

#2 The 1979 carbs' I have been rebuilding were an impulse-buy off E-Bay. After confirming with the seller that the bank of carbs were complete in every way I thought I'd tackle them head-on and from strictly a personal-challenge P.O.V. to see what would come of the project. Worst case scenario they'd make an interesting paper-weight/conversation piece.
I have now finished the re-assembly to the point of needing to complete the top cover and bowl polishing. My intention is to then install them on my 1980 and see what comes of the internal work that has been documented, here. With it being "winter" (Canada) and currently no insurance on the bike I can only do a static set-up on these 1979 carbs. As much as common-sense dictates I wait 'til Spring so I can "road-test" my efforts I will likely not demonstrate any such characteristic and will have them on the day the polishing is completed because I'm a sucker for punishment and common-sense is sometimes highly over rated ! Never the less the "proof will be in the Pudding". Given these circumstances I'll be satified to get them dialed-in for a solid idle and no hesitiation throttle increase.

#3 In march of 1979 I stopped in at the Kaw/Suzuki dealer for a new pair of gloves. At that time I was riding a new Honda 750F. My buddy behind the service desk said I needed to see something and took me to the receiving area where I saw for the first time a 1300, still sitting on the crate-bottom. We did the deal then and there. My new '79 was a "bitch" ! So rich-running it would foul the plugs in 5 minutes and not start. 2nd gear (gears/bearing) was a siren almost to the point of hurting my ears. Long story short- I sued, won and got a new "0" mileage 1980 to replace the '79. The '80 has been with me ever since.

#4 One word: Appearance ! The moment I saw it I got a "woody" and it has the same affect today. I simply love the appearance. It's big. It's mean looking. It's not covered in plastic. It is formidable on the road and the sound (DG header)........... !

1300's are not unlike anything else we see. You luv 'em or hate 'em. Nothing more - nothing less.

If and when I decide the 1979 carb rebuild has been successful I may choose to sell them. This forum will be the first and only venue for that purpose if I decide to do so.

Thanks for the interest and positive comments for my articles and also for the sales patronage of my Brass Floats. I never anticipated the positive response to the floats as I have had and will continue to make them as required. It has all been a labour of love and as we all know: Owning a 1300 is a Love-Hate relationship!

Cheers, scotch

Thanks, Scotch. I tried posting a longer reply, but this website is still experiencing problems, so my message got lost when it timed out!
Your bike looks great. I like the black cam cover.