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1984 Kawasaki ZN750a Shaft drive
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Discussion Starter #1
Good morning,

I am a complete newbie with just basic knowledge of motorcycle mechanics. I do have good intuition and abilities.

I just picked up the bike a few weeks ago. Bought the repair manual and started teardown. The bike likely needs new pistons and rings along with just normal clean-up and replacement of worn parts, mostly old rubber like tires and trun signal posts. Other than that, it is is good condition.

Owner said that piston/ring work had been done incorrectly and needed to be corrected. I will find out more when I get there.

I am at the stage where I am trying to get the carb assembly off. Does anyone have any advise? It seems the carbs are attached to the engine with a centre post. I have all of the rings for each rubber connector loosened and am about to start removing the air box side. It seems to be the logical sequence since these are the only ones I can access to gain room to move the carb assembly around. The engin side hoses are made of stiffer rubber and don't have any give.

I look forward to hearing from anyone with experience on this fairly rare bike...
 

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Hi Philippek,

First off, welcome to our club of dedicated Kawasaki owners!
We have members here who own or have owned ZN's and they speak highly of them and that includes me with my recently restored 84 ZN1100.

The carbs can be difficult to install and remove due to the hardening of the rubber boots or what some call the ducts. I highly recommend softening them or buying new ones. It will make life so much easier to have soft, pliable rubber instead of rock hard rubber.

Once you get the airbox-side rubber boots removed, the carbs will slide straight back towards the airbox and can then be removed from the bike. If the rubber is really fighting you, some gentle heat from a hair dryer can help to temporarily soften the rubber. Just don't tell the wife you borrowed her hair dryer.
 

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1984 Kawasaki ZN750a Shaft drive
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6 Posts
Discussion Starter #3
Thanks. I appprecaite the note of welcome and look forward to being a part of the community. I will definitely try the hairdryer and make sure the wife remains in ignorant bliss;)!

Does a rubber restoration compound exist or some form of liquid that can be used to soften thoses boots? I am reluctant to work these too hard for fear of damaging them before i can replace them...
 

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There are many ways to soften old rubber but the softening effect is not permanent. It may last 6 months to a year or more. You can google it and there are scads of different ways to soften rubbber. I used wintergreen oil which is available at your drugstore for a small fortune, or available from an equestrian supplies store for a fraction of the cost. I got mine from Big Dees.

Mix it 1 part wintergreen to 3 parts isopropyl alcohol. Immerse rubber in this solution for about 3-5 days. Caution: do not breathe fumes or get this stuff on your skin. Keep in a tightly closed container and flush part with warm soapy water.

I have to say however that there are limits to what can be done. There is no question that the rock hard rubber boots came out as pliable as they day they were new, but wintergreen cannot cure any physical problems that existed before treatment. This includes any shrinkage that may have happened to the boots.

Bottom line: if you are going to replace them, then you can saw them off if necessary. Just make sure replacements are available before you do this. If you want to preserve the old boots anyway, then soften them one at a time with the hair dryer and remove quickly before the rubber cools and then move on to the next one.
 

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1984 Kawasaki ZN750a Shaft drive
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6 Posts
Discussion Starter #5
Thanks, the tip on Wintergreen oil mixture is helpful. I will try to preserve the boots once I get them off using the hairdryer.
 

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Totally agree with all WFO-KZ said. Evidently he has dealt with this before as I have. The boots are not that expensive & are readily available. Save some skin & just buy new ones. I finally got mine out from the inside of the air box. Wish I had thought of cutting them initially. I could not believe the difference in the pliability of the new ones, compared to the aged ones. Mine were on an (82) GPZ 750. I guess in (39) years a lot changes.
 

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1984 Kawasaki ZN750a Shaft drive
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Discussion Starter #8
Thanks guys! I Got everything off yesterday. Boots came off pretty easily once I heated them with hairdryer. Do you have any tips on how I can best store the carbs now that they are off? I am focused on getting to the cylinders and pistons for now so I am going to store the carbs for a while until i am done with the cylinder project.
 

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You really don't have to do too much to store the carbs. Protect them with a cardboard box and covered with something to keep the dust and dirt off them. You could try to drain the float bowls but if the bike has been sitting the gasoline may have long since evaporated and left a nice mess for you to clean up. If you have a birthday coming up you could hint that you need an ultrasonic cleaner. It helps when you add that these are excellent for cleaning jewelry as well as carb parts.
 

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1984 Kawasaki ZN750a Shaft drive
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Discussion Starter #10
Hi, indeed, the carbs were empty. At first glance they don't look bad. My focus is ro getnto the cylinders so im storing the carbs and will deal with them later.
 

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1984 Kawasaki ZN750a Shaft drive
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Discussion Starter #12
I keep forgetting to document my progress... Thanks for reminding me... I will try to remember the next time I'm working on the bike... I'll then be able to post!
 
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