82 KZ750 Carb/Vacuum ID

Hi Folks,

I inherited an 82 KZ750 twin and it would fire up but wouldn't keep running. It had been sitting with gas in it before it came to me so I decided to clean the carbs. In the process I found a nipple with nothing connected to it. I was thinking it could possibly be a vacuum hose but I'm not entirely sure. I've included the blown apart diagram of the carb and have circled said nipple. Any input you have would be greatly appreciated!

Also - if you want to throw any advice or tips for this particular bike in my direction I would appreciate it!

That's the vent. connect tubing and route it behind the engine, forward of the swing arm & away from the chain & mufflers.

Each carburetor probably has a vacuum port press-fit into the carb bodies. Stock, there would be tubing connected to the vac ports for the Kawasaki clean air system. If the cas sys is removed, then the vac ports would be capped & the cas ports in the valve cover & airbox would need to be plugged.

Welcome aboard -

Here are some tips that you may find helpful:

Many newbies and not so newbies run into or issues with their bikes which could be easily avoided with a little preparation or information. Here are a couple recommendations that I hope you will find useful.

Before riding your KZ you should take a little time to become familiar with it. Simple things like checking the oil, tire pressures, etc. are explained in the Kawasaki Owner's Manual. If you bike didn't come with one (they normally are in a little holder on the bottom of the seat) you can usually find one on eBay - be sure to get one for your exact year/model.


MANUAL

You really should consider buying the Kawasaki Factory Service Manual for your bike. The factory service manual provides instructions on the various maintenance procedures and schedules for your bike, procedures for diagnosing problems, proper torque values for the various fasteners (VERY IMPORTANT), and insight into how each system on your bike works even if you are not repairing that system. Studying the manual before you attempt performing service on your bike will impart an understanding of the system you are working on which will increase the odds of success.

The manuals usually are readily available for most models on eBay and other sources; but be sure to get one that has your specific year and model in it as there are differences between the various KZ650 models. I do not recommend Clymers, Haynes, or other aftermarket manuals as I have seen instances where they provide inaccurate advice. You may decide to use those to supplement the factory manual, but in my opinion they are not a suitable substitute. If you have trouble finding one for your model ask us to help.


TOOLS

WARNING! Do not even try to use Phillips screwdrivers on the Kawasaki cross head screws. Despite their appearance they are not Phillips screws. They are Japanese Industrial Standard (JIS) screws. The tips of Phillips screwdrivers are too long & pointed to allow the 4 blades of the screwdriver to properly engage the screws, so when you apply force the screw head slots will deform and look like crap. The fact is that Phillips screws were deliberately designed to have the screwdriver bit "cam out." This was done to prevent production line assembly from over-tightening, stripping, or breaking the screws. JIS screws do not have this problem. A proper fitting JIS bit can tighten a JIS screw to and beyond the torque spec without camming out. Here's the good news - you can easily modify standard Phillips screwdriver tips to fit the JIS screws.

I have ground down the tips of DeWalt #2 and DeWalt #3 Phillips to make them fit JIS screws. The large crosshead screws on the cases take modified #3 bits (or genuine #3 JIS bits). To modify the DeWalt bits you need to grind the very tip a little, then test fit, then grind a little more and test fit, etc. until the bit no longer "rocks" back and forth in the screwhead. Picture 1 below shows how a DeWalt #3 bit fits the case screws of my KZ650 after being ground properly. The #2 DeWalt bits can be modified the same way to fit smaller JIS screws. Pictures 2 and 3 below shows DeWalt #2 and #3 modified bits.

I did find a place that sells authentic JIS bits. They don't list the #3 bit, but if you contact them they can provide the #3 JIS bits even though they are not listed on the website. These folks were very easy to work with, and the authentic bits do work great. Here's their site:

www.rjrcooltools.com/shop_item_detail.cfm?subcat_ID=89

Pictures 4 & 5 below show a comparison between my home made modified bits with the authentic JIS bits, and picture 6 shows a comparison between Philips and JIS bit tips.

PICTURE 1

PICTURE 2

PICTURE 3

PICTURE 4

PICTURE 5

PICTURE 6



Before reaching for that wrench or ratchet consider the following. The bolts are steel, but your engine and front forks are aluminum. The bolts are much tougher than the aluminum and if over tightened will strip the aluminum threads. Although these can be repaired, preventing damage by applying proper torque will save you grief, time, and money. Tightening fasteners properly requires torque wrenches. Various vendors, including Snap-on, CDI, Sears, etc., market torque wrenches. The two most popular types are the bar type and micrometer type. Either will work, but the micrometer type is a bit easier to use, especially if you are tightening several fasteners with the same torque - such as cylinder head covers. You will need a torque wrench calibrated in INCH POUNDS for many of the bolts. You will also need a torque wrench calibrated in FOOT POUNDS for the larger bolts. Don't try to use the foot pounds wrench on the smaller bolts as it will not be sensitive enough at low torque settings to provide accurate torque. There are many fasteners that require low torque. These include such things as 6mm oil pan bolts, cylinder head cover bolts, etc. for which the torque in 61-78 inch pounds. These low torque bolts require a wrench that is accurate at low settings and this wrench should be graduated in inch pounds. In addition, there are numerous high torque fasteners such as the front axle nuts (51 - 65 foot pounds) or swing arm pivot shaft nuts (58 - 87 foot pounds). These require a wrench that is accurate at higher settings; this wrench should be graduated in foot pounds. Using the proper torque wrenches to correctly tighten fasteners will help prevent damage and contribute to a safe bike. The Kawasaki Service Manual will list the various torque specs for the bolts. I suggest you get the manual before buying the torque wrenches so you can decide which wrenches best meet the torque specs.

Consider buying a can of Kroil penetrating oil and use it to soak stubborn fasteners for a couple days before trying to loosen them. Remember, the original screws and bolts were installed on your bike when Jimmy Carter was President, so many of them may be hard to remove. Kroil can be bought online, at guns shows, and at some other venues.


MOTOR OIL
The ingredients in oils have changed over the years. For example, today's Castrol GTX (and pretty much all AUTOMOBILE oil) is not the same as it was in the 1980's. Back then it worked great in KZ bikes, but things have changed. Zinc and phosphorus additives (ZDDP), important to protect engine components from metal to metal contact, has been reduced since it’s been found to shorten catalytic converter life. Today’s auto oils contain about ½ the ZDDP they used to and different additives have been developed as substitutes. Unfortunately, some of these newer additives, in particular molybdenum disulfide, don’t get along with the wet clutches in our bikes. Newer oils, especially those labeled “Energy Conserving” (EC), which have a high quantity of friction reducing additives, should be avoided. These oils work fine in automobiles but there are better choices for motorcycles.

KZ bikes need oil which is suitable for wet clutches. That distinction was defined by the Japanese Engine Oil Standards Implementation Panel (JASO), and can be noted by oils that meet the "4T” (4 cycle) specification, MA (wet clutch) classification. These oils, which include various synthetic, semi-synthetic, and non-synthetic oils, are sold as specific motorcycle oils. Another type of oil which works well in our bikes is diesel engine oil. These oils are governed by the API (American Petroleum Institute) CI-4/CJ-4 spec and don’t contain clutch-damaging EC additives. You can even purchase Shell Rotella oil which holds a “JASO-MA” certification assuring it will get along well with your wet clutch. All of these newer oils have a reduced ZDDP level too (about 1/3 less than before instead of ½ like the auto oils) but the substitute additives get along better with our bikes needs than automotive oil. Oils that do not hold the JASO-MA rating have either failed the wet clutch test or have not been tested for use in engines with wet clutches. Good luck with your bike! Ed

Thanks Ed,

This is all amazingly helpful. I do have the digital versions of the manual and all the original paperwork that came with the bike. The bike is mostly original but has been repainted. I am definitely taking the time to get familiar with the bike and learn its parts and systems prior to really taking it out.

650ed wrote: TOOLS

WARNING! Do not even try to use Phillips screwdrivers on the Kawasaki cross head screws. Despite their appearance they are not Phillips screws. They are Japanese Industrial Standard (JIS) screws. The tips of Phillips screwdrivers are too long & pointed to allow the 4 blades of the screwdriver to properly engage the screws, so when you apply force the screw head slots will deform and look like crap. The fact is that Phillips screws were deliberately designed to have the screwdriver bit "cam out." This was done to prevent production line assembly from over-tightening, stripping, or breaking the screws. JIS screws do not have this problem. A proper fitting JIS bit can tighten a JIS screw to and beyond the torque spec without camming out. Here's the good news - you can easily modify standard Phillips screwdriver tips to fit the JIS screws.

I have ground down the tips of DeWalt #2 and DeWalt #3 Phillips to make them fit JIS screws. The large crosshead screws on the cases take modified #3 bits (or genuine #3 JIS bits). To modify the DeWalt bits you need to grind the very tip a little, then test fit, then grind a little more and test fit, etc. until the bit no longer "rocks" back and forth in the screwhead. Picture 1 below shows how a DeWalt #3 bit fits the case screws of my KZ650 after being ground properly. The #2 DeWalt bits can be modified the same way to fit smaller JIS screws. Pictures 2 and 3 below shows DeWalt #2 and #3 modified bits.

I did find a place that sells authentic JIS bits. They don't list the #3 bit, but if you contact them they can provide the #3 JIS bits even though they are not listed on the website. These folks were very easy to work with, and the authentic bits do work great. Here's their site:

www.rjrcooltools.com/shop_item_detail.cfm?subcat_ID=89

Consider buying a can of Kroil penetrating oil and use it to soak stubborn fasteners for a couple days before trying to loosen them. Remember, the original screws and bolts were installed on your bike when Jimmy Carter was President, so many of them may be hard to remove. Kroil can be bought online, at guns shows, and at some other venues.

First off, your whole reply should be stickied at the top of each forum it is applicable to. If I missed it, damn. I have gotten by using the Phillips 2 & 3. I assume those damned screws on the choke plates are J2? I almost shredded one.