1st Kawasaki - 79 Z650 C3

Hi there just uncovered a near mint 79 KZ650 and it looks and runs fantastic with 5000 original miles. Bike is bone stock except for mirrors (hope to find OEM). Only issue is head gasket leak on left side and another leak probably behind countershaft sprocket. Need to figure out why the bike lost 2hp vs 1978 and earlier bikes. Will post questions in tech section.

I'm excited about getting this bike properly sorted
Tried to ad pic
Guzziman

Welcome aboard - NICE BIKE!!!! I'm glad to see you plan to keep it stock since really nice stock examples are so rare!

The good news is that the 1979 KZ650-C3 did not have less HP than the earlier KZ650 models. It had 64 hp @ 8,500 rpm as did all 1977 and 1978 KZ650-B and C models - this info is directly from the Kawasaki Service Manual. There was an error in one version of the manual that shows the B3 and C3 as having 62 HP @ 8,000 rpm, but this error appears to have been made by the manual writer copying info from the 1979 KZ650-D2 which did have 2 HP less (62 @ 8,000 rpm). This lower HP was the result of the different exhaust system (criss-cross) the D2 came with.

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 oil (and pretty much all other 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. Early AUTOMOBILE oils contained zinc phosphorus compounds (ZDDP) to protect engine components from metal to metal contact. This was good for engines, but it was found to be destructive to catalytic converters. Consequently, in AUTOMOBILE oils ZDDP was virtually eliminated and replaced with different chemistry generically referred to as "Friction Modifiers." These work fine and offer good protection for normal AUTOMOBILE engines. However, today's AUTOMOBILE oil "Friction Modifiers" are destructive to wet clutches. KZ bikes (and many other brands) have wet clutches. As a result of these oil chemistry changes a distinction needed to be made between those oils which are suitable for wet clutches and those which are not. That distinction was documented by the Japanese Engine Oil Standards Implementation Panel (JASO). JASO developed a number of different oil specifications for different applications. The specifications that apply to 4 stroke motorcycles fall under the "4T Specifications." Within the 4T specifications the JASO MA class oils are specifically formulated for 4 stroke motorcycles with wet clutches.

There are synthetic, semi-synthetic, and non-synthetic oils that meet the JASO-MA standard and any of them will work ok. However, using oils that are not designated as meeting the JASO-MA standard is destructive to KZ clutches.

Good luck with your bike; its a beauty! Ed

Welcome!
That's an awesome looking KZ you have! Color me jealous. My 650 seems to have been the polar opposite of yours, condition-wise.
Keep the pics coming. Love that paint. Looks new!

Thanks so much for quick insight. Yes, my owner's manual shows 62hp at 8000 rpm. Which is officially incorrect! I saw that mufflers, cams and carbs were the same so I was really wondering if that air suction valve was sapping power.? Will likely remove offending plumbing. When head is off I have a good metallurgy welder who could well up holes of system if that's recommended.
I have had success with impact drivers but I will look at making jap Phillips tools. I am pretty handy. Reviving a 72 Titan to sell and 76 cb750SS as well.

Don't worry, purchased from original owner and bike will remain as such. Maybe suspension change but will keep parts. Yes paint is mint never down. Paint flaked off around master cylinder. So will repaint with your recommended paint
I have a very short video taken with phone walking around bike as its runningbut I think it's too big.

Thanks much for the warm welcome.
Guzziman

Welcome.

The air system you mention uses 0 horsepower. If you want to remove it, the easiest way is to remove all the hoses and the vacuum valve, then cap the small vacuum port on the carb that controlled the system. I believe on the 650 you will also need to buy or make plugs for the airbox. You can then take one of the large hoses you removed and use it to connect the two reed boxes and be done. If you really need something neater looking, you can make or buy some aluminum block off plates for the reed boxes.

If you purge the old fork oil and use the correct amount of Bel Ray 15w fork oil I believe you will find the front forks to be very acceptable. I've been using it for 39 years, changing it every 2 years, and my front forks have always worked great.

The rear shocks are a different matter though. I bought my 1977 KZ650-C1 new and the rear shocks were only adequate (at best) when new. I've been using Hagon shocks on it for the past 9 years (15,000 miles) and they still work and look like new. The image below shows them on my bike. They are similar in appearance to the stock units, but they work 100 times better. Dave Quinn at davequinnmotorcycles.com/cgi-bin/webc.cg...GON_TWIN_SHOCKS.html set mine up for me based on my bike, my weight, riding style, etc. He did a GREAT job. The type I bought are shown marked #4 in the bottom picture of the link. Stainless steel bodies and shrouds and other high quality features make them really nice. Ed

Good Fortune!

Beautiful bike, I too like the classic original look.

Too many get hacked up then sold never to see it's full potential again.
Steve