New KZ Owner-Issues to be aware of?

Hello all,

I am new to the forum and new to owning a KZ. My neighbour just gave me his 1981 KZ750 LTD (that's right, cost me $free.99). Anyway, we had gotten it running last year but the carbs needed to be tuned up a little bit. Since it is now my bike I'm going through it front to back to get it into nice relatively healthy shape. I'm wondering if there are any issues that these bikes are known for, or any particular trouble areas I should be aware of. I am fairly technical and do almost all of my own work. I was planning on checking valve clearances, already cleaned and gapped the plugs, boroscoped the cylinders (they look surprisingly good for sitting for a year and 40,000 miles). Also going to change the oil and filter obviously. The rear brake seems to be inop so was going to dig into that and see what I find. Looking for general tips hints and suggestions. Thank you all for the time!

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.

PICTURE 1

PICTURE 2

PICTURE 3

PICTURE 4

PICTURE 5

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. Ed

Hi Kevin, welcome to KZR. These old inline 4s are pretty reliable; sounds like you are on the right path checking the valve clearance, and tuning the carbs. If you need to adjust the valve clearance I would get a factory service manual, because you can do damage to the valve train if you do not deal with the cam chain adjuster correctly after removing the cams. A new air-filter would probably be a good choice too.

Welcome! I have a 1980 750 Ltd myself. The biggest issues these bikes tend to have is the starter clutch slipping/cracking, which causes the bike to not want to electrically start. It will spin and spin an maybe catch 1 out of 10 times once it's really bad.... They seem to go out slowy for most people... It's been described as sounding like a can of marbles in the engine.... Hopefully yours is fine.

You have to either remove the engine, or turn the bike omn its side to replace it. They're also getting hard to find, and IMO the gear should also be replaced at the same time.... If you could have a couple NOS parts to put back, I would say those would be highly recommended..

Hey guys, thanks for the tip. I do have a factory manual so no worries there. I should clarify, I'm not a complete newb haha, my first bike was a EX500 that I took down to the frame and rebuilt from the ground up (it was a lot of fun). I am new to the KZ bike though so I do greatly appreciate the tips. I have access to LOTS of tools too through work (aviation maintenance shop). I'm looking forward to getting to know this bike and getting it into shape. Thanks for the tips guys, keep them coming!

Welcome to KZR. Questions are good, Pics are better.
Steve

Very important to change the air in the tyres. Especially if its been sitting for a long time. NOS Kawasaki air ,is no longer available for the old KZs but there are aftermarket brands (which are a lot cheaper anyway and good enough quality). Dont be tempted to use air for more modern kawasakis as the ratings are different and this can be dangerous. Weve all heard horror stories of high speed flatulence on old bikes.So, be safe.
Good luck.

Can't ya replace it with nitrous? ;P

Randombeat wrote: Can't ya replace it with nitrous? ;P

Are you having a laugh??

You forgot the LOL's. :lol: :lol: :woohoo: Brought me back to the using your 'wanger" to measure the valves reply. Could have moved it but it was too funny. :woohoo:
Steve

Maybe he means nitrogen? Lol. The tires look brand new, no dry rot on either of them and extremely little wear, so I'm not too concerned there. Issues that this bike seems to have are; upon pulling the plugs, they were all consistently white, telling me that it has been running lean and as I suspected the carbs need some help and tuning. No signs of burning oil or anything like that though so thats nice. The rear brake seems to be completely inoperative, just goes straight to the stop no resistance, so I'm going to tear into that and see what I find. Maybe just needs to be bled. The motor itself has oil on the front of it. The PO did say it used to leak some oil, but they couldn't figure out where from. They replaced a few gaskets (can't remember which he said) and it didn't seem to stop it. He said it wasn't a huge oil leak, just needed to be topped off once in a great while. I'll try and get some pics up when I take more. Can you insert them directly into a thread, or do they need to be hosted somewhere?

Make the as small as you can then hit the add file button. It will take you to your computer, right click and click select until you get to the pic you want.
Steve