That indent you describe is a common problem. It is the result of damage known as "brinelling" see en.wikipedia.org/wiki/Brinelling .

There is no repair for the problem other than replacing the bearings. You should replace the steering stem bearings with tapered roller bearings. The folks at www.allballsracing.com should be able to tell you exactly which ones you need for your bike. I installed their tapered roller bearings in my KZ650-C1 years ago and have found them to be vastly superior to the original ball bearings that came in my bike's steering stem.

Brinelling is the result of the balls making impressions in the races when the bike hits a bump or by the bearing pressure squeezing the balls against the races. If it is somewhat severe it can cause notchiness in the steering and sometimes you can feel the front end tend to seek being pointed straight ahead. This is sometimes referred to as "indexed steering." When these conditions occur the front can develop a bit of a low speed wobble (at least this was the case on my KZ650).

Tapered roller bearings give much more bearing surface area than loose ball bearings. Think of the bearing contact area of a tapered roller as a "stripe" for each roller that goes from one end of the roller to the other where the roller contacts the races. Then consider the bearing contact area of a ball as a small "spot" for each ball where the ball contacts the races. The total contact area of the roller bearing "stripes" is much greater than that of the ball bearing "spots." This additional contact area spreads the load reducing the pounds per square inch of pressure at the contact area and eliminates the "dimpling" that is common on ball bearing steering stem races. This reduced pressure also makes tapered roller bearings last longer than ball bearings mainly because the races are much less affected. The reason is easy to visualize when you consider the roller bearings making contact with the full width of the bearing races compared to the ball bearings running in a single line near the center of the races.

That may or may not be the total cause of the wandering, but you should not ignore it. If you have time, a torque wrench, and some other common tools and follow the instructions in the Kawasaki Service Manual you can replace the steering stem bearings yourself.

Here's how I did mine several years ago:

To do this work I had to remove the front forks. I did the work in my basement during the winter. I laid a 4’ x 8’ sheet of 7/8” hardboard on the floor and parked the bike on it. This was to protect the basement carpet from possible stains, and it also enabled me to very securely anchor the rear of the bike while the front forks were removed. With the bike on the center stand, I put a small bottle jack under the front of the engine with a piece of wood between the jack piston and the oil pan to protect the oil pan (image below). I jacked up the front of the bike until the rear wheel came in contact with the hardboard. Then I ran a cargo strap through the swing arm, attached the “S” hooks on the ends of the strap to the edge of the hardboard, and took the slack out of the strap. That strap made the bike very secure. You may want to use this same method if you remove your forks.
Ed

Longer term plans is to modify a GL1800 single sided swingarm and run it upsdie down to enable a 190 tyre and different wheels with a monoshock. The goldwing arm is 4.5cm wider at the pivot so it will take some substantial fabrication, and modified offset (car) wheel narrowed to 5.5 or 6" in order to get things back into alignment, But I'll look back into this at a later stage.

Ok so small updates. Been sourcing parts to get this underway.

The engine is with a Kawasaki engine builder. Getting a refresh with new OEM crank and rod bearings. The cruizin image pistons arrived too and they look good. Almost forged.

I've also been struggling with the direction of the wheels, tyres, possible chain conversion etc. In the end it looks like I'm going with the KZ1000 swingarm. I also have a KZ1100 swingarm but the st1000 has a cleaner look. It also uses a brake caliper that attaches to the swingarm vs a torque brace like the gt750 and the kz1100.

The 1000 swingarms are 30mm longer and I personally think it makes a nice difference to the stance of the bike. They are narrower at the pivot point which I still have to resolve, while trying to keep the wheel and drive shaft in the correct locations.

The 1000 rim is 17x2.5 vs 18x2.15 of the 750. I'm able to run a 150/70/17 tyre, but it's cutting it fine at the swingarm. The 150 tyre doesn't look any wider than the 130 to be honest. But it has a more rounded profile which should help handling. Could also be cause it's on a tiny 2.5 rim....

Anyways, here are some pics. [attachment=105659]

Pictures 4 & 5 below show a comparison between my homemade modified bits with the authentic JIS bits.

PICTURE 4


PICTURE 5



Here's a pic comparing JIS bits to Phillips bits. Ed




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 the bike! Ed

yup......so while i got my bike stripped down to a bare frame, de-rusted it, checked welds, added welds in places i thought needed total welding.....i got to browsing craigslist for parts.....mostly in the frontal area..........in a few hours i will have a donor bike, a 1983 GPZ750. so...heres the plan. gonna swap the front fork over, convert the 550 frame to taper bearings, a friend is gonna cut off and weld in the uni-track mount from the gpz frame and weld it to the 550's frame, install the swing arm set up and the "new" disk brakes and hooooopefuly have a rideable bike within the next few millenia. will post pix of the progress. but today......when it warms up some.....primer and paint on the frame!

Setton wrote:

Ed may still be on the right path. Could be hitting inside the engine sprocket cover

If that were the case, wouldn't the sound happen regardless of whether or not throttle is being applied?

...

No.
Consider this -

When the throttle is being applied with the tranny in gear the engine sprocket is pulling the top length of the chain taut as it pulls on the drive sprocket. When that happens all the slack in the drive chain ends up on the bottom length of the chain. This extra slack in the bottom length of the chain can cause the chain to rub things if the chain has too much slack in it.

One word of caution though - do NOT adjust the chain such that there is no slack in it. Doing that will very quickly ruin a chain because it needs some slack to cope with the fact that as the rear axle rises to a point where the axle, engine sprocket center, and swing arm pivot are aligned the distance between the sprockets increase. If the chain is adjusted with insufficient slack the chain will stretch and be damaged. Be sure to follow the instructions in the Kawasaki Service Manual or the bike's Owner's Manual for adjusting the chain. Ed

From previous research width between the swingarm pivots for the KZ400 is 8.5 inches. Width for the larger KZ bikes ( KZ650 and KZ750 twin confirmed, I assume others are the same, not sure about KZ550 ) is 9" or approx 228.5mm. The GSXR 750 should be a good fit. It looks like some of the VFRs will work too. I'd also look for R6 swingarm specs too.

Hello jfarhanbod
Here some charts for swing arms,shocks and forks.





Translation

Breite Schwinge Vo. = width swing arm to frame (pivot diameter)
Breite Schwinge Hi. = width swing arm for rear wheel + all components, sprocket holder/rear brake (pivot diameter)

Michael

Has anyone swapped a more modern swingarm in? All my searches have led to some of the bigger bikes. I'd like to get a VFR or GSXR swing arm in there if possible but really anything that will allow me to run a wider rear tire would be perfect. With the stock 84 gpz550 swingarm, the 130/80/18 seems to be the max.

I know i can probably make anything fit in there but before I start ordering random expensive parts, it'd be nice to see if there's anything documented.

Here's a pic of the bike:

For anyone interested in how unsprung weight affects a bike here's part of a conversation I read...........

QUESTION
Dear Fred,
I hear people talking about unsprung weight and how important it is on a motorcycle, but I do not know what it is. How is it measured? What are its benefits of unsprung weight? Can a local guy like me feel the difference? If so, what can I do to get more of it?

ANSWER

First and foremost, you don’t want more of it. Here is a quick test that you can do in the comfort of your living room to see how unsprung weight affects a motorcycle. Stick your arms straight out. Rapidly lower them to your sides and back up again. Do it ten times. Do it fast. Now grab a 10-pound weight in each hand. Repeat. Feel the difference? Guess what? It takes serious effort to imitate the up-and-down motion of a bird with weight on each arm. If you are human (as opposed to avian), your arms moved slower and responded sluggishly when changing direction while holding the weights. Additionally, the strain of holding the weights could be felt in your shoulders. There is no doubt that you could move your arms quicker and with less stress if you didn’t have any extra weight attached to them.

Now, imagine your arms are your bike’s swingarm. The 10-pound weight mimics the mass of your bike’s wheel. Your arm is the swingarm, your shoulder socket is the swingarm pivot and your muscles are the shock absorbers. The increased muscle strain and sluggish reaction time that your body felt can be extrapolated over to the mechanical parts of your bike’s suspension. Extra weight on moving parts is a big no-no.

Extra weight that isn’t supported by the springs is called unsprung weight. There are three kinds of weight on a bike: sprung, unsprung, and hybrid.

Sprung Weight: The complete chassis, including all the parts that are suspended above the suspension’s springs, is considered “sprung” weight. That includes the frame, engine, plastic, controls, saddle, upper fork tubes and shock body, and rider. It’s called sprung weight because springs are used to hold it up and to isolate it from the bumps that the wheels hit.

Unsprung Weight: Unsprung weight is the mass that hangs below the springs (fork legs, hubs, brake calipers, rotors, spokes, rims, swingarm, linkage, tires, tubes and rim locks). Unsprung weight is more closely connected to the ground than the parts above it, because when you hit a bump, unsprung components compress toward the chassis to absorb the impact.

Hybrid Weight: One of the conundrums of calculating sprung and unsprung weight is the question of whether the shock and fork springs are one or the other. The answer is complicated, but it does have a definitive answer. While the chassis floats on the shock and fork springs as if the coils were part of the sprung mechanism, the wheels push into the springs as if they were part of the unsprung weight. Thus, the weight of the springs is split 50/50 between sprung and unsprung weight. Thus, the weight of the springs is different from sprung and unsprung weight; it is referred to as “hybrid weight.”

The discussion of whether the springs are sprung or unsprung leads us to question the status of the fork and shock fluids. Since the shock fluid is housed in the body of the shock absorber (and the shock body is bolted to the frame), it is sprung weight. It’s not as clear-cut with the front fork oil. More oil is used in the fork than the shock, and most of it resides down in the bottom of the fork legs. This fluid moves with the unsprung fork legs, brake parts, axle and front wheel — thus it is unsprung. The saving grace of fork oil is that it gets splashed around in the upper tube assemblies, lessening the amount that is actually unsprung. It’s best to presume that one-half of the fork oil is hybrid weight.

While on the subject of hybrid weight, the weight of the front brake hose is split between sprung and unsprung weight. Most of the rear hose is unsprung weight.

NEGATIVE EFFECTS OF WEIGHT BELOW THE SPRINGS

Your bike’s suspension is constantly moving. If it’s not compressing, it’s rebounding. At the top and bottom of the suspension’s stroke, whether fully bottomed, topped out or somewhere in between, the wheels must change direction as quickly as possible. The less weight hanging from the suspension components, the easier it is for the mass of the wheels to stop and accelerate in the opposite direction. It’s no secret that the quicker the wheel reacts, the better the suspension will be — otherwise the next bump is coming faster than the mechanism can respond.

It goes without saying that the less unsprung weight, the less strain will be placed on the pivots, springs and dampers. The lower the unsprung weight, the quicker the suspension reacts to bumps. The improvement is most significant over repetitious, high-frequency bumps (like braking and acceleration bumps). Why? The more weight you load on the wheels, the more the shock absorber has to struggle to bring the mass to a stop. As the damper struggles with the weight, the suspension packs, the wheels kick over the bumps and the bike becomes a handful.

Have you ever wondered why the shock body and fork stanchions are mounted on top of new, high performance units, instead of on the bottom like they were back in the 1970s? The designers turn the shock and forks upside-down to change the weight of the heaviest parts of the suspension into sprung weight. On the shock, this leaves only the shock shaft and spring collar below the spring. As for the forks, upside-down forks remove the cast stanchions away from the wheel.

Factory racing teams spend beaucoup bucks to reduce unsprung weight. Most works bikes have magnesium hubs, titanium linkage bolts, Ti axles, aluminum spoke nipples, tapered and butted spokes, and magnesium (or beryllium) brake calipers.

HARDTAIL
In light of the facts stated above, anyone considering making their bike a hardtail should consider this - since the rear of hardtail bike has no rear shocks. springs, or other suspension parts that would provide sprung weight, all the weight on the rear wheel is undesirable unsprung weight. That is why hardtail bikes do not handle bumps, braking, etc. as well as bikes that have a sprung rear suspension. Ed