All things bike-related

Motorcycle Tire Balancing Procedure

2010-08-10T09:05:00.001-07:00

Balancing the tire only takes a few minutes and tools you probably already own. Having a properly balanced tire makes your bike ride more smoothly and your tire wear in an even fashion. In addition, if you balance tires the way I do, you end up inspecting your wheel bearings at the same time so you're killing two birds with one stone.

Tools required:

A pair of jackstands
Some bearing grease
Wheel weights (stick-on or spoke-type)
Masking tape
Chalk (optional)
Piece of string and a nut (also optional)

    * Adjust the jackstands all the way to the top and set the wheel (with axle) across them.

    * Spin the tire, checking for freedom of movement, grease/replace bearings if necessary.

    * Let the tire settle, the heavy spot will settle to the bottom, plus or minus friction induced by the wheel bearing.

    * Turn the wheel 90 degrees clockwise and release; As the tire settles, take the string and tie it to the nut, making a plumb bob. Hold it up in front of the tire, in line with the axle. Mark the top of the tire with the chalk or a small piece of tape, or just guesstimate if you don't have one.

    * Turn the wheel 90 degrees counter-clockwise and let it settle again. Repeat the process of marking the top of the tire.

    * Half-way between the two marks will be your light spot. Mark this with your chalk or tape and remove the other marks.

    * Estimate the number of weights you'll need (3 or 4 1/4oz weights usually does it) and tape them to the rim at the light spot.

    * Turn the wheel 90 degrees so that the weights are on the 3 or 9 o'clock position of the tire. If the tire stays where it is when you let go, you have it right. If not, adjust the number of weights until it stays put.

    * Once you know how many weights you need, fix them in place, in the usual manner.

    * Re-pack your bearings since you're already looking at them.

Automotive vs. Motorcycle oil

2010-04-21T20:32:00.000-07:00

Nothing sparks a greater debate than oil for a motorcycle. I've always questioned the price of motorcycle oil in comparison to automotive oils. I have, however always been a big fan of synthetics. This study, while a little old, tends to bear out my hunch.

Relative Viscosity Retention Comparisons Among Five Brands of Automotive and Motorcycle Oils

by John C. Woolum/ Ph.D.
Professor of Physics
California State University, Los Angeles
The central dogma of motorcycle oil manufacturers and distributors has always been that motorcycles put different demands on their lubricants than do automobiles. In particular, they point to the facts that motorcycles run at higher temperatures and use the same oil in their transmissions as in their engines. The transmission gears supposedly put extreme pressures on the oil molecules, thus causing the long oil polymers to break down. High temperatures can have the same basic effect, as well as additional effects such as the increase in oxidation products.

When the size of the oil polymers decreases ("cut up by the transmission gears," as at least one manufacturer claims), the oil thins. In other words, its viscosity decreases, as well as its ability to lubricate properly. For example, what started out as a 40-weight oil could effectively become a 30-weight oil, or even a 20-weight, after prolonged use. What this means, effectively, is that if the claims of the motorcycle oil producers are valid, they can easily be verified through measurement of viscosity changes on various oils as they are used in different applications.

Measuring the viscosity drop in oils did not seem like too difficult a task, especially since measuring viscosity of solutions of large molecules is a common practice in many biophysics laboratories - mine included. My lab had all the correct equipment - in fact the viscometers that I normally used for solutions of DNA and proteins were originally designed for oil measurements.

Setting the Stage

Viscosity is a measure of the friction between two layers of a liquid sliding relative to one another. It is usually measured in poise, or grams per centimeter per second (g/cm. sec). The basic principle of many viscometers is to measure the time required for a known amount of a liquid to pass through a capillary tube under gravitational force. The time taken will depend on the viscosity and the density of the liquid. The more viscous or less dense the liquid. the longer the time it will take to flow through the capillary.

Therefore in reality, this kind of viscometer does not measure viscosity directly, but rather the ratio of the viscosity to the density of the liquid being tested. This ratio is called the kinematic viscosity. and the common unit for expressing it is in stokes or poise cm^3/gram.

The viscometer used for my measurements was an Ostwald-type, Cannon-Fenske 200, designed to measure kinematic viscosity in the range of 10 to 100 centistokes (a centistoke is one-hundredth of a stoke). The oils being measured had kinematic viscosity between about 10 and 25 centistokes.

For the test samples, I decided to use two types of oils designed specifically for motorcycles and three types of fairly standard automotive oil.

The automotive oils were Castrol GTX 10W40 (petroleum based, $1.24/qt.), Castrol Syntec 10W40 (synthetic, $3.99/qt.) and Mobil 1 15W50 (synthetic, $3.48/qt.). The motorcycle oils were Spectro 4 10W40 (petroleum based, $4.99/qt.) and Honda HP4 10W40 (petroleum/synthetic blend, $5.99/qt.).

Each of these oils was run in the same motorcycles 1984 Honda V65 Sabre-under as near to identical conditions as possible. The oils were sampled for testing at 0, 800 and 1500 miles each.

As temperature has a strong effect on viscosity, I had to make certain it was carefully controlled for the experiments. Using a laboratory temperature control chamber, all measurements were made at 99 degrees Celsius (error factor of plus or minus 0.5 degrees), which is about 210 degrees Fahrenheit. This is the most common temperature used for oil viscosity measurements. It usually took about 15 minutes for each sample to achieve equilibrium within the chamber.

Each oil's kinematic viscosity was compared with its own kinematic viscosity at 0 miles to establish the viscosity ratio. In addition, measurements were made of each oil's density at each state of the tests. The densities were found to change by less than one percent, which is about the limit of the accuracy of the measurements. Therefore, a ratio of the times taken for the oils to pass through the viscometer effectively gives the ratio of their actual viscosity, since the densities cancel out.

What this all means in layman's terms then, is that the ratio established for each oil at the end of each test is a percentage of the amount of original viscosity retained at that point. For example. the Castol GTX sample at 800 miles showed a relative viscosity of 0.722, meaning it had retained 72.2 percent of its original viscosity. Or, if you want to look at it the other way, the Castrol had lost 27.8 percent of its viscosity after 800 miles of use in the motorcycle.

Just for comparison sake, I also tested the viscosity drop of the Castrol GTX automotive oil after use in a 1987 Honda Accord automobile. At 3600 miles of use, the Castrol GTX showed a relative viscosity of 91.8 percent.

As the Mobil 1 had retained so much of its viscosity after the 1500 mile test, it was the only oil I allowed to run longer in the motorcycle. After 2500 miles, the Mobil 1 recorded a relative viscosity of 79.1 percent.

Also, it is worthy of note that from a testing standpoint, the two most similar oils were the Castrol GTX automotive oil and the Spectro 4 motorcycle oil. By similar, I mean that they tested as having almost the same absolute kinematic viscosity and density right out of the container. So starting out as equals, the Castrol maintained its viscosity several percentage points higher than the Spectro, under the same use in the same motorcycle yet the Spectro costs about four times the price of the Castrol.

The Error Factor

As a scientist, I must always ask myself. Are there possible errors in these measurements that would make them invalid? One possibility here would be that there was more particulate matter (contaminants) in some oil samples than in others, which would increase the viscosity numbers of that oil. Particulates disrupt the streamline flow and so increase the viscosity. (Einstein was the first to derive the quantitive expression for the increase in viscosity due to spherically, shaped particles.)

Large particulates should have been removed by the oil filter, and a new filter was used for each test. Still, to determine the effect of smaller particulates the oil samples were centrifuged at 11,000 g (11,000 times the acceleration of gravity) for a period of 10 minutes. A considerable amount of particulate matter was found and removed in all of the 800 mile and 1500 mile samples. However, the change in viscosity made by eliminating these particulates was found to be negligible.

Another possible source of error would be that the conditions to which the oils were subjected were different. In all cases, the distances were comprised of approximately 70 percent city riding and 30 percent freeway riding. The range of temperatures and the average ambient temperature during which the motorcycle was ridden were approximately the same. If anything, the average ambient temperature was higher during the operation of the motorcycle with the Mobil 1 oil, which should have put it at a disadvantage, yet it scored the highest overall in the viscosity retention tests.

Of course the motorcycle did age somewhat during the testing period, which took place over a year-long span. It registered about 4000 miles at the beginning of these tests and about 14,000 at the end. The order in which the oils were tested was: 1) Castrol, 2) Spectro, 3) Mobil and 4) Honda.

Other Criteria

The motorcycle oil producers have suggested that other criteria. such as the amount of wear metals and contaminants, might be unacceptable when using automotive oil in a motorcycle. To test this theory, I sent a sample of the Castrol GTX at 1500 miles to SpectroTech. Inc., for a complete oil analysis. Their findings were that all contaminants (water, dirt, coolant and sludge) were normal.

SpectroTech also reported that all wear elements (antimony, titanium, silver, copper, lead, tin, aluminum, nickel, chromium, cadmium, sodium and boron) were normal except for iron, which was reported as "mildly above normal" at 51 parts per million.

SpectroTech lists acceptable levels for all of the above listed metals except iron, for which they state, "values vary greatly with systems and parts." so it is not clear what exactly is meant by "mildly above normal." Perhaps it was in comparison to cars with 1500 miles on the oil. Also, this could have been due to cam wear, since the early Honda V-4s were known for excessive cam and rocker arm wear.

In any case, again I could find nothing to support the argument that automotive oils were somehow less effective than motorcycle-specific lubricants when used in a motorcycle.

Bottom Line

It could appear from this data, then, that there is no validity to the constantly-used argument that motorcycle-specific oils provide superior lubrication to automotive oils when used in a motorcycle. If the viscosity drop is the only criterion, then there is certainly no reason to spend the extra money on oil specifically designed for motorcycles. There does, however, appear to be a legitimate argument for using synthetic and synthetic-blend oils over the petroleum based products.

MCN's Conclusions

In speaking to a number of people involved in the production, marketing and distribution of motorcycle-specific oils, we could not find anyone who could present a valid argument for discrediting the testing done by Dr. Woolum. In general, they all tried to turn the conversation another direction by bringing up other possible advantages to using their products, while ignoring the viscosity-retention question. Yet without exception it is their own advertising that consistently brings the subject up, touting the special shear-stable polymers as the primary reason motorcyclists should purchase their products.

It is this practice to which we take exception, as we have been unable to find evidence to support these claims. In short, it seems to be nothing more than a clever marketing ploy designed to enhance their products' image and separate motorcyclists from their money.

MCN is ready to print any research or test results provided by the oil companies to support their claims of superior viscosity retention, with this one proviso: The comparisons must be against actual, SG-rated oil products that can be purchased off the shelf at the average auto parts store. Tests against generic, basic-stock mineral oil or against the lower-rated SE and SF oils would lack any credibility in a real-world context.

Despite more than six months of research, reading all the claims and counter-claims printed by dozens of industry experts and lubrication experts, MCN cannot and does not purport to know all there is to know about the differences between automotive and motorcycle oils. However, what we do know is that we can find no substantive evidence that using a high-quality, name-brand automotive oil in an average street motorcycle is in any way harmful or less effective in providing proper lubrication and protection than using the more expensive, motorcycle-specific oils.

**Figure I**
Petroleum Based, Multiple Viscosity, SG-Rated, Oils Best Retail Prices Found *Motorcycle Oils*
Name	Price
Honda GN4 Kawasaki Premium Maxum 4 Premium Motul 3000 Spectro 4 Torco 4-Cycle Torco MPZ	2.95 2.65 3.79 4.99 4.99 3.25 3.95
Average Price/qt.	3.80
*Automotive Oils*
Name	Price
Pennzoil Havoline Quaker State Motorcraft AC Delco Castrol GTX Valvoline	1.24 1.09 1.23 1.09 1.24 1.24 1.23
Average Price/qt.	1.19
Average Price Differential: 319.5%
Synthetic Based and Petroleum/Synthetic Blend Multiple Viscosity, SG-Rated Oils Best Retail Prices Found *Motorcycle Oils*
Name	Price
Honda HP4 Golden Spectro 4 Maxum 4 Maxum 4 Extra Motul 3100 Torco T4-R	5.99 5.99 6.48 9.79 4.99 5.95
Average Price/qt.	6.53
*Automotive Oils*
Name	Price
Castrol Syntec Mobil 1 Valvoline Hi-Perf. Valvoline Racing Pep Boys Synthetic	3.99 3.48 3.59 3.59 2.99
Average Price/qt.	3.53
Average Price Differential: 185.0%

**Figure II**
Relative Viscosity Retention(as a percentage of initial viscosity retained after normal use in the same motorcycle)
	0 miles	800mi	1500mi
Mobil 1 Castrol Syntec Castrol GTX Honda HP4 Spectro 4	100% 100% 100% 100% 100%	86.6% 78.1% 72.2% 69.2% 68.0%	83.0% 74.5% 68.0% 65.6% 63.9%

Setting up the bike for touring

2010-03-08T11:15:00.000-08:00

I know it's been a while since I posted to this blog, but I'm currently working on setting up the KLR for touring. I've been slowly making mods over the last few months to make it more highway-worthy.

Among them:

Grip Puppies

Laminar Lip

Pannier Racks

Cruise Control

And tons of other mods. I promise I'll get back here and add some content soon.

Carburetor Tuning Procedure (Mine)

2009-09-14T00:50:00.000-07:00

Carburetor tuning is an art, and I have spent many hours of frustration trying to come up with a procedure that works well. After all the headaches, I have developed this procedure and have used it on three bikes:

My '09 KLR
My '92 Seca II
My friends V-star 1100

This may not be the "by the book way" of doing it, but I get really good results from this.

The instructions that come with a DynoJet kit will get you CLOSE. You will still have to do some tuning to get it right. If you have driveability problems, give this a try. I'm not a mechanic, but I'm an enthusiast who's played a lot with carb tuning.

Primer:
Pilot and (and starter, if equipped) jets affect ONLY the idle and transition from idle to needle. The mixture screw affects ONLY this circuit.

1. Adjust the size of the main first. The main jet in most CV slide carburetors feeds the needle as well, so changing the main will most likely require adjusting the needle. You can do this by sound/feel if you have a good ear for it, or try the spark plug color trick. Set the needle mid-range to adjust the size of the main.

To do this: find a nice, deserted stretch of road at your operating altitude of choice. Warm up the bike to operating temperature. Don't worry about hesitations or bad behaviour at anything other than full throttle right now. Take the bike out on the road and run it out to full throttle, let it run for 15-20 seconds, then simultaneously pull in the clutch and hit the kill switch. Coast to the side of the road. Pull a spark plug and examine its color. You're looking for a nice gray. White = too lean, darker = too rich. Another indicator is rough running at full throttle, indicating a rich condition. Change the mains until you get the desired full-throttle performance.

Next, adjust the needle up until you get mid-range hesitations when the bike is hot, after leaving it idle for a bit until the fan kicks in, then drop it a notch. This gives you the richest setting without incomplete atomization.

Put it all back together and warm the bike up again. Adjust the idle to its highest point that does not drift down when you blip the throttle. When you blip the throttle, it should return to idle quickly, not slowly glide down. Once you've done this, adjust the idle mixture screw until you have it set where you have the highest idle. Then back off the idle thumbscrew to desired hot idle rpm (blip the throttle a few times to ensure it stays where you want it). Bear in mind that when the bike is cold it will idle at a lower rpm than when it's hot. This may take some massaging.

Your bike should now cold start easier, pop less on deceleration and have more go-fast.

Synchronization of multi-carb engines is out of scope of this posting.

Carburetor Jetting and Tuning Tips

2009-09-14T00:46:00.000-07:00

Just as a primer to those messing with jetting, here are the results of my learnin' based on spending a lot of time tuning my old Seca II. I learned this the hard way, and it's even harder because you have to do everything x4. These are some general tuning tips I've learned by trial-and-error.

* Any time you do anything to increase flow of air or exhaust, you need to richen everything. The opposite is true of restriction.
-From idle to 1/8 throttle or so: Pilot (Idle mixture) screw
-from 1/8 to about 2/3 throttle: needle
-2/3 and up: mains
These areas overlap, but this is a good rule-of-thumb

*watch out for altitude. If you tune at sea level, then go up a few thousand feet, behaviour could be different.

*If you get popping on deceleration (with throttle closed) most likely you are too lean, but you could also have an exhaust leak or air injection problem if your bike is so equipped. This could also be an indication that your pilot jets are becoming clogged if you have made no adjustments, especially if the bike has sat for a while.

*If the bike runs well cold, then develops a hesitation when it warms up, you're too rich.

*If it runs well warm, but is cold-blooded and you have to choke the crap out of it, you're too lean.

*If you install a needle with an aggressive taper, like the KLX needle, and you have stock exhaust, you may have to go DOWN a jet size or two.

*if it hesitates coming off idle when warm, lean up the pilot circuit a hair.

*If it does the same at 1/4 throttle or so, lower the needle a notch.

*If you rejet and actually lose top end, but gain accelleration, the main is probably too rich. (you'll hear a distinct change in tone if you're too rich. )

All of these changes affect the others, so unless you're an expert, you'll have to keep tweaking until you hit that magical driveability balance... where it's smooth throughout the whole range.

Remember. In carburetors, RPM is not important... it is about throttle position.

Care and feeding of your carbureted motorcycle.

2009-07-27T21:44:00.000-07:00

Among the most common problems that people have with their motorcycles are plugged jets and passageways in the carburetor(s). This clogging is caused by varnish that accumulates over time due to the evaporation of the gasoline in the bowls and passageways of the carb. The varnish consists of gasoline additives, and here in California we have more additives in our gas than just about anywhere in the country.

To prevent this, there are some very simple steps you can take to save yourself time and/or money with carburetor problems. I will give several methods in order of preference to keep the varnish from forming:

Method #1: Ride your motorcycle

This one is the easiest and most fun. Riding your motorcycle often (every few days at least) will keep fresh gasoline in the carburetor bowls and will prevent the gas in the tank from going sour over time. Riding your motorcycle also has the added side benefit of reducing stress and generally having a good time.

Method #2: Drain your carb(s) if you plan to store your motorcycle for more than a week.

Draining your carbs is easy and the best way to keep varnish from forming. On most bikes, all you need is a short length of rubber tubing, a screwdriver and a small bottle.

On the bottom of most carbs, you will see a small nipple on the very bottom of the bowl, and there will be a valve screw in the bowl as well. Turn off the fuel petcock* (see below), then simply put one end of the tube on the nipple, the other in the bottle and loosen the screw a bit. A small amount of gas will drain into your bottle from each bowl. Tighten the screw when you're done, and be careful not to over-tighten. When you've drained them all, pour the gas back in to the tank, not on the ground or sewer, please.

When it comes time to start your bike, turn on your fuel, wait a minute or two for the bowls to fill and crank away. Depending on the type of fuel delivery, it may take quite a bit of cranking to start, especially if you have a vacuum-powered fuel pump. Gravity-fed bikes and MOST bikes with electric fuel pumps usually start right up.

Method #3: Run your carbs dry.

This method is not as preferable as draining, but it will help significantly to extend the length of time between carburetor rebuilds. The process is simple, but cannot be performed on a bike with a vacuum-controlled petcock. Turn the petcock to [off] and start the bike. Hold the throttle open to about 1/4 throttle to ensure that the main jets are active. This draws fuel from a lower part of the bowl than the pilot (idle) jets and will remove more fuel from the bowls. There will still be some fuel left and varnish will form in the bottom of the bowls, but at least it won't be on the jets.

Method #4: Use a fuel stabilizer

This is the least-preferred method, but it's better than nothing. Use the recommended amount of "Sta-bil" or "Sea Foam" fuel additives that will retard varnish formation. Make sure you add it to the tank and ride a few miles to make sure that it makes it down into the bowls from the tank, and make sure your petcock is off.

Long-term storage:

If you plan to store your bike for more than a month, drain the tank in addition to the carburetors. Over time, the same evaporation happens in the tank and can varnish your tank and fill it with sediment. Even longer periods of storage can make the gas in the tank unusable sickly-sweet smelling sludge. The time you take draining it can save hours of work cleaning and rebuilding your fuel system.

* There are two types of fuel petcocks: standard and vacuum-controlled. The standard ones are marked [on - off - res]. The vacuum-controlled ones are typically marked [on - pri - res]. If you have a vacuum-controlled petcock, the fuel is only turned on when vacuum is applied via a second hose from one of the intakes when in the [on] or [res] positions. [Pri] stands for "Prime" and is the equivalent of [res] on standard petcocks.

Welcome and FAQ

2009-07-06T20:52:00.000-07:00

Hello,

This is my motorcycle-related blog. I've decided to separate my hobby blog from my opinion blog, as some people are just looking for that type of material and probably don't care about my opinion on topic x.

Enjoy!