3 or 5 angle valve seats

Cylinder Heads (3 or 5 Angle Valve Seats)

The greatest flow restriction in any engine is the cylinder head. Having the air / fuel mixture to efficiently pass through this restriction will increase an engines HP and Torque.

The Intake and Exhaust Valves are part of the cylinder ports, and when they are closed their ability to flow is zero. This means until they have opened to a very large opening, the valves are the main restriction to the engine’s cylinder head’s airflow.

Even when the valve is at a large lift, it still presents a difficult path for the air to travel on its way into or out of the cylinder. The priority is to make the valve capable of passing as much air as possible, whatever the lift is. To do this both the valve size and the valve’s seat must be considered.

Although it may be the last operation during a porting job, the valve’s seat design is the most important priority toward effectively filling the cylinder. It would seem that the hole under the valve head needs to be as large as possible so as to flow the most air. Before flow benches were developed, it was a common practice to make a valve seat as thin as possible in order to achieve the maximum throat diameter. Objective flow bench testing found this to be untrue. In the real world the maximum flow is always a combination of size and form around the valve before and after the seat.

Air has mass and does not like to hug a port wall around a short-side turn. With low-angle ports, the air at mid and high valve lifts do not make the transition around the short-side turn very well. As a result, most of the air goes out of the long-side turn.

This situation is even greater as the higher the valve lift becomes. As a result, the streamlining of the port on the long side needs to be addressed for low, medium and high lifts, while the valve seat approach on the short side needs only to deal with the requirements of low-lift flow.

It does not matter if it is the intake or exhaust port, the worst part of the port for air to travel is the short-side turn. If the air fails to make it around the short-side turn, there obviously won’t be much air exiting the valve in that area.

Changes in the valve’s seat angles can make the valve appear bigger than it really is and flow more air during the beginning of its opening phase.

Cylinder block

Cylinder Block

Well looking back at this thread my expectation was to encourage additional information from other OSS members to be added to this thread, although there was some I guess my expectations were greater. That being the case this will be my last input of information in this thread for the remainder of this year.

The following information can be used for race or street engines, several Worldclass engine builders have known and have been using the technique for decades.

If you REALLY want to have cylindrical cylinder bores when it comes time to hone your cylinder block, the block needs to be at operating temperatures. Getting the block up over 120f degrees is a good temperture to hone it, but if you can get it to 150f degrees, it’s even better. In addtion any honing oil that you use must be of equal temperture of the cylinder block, when the cylinder block is heated and you douse cold honing oil on it and then hone it, the localized cooling is going to distort the bore.

Many times people ask me how I am able to consistantly build long term reliable high HP race engines, well M8’s this is one of my secrets.

Copper Head Gaskets

Copper Head Gaskets.

Copper head gaskets are great for extremely high compression ratio (over 13:1), turbocharged or supercharged engines that are running lots of boost pressure (over 15 psi), or engines with nitrous oxide that add an extra 150 to 200 or more horsepower.

Due to the fact that Copper conducts heat much better than most other metals, Copper will help to stabilize a cylinder head and cylinder block temperatures. This will prevent any hot spots that can cause detonation or head warpage, and a Copper head gasket reduces the risk of the head gasket blowing out or burning through.

Copper has a 25 percent coefficient of elasticity which allows it to stretch before it will fail. if an engine starts to detonate because the air / fuel mixture leans out, or there is excessive ignition advance or too much compression and low fuel octane, a Copper head gasket will provide a margin of safety. Copper is strong and the alloys used for copper head gaskets may have a tensile strength of up to 32,000 psi, which is many times stronger than that of the materials used in conventional performance head gaskets.

Copper head gaskets are reusable for a limited number of times (3). This is a plus in situations where the heads are on and off the block between races, or frequent tear downs are required. One of the downsides of Copper head gaskets, though, is that they do not seal oil very well. A Copper head gasket must be coated with some type of sealer, and both mating surfaces must be absolutely flat and clean.

The way to anneal a Copper head gasket is that the gasket should only be heated until it is a dark red color and no more. After the Copper head gasket gasket has air cooled, the surface needs to be cleaned with a brush or abrasive pad to remove oxide from the surface. The Copper head gasket should then be cleaned with brake cleaner or a similar product and allowed to dry before it is coated with a sealer.

The sealer must be allowed to dry before the gasket is installed. Some aerosol sealers may require multiple coats for the best results. RTV silicone also works, and may be applied around oil galley openings in the cylinder head gasket, the cylinder block or cylinder head, only a thin coating should be used, and it must be allowed to set before the gasket is installed.

Copper is a soft metal and it does not provide much conformability. This is a good aspect because the gasket doesn’t crush when the head bolts are torqued down, thus the thickness of the gasket remains the same and does not change. Unfortunately a Copper head gasket does not conform very well to small indentations and surface irregularities in the cylinder head or cylinder block

If a copper head gasket is accidentally bent during removal, it can be straightened and annealed. But if the gasket has kinked, it should be replaced because a kink concentrates stress and hardens the metal. This will increase the risk of a Copper head gasket cracking. Copper head gaskets should not be cleaned by bead blasting because it will harden the metal. The same is true for hammering the metal.

On all applications using Copper head gaskets there should be annealed / softened Stainless Steel or Copper wire O-rings installed in grooves that machined into the block or cylinder head. The wire rings help concentrate loading around the cylinders to prevent combustion pressure from blowing past the gasket. These wire rings are typically .041″ in diameter, and are placed in a .039″ wide x .030″ deep groove. The wires should protrude only about .010″ above the surface of the deck, and the thickness of the gasket should be about four times the protrusion of the wires in their grooves, or about .040″. Engines that produce over three horsepower per cubic inch should also have a corresponding receiver groove machined into the head opposite the O-rings in the block for optimum sealing. The depth of the receiver grooves should be 75 percent of the O-ring protrusion and the width of the grooves should be 1.5 times that of the wire.

Compression test gauge

COMPRESSION TEST GAUGE READINGS.

Your Motorcycle will always have a higher reading on your compression tester gauge with a stock or low duration cam, due to the fact that you will be closing the intake valve earlier on the compression stroke. This longer effective compression stroke always delivers a higher gauge reading.

Installing a longer duration cam, your intake valve will close later, thus giving a lower gauge reading because of the shorter effective compression stroke. Some individuals feel that this is impossible, claiming that if it were true, why will your Motorcycle go faster with the bigger cam? The reason is that a bigger cam will have higher compression effect in the cylinder at higher engine speeds where all that additional valve timing can do you some good, but at lower speeds and especially at starter-cranking speeds, the effect will be lower.

Compression ratio

When you increase the compression of an engine it will produce an increase in the HP and Torque output throughout an engine RPM range. If a long duration cam is installed in the engine, increasing the compression ratio at the same time has a greater advantage than these two modifications made separately at different times. By raising the compression ratio of an engine, the peak combustion pressures are increased.

Engineering studies have found that cylinder pressures are about 100 times what the compression ratio is. That means that an engine that has 10:1 compression ratio, would create 1,000 psi of peak combustion pressure. Increasing the compression ratio will increase an engines cylinder pressure and this increase in compression also increases the an engine’s thermal efficiency. Thermal efficiency is a measurement of how effectively the an engine converts heat into mechanical power.

Due to the fact that a high compression cylinder makes its power much earlier on in the power stroke there is another issue that can be taking an advantage of. That is that the early opening of the exhaust valve opening needed for high RPM output can be utilized without effecting the engine’s low RPM output.

How much HP and Torque can be gained from an increase in an engine compression ratio?

By using the chart below you can fiqure the thermal efficiency at any given compression ratio. First locate the original compression ratio listed horizontally, then locate the new compression in the first column. Where the two compression ratios intersect, that is the gain that can be expected. For instance if the compression ratio of an engine is raised from 9:1 to 12:1 the two values intersect at the box with 7.7 in it. This is the percentage increase of thermal efficiency that can be obtained from raising the compression from 9:1 to 12:1.

ORIGNIAL COMPRESSION RATIO New Compression Ratio
9:1 10:1 11:1 12:1 13:1 14:1 15:1

10:1 2.9
11:1 5.5 2.5
12:1 7.7 4.7 2.1
13:1 9.7 6.6 4.0 1.9
14:1 11.5 8.3 5.7 3.5 1.6
15:1 13.0 9.8 7.1 4.9 3.0 1.4
16:1 14.5 11.3 8.6 6.4 4.4 2.8 1.4

Comp ratio

On normally aspirated engines at low engine rpm’s there is little ramming from intake charge velocity into the engine’s cylinder. When the piston starts to move up in the cylinder bore on the compression stroke prior to the intake closing, some of the air / fuel mixture is pushed back into the cylinder head’s intake port. This creates the situation were the volumetric efficiency and the effective displacement of the cylinder is well below 100 percent.

Raising the compression ratio one point from a low ratio has a greater effect then raising the compression ratio up from an already high ratio. This means the larger the duration and lift of a camshaft the more responsive it is to a increase in the compression ratio, especially in the lower engine rpm.

Camshaft lobe centres

Here is some info that might be helpful for those who are interested in fine tuning their bikes camshafts.

The common range of lobe center values for SUZUKI engines is only about 10 degrees wide from about 102 to 112 degrees, a change of one degree can have considerable effect on the power delivery characteristics of a SUZUKI engine.

The effect of moving lobe centers is that by advancing the intake and retarding the exhaust, known as CLOSING UP THE CENTERS, it will increase the valve overlap and will move the power UP in the RPM range, although it will at the sacrifice LOW- RPM power. The result would be LOWER numerical values on both intake and exhaust lobe centers.

If you retard the intake and advance the exhaust, known as SPREADING THE CENTERS, valve overlap will decrease and will result in a WIDER power band while sacrificing HI – RPM power. This is indicated by HIGHER numerical values on both intake and exhaust lobe centers.If you move only one cam the results are not as predictable, traditionaly it is the INTAKE CAM that is moved to change power characteristics since small changes here seem to have a greater effect.

Benefits From Increasing the Compression Ratio

Increasing the compression ratio is one component of many that will increase a SUZUKI GS / EFE’s HP. An increase in an engine’s compression ratio will provide more power for less fuel and add some snap when the throttle is opened.

Raising the compression ratio gives the greatest benefits with initial increases. This means that more HP is produced by the first point increase of the compression ratio as compared to the next point of increasing the compression ratio. To illustrate this lets use a stock 1985 (USA model) GS1150 (EFE) as an example. The stock compression ratio is 9:7.1 if you increase the compression ratio to 10:7.1 there might be a 4 or 5 percent increase in HP. Further increasing the compression ratio to 11:7 might only provide a 2 or 2.5 percent increase.

The reason for the a smaller percentage in the increase in HP with a further increase in the compression ratio is due to the aspect of the GS / EFE cylinder being like an lung, increasing its volumetric effiecieny basically means the lung is filling with more air and is breathing out more through the exhaust. It is not enough to just increase intake or exhaust. Both must be made more efficient.

GS / EFE 1150 stock cams open and close the engine’s valves with little or no overlap. This prevents emissions from escaping, but it also limits an engine’s breathing efficiency.

In conclusion a moderate increase in compression will use less fuel to produce more power and the extra cylinder pressure and heat generated will increase the gasoline’s burning efficiency. But if you really want to maximize the advantage of increasing a engines compression ratio this use of a Hi-performance camshaft is required.

Air density, a secret tuning factor

Air density is a computation mainly dependent on the temperature, barometric pressure, and the humidity of a volume of air.

Temperature in the USA is generally measured in degrees Fahrenheit, barometric pressure in inches of Mercury (inHg), and humidity in percent of Relative Humidity.

You can relate to how these factors effect the density of the atmosphere by using a balloon to simulate the earth’s atmosphere. When a balloon is filled with air and placed into a refrigerator it begins to shrink, this is due to the drop in temperature of the air inside the balloon. As the air cools it releases energy and slows down,because the air molecules are not bouncing off each other as much, they remain closer together and more of them will now fit in a smaller area. The opposite will occur if the balloon is heated.

The effect of humidity is a little more complicated. A change of humidity in the atmosphere is caused by a change in the amount of water vapor mixed in with the common gases already present in the air. As more water vapor is put into the air is displaces these gases. The water vapor is also less dense (weights less) than the gases in the air. When we take air that is at a set temperature and pressure and start introducing increased amounts of humidity we begin to cause the overall density of the air to decrease. Therefore, the density of the air is the greatest when there is no humidity.

Changes in temperature, pressure, and humidity can have different amounts of effect on the associated change in air density. A change in temperature or pressure causes a proportional change in density. In other words, a 1% change in temperature causes a 1% change in density. Again, the effect of humidity is more complicated, because the effect of humidity on density is also dependent on the temperature. A 50% increase of humidity when the air temperature is 70f degrees may cause a 1% decrease in total air density, but a 50% increase of humidify when the air temperature is 90f degrees may cause a 2% decrease in total air density. This effect is due to the fact that it takes lot more water to cause 50% relative humidity at a 90 degree temperature than it does at 70f degrees. The humidity must also be considered in that it makes up some of the density of the air, but it has no value being there.

The air in the earth’s atmosphere is made of various gases and water vapor. Neglecting the effect of pollution there normally is 20.9% of oxygen, 75% of Nitrogen, Carbon and very small amounts of some other gases. Oxygen is the most important gas in the atmosphere as far as an internal combustion engine is concerned. This is due to the fact that the oxygen is used to burn the fuel placed in the chambers of the engine. When more oxygen can be placed in the chamber it allows one to also place more fuel along with it and therefore create more power. The air density relates to this because when the air density increases the amount of the combined gases and water now fit into a smaller area, this includes oxygen. If the air is denser than there is more of it therefore more amount of oxygen will be taken into the engine.

The term commonly heard among racers is “density altitude”. Density altitude is the density expressed if feet instead of grams per cubic centimeter. It’s a lot easier to relate a change of density in a couple hundred feet rather than a change of 2.534 g/cm^3. The use of density altitude is taken from the U.S. standard atmosphere table. This table relates the density of an average day at sea level (59 degrees, 29.92 inHg) and how it changes at different elevations in the atmosphere. As one climbs in altitude the density falls off at a predetermined exponential rate.

In conclusion I highly recommend either an Air Density Gauge or a Altimeter as tools to be used for adjusting your Fuel Curve and Ignition Timing. I firmly believe that these items are essential for tuning at the Race Track

All you wanted to know about GSX tuning but were afraid to ask

Speedy Steve Racer was one of the original sites GSX engine tuning gurus. Steve produced a complete guide to GSX engine tuning and we will republish it here through the vault.

Here is Steve’s original introduction.

Steve racer

HELLO RACE M8’s,The objective of this thread is to create a information baseline for all of the OSS members who are currently or who are planning to race ‘AIRCOOLED SUZUKI’S’ in Santioned Motorcycle Racing Events throughout the world.

Currently we have a number of OSS Members who in the past or present have won racing Championships competing with their ‘Old Skool Suzuki’s’. The wealth of knowledge and experience from these individuals can help other OSS Members who have desire not only to WIN Races but Championships also.

Presently OSS Members have won National & World Championships
in ‘Road Racing’, ‘Sprinting’ and ‘Drag Racing’, and with the help and informational input from these successful racers there is no reason that in the near future when a competitor see’s an bike with an ‘OSS STICKER’ they will consider that Sticker as a “SECRET WEAPON”.

I am looking forward to your feedback in order for this Hardcore Race Thread to begin. So DnD, AT_, LUKE, PETE 750ET, H_ippy, Gary 1371, BBK and the rest of my OSS RACE M8’s and Members, let’s get this thread going.

CHEERS

SSR

I Shut Them Down, Then Shut Them UP

 

How-to fitting 3.5 GSXR front wheel into EF front end

Capitan Chaos site moderator, motorcycle mechanic and EFE addict shares some useful info on upgrading the front wheel on your EFE.

Here’s how:

– remove the bearings from the EFE front wheel, and take the tube which is in between them. Do the same with the GSX-R one.
– you will find out the EFE one is 16mm longer than the GSX-R one. It needs shortening 16mm.
– buy some bearings which fit in the GSX-R wheel and on the EFE spindle. I don’t remember exactly the sizes, but you need bearings with the ID of the EFE ones, and the OD and width of the GSX-R ones. They were off the shelf in the local bearings shop.
– the tubes in the bottoms of the EFE forks are now too short. Make some new ones which are 8mm (each) longer.
– the EFE speedo drive will fit after a little bit of material has been removed. Offer it up on the GSX-R wheel and you’ll see exactly where.

And now, with that nice 3-spoke wheel, it would be a shame not to upgrade the brakes as well.
The Slingshot Nissin 4-pots, and the later GSX-R models’ Tokico 4- and 6-pots all fit on the EFE forks, 90mm spacing between the bolts. But the Slingshot discs are too large.
Now Suzuki had thought about this and launched the GSX600F in the late eighties, this bike has brake discs that fit perfectly on the GSX-R wheel and are small enough to accept the more modern calipers when mounted in the EFE forks. All it needs is some small rings to space out the calipers a bit towards eachother.
Use the EFE caliper mounting bolts, they are longer than the GSX-R ones.

Captain Chaos

Discuss here