GSX-R engine mounts for a GSX Frame

Enginemounts1

Below are drawings of engine mounts to fit an early air-cooled GSX (round frame tubes) or EFE (square frame tubes) with a GSX-R engine. Both place the engine in the middle which is aesthetically best but may cause some problems with the exhaust headers interfering with the frame downtubes, which can be solved by using spacers or modifying the headers if necessary.
Engine mounts for a GSX1100 frame to take a GSX-R engine.
By “jonboy”

A Katana with the above engine mounts installed…

katanagsxr3

Engine mounts for a GSX1100EFE (GS1150) to take a GSX-R engine.
By “GJG”

Below are drawings from the engine mounts, as I used them a few years back. I built at least two EFE’s using these plates. They mount the engine pretty straightforward, like in the Katana I send you pics from a few months back. I also included the cutting contours in .dxf format, that could straight be fed into a laser.

Parts description:
PL-105 and 106: Take front rubber engine mount, and lower below crank. Need shims or bushes to compensate for offset.

PL-107 and 108: These should be welded in with the engine or cases in place, mounted with the previous mentioned plates. PL-108 is a bit long, and could do with a brace, taking sideward loads to the cross tube from the shock. The stock plate should be removed. The lower cross tube in the frame will need some cleaning up and removing of the stock lower rear plates, before taking PL-107.

PL-110 and 111: These make the removable, welded upper rear engine mount taking loads to the stock bolt holes/bushings welded into the side of the frame.

GSX1100 Laser drawings

Making your GSX frame stiffer

Making your GSX frame stiffer
Written by Mr.7/11, inspired on earlier work done by Tony Foale, Arnout and Tinus.

It may be well known to anybody that creating a stiff frame has to do with connecting the headstock to the swingarm pivot as direct as possible, which is what modern “Deltabox” frame designs do. So the best possible solution is to weld f*cking huge bars from the headstock directly to the swingarm pivots. There is just one problem with that… there’s a huge mother of an air-cooled engine in between that hasn’t followed any diet …ever.

frameremovals
To keep the weight down we remove some before adding any.

And besides she’s so beautifully shaped that we wouldn’t want anything hiding those luscious curves from full view now would we? So we’ll have to resort to beefing up the frame we have as well as possible so the front wheel will keep in line with the rear during heavy braking/acceleration as well as big bumps in the road.

The GSX frame is of the “cradle” type which means the main frame tubes are routed above and below the engine. We haven’t got many options for reinforcing the lower cradle as there are exhaust pipes, oil cooler lines and the oil sump between them and we don’t want to create problems while performing regular maintenance.
So we leave it alone with it’s primary task to keep the engine in place concentrate on the part of the frame that runs above the engine.

Take a look at the picture below.
The weak point of the frame is the green section between the headstock (yellow) and the swingarm pivot area (blue). If you look at early GSX-R frame designs you see that on race bikes they have allways tried to beef up that area with additional plates. There’s also a rumour this is what Yoshimura used to do with their GSX superbikes.  Suzuki have allready paid lots of attention into making the headstock as stiff as possible so the effect of additional bracing here will be minimal. If you intend too keep the standard airbox and the battery in it’s original place then options for bracing around the swingarm pivot will be minimal too. So if you would like ot improve the stiffness of your old dinosaur I’d make modification C. first, and consider dumping the airbox in favor of separate K&N filters to be able to add D. and E. When you’re at it you might as well go along and add braces A. and B. but I don’t consider them to be essential.

Be warned that reinforcement C. can hit the inside of the tank if you make it too big and will also make it hard to find enough space for the air filters! You should make all reinforcements from cardboard first anyway to check that they don’t interfere with anything.

framemods

A. these tubes support the headstock against torsional movement. The plates B. support the frame tubes to prevent them from bending due to the load created by tubes A.

The cross-bars D. stiffen the area above the swingarm pivots. The tube connecting both sided is placed at the same height as the engine mounts to keep the engine in place under acceleration. If we replace the cross-bars with a pyramid D1. we add even more stiffness to that area and prevent the swingarm pivots from moving back and forth in addition to up and down. It may look a bit awkward and I question if it adds anything as you must not underestimate the strength and function of the rear subframe.
This might be why Yoshimura adds gussets to the subframe on the Katana 1135R, but they have also changed position of the shock mounts considerably. They probably did this because they use a very short swingarm to decrease the wheelbase and so improve steering into corners and if they kept the original mounting point the shock would be too upright making them too hard.

framebraceexample
Examples of frame braces on the Yoshimura Katana 1135R

The connecting rectangular tubes E. help to distribute loads from the swingarm pivots to the rear of the frame, as well as providing a mounting point for the rear brake amongst other things.

F. There’s very little room to triangulate the space in front of the cylinders because of the exhaust pipes but it is possible. You may need to dent the tubes a little to make them clear the exhaust pipes but this is better than making the V smaller. Tightening the two center exhaust clamps will prove difficult too.

Gussets © Tony Foale
Gussets © Tony Foale

Now that the headstock and swingarm pivot areas are beefed up the connecting tubes are supported by plates C.

You should also consider making B. and C. box sections, so placing a plate on both sides of the tube with a strip in between to close the box. Or use rectangular box-sextion like I did (60×20)

Tubes only need to be around 16mm in diameter with a 1mm wall thickness. Box sections need to have 1mm wall thickness and single gussets 3mm.

Below are images of a braced GSX1100S Katana frame.
The bracing is designed by Mr.7/11and welded by Postma Motoren from Haarlem (NL)

Usually I don't get horny from stiff objects but this is a completely different matter...
Usually I don’t get horny from stiff objects but this is a completely different matter…
You can allmost feel the flow of the forces trough the frame tubes
You can allmost feel the flow of the forces trough the frame tubes
The big cross means "no airboxes allowed" and will probably be painted red
The big cross means “no airboxes allowed” and will probably be painted red
The use of rectangular beams in the subframe means it's easier to bolt stuff onto it like electronics, brake pumps, nitrous solenoids etc.
The use of rectangular beams in the subframe means it’s easier to bolt stuff onto it like electronics, brake pumps, nitrous solenoids etc.

Piston-deck height

Deck height is defined as the distance between the top edge of the piston crown (with the piston at TDC) to the edge of the cylinder liner. The closer the edge of the piston crown is to the edge of the cylinder the high the compression ratio will be.

So if you have pistons that are 10.5:1 and they are 0.010″ below the edge of the cylinder and you are able to reduce the deck height by 0.010″ then the actual compression ratio of the cylinder will be increased.

The reduction of the piston deck height can be accomplished in several ways. Machining the cylinder block is the most common method.

A word of caution you must know exactly the minimum valve to piston clearance that is required. this varies in different engine designs. To increase the piston to valve clearance usually the valve relief pockets on the piston’s crown are enlarged or the height of the piston at TDC must be lowered in the cylinder.

Oversize Valves

Some tuners believe that larger size valves enhance Hi-RPM power at the expense of Low-RPM power. This has proven to be false due to the results of dyno tests and theory. Larger valves enhance Hi and Low RPM.

When a valve is closed it has no size whatsoever for a cylinder’s ability to induce air flow. A valve that is opened, 0.015”, appears to the cylinder as a small valve. Only when the valve reaches 25% of its total lift point does the cylinder actually experience anything near the true size of the valve. If a cylinder was stuffed with valves as big as possible to create a greater movement of the air/ fuel mixture and exhaust gasses and the larger valves proved to be excessive (too large), the solution of the problem would be to reduce the valve’s lift, besides reducing the air flow it would also reduce the wear and friction on the valve train. In the real world, the criterias for the intake and exhaust system for making peak HP and torque at a given engine RPM is the cross section area of the intake and exhaust ports, not the size of the valves.

The real advantage of using oversize valves is that, for a specific rate of the valve’s opening, an oversize valve will give a greater breathing area to the cylinder quicker. This is equal to as a smaller valve opened at higher rate of acceleration. Any time there is a higher acceleration rate in the valve train, more stress is created.

As long as valve shrouding is not a factor then the largest possible valve in a cylinder head will allow the engine to develop power over the widest RPM range, not just increase the flow at high lift rate. If a dyno test of a engine with a cylinder head that has oversize valves reveals a loss in low RPM power it is because the engines camshaft has to much overlap.

For carbureted normally aspirated Suzuki engines in the 9.5 to 12:1 compression ratio range the exhaust flow needs to be 75 percent of the intake flow. Overall when the compression ratio of an engine increases, in order to obtain the maximum results an exhaust valve can be made smaller in relation to the intake valve. This is due to the power developing earlier in the expansion cycle of a cylinder in high-compression engine, thus allowing the exhaust valve to be opened sooner and longer without any problems. A small exhaust valve will create the opportunity to use a larger intake valve.

Nitrogen

Nitrogen
RACING: NITROGEN “A GAS THAT CAN HELP YOU WIN YOUR CLASS”.

If you read my previous post about ‘AIR DENSITY’ in this thread then it will be easy to understand the advantages Nitrogen has over Air, for those who haven’t, I would recommend to do so.

The first advantage of Nitogen is for it’s use in your tires, by doing so you will eliminated tire pressure build up, this is a really important factor in order to maintain a tire’s performance criteria. The Racing Displines of Road Racing or Drag Racing require consistency of a tire performance and the use of Nitrogen will give you that advantage.

In Drag Racing when using an ‘Airshifter’, the use of Nitrogen will add the the unit’s reliability ( No Water contained in Nitrogen) and you will find that the shifter activation responce time is faster.

Longer exhaust duration

Most stock camshafts from production 4 cylinder engines manufactured today are ground with the longer exhaust lobe duration,or that they are ground with shorter intake durations. This can be viewed that either the Exhaust Ports or Exhaust Pipe system is somewhat restrictive, and needs assistance, or that the intake system is very efficient and cam timing can be trimmed back without a sacrifice in power, in order to maximize throttle response and cruising efficiency. There is no absolute correct viewpoint in a stock engine running at conservative RPM levels, for the sake of overall efficiency, fuel economy and a quiet smooth running engine, this staggering of intake and exhaust duration is quite common and appropriate.

High Performance is another thing entirely. Change one factor, such as the exhaust system installing headers and larger pipes and the need for that longer exhaust lobe has been eliminated. Now add to this change a different carb system and camshaft and you have really changed the equation. But, why is it that so many racers & cam grinders insist on running a cam with longer exhaust duration regardless of what equipment is used? The answer is habit, many have been somewhat successful in doing it this way and will never change unless forced by circumstances.

The best result comes when we realize that an engine is basically an air pump. Air is pumped in and out and there are problems when one side or the other is restricted. Balance and flow is our objective, unless you are NOT trying to make more horsepower!

Most experienced Tuners run a single pattern cam, equal on intake and exhaust duration. This type of designed cam always make more torque.

Logbooks

THE LOG BOOK:

I have 2 Log Books, the first one is for the engine and the second one is for the bike.

ENGINE LOG BOOK:
Contained in this Log is every measurement or weight of components that are subjected to wear, this includes the transmission, clutch plates, clutch springs, crankshaft, connecting rods, pistons, piston pins, piston rings, camshafts, valve guides, valve stems and valve springs, drive chain and sprockets . Although you may consider this time consuming the benefits are substantial. Once you have a baseline of your measurements then the next time you disassemble your engine you will have a very good picture of the wear rate of all the components. This process will virtually eliminate parts breaking from fatigue and you will be able to determine what aftermarket parts are more durable. For example I know using a certain type of piston ring in my 1327cc EFE race engine that for every 165 passes down the race track that both my top and second ring end gap wears 0.001″ of any inch. This was the same wear rate that I encountered with my 1230cc EFE race engine using the same type of piston rings. So I know that the oil that I am using is working and the quality of the part is consistant no matter what the power out put is and that after x ammount of passes I have to replace the rings before the power starts to drop. Utilizing this measurement process for the last 20 years I have found that the one part of the GS /EFE engine’s that wear out the fastest are the valve springs, and by the way I have never broken a valve spring in over 7,100 passes down the track.

RACE BIKE LOG BOOK:
In this log I list my tune-up ( jets, timming, drive sprocket size, tire psi,), in additon to the brand of race fuel and octane, my launch and shift RPM for the particular track that I am racing at. Also before I unload my bike, I list measurement of the temperture, humidity, wind direction including approximate speed, and air density and record the time of day. I remeasure and list all of the above items every hour that I am at the track. The info gained from these measurements is very beneficial when you are racing a dial-in type of class, because it makes the tune decission for every round easier. Also once you collect all of the above info you will have an insight on your bikes performance the next time you race at the same track if the weather and time of day is very close.

Intake & Exhaust Port Surface Finish

As long as the intake port surface finish is fine enough so that the highest protrusions are not above the air /fuel mixture boundary layer thickness, then improvements on the finish will have little effect on air / fuel mixture flow . A rougher finish is actually an advantage. Do not over polish an intake port because of its wet fuel flow capability.

A polished exhaust port will increase the exhaust gas flow and will reduce the potential for carbon to build up on the exhaust port surface.

In conclusion 97% of a performance gain from porting a cylinder head is from the shape of the ports and only 3% is from a polished finish.

Induction System Volumetric Efficiency

here are two real world effects that determine how much fuel/air charge can get into the cylinder. The first is that air is compressible, the second is the dynamics (acceleration/deceleration) of the air. The compressibility of the air becomes a factor when the air enters the intake port around the intake valve. The intake port/valve forms a constriction, like the throat of a nozzle. Because air is compressible, it can only be pushed through a constriction so fast. Regardless of how much pressure you apply, the maximum velocity possible through the throat of a nozzle is a velocity equal to the speed of sound .

The same effect happens at the intake valve. The ratio of the typical velocity to the intake sonic velocity is called the inlet Mach index. From the science of fluid mechanics the controlling velocity in a compressible flow system is usually the intake valve opening. For a given cylinder and valve design, the inlet Mach index is proportional to the piston speed, and that the fuel/air charge flows in faster when the piston moves down faster. Of course, at some point the constriction of the valve opening starts to limit this. When the inlet Mach index exceeds 0.5 (intake velocity equal to half the speed of sound), the volumetric efficiency falls rapidly with increasing speed. Therefore, enginest are typically designed so that the inlet Mach index does not exceed 0.5 at the highest rated speed.

The effect of this constriction shows up as a pressure drop through the intake valve. Why don’t we just open the intake valve further? Because when the valve is lifted a distance equal to 1/4 of its diameter, the area of a cylinder around the valve (that the fuel/air charge passes through, not the engine cylinder) is equal to the area of the valve face and intake port, ignoring the valve stem. Mathematically, the area of the cylinder is (2 r)(d/4). Since d = 2r, this evaluates to r2, which is the area of the intake port, the amount of additional flow through the intake port increases very slowly as the lift of the valve increases beyond 1/4 of the valve diameter.

Because of the dynamics of the fuel/air charge, the intake valve normally closes at some time after the piston passes bottom dead center. As the piston moves down, it draws the fuel/air charge into the cylinder. This movement builds up momentum in the intake manifold. When the piston reaches bottom dead center, the fuel/air charge is still flowing into the cylinder as a result of this residual momentum. Thus, at the speed desired for maximum torque, the intake valve closing is timed to correspond with the velocity of the fuel/air charge through the intake port dropping to zero. This closing will occur at some time after the piston has started the compression stroke, and will result in the maximum amount of fuel/air charge being drawn into the cylinder. This maximizes the volumetric efficiency, and maximizes the torque delivered to the crankshaft, ignoring friction effects. The angle of the crankshaft at the time the intake valve closes is called the intake valve closing angle.

So what effects does this later valve closing have at other speeds? At low speeds, the momentum built up in the intake manifold will be small, such that part of the fuel/air charge will be pushed back into the intake manifold as the piston starts up prior to the intake valve closing. At speeds above the speed for maximum torque, the constriction of intake valve opening will cause a pressure loss which will reduce the amount of fuel/air charge entering the cylinder. In either case, the amount of fuel/air charge in the cylinder is reduced, and thus the torque is reduced.

The design of the intake manifold also affects the amount of momentum built up in the flow of the fuel/air charge. The momentum of the fuel/air charge is the sum of the effect of standing waves built up from previous intake strokes keep in mind that any tube will have a resonant frequency and effect the transient wave caused by the current intake stroke. While the standing waves contribute to the overall effect, there are no sudden changes in the volumetric efficiency when the RPM of the engine is an even multiple of the natural frequency of the intake manifold.

Long, skinny intake manifold pipes give high volumetric efficiencies at low piston speeds because high momentum lots of velocity is built up in the pipe during the intake stroke. At high piston speeds, the small diameter of the intake pipe causes a constriction and the volumetric efficiency falls. Fat intake pipes show a maximum volumetric efficiency at intermediate piston speeds. However, at high piston speeds, the larger mass of the fuel/air charge in the fat intake pipe is slow to accelerate, and thus the volumetric efficiency falls off.

As the manifold pipes get shorter, the maximum gain in volumetric efficiency over having no intake manifold at all decreases. However, the gain you do get with shorter intake pipe happens over a greater range of piston speeds. Basically, it comes down to the intake manifold pipe should be designed according to the engine requirements. If you need high torque at slow piston speeds, use long skinny intake pipes. For high torque at intermediate piston speeds, use long fat intake pipes. For high torque over a wide range of piston speeds (i.e. a flat torque curve), use shorter intake pipes.

Ignition components

This article has been reproduced with the permission of Ross Farnham. It was first published by Ross in 1998 http//sdsefi.com/techcomb.htm

Inductive Discharge Coils – Ignition spark for motorcycle is accomplished by the iginiton coil, coils have 2 sets of windings, a primary and a secondary. A typical coil will have around 250 turns of wire on the primary and about 25,000 on the secondary for a ratio of 100 to 1. The secondary section often uses an iron core to increase its inductance. Coil resistance on the primary will be from .3 to .5 ohms usually and on the secondary, between 5000 and 12,000 ohms. The inductance and resistance of the coil will determine how quickly a coil can be charged and discharged.

A transistor is used to switch the current flow off and on in the primary coil. When the transistor is switched on, current rapidly builds from 0 to a maximum value determined by the coil inductance and resistance. This current flow induces a magnetic field within the primary. When the current is turned off, this magnetic field collapses which cuts the windings of the secondary coil and induces a high voltage surge.

Output voltage is determined by the rate of field collapse and the windings ratio between primary and secondary. Because the path to ground for the current involves the spark gap, initial resistance is extremely high. This allows the voltage to build to a high value until it gets high enough to jump the plug gap. The difference must be high enough to first ionize the gas between the electrodes. The ionized gas creates a conductive path for the current to flow, at this point the arc jumps and current flow is established.

If only 10,000 volts are required to jump a plug gap under a given condition, that will be the maximum delivered. It is also important to note that the spark duration is determined by coil inductance and total resistance of the circuit, plus spark plug gap. Most inductive discharge systems have a spark duration of between 1 and 2 milliseconds.

When cylinder pressure increases, the voltage required to jump the plug gap increases. The second problem on high performance engines with high rev limits, is that there is less time to charge the coil with increasing rpm, high rpm and high output puts greater demands on the ignition system.

Coil Charge Time and Saturation – The time it takes to charge the coil or bring the current to maximum in the primary windings is called charge time. Input voltage and coil resistance are the main parameters relating to charge time, when the current has reached its maximum value in the primary, it is said to be fully saturated.

If current is applied longer than the time needed to fully saturate the primary, energy is wasted and there is nothing to be gained. If the current is cut off before saturation is achieved, the maximum spark energy available will be reduced.

Coils require charge times of between 2.1 and 6 milliseconds. Obviously, a coil requiring 6 milliseconds to saturate would be unsuitable on a high revving engine as there is not 6 milliseconds available to charge it between discharges at high rpm. For this reason, most racing coils have low primary resistances between .3 and .7 ohms and are fully saturated in less than 3 milliseconds permiting full coil output at very high rpms.

Capacitive Discharge Ignition – On very high output engines, an inductive discharge coil is inadequate to supply spark at high rpm and high cylinder pressures. A CD ignition or CDI is used to reduce charge times. The MSD system is very popular worldwide.

In normal inductive discharge coils, only 12-14 volts is available from the battery to charge the primary. The CDI charges capacitors to store a high voltage kick to fire to the primary side, putting between 30 and 500 volts onto the primary windings which reduces the charge time substantially. A coil that would take 3 milliseconds to become fully saturated with 12 volts is now fully saturated in less than 1 with a CDI. The same engine now will be able to turn twice the RPM and experience a major increase in cylinder pressure before encountering misfire.

Some CDIs also include a multispark function where more than 1 spark is generated after the first spark. This improves ignition probability besides the high rpm coil saturation advantages and a greater resistance to plug fouling.

Ignition Wires (Spark Leads) – The purpose of the ignition wires is to conduct the maximum coil output energy to the spark plugs with a minimum amount of radiated electromagnetic interference (EMI) and radio frequency interference (RFI). There are 3 basic types of conductors used in racing applications: carbon string, solid and spiral wound. Most production engines come equipped with carbon string. The solid core types are used exclusively for racing, mainly with carbureted or non-computer controlled engines because they offer no EMI or RFI suppression. They generally have a low resistance stainless steel conductor. These types are rapidly losing favor, even in racing circles.

The carbon string type is the most common and work just fine in racing applications. The conductor is usually a carbon impregnated fiberglass multistrand. Suppression qualities are fine with resistances in the 5K to 10K ohms per foot. They are cheap and reliable for 2 to 5 years usually, then they may start to break down and should be replaced. High voltage racing ignitions will likely hasten their demise. Dynatech makes low priced wire set which works well in performance applications.

Ignition Wires (Spark Leads) – The spiral wound type is probably the best type for any application. The better brands offer excellent suppression, relatively low resistance and don’t really wear out. Construction quality and choice of material vary widely between brands. NGK makes low priced wire sets which work well in performance applications.

Some amount of resistance is required along with proper construction to achieve high suppression levels. Resistance is also important to avoid damaging some types of coils and amplifiers due to flyback and coil harmonics. Beware of wires claiming to have very low resistance. These CANNOT have good suppression qualities.

Beware of any ignition wires claiming to increase hp. Ignition wires CANNOT increase hp. As long as the wires that you have are allowing the spark to jump the gap properly, installing a set of $200 wires is strictly a waste of money.

Lately, some truly “magic” wires have come onto the market claiming to not only increase power but also to shorten the spark duration from milliseconds to nanoseconds. As previously mentioned, spark duration is determined primarily by coil inductance and coil resistance so these wires CANNOT shorten the spark duration by the amount claimed. The wire resistance has a minimal effect on discharge time because of the high voltage involved. A very short duration spark is in fact detrimental to ignition because of lower probability.

These same wires claim to increase flame front propagation rates and the ability to ignite over-rich fuel mixtures for more power. Once ignited, the mixture undergoes a flagregation process and that the progression rate of the flame front is totally independent of the spark. As previously mentioned most gasolines will not ignite nor burn at air fuel ratios richer than 10 to 1, period, and that maximum power is actually achieved at around 12 / 13 to 1 AFR so the claim also has no basis in fact.

These wires use a braided metal shield over the main conductor which is grounded to the chassis. This arrangement offers poor suppression because it does not cover the entire conductor. Any energy leaking out of the main conductor by induction is actually wasted to ground and will not make it to the spark plug. These wires also have very low resistance which as mentioned can have a detrimental effect on coils and ignition amplifiers due to severe flyback effects which are normally damped by circuit resistance.

Other claims for these wires include current flows of up to 1000 amps. The current flow in the ignition circuit is determined by the coil construction and drive circuits, not by the ignition wires. Most ignition systems are current limited to between 5 and 15 amps. The most powerful race systems rarely exceed 30 amps. To flow current at 1000 amps, you would require #0 welding cable for the ignition system!

Spark Plugs – The final part in the ignition system is the spark plug itself. The average plug consists of steel shell which threads into the cylinder head, a ceramic insulator, an iron or copper core leading to a nickel or platinum center electrode and a ground electrode of similar material. The spark jumps between the center and ground electrode. Certain special application plugs may have multiple ground electrodes. Different heat ranges are available depending on application. For constant high power applications, a colder than stock plug is usually selected to keep internal temperatures within limits.

Again, many “trick” plugs come onto the market from time to time expounding the virtues of their incredible new design, usually offering more hp of course. Split electrode plugs are a waste of money because the spark will only jump to one of the electrodes at a time in any case.

You will find that most reputable engine builders for racing use standard NGK, Bosch or Champion plugs with a standard electrode setup. A properly selected, standard plug will easily last 25,000 miles of hard use in most engines. A platinum tipped plug will easily last twice as long on most engines. There is no rocket science here, modern spark plugs coupled to modern ignition systems in a modern engine are extremely cheap and reliable, even on race engines, a $2, off the shelf, NGK plug will work just fine.