Alternator overcharging problems, oil-cooled engines

Alternator overcharging problems.

Right then ive got to the bottom of this problem and i bet most oil coolers have got this problem thanks to stuart who is a very clever electrical engineer/design.

Suzuki have tried to be clever using a closed loop design which may work when everthing is new perhaps.

Out of alternator are two leads the main power to battery and the other is the ignition feed to alternator which is trigger to turn reg on.
Problem here is voltage drop on the trigger wire, ive measured half volt purely at ignition switch, suppose age takes its toll. ive got further .3 volt loss through wiring and joints i can tell you the connectors are clean and look good.
So alternator battery lead reads say 12.6 volts (engine off) ignition lead reads 12.5 volts but lights on this drops to 11.5 volts where the battery lead reads 12.3 a drop of .8 through switch and harness, so when running when lights are turned on alternator compensator by ramping up output to 15.4 volts which cooks the battery.

Remove ignition feed wire to the alernator and use it to power a relay (switch side) the ignition wire out of alternator straight to positive on battery via the new relay.
Result constant 14.3 volts depending on battery state no matter whats on or off, result.

You have to connect via a relay as the reg would drain the battery in no time as this is trigger to turn reg side of circuit on as its a basic deign not like car 1 wire systems where the actual rotation of alternator triggers it on.

In the past ive destoyed batteries for no reason luckily the powerful little gel battery has lasted 3 years but at least now know the reason why, this has got to affect a lot of bikes this sort of age pointing bto reg when actually its working correctly.
Hope this is of i must also do a right up on cvs and good design change, to stop emulsion tubes wearing out.

Ignition wire from alternator ( to work out which of two wire this is it will be the wire that only has 12 volts on it when ignition is turned on, ie black wire on multi meter to earth red on meter prod each of cables in back of plug)

Cut this wire, the one coming from alternator now connect to positive on battery via a relay.
The other side of cut ignition wire coming out of loom connects to the switch side of this new relay obviously the other side of switch side goes to earth.
So when ignition is off relay is open so connection of battery to ignition wire on alternator and visa versa.

Just one thing: first i tried with a cheap relay, it had a difference of 0,2V on the switched wires, so it charged 14,7V. Then I got a better relay (no difference measurable) and it charges perfectly.

Setting up CV carbs for a turbo

See below all I know about blowthrough CV carbs. This is worth several hundred hours of sorting out and at least €1000,- worth of dyno time, so feel free to thank me! (and/or make a paypal donation)

Bowl pressure
If pressure in venturi of carbs is raising due to boost, so should the pressure in bowl raise. Because if pressure in bowls is lower as it is in venturi, no fuel can be taken into the engine.
In my experience dynamic boost is absolutely nessecary, and it’s best to give each connection on the carbs it’s own spot on the tube going to the plenum: not in the plenum itself as there is to much pulsing. Make sure they are “angelcut” and in the middle of the airstream. (also known as pitot tubes)

On the GSXR1100 model 92 with the 40mm carbs you need to fasten the rubber T’s for instance with steel wire to prevent leakage and pressure drop.

Membrane pressure (CV carbs only)
Pressure above slidemembrane is not needed: it got it’s signal/pressure through the hole in the slide. Don’t enlarge the holes because the slides go up too fast and cause stuttering. (beware of dynojet kit modifications: larger holes and softer springs are a real pain in the butt for the midrange!)

Pressure below the membrane is needed. On the GSXR1100 model 92 with the 40mm carbs you have a seperate “venting” system with external hoses. Those are not suitable to pressurize. I removed that system, plugged the holes and drilled holes from the bellmouth towards under the diafram. When you drill you cross a not used hole. You have to plug that up also to prevent leakage and pressure drop. So it is made like the earlier models: the 36 and 38 mm CV carbs do not have this system.

Fuel pressure
The pressure of the fuel going to the bowls should be higher than the pressure in the bowl. If not, not any fuel is flowing into the carbs causing starvation as soon as boost starts to build.
Therefore you need a pump capable of making enough pressure to overcome boost + 2-3 psi at sufficient amount of fuel. The standard membrane pump on some carb bikes is definitely not up to the job: don’t even try it. An automotive EFI pump coming out of a car with the same amount of horsepower you are aiming for should work allright.

If you don’t use a regulator: you will have the maximum pressure on the bowls the pump can handle, and that will be around 90 psi and the end of your carbs.
A regulator is used (I use a malpassi and highly recommend it) to give the carbs a 2-3 psi above boost, so difference in pressure between pump and carbs is always the same independent of boost. Make sure you use a bypass type, not a deadend type as it is less accurate. If you can get away with 5 psi on the carbs without leaking, you can use static pressure and don’t need to modify the malpassi. It you have trouble with it, as I have, you need to shorten the spring in the malpassi a bit to achieve 2-3 psi. I also needed a bigger 8mm return line to be less restrictive. Than you definately need the dynamic pressure to prevent starvation under boost!

Don’t make holes in the slides bigger, or use soft dynojet springs! They make things worse in the midrange area.
If you have your carbs and fuelsupply correctly setup: you don’t need to make big adjustments to needles and jets. Mine is actually on 125 mainjets (stock!) functioning just fine at 11.5:1 A/F
Don’t get an A/F any leaner then 12:1 A/F when you use some serious boost. You will burn up some pistons/valves. 11.5:1 is safe imho.
Use an A/F meter to see what’s going on. Looking at plugs is not saying too much, because if their getting hotter then normal on a turbocharged motorcycle they are white anyway.
Symptoms of lean and rich while driving can sometimes be very similar so in doubt always consult the A/F on a dyno!
Because of the lowered fuellevel it is nessecary to give more fuel for the idle, in my case 8 complete turns out for the mixture screws.

Extra tips:
Place a fuelfilter between pump and regulator. Not before pump because you restrict too much, and not after regulator because you messing with pressure which is critical on a carb/turbo setup. Make sure the fuelfilter can hold the pressure!
The return line of the regulator should be as less restrictive as possible: inside minimum 6mm returning into TOP of tank, not below fuellevel in tank. Otherwise fuel pressure cannot go as low as 2-3 psi. Don’t ever (I mean ever!) bend this line because fuel pressure can reach scary levels damaging your carbs seriously!!!!
Mount a fuelpressure gauge direcly next to the boost gauge so you can easy troubleshoot. Remove later if you want to.
Remove filter in your petcock, or better mount a less restrictive petcock without filter. Pingel makes these, but I machined a custom one with build in fuelreturn to the top of the tank so you don’t have to weld in a separate fitting in the tank
If it’s a vacuum operated petcock make sure you use the bypass mode: otherwise on boost the petcock will shut! This is a nice one, as you easily overlook it. On some models the petcock is really restricted in bypass mode so you have to modify that in some way.
If carbs overflow: put in new needles and valves. Make sure fuellevel is not too high: pressurized bowls have a slightly higher fuellevel so you maybe have to adjust it a few milimeters.
On very high horsepowerlevels there can’t flow enough fuel past the needles. Put in thinner/sharper dynojetneedles to solve this. Typical symptom is a sharp leaning out around peak torque, were you need the most fuel every stroke. This makes it harder to get the midrange ok.
At higher boost you can press out the choke plungers! This causes unwanted rich situations and stalling at closing the throttle. Put in stronger springs to solve.

This info is true for my bike and my application. Some of this info is also true on other bikes/carbs but you have to check yourself. If it doesn’t work or you burn your engine up: I don’t accept any claims. If you crash due to an exploding engine: I’m really sorry and I will send flowers to your family but I am not responsible!

Good luck!

>> Check out the hints section of, site has an illustrated guide for “converting” CV’s for turbo use.

The small 34mm gsxr750 carbs with alloy throttles and 4 screws on the caps and floats are actually the best you can use when going turbo. A friend (at is cranking out 420 rwhp at 2.2 Bar of boost.

I’m also using 34mm carbs on my turbo GSX with alu caps. One more tip: Replace the o-rings in the T-s that go to the floatbowls; 9 times out of 10 they are old and brittle and will leak your precious dynamic boost so the motor runs like a pig at the transit from vaccuum to boost.
One important thing that I noticed during dyno-testing is that you (usually) start with std. mains, then lean it out a bit. If you go down-or upsize the mains, they have a bigger effect on fuelling than it would on an NA engine. So where you would normally say take it 3 sizes down at a time, you need to take one size at at time with this setup.


for 38-40 mm carbs



Extra shift detent spring

EXTRA SHIFT DETENT SPRING: “There Is Enough Tension In Drag Racing”

I just read a thread about adding an additional dentent spring in your GS / EFE Transmission. This is an acceptable modification for a stock activated shift linkage.

A lot of my hands on mechanical knowledge has been gained thru many decades of working as a R&D Engineer for various Automobile and Motoccyle Maufactuers such as G.M. Toyota, Isuzu, Suzuki, Yamaha, Kawasaki and H-nda. An advantage of working for these Companies is that I would spend a lot of time with a large variety of data acquisition instruments. Fortunately I was able to use and apply many of these instruments to my EFE Drag Bike.

Many of our OSS members are well aware of the fact that Drag Races are won or lossed by a thousand of a second. I have had the opportunity to do A -B -A testing methods using test instruments that are capable of taking measurements in miliseconds, comparing the use of a single or double detent springs with a MRE Pro-Airshifter.

The results of the tests (confirmed repeatability) is that a bike utilizing an MRE Pro-Airshifter will engauge a gear faster with a single spring as compared to using a double spring.

You can consider the above information as another “SSR Race Trick” donated to the OSS site. I still have several more when it comes to Suzuki transmissions that will remain propriety information.

“May The Shift Be With You”

Exhaust System Efficiency

Part of getting a large fuel/air charge into the cylinder (volumetric efficiency) has to do with getting the combustion products of the previous cycle out of the cylinder. At first thought, it would seem that simply making the exhaust valve bigger would help get the combustion products out. As it turns out, the exhaust valve can be as small as 50% the size of the intake valve without affecting the volumetric efficiency over the usual range of inlet Mach speed. Normally the exhaust valves are at least 60% the size of the intake valve. This effect may arise because the combustion products are “pushed” out of the exhaust port by the piston, while the fuel/air charge is “sucked” in the intake port, pushed only by the manifold pressure.

To enhance the removal of the combustion gasses, the intake valve is opened prior to the end of the exhaust stroke. Since both valves are open at this point, this is referred to as valve overlap. If the pressure in the intake manifold is greater than the pressure in the exhaust manifold, the in rushing fuel/air charge will help scavenge the remaining combustion products in the cylinder as the piston reaches top dead center by pushing them out the exhaust port. While some of the fuel/air charge may go out the exhaust port, an engine tuner tries to design the timing such that the exhaust valve closes just as the last of the combustion gasses leave the exhaust port. An additional benefit of valve overlap is that the intake valve is essentially fully open at the start of the intake stroke, thus reducing the pressure loss through the intake port during the intake stroke. The angle that the crankshaft turns between the intake valve opening and the exhaust valve closing is called the valve overlap angle.

Of course, scavenging does not occur at all speeds. At low speeds, the throttle valve reduces the pressure in the intake manifold, such that the intake manifold pressure is less than the exhaust manifold pressure. In this case, a small portion of the combustion products enter the intake manifold, to be pulled back into the cylinder on the intake stroke. Additionally, the combustion gasess in the space above the piston at top dead center are not scavenged. Even so, at low power settings this is not a problem.

CONCLUSION- In general, we have seen that the torque, and thus the horsepower produced by an engine depends on the amount of air that can be pumped through the engine. The more fuel/air charge drawn into the cylinder, the higher the volumetric efficiency. The higher the volumetric efficiency, the higher the torque. The biggest factor affecting the volumetric efficiency is the valve timing, specifically the valve overlap angle and the intake valve closing angle. Volumetric efficiency can also be improved by the intake manifold design. Since the camshaft used determines the valve timing, changing the camshaft will change the shape of the torque curve, and thus the horsepower curve.

Exhaust Reversion

Exhaust Reversion

There is a myth that an earlier opening of the intake valve even by 2 or 3 degrees causes the phenomenon known as reversion. This misconception is false from which other incorrect conclusions are made. When you focus on overlap you are on the wrong end of the cam-timing event.

Reversion or the effect of the backing up of the intake fuel air mixture is normally associated with longer duration high-performance camshafts, is actually caused by the intake valve closing later. The answer is in the basic principles of physics. just as with trigonometry and geometry the truth does not change because a person chooses to ignore it.

When the intake valve opens some 40 or more degrees before T.D.C. at the end of the exhaust stroke, very little exhaust gases remain in the cylinder. The piston is close T.D.C and no threat is posed to the incoming intake charge.

A false reversion theory when taken to an extreme would lead to a false conclusion that any overlapping of the intake and exhaust valves is totally undesirable. Engineers of the late 1800’s and early 1900’s used to think this way and they feared of overlap so much so they actually employed negative overlap of – 5 or -10 degrees to be sure none would occur.

The results were that these engines were severely limited to low speeds and marginal output. Engineers in the early 1920’s performed experiments with longer duration cams and proved that camshaft overlap fears are false, as both power, RPM and performance were actually improved. These engineers demonstrated that overlap did not cause engines to lock or backfire.

To further prove that reversion is not caused by earlier intake opening and the resulting extension of valve overlap, look what happens when you advance any camshaft, the intake and the exhaust valves open earlier, this advancement of the cam does not cause more reversion, yet throttle response and torque are improved.

If this myth were correct an engine would run poorly especially at lower RPM. By investigating what is occurring on the other end of the valve timing event will give you the explanation.

When a camshaft is advanced, not only do both valves open earlier but they also close earlier and there is the answer to reducing intake reversion. Closing the intake valve earlier and the reversion of the intake charge as the piston rises on the compression stroke will be reduced. It is not a mystery it is just the truth.

Exhaust Performance Criteria

Exhaust Performance Criteria

When the piston approaches top dead center the spark plug fires a spark kernel igniting the fuel mixture into a fireball just as the piston rocks over into the power stroke. The piston transfers the energy of the expanding gases to the crankshaft as the exhaust valve starts to open in the last part of the power stroke.

The gas pressure is still high (70 to 90 p.s.i.) causing a rapid escape of the gases. A pressure wave is now generated as the valve continues to open. Gases can flow at an average speed of over 350 ft/sec, but the pressure wave travels at the speed of sound (Mach 1) and is dependent on the gas temperature. The expanding exhaust gases now rush into the port and down into the primary header pipe and then the gases and waves converge at the collector. In the collector, the gases expand quickly as the waves enter into all of the available orifices including the other primary tubes. The gases and some of the wave energy flow into the collector outlet and out the exhaust pipe.

Due to the above there are two basic phenomenon that are created in the exhaust system, gas particle movement and pressure wave activity. The absolute pressure difference between the cylinder and the atmosphere determines gas particle speed. When the gases travel down the pipe and expand their speed decreases. The pressure waves, base their speed on the speed of sound (Mach 1). The wave speed also decreases as they travel down the pipe due to gas cooling, the speed will increase again as the wave is reflected back up the pipe towards the cylinder. All the time the speed of the wave action is much greater than the speed of the gas particles.

Waves behave much differently than gas particles when a junction is encountered in the pipe. When two or more pipes come together such as in a collector, the waves travel into all of the available pipes backwards as well as forwards. Waves are also reflected back up the original pipe, but with a negative pressure. The strength of the wave reflection is based on the area change compared to the area of the originating pipe.

The reflecting negative pulse energy is the basis of wave action tuning. The concept is to time the negative wave pulse reflection to coincide with the period of overlap this low pressure will pull in a fresh intake charge as the intake valve is opening and helps to remove the residual exhaust gases before the exhaust valve closes. This phenomenon is controlled by the length of the primary header pipe. Due to the critical timing aspect of this tuning technique, there may be areas of the power curve that may be harmed.

The gas speed characteristics is a double edged sword. Too much gas speed indicates that that the system may be too restrictive hurting top end power and too little gas speed tends to make the power curve very peaky hurting low end torque. Larger diameter tubes allow the gases to expand and this will cool the gases by slowing down both the gases and the waves.

Exhaust system design is a balance all of these events and their timing. Even with the best compromise of exhaust pipe diameter and length, the collector outlet sizing can optimize or minimize the best design.

The bottom line on any racing exhaust system is to develop the most useful power curve. the final design is how the engine responds to the exhaust tuning on both the dyno and on the race track.

The following components must be considered, Header primary pipe diameter whether constant size or stepped pipes, the primary pipe overall length, the collector design including the number of pipes per collector and the outlet sizing and the megaphone design.

The header pipe sizing and the primary pipe sizing is related to exhaust valve and port size. A header pipe length is dependent on wave tuning. Usually longer pipes tune for lower r.p.m. power and the shorter pipes favor high r.p.m. power. The collector package is dependent on the number of cylinders, and their configuration firing order and their design objectives and the collector outlet size is determined by primary pipe size and exhaust cam timing.

Porting (general)

There are two ways to port cylinder heads: The right way and the wrong way.

The right way is to refine the flow characteristics of the head and intake manifold so as much air as possible enters the cylinders at the engine’s peak power curve. Every engine is different so there’s no ‘standard’ port configuration that is guaranteed to deliver maximum air flow on every application. The port profile that works best will be limited by the physical dimensions of the cylinder head.

Limiting factors include the size, position and angle of the stock ports, the size configuration and angle of the valves, the thickness of the casting around the ports.

But other factors must be taken into account, too, such as engine displacement, the engine’s bore and stroke, the shape of the combustion chambers, compression ratio, the depth and angles on the valve seats, total valve lift, camshaft profile (duration, overlap,), and type of intake manifold and induction system.

One of the basic goals of head porting is to minimize obstructions so air can flow relatively unimpeded from the throttle plate to the valves.Two things that get in the way are the valve guides and valve guide bosses. Using valves that are necked down just above the valve head improve the air flow.

Transition areas in the port also need to be reworked so air will flow more easily around corners with a sharp radius and into the seat throat just above the valves. Any sudden changes in the cross-section of the port can disrupt this effect and restrict air flow.

The point where the intake manifold and cylinder head intake port meet also is a critical area. If the runners in the rubber intake manifolds are not perfectly aligned with the ports in the head, sharp edges can interrupt normal air flow and impair performance. The same goes for exhaust ports. The head ports must be aligned with the header openings so the exhaust gases can pass freely out of the engine without encountering any sharp edges or obstacles.

The right way to improve air flow is to locate the best places to remove metal. This takes experience, knowing what changes work and what ones don’t and using the right tools for reworking the various portions of the ports, valve pockets and intake manifold

The wrong way to go at it is to grab a die grinder and start hogging out the intake and exhaust ports with no idea of where you’re going or what you’re trying to accomplish other than to open up the ports.

Bigger is not always better. Grind away too much metal and you may end up ruining the casting. But even if you don’t grind all the way through, removing metal in the wrong places can actually end up hurting air flow more than it helps.


Big ports with lots of volume will obviously flow more air than a smaller port with less volume, but only at higher rpm. A lot of people don’t know that. At lower rpm and mid-range, a smaller port actually flows more efficiently and delivers better torque and performance because the air moves through the port at higher speed. This helps push more air and fuel into the cylinder every time the valve opens. At higher rpm, the momentum of the air helps ram in more air, so a larger port can flow more air when the engine needs it.

The bottom line is this, to realize the most power and performance out of an engine, air flow has to match the breathing requirements of the engine within the engine’s rpm range where it is designed to make the most power.

As a rule, the roof of an intake or exhaust port has much more influence on air flow than the floor or sides of the port. The greatest gains in air flow can often be realized by removing metal from the top of the port only and leaving the sides and floor relatively untouched. The shape of the port is far more critical than the overall size of the port. The largest gains in horsepower are found on the intake side by raising the roof of the port. On exhaust ports, if you tried to match the port to a header gasket you’d probably destroy the port. The secret of exhaust porting today is not how big the port is, but the shape of the port and the velocity of the exhaust flowing through it. Any time you start making the ports bigger on the exhaust side, you usually end up killing air flow in the head.

As for polishing, a smooth finish is great for exhaust ports, but a rougher finish flows better on the intake side. A slightly rough surface texture in the intake ports creates a boundary layer of air that keeps the rest of the air column flowing smoothly and quickly through the port.

Intake porting

You can optimize the short-side turn of a cylinder’s intake port by expanding the sides of the port. This is necessary in order to address both of the aspects in order to make the turn more effectively and to compensate for the valve guide boss and valve stem which uses some of the available cross sectional area. A well streamlined valve guide boss can enhance results especially swirl rather than hinder it. Expanding the cylinder head walls helps to accomplish the filling of a cylinder when the port and valve is feeding a pair of intake valves in a multi-valve head.

When cylinder head modifications are limited to removing metal dealing with the short-side turn means making the most of whatever is already there. Most production heads have a more abrupt turn than is necessary due to the result of machining the valve throat below the seat. Rounding this off is the best possible solution to what can be done to improve the form of the short-side turn, once the smoothing out of the contours in the valve throat have been completed.

The best way to get the air to move to the back of the valve is to slow it down so that it can make that turn, expanding the intake port’s wall area creates a significant change. When the port is progressively widened and the intake port’s roof is raised in the turn area the slowing of the air just before it reaches the valve can create some substantial HP and Torque gains.

The majority of the air wants to flow in the top half of the intake port, so that area should be favored when removing metal. The increase in cross-sectional area in the valve’s throat area will also create an improvement by converting some of the high velocity into pressure energy, thus intensifying the air / fuel mixture charge into the cylinder.

Exhaust porting

Even when the exhaust valve is at relatively low lift, the exhaust gasses can exit the exhaust valve’s seat area at super sonic speeds, during this phase the exhaust gasses responds more to the opening area of the exhaust valve rather than the shape of the exhaust port.

As the exhaust valve’s lift increases, the exhaust gas velocity drops to subsonic, and now the shape of the exhaust port becomes the overall factor towards creating high flow. It is also worth noting that for a given size, an exhaust port flows better than an intake port. This is due to the fact that as the exhaust passes from the cylinder into the exhaust port, the flow becomes more organized, which is just the opposite of what takes place at the intake valve.

Another condition that helps the exhaust gasses reach a higher flow efficiency is due to the exhaust valve is typically lifted higher in proportion to its diameter than the intake valve, thus creating the situation that the valve head spends more time out of the influence of the exhaust valve seat.

If an exhaust port has a steep up draft angle and a large short side turn, then the exhaust port begins to resemble a venture like nozzle and a pressure recovery will occur after the gases have passed through the port’s minor diameter. If an exhaust port has a reasonable up draft angle and a short side turn, it will work well for evacuating the cylinder’s exhaust gasses.

Due to the way the exhaust works, a good exhaust port must have an efficient approach to and from the actual exhaust valve seat, otherwise there will be no effectiveness no matter how good the rest of the exhaust port is.

For a general rule, the minor diameter right under the valve seat needs to be 85% to 88% of the exhaust valve’s diameter. Additionally the outward taper from the minor diameter needs to be about 4 to 6 degrees. When the port area gets to be equal to the exhaust valve, for most purposes, it is as large as it needs to be. Also you must make sure there are no low flow spots in the port, as these areas will amplify the low-speed losses seen with Hi-performance camshafts.