Ultrasonic Cleaning Service

Mcmental ( Chris McNicoll) is a long time member of OSS and he has been ultrasonically cleaning carbs, looms and other engine components for nearly 5 years
Chris operates a 22 litre tank ) and uses an expensive, quality American designed fluid that is used worldwide in the aviation industry.  To give you an idea of what size the tank is, Chris can fit a full GSXR head in the tank as per the photo.
261352_224425774248998_851233_n 261834_224425497582359_6532749_n

For a completeGSXR head OSS members will benefit from the bargain price of £45 , including return postage.

For a bank of 4 carbs,  Chris will  strip,clean,rebuild,set float heights for just £45 and that includes insured (£200) return postage. If while stripping and cleaning he finds  anything  that is worn and needs to be replaced e.g. gaskets, o rings etc,  he will source replacements at cost and fit them free of charge.
10444639_833869266637976_6812862515526684407_n 10500446_834782759879960_1774908787221716694_n
Chris  can also clean your complete wiring loom, stripping off all the old sticky black tape and replacing with nice new non sticky loom cloth tape this costs £25 inc return postage.
23965_494228110602095_1248464122_n 251227_494243563933883_1594562823_n
If you are interested in using the service you can PM Chris through  his Mcmental trader profile in our trader section. Chris has kindly offered a free loom clean worth £25 to the winner  of our  OSS member competition. Find out more here.

About Ultrasonic Cleaning

Ultrasonic cleaning is a process that uses ultrasound (usually from 20–400 kHz) and an appropriate cleaning solvent (sometimes ordinary tap water) to clean items. The ultrasound can be used with just water, but use of a solvent appropriate for the item to be cleaned along with the soiling enhances the effect. Cleaning normally lasts between three and six minutes, but can also exceed 20 minutes, depending on the object to be cleaned.Ultrasonic cleaners are used to clean many different types of objects, including jewellery, lenses and other optical parts, watches, dental and surgical instruments, tools, coins, fountain pens, golf clubs, fishing reels, window blinds, firearms, musical instruments, industrial parts and electronic equipment. They are used in many jewellery workshops, watchmakers’ establishments, and electronic repair workshops.Ultrasonic cleaning uses cavitation bubbles induced by high frequency pressure (sound) waves to agitate a liquid. The agitation produces high forces on contaminants adhering to substrates like metals, plastics, glass, rubber, and ceramics. This action also penetrates blind holes, cracks, and recesses. The intention is to thoroughly remove all traces of contamination tightly adhering or embedded onto solid surfaces. Water or other solvents can be used, depending on the type of contamination and the workpiece. Contaminants can include dust, dirt, oil, pigments, rust, grease, algae, fungus, bacteria, lime scale, polishing compounds, flux agents, fingerprints, soot wax and mold release agents, biological soil like blood, and so on. Ultrasonic cleaning can be used for a wide range of workpiece shapes, sizes and materials, and may not require the part to be disassembled prior to cleaning.[4] Objects must not be allowed to rest on the bottom of the device during the cleaning process, because that will prevent cavitation from taking place on the part of the object not in contact with solvent

Bike of the Month July 2015

BOTM 07 2015
After so many years in the wilderness it is great to have our URL live again with a front page and a buzzing and active forum. While the Admin team that built this new site were busy running the Facebook page and plotting the return of OSS one man called Ash took the initiative to start the temporary forum. We and many other OSS junkies owe you a big fat thank you for all the work that you put in to running that forum.
To celebrate the return of the site and as a way of showing our thanks to you for all your work we want to bestow upon you the honour of being the recipient of our very first “Bike of the month”.

Bask in the glory my fiend, you earned it.

With thanks from all of us.

BTW, yes BOTM is back so get building 🙂

Discuss this post here.

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.



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.



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

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.

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.