Cylinder Head Work

In order to extract maximum performance from your engine, it is usually necessary to modify the cylinder head.  Without doing this, you will never see big performance gains, regardless of what else you chuck into it.  Big camshafts may allow more air into the engine, but if the head is already causing a restriction then this is the first area that needs improving.

As they come out of the factory, cylinder heads are machined to a very basic specification and the tolerances are quite loose.  The picture below show a typical cylinder head.

      

You will notice that there is a rough cast finish to the ports and combustion chamber. There is also a very sharp ridge left from factory machining as indicated above. These areas are extremely bad for airflow and need to be smoothed out.  Below is a picture of a combustion chamber and parts that are nearing finish.  Notice here that there is no sign of the ridge anymore.  Also the casting marks have all been smoothed out and the combustion chamber and exhaust ports will eventually be polished to prevent carbon buildup.

You may also notice in the picture above that the valve seats are now multi-angle.   Standard heads usually have anything from 1 to 3 different angles with the valve seat nearly always being at a 45 degree.  We modify the seats using a MIRA valve seat maching centre which can create pretty much any seat from simple 3-angle to full radius.  This improves airflow and also ensure that the valves are seating perfectly, as most used heads will have worn, pitted and often poorly machined seats.  Just remember, any leakage here will cost power!

When a customer asks for a gasflowed head, there are a couple of options available. As shown above, the head can be improved by cleaning up and matching areas in the ports, re-machining the valve seat area and also re-working the combustion chamber. The other option available and also what is required for a great spread of power and also big power numbers is to reshape the ports on many modern bike engines. Even the latest so-called cutting edge supersport bikes like the 06 CBR600 and 06 R6 suffer with poorly designed ports. Properly reshaped, the example engines mentioned here will show more than 10bhp peak gain, 10bhp mid and develop useable drive from about 3,000 rpm earlier than the stock ports. The work required in this is extensive and hence the cost is at least double that of regular port work.

Below are a couple of reshaped inlet ports. Port reshaping is done using epoxy resin. The type we use does not come loose after 2 days like some stuff others use. We have heads still running after years without this coming loose.

On the left is a 2002 R1 inlet port mold. The upper mold is the standard port and the lower is the modified one. It clearly has had a lot of work done in raising the port floor, reshaping the turn into the chamber and much more than is not visible in this picture.

On the right is a 03 cbr600rr port reshape. The upper is stock and the lower is an early development mold. Again, you can see that it looks completely different.

   

In addition to the above inlet port modifications, the exhaust ports are sometimes reshaped. This is done using our 300Amp Tig welder and again this adds considerably to the amount of work involved.

Unfortunately, due to the nature of our work, we cannot show too much information or too many pictures, so some of the pictures are very early development ones. Hopefully what you see here will give you a brief insight into the nature of our work

As you can see, we are very serious about the amount of work that goes into our cylinder heads. We are also constantly developing heads on the flowbench, dyno and racetrack and don't rely on the results of any one solely, but combine data from all areas to further what we do. What we do is 2nd to none at this level of headwork and the attention to detail and attaining perfection is borderline madness. Many people in the head porting business will just run a sanding roll down your ports and use words like 'port and polish', then take your money. Others will drive up your compression and fit big cams and all you get is a good peak HP number with shit midrange. Have a look at our dyno pages just to see where we are at, with many of these incredible engines using standard parts which goes to show just how important the head actually is. Any further questions, feel free to give me a call or drop me an email.

See the Flowbench page for further information.

All heads that we modify are inspected before work commences and the customer is advised of any forseable problems.  All work carried out will be matched to your budget, so prices can be customised to suit.

For further information or to ask any questions, please email us