Twin Cam Head Work

Harley Davidson changed their valves and guides to a 7mm stem in 2005 and in 2006 they improved the core casting to feature bigger exhaust ports and a raised intake floor. Due to this improved design, there is less work involved in porting the 2006 onwards heads, and this is reflected in the price. I have designed three head porting packages for the Twin Cam - The Street Port, Street Port Plus and the Pro Port.

The Street Port

This is an economical and effective way to improve torque on a limited budget. This service is designed with mild cams up to 0.510 inch lift for 1999 - 2006 heads and up to 0.550 inch lift for the 2006 and onwards heads.. The Street Port retains your stock valves, springs and guides and is suitable for 88 or 95/96 inch motors. Heads are received, stripped then the ports and combustion chamber soda blasted and inspected. The valve seats are given a performance multi angle and radius profile and blended into the bowl area of the port. The casting imperfections are removed and the short side radius flaws are addressed. All seats are vacuum tested to ensure a gas tight seal and valve to valve clearance at TDC is checked. The gasket surface is then diamond cut to give the correct compression for your choice of cam before being fitted with new valve seals and returned to the customer.

£ 300 All production years

The Street Port Plus

This is my most popular service and it consists of the same steps as the Street Port but also includes some additional power producing features. The intake seating areas are enlarged and blended to allow fitment of high performance 1.9 inch racing grade stainless steel intake valves which are complemented by matching specification 1.57 inch exhaust valves. This ensures more flow throughout the lift range and also the correct exhaust to intake flow ratio. On pre 2006 heads the intake guide is shortened and re profiled and the weak exhaust port is corrected. All seats are vacuum tested to ensure a gas tight seal and valve to valve clearance at TDC is checked. Assembly is completed with valve to valve and valve to piston TDC clearance checks and fitment of viton valve seals. This service maximizes performance from any cam up to 0.510 inch lift on pre 2006 heads and up to 0.550 lift on the later heads. There is the option for a valve spring change from dual to single beehive springs on the early heads. This allows the use of cams up to 0.600’ of lift. Suited to 95, 96 and 103 inch motors.

2006 to present heads £400

1999 - 2005 heads £500

The Pro Port

This is an advanced service for maximum performance and is designed for cams between 0.510 and 0.625 inch lift. It is best suited to motors from 95 to 110 cubic inches. Received heads are flow tested then stripped, soda blasted and inspected. The stock guides are removed as this allows greater access for far more extensive porting work to be done. The ports are then formed to ensure optimum velocity at the throat and valve seat area whilst delivering the higher volumes required for bigger motors. The inlet seats are replaced if required to match the inlet valve size and I then fit correctly sized long life manganese bronze valve guides which are shaped for maximum flow. The intake seats are cut with a multi angle profile to match the valve size while the exhaust is given a multi angle and radius profile. Next, new high performance racing grade stainless steel intake and exhaust valves are fitted along with new Viton seals. Valve sizes are determined according to the flow ratio requirements, cam demands and the riding habits of the customer. Intake valves can be from 1.9 up to 1.99 inch and exhausts are1.57 or 1.61 inch. Head assembly is completed with new premium beehive springs, which are stronger than stock, to allow better valve control at high rpm. Pre 2006 head exhaust ports are given a D shape to optimize flow and minimize reversion. Finally the combustion chamber is diamond cut to the required volume to give the correct compression ratio, blended into the valve seat area and hand polished to resist carbon build up. The heads are then checked for valve to valve and valve to piston TDC clearance before being tested on the flow bench and returned to the customer.

2006 to present heads £550

1999 - 2005 heads £650

CVO head work for 110 inch engines

The stock CVO 110 cylinder head castings come with manufacturing flaws that can be improved upon to give a sharper throttle response. I replace the stock 2.080" intake valve with a 2.120" or 2.15" valve which changes the throat ratio. This modification changes the speed of the intake charge passing through this area thus increasing cylinder fill efficiency. The CVO service includes new intake valves, intake and exhaust port work and diamond cutting the gasket surface to set the combustion chamber to achieve the desired compression ratio for the cam. Early castings may also require guide replacement.

All production years £300

CVO head work for 117 inch engines

This service consists of all of the steps described for 110 inch builds but with the addition of a 1.65” exhaust valve and the associated port and valve seat work. As higher lift cams are appropriate for this level of performance there are also steps included to restore valve train geometry.

All production years £400