Metric Motorcycles Cylinder Head Service

With years of porting and cylinder head repair experience behind us, we at Metric Motorcycles can handle all of your requirements. We have a modern machine shop, equipped with the latest, most advanced tools and equipment to modify your cylinder head. For car or motorcycle; street or track; multi, twin, or single cylinder. From copper based seat replacement for titanium to fully radiused seats. Metric Motorcycles is FULL SERVICE.

To give you some idea of what is involved when Metric Motorcycles is modifying or repairing your cylinder head, we will walk you through an overview of the process we complete for every cylinder head.

Here we have a Suzuki SV650 cylinder head.

First, we assess the general condition of head. Then, we take very accurate measurements of:
A) The camshaft bearing clearance.
B) The bucket bores to make sure they are not damaged.
C) And the spark plug hole.

In some cases, such as with this five-valve head, we can make all needed repairs, but it is likely to be cost prohibitive for the owner.

If the cylinder head passes the initial inspection, it goes to Step Two.

Almost all the parts are replaceable on the head. Generally, most heads will receive guides and valves--standard or oversize. Special applications, such as for heads in race engines, will receive different seat materials appropriate for the extreme conditions applicable for high performance.

Before

In these before and after photos, we have a Suzuki GSXR 750 cylinder head fitted with Copper Beryllium exhaust seats.

After

Back to our example SV650 head, we have determined it needs +1 mm oversized valves and new guides. The seats will remain stock.

Work Begins
A) Clean heads and prepare for guide removal and installation.
B) Remove old guides and install new guides (heat up head to 280 deg to aid the process)

C) Guides are reamed or honed to size. I like to run 0.0015 to 0.0030 clearances.
D) The head is ready to have its seats machined.

Romeo and Juliet
Now, let me introduce you to Romeo and Juliet, the latest and most advanced machining equipment for any type of cylinder head work.

Juliet

Romeo

Seats are machined on Juliet using very precise carbide form tools. The form tools are designed by me and made by Newen to my specifications. The science behind it is rather complex. The only sure thing is the valve seat angle is 45 degrees. The width and corresponding angles and radii are up to the tuner. I must say we have borrowed greatly from a certain Italian race teams 4 valve specs.

Machine work gets complete and all valves get seated in to the head at exactly the same depths. This ensures perfect even compression ratios and ultra precise work.

Heads are then sent to Romeo.
The picture above left shows a GSXR head receiving a compression ratio “adjustment” let’s say. Note the depth gauge. This tool helps me maintain accuracy on the amount of material being removed. Both of these heads will be “CC’d” so that we can calculate the compression ratio.

Here we show a ZX12 cylinder head being measured for volume. Those with a keen eye will notice the enshrouding work on the combustion chamber. Those with a REAL keen eye will notice. So much material was removed that the edges of the valves protrude from the chamber.

OK, the hard work is done. All that is left is to chamfer all the hard edges around stud holes and water jackets. The head the receives a thorough cleaning. I actually wash them with hot water and soap. Miniature brushes are used to scrub each valve guide.

Cleaned, it’s ready for new valve guides seals and final reassembly.

Now stick it on one of these and enjoy.

Pricing
Pricing is for loose cylinder heads.

Trivia question: Can you guess why we named these two key machines and their fixtures Romeo and Juliet? Watch the MOVIE!