C1930 Vintage motorcycle Sunbeam Model 9 Cylinder head Twin Port

C1930 Vintage motorcycle Sunbeam Model 9 Cylinder head Twin Port


Circa 1930 Vintage motorcycle Sunbeam Model 9 Cylinder head. Twin Port version.

I have had this Sunbeam Model 9 cylinder head for a few years. I had a 1930 saddle-tank Model 9 and kept quite a few spares. I especially made the point of holding parts for the engine and gearbox, including most of a 1930 engine. I have now sold the bike and some of the spares.

I have to admit that I don’t have a parts book. So, I can’t check this Sunbeam Model 9 cylinder head against others. I know that Sunbeam had a habit of changing quite a lot of parts either side of 1930, so please study the images and decide whether it’s correct for your needs.

Things like the angle of the inlet manifold will help to determine which model / year it’s from. However, dimensions usually sort it out. So here are some dimensions for you:

Centre to centre of studs:

  • Between front studs: 3-1/4″
  • Between rear studs: 3-1/4″
  • Between front and rear studs: 3-1/4″

Carb manifold:

  • Outside diameter:  1-7/8″
  • Inside diameter (top of threads):  1-5/16″

Combustion chamber:

  • Max width of cylinder barrel seat:  4-1/2″
  • Width of chamber:  3-1/8″


Condition of the Sunbeam Model 9 Cylinder head

C1930 Vintage motorcycle Marston Sunbeam Model 9 Cylinder head Twin Port

Twin Port Marston Sunbeam Model 9 cylinder head

The head has a few broken fins as shown in the images. The threads could do with a good clean but they don’t look damaged or cross-threaded. One thread is a bit better than the other. The carb manifold threads are decent.

One valve guide is broken as shown.

Bottom line: This twin port Sunbeam Model 9 cylinder head isn’t pretty but it will do the job with some work. If you want to make it pretty by repairing the fins, it’s possible.

These are not easy to find. Even if you don’t need it now, it’s probably worth having on the shelf.

Other Marston Sunbeam motorcycle parts

If you are looking for early saddle tank Model 9 Marston Sunbeam engine parts, I have a bit more than this rocker box. Please check the other adverts for availability, or ask. When I began, I had the following: (They are not included in this sale), so please go to the SUNBEAM SPARES here.

  • Engine cover plate
  • Inner timing cover
  • Outer timing cover
  • Rocker box with rockers
  • Cylinder barrel
  • Piston with pin
  • Two cams
  • Pair cam followers

The engine kit was bought as an insurance policy as I used to have a 1930 Marston Sunbeam Model 9. It worked, as the bike never needed any of these spares.



Shipping is charged ON TOP of the price for the item. There are too many variables to include shipping in the checkout, so please contact me before you buy and I will give you a shipping price.

I usually ship to most destinations.

International shipping available. Let me know where you are and I will send you a price for shipping with tracking

Combined shipping available. 

Viewing: Please come and check it over before you buy. It is at PE28, near St Ives in Cambridgeshire.

Collection: If you don’t want it shipped, I have plenty of space. If you can’t collect for a while, it’s not a problem. However, I will need to be paid very soon after the sale. Thanks.

Payment: Good old fashioned money on collection is preferred. I can accept payment through PayPal or by bank transfer as well. I can accept EUROS. Please ask. 

Import Taxes: Please note that IMPORT DUTIES are not something I can control. If you are buying from outside the UK, there is a chance that you will have to pay import taxes. Import taxes vary from country to country. If there are charges to pay, it is the buyer’s responsibility to research the cost and pay the duties. The price that you see on my advert is for the item and not the item plus whatever taxes might be due.


If you aren’t already a member, it might be worth joining the Sunbeam Motorcycle Club.


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