Brooks Motor Works

Want an R69S with a little more zip and a lot more top-end?

I already have it all done for you. I have designed and developed a valve train system based on the principles we have incorporated into the 500cc Bonneville racebike and the results from there. I have scaled them up to the requirements of the R69S and run a 35mm exhaust and a 39mm intake with a much flatter tulip profile and a less restrictive stem. This results in a 60% weight savings over the stock system along with better breathing and much smoother running. I am running these heads on a dozen streetbikes in this area with no issues at all. Valve springs are also smaller and lighter, and we are able to run less spring pressure and reduce the parasitic loss there. All parts are new of course and include titanium upper spring retainers, custom valve guides and stem seals.

This is a fully developed and sorted system which bolts right on and gives you safe valve train operation to 8500-9000 RPM. They cost $1800.00 exchange with your rebuildable heads, or I can do your heads for you for the same cost. Turn around time is about three weeks.

Are you building the motor yourself? There are a few considerations when combining all the parts, just to be sure that everything works well together. The trick to getting REAL HP out of the motor is breathing and balance, not just 'hot-rod' parts!

What cam will you run, and what is the lift/duration? How large ( diameter ) are the cutouts in the pistons and do they go deep enough for the lift in your new cam? Are the cylinders original cast iron or coated? This will determine your choice of rings. Lots of fitting and checking and remember that the rods do stretch during high speed running as well as the piston tops will bounce. You need adequate clearance to avoid hitting a piston, esp with higher lift cams and larger valves. I'd suggest having the lifters magnafluxed and check the pushrods as well especially if you will be using the stock ones. All the 'replacement' ones seem to be stainless steel which is a very poor material choice, and they are not built as well.

If you run my heads you'll easily be able to handle carbs up to 30mm on the street with no loss of tractability. I'm currently running 38mm PHMs on the sidecar racer, and that is only a 500cc motor! But I am the first to admit it is not very happy below 3,500rpm; but then it is NOT a streetbike!

Need some help with what you are building? You can call me for a FREE consult during normal business hours ( West Coast ) and I will try and help. HOWEVER I cannot build your motor over the phone, and will not even try.

These motors have so much more to offer than is available in the stock state of tune. Let them loose and have some FUN !