I like the idea of racing a single cylinder Ducati, but the bevel singles are a little too dated for me. No disc brakes and pretty clunky transmissions. I can’t afford a real Supermono. Who can? So I thought about trying to make my own single from a twin. Turns out people have been doing this for quite a while. There are 3 different ways I have seen to do this.
1. Remove one rod piston and cylinder and rebalance the motor like a typical single without a counter balancer. A bob weight is clamped to the crank to take up the space from the removed rod.. I rejected this since it would vibrate too much and wouldn’t be able to rev high.
2. Create a pivot arm and connecting rod as a counter balancer similar to the Supermono. This is pretty complicated to construct and turns out very complicated to get the weights correct.
3. Leave the extra rod/piston/cylinder in place as a counter balancer and remove the cylinder head and replace with a perforated aluminum plate to allow air in and out.
The 3rd option seems the best to me as the L twin has perfect primary balance and nearly perfect secondary balance. No counter balancers needed and not too complicated to construct.
There is a Facebook page called Ducati Supermono Replicas where a few people have been running engines like this for years with great success.
So here is my plan.
I want to build a “proof of concept” bike that uses a lot of stock Ducati parts so I can concentrate making the engine conversion and not spend a lot of time and money on trick wheels and a custom chassis.
For the engine I’m starting with an 1100 air cooled 2 valve monster motor. So it will end up a 550 single. (Actually 539cc)
I’m using an ST2 style frame since the original Supermono used a chassis layout similar to the St2.
Curious: Will the vent in the cylinder head "cap" have an upward-facing vent and some form of breather or filter on the end? Something to keep some slight oil through the rings from escaping?
I read again and now see you did not say which head you would keep. Which and why?
I finished the “cap” and it is replacing the vertical cylinder head. I am just venting the cylinder directly to the atmosphere. Some of the supermono replicas I have seen actually put a small oil cooler right over the holes. Not sure if it actually provides enough airflow to aid in cooling.
Here is a couple of photos of the finished piece.
I also chucked up the cylinder and shaved most of the fins off.
Cool.....Thanx for posting I get the aired out head. Do you air out/port the piston crown too?? That vertical cylinder may ventilate the crotch of your leathers at 8k.
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