Another Knucklehead, built via castings, as a Draw-Tech design, upscaled

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
electric motor for starting
Compatibly with the dimensions allowed by the project, this is the most powerful engine I have found.
It is a 12-24 volt drill motor, 895 low speed model: 3000 rpm at 12V, maximum torque of 5.2 kg Cm, 6000 rpm at 24V, maximum torque of 10 kg Cm .
Engine speed is further reduced 3 times with toothed belt transmission.
A one-way bearing between the belt drive and the crankshaft prevents the electric motor from being dragged when the engine is running

Electric motor.jpg



IMG_5814.jpeg


IMG_5815.jpeg

IMG_6113.jpeg

IMG_6115.jpeg
IMG_6116.jpeg


IMG_6114.jpeg
 
One of the mistakes I made while building this engine , note the rear cylinder inlet cam with the red arrow.
In the drawing I did not put the negative sign in front of the degrees of rotation, the result is that this cam is out of phase, the other 3 are ok.
I discovered this by manually rotating the engine, the rear cylinder intake valve was completely out of phase.
Several hours of work wasted , lesson learned, check out the drawings !

IMG_6186.jpg
 
Calculating the cam timing on a V twin takes some thinking. First of all you have the angle of the cylinders. Then there's the fact that the intakes are inboard and the exhausts are outboard so it's not just a matter of adding the cylinder angle to the timing events.
 
Fuel tank and CDI ignition box

The tank is made of aluminum, the box is 3D printed
The same box also contains the peristaltic pump that supplies fuel to the carburetor, the excess fuel returns to the tank.
I can regulate the fuel flow via a voltage regulator. ( 12 Volt)

IMG_6199.jpg


IMG_6200.jpg


IMG_6205.jpg
 
Just be careful with the silicon tube in the pump. Hydrocarbons in the fuel will make the silicon swell that is why you have to use Tygon type tube for fuel lines on 4-stroke models if running on petrol.

Same reason fog buster lubrication systems that use these pumps need to run fully synthetic coolant.
 
Just be careful with the silicon tube in the pump. Hydrocarbons in the fuel will make the silicon swell that is why you have to use Tygon type tube for fuel lines on 4-stroke models if running on petrol.

Same reason fog buster lubrication systems that use these pumps need to run fully synthetic coolant.
Yes I know this problem, silicone tubes are not compatible with gasoline.
I kept the pump immersed in gasoline for a week, the tubes became softer and sloppy but it still works. I don't know for how long yet.
Thanks for your advice, I will replace the silicone tubes with Tygon tubes
 
It is when they start to disolve and that gets carried into the carb needle that things get worse.

Regular RC Engine Tygon is much too hard to work within the pump, they do make a specific one for Peri pumps but not so easy to come by in small amounts
 
Great job! I'm still working on mine. Just not very fast.

Ron
 
Yes I know this problem, silicone tubes are not compatible with gasoline.
I kept the pump immersed in gasoline for a week, the tubes became softer and sloppy but it still works. I don't know for how long yet.
Thanks for your advice, I will replace the silicone tubes with Tygon tubes
I have two engines using the same peristaltic pump. I run them on methanol, which is compatible with silicon hoses, no problems a couple of years on. I add a little Castro R for lubrication as mineral oils don't mix.
 
It really does look and sound great !!
I noticed that you started it with a drill, Are you not done with the starter or was the motor not strong enough?

Beautiful work !

Scott
The electric motor that I installed cannot rotate the crankshaft.
I was hoping that by powering it with 24 Volts it could start the engine, but a higher reduction ratio is needed.
I am waiting to receive a planetary gearbox to increase the torque, in the next few weeks I hope to start the Knucklehead via an electric button.
 
What has been said, again.

Beautiful engine.

Fantastic Build.

Starts and Runs Well.

Sounds Great.

I'm looking forward to the push-button starter.

--ShopShoe
 

Latest posts

Back
Top