trying to understand cam logic more
- Thread starter JRW31526
- Start date
flattop1
Dawg 89
Interesting info .
Bbrstompit
Member
How much of this has changed with today’s understanding of these engines?
Good afternoon. I have a china clone motor, Features: 70mm piston, 18cc head, 27.5mm inlet 25.5 outlet valve. The camshaft is standard but its base is reduced to increase the lift, now the lift is + 1mm (0.270) to the standard camshaft. Springs 26lb, HD champions rockers. Carburetor Chinese clone Keihin 30mm. ARC connecting rod, flywheel aluminum PVL. This motor works with a dry clutch to enable 2500 rpm. And it is used in karting.
I would like to change the camshaft, and add the cam duration, But I am in Russia, and for me it is quite an expensive job, so I chose 2 not very expensive camshafts:
1) Camshaft, Dyno Cams Mod 2 - GX200
2) Camshaft, 272 Mongoose Performance Cam
They have about the same duration, but the Dyno Cams lift is the same as the standard shaft, I'm afraid it will give less improvement over Mongoose. ??? I would like to achieve more cylinder fill and longer intake time.
On races I use a motor with revs from 3000 rpm to 8500 rpm.
We are also now negotiating and developing an adjustable ignition for our motor. We have one ignition sample, and we are testing it, it means adjusting the advance angle to 10000 rpm.
Sorry if it sounds a little confusing, I used google translate.
I would like to change the camshaft, and add the cam duration, But I am in Russia, and for me it is quite an expensive job, so I chose 2 not very expensive camshafts:
1) Camshaft, Dyno Cams Mod 2 - GX200
2) Camshaft, 272 Mongoose Performance Cam
They have about the same duration, but the Dyno Cams lift is the same as the standard shaft, I'm afraid it will give less improvement over Mongoose. ??? I would like to achieve more cylinder fill and longer intake time.
On races I use a motor with revs from 3000 rpm to 8500 rpm.
We are also now negotiating and developing an adjustable ignition for our motor. We have one ignition sample, and we are testing it, it means adjusting the advance angle to 10000 rpm.
Sorry if it sounds a little confusing, I used google translate.
it will be a homemade ignition, my friend is now adapting it, we have the first prototype on which we are testing. It consists of a control unit with display, a sensor for the flywheel, and a coil for the moto scooter, it requires power from a battery or an integrated generator coil.
We used induction sensor is used that reacts to the flywheel magnet, the opening points of the sensor and its closing points, and the continuation between the points are also set. Thus, the ignition is adjusted to each motor. Now we have the following parameters for ignition advance: 0-1000 rpm 5 degrees in order to better start the engine, up to 1000-2500 rpm 15 degrees, 2500-4500 30 degrees, up to 4500-6000 35 degrees, and up to 6000-9500 38 degrees.
flattop1
Dawg 89
The single fire ignition modification on the Harley v twin worked good .
In the 80's they had a local class here; any 5hp flathead, stock bore & stroke, stock valves, cam lift rule, carb bore rule.
We drilled and tapped the cam for a shaft through the block, sealed with a Briggs throttle shaft lip seal. We made a small cam lobe attached with a set screw to operate a set of points under the flywheel to ground out the coil during overlap. The old tachs read 1/2 the actual RPM and the engine had a slightly deeper sound. It made a slight increase in upper RPM power,, about the same torque peak. Gave us a minor advantage.
The class was good for us Saturday night racers and backyard builders.
Best, WP
flattop1
Dawg 89
Any chance of a schematic for this digital ignition .
We have made 3 prototypes. 2 of them are powered by a flywheel magnet. And we made one to read the steel plate on the flywheel. And during testing we encountered a problem, the system with a magnet failed, a high-voltage transformer burned out in them. And the System on a steel plate is still working, but we noticed that the angle that we set and the angle according to the straboscope are slightly different by about 5 degrees.
We have a control unit, a magnetic or inductive sensor, and a coil from a motorcycle. Power is supplied from 12V or the built-in electrical system in the motor.
Sorry i used Translator.
the module has buttons and a display, where we use the formula to calculate the constants depending on the position of the sensor and the flywheel diaseter. for each motor, its own values are obtained. then we set the angles for different revolutions. Yes, the entered angle and the actual angle are different, so online tuning is required on the running motor.