Frank Acampora
Supreme Mariner
- Joined
- Jan 19, 2007
- Messages
- 12,004
Re: 35 hp RPM
The marks on the control handle are basically "suggestions" and will change given adjustments at the engine and at the threaded ends of the cables. ALL settings for idle and high speed are accomplished at the engine. The scribed line on this cam is different than on the three and four cylinder engines. It indicates FULL throttle whereas the three and four cylinder cams indicate only the starting setting with the butterflies closed. However, it should be set the same, with the scribed line centered on the roller. If the 2 cylinder engine is battery ignition, no tools are needed to set timing. You turn the flywheel by hand and see when the top plug sparks. Magneto ignitions need to be timed with a light while running. Electronic ignitions can be timed static the same way as three and four cylinder engines.
To the OP: Timing on these engines is more important for speed than throttle opening. The linkage is designed so that for cruising (economy) timing is almost fully advanced while the carb is only about 1/2 open. IF the engine was at wide open throttle in the photo as you stated, timing will be fully advanced. Opening the throttle fully will give increased RPM but not a great amount more. Don't expect (for example) double the RPM. A more realistic expectation would be 15-20% more.
Even with the increased RPM, don't expect much more speed from your 'toon. In fact, it may not go ANY faster. That may be why the original owner set the linkage so maximum throttle was at cruise position, figuring to save a little gas.
The marks on the control handle are basically "suggestions" and will change given adjustments at the engine and at the threaded ends of the cables. ALL settings for idle and high speed are accomplished at the engine. The scribed line on this cam is different than on the three and four cylinder engines. It indicates FULL throttle whereas the three and four cylinder cams indicate only the starting setting with the butterflies closed. However, it should be set the same, with the scribed line centered on the roller. If the 2 cylinder engine is battery ignition, no tools are needed to set timing. You turn the flywheel by hand and see when the top plug sparks. Magneto ignitions need to be timed with a light while running. Electronic ignitions can be timed static the same way as three and four cylinder engines.
To the OP: Timing on these engines is more important for speed than throttle opening. The linkage is designed so that for cruising (economy) timing is almost fully advanced while the carb is only about 1/2 open. IF the engine was at wide open throttle in the photo as you stated, timing will be fully advanced. Opening the throttle fully will give increased RPM but not a great amount more. Don't expect (for example) double the RPM. A more realistic expectation would be 15-20% more.
Even with the increased RPM, don't expect much more speed from your 'toon. In fact, it may not go ANY faster. That may be why the original owner set the linkage so maximum throttle was at cruise position, figuring to save a little gas.
Last edited: