Hello. I'm throwing this out into the universe, hoping someone has had a similar problem and solved it. I'm installing two Tanaka 47R engines on my 7-speed bike. Each has its own identical chain drive, sprockets and 5:1 reduction gearboxes. Gearboxes bolt onto each engine and have 11-tooth sprockets. They each chain to separate 72-tooth driven sprockets at the bike's bottom bracket. All three sprockets at the bottom bracket spin on a freewheel, and a single 24-tooth chainring sprocket drives the 14t-28t rear cassette.
The bike hasn't run yet. Being that each gearbox has a clutch, I figured that would keep both engines to run separately, with their individual throttles.
Twin engines CAN run independently of each other. I know this, because I built a cruiser with an engine on each tire(friction drive.)Their throttles need not be synchronized.
It's like two football players pushing a small car. One guy's using all his might, and the other player's faking it and just has his hands on the car.
It was a given that both engines' drivetrain would be spinning, even if I chose to fire up just one engine. I figured since they both have clutches which engage at about 1500rpm, the dead engine wouldn't be spinning its own clutch.
Knowing that both engines' drive trains would be turning, an engine speed of 3000rpm will have the rpms reduced by the time it gets to bottom bracket. The engine spins at 3000rpm. Its gearbox reduces it to 600 rpm. The 72t/11t further drops the revs to 92rpm.
Then something odd happens. The 92rpm from the bottom bracket now spins the non-running engine's gears. From 92rpm, it rises to 600rpm at the gearbox's shaft.....then spins that clutch and compounds(not reduces) the revolutions to 3000rpm at the dead engine's clutch!
Talk about the tail wagging the dog! LOL!
So the dead engine's clutch spins to 3000rpm, engages the engine and fires it up, if the ignition switch is on!
My question is.....do you think this will happen? I can't install 5000rpm clutch springs on the dormant engine. Then I wouldn't be able to run both engines at low speed.
Eventually, I'll find out, when the bike's done and running. I'd like to know now, if possible.
Thoughts?
The bike hasn't run yet. Being that each gearbox has a clutch, I figured that would keep both engines to run separately, with their individual throttles.
Twin engines CAN run independently of each other. I know this, because I built a cruiser with an engine on each tire(friction drive.)Their throttles need not be synchronized.
It's like two football players pushing a small car. One guy's using all his might, and the other player's faking it and just has his hands on the car.
It was a given that both engines' drivetrain would be spinning, even if I chose to fire up just one engine. I figured since they both have clutches which engage at about 1500rpm, the dead engine wouldn't be spinning its own clutch.
Knowing that both engines' drive trains would be turning, an engine speed of 3000rpm will have the rpms reduced by the time it gets to bottom bracket. The engine spins at 3000rpm. Its gearbox reduces it to 600 rpm. The 72t/11t further drops the revs to 92rpm.
Then something odd happens. The 92rpm from the bottom bracket now spins the non-running engine's gears. From 92rpm, it rises to 600rpm at the gearbox's shaft.....then spins that clutch and compounds(not reduces) the revolutions to 3000rpm at the dead engine's clutch!
Talk about the tail wagging the dog! LOL!
So the dead engine's clutch spins to 3000rpm, engages the engine and fires it up, if the ignition switch is on!
My question is.....do you think this will happen? I can't install 5000rpm clutch springs on the dormant engine. Then I wouldn't be able to run both engines at low speed.
Eventually, I'll find out, when the bike's done and running. I'd like to know now, if possible.
Thoughts?
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