Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Csecrist12]

I am in the process of converting a 1981 Honda CM400T, twin inline cylinder. My idea is to use the timing chain connected to the crankshaft as the driving force. On a more simple term, I'm wanting to use the existing transmission matched with an electric motor and battery set up. I've done some testing so far and have had good results. I removed the pistons, the head and the stator to reduce as much friction as possible. My grandfather has created an adapter for the electric motor I have to connect with the sprocket of the timing chain. I have some photos to show where I'm at. I currently have a 48V 2000W 4300 RPM brush less motor with a matching controller (bought it on amazon because it was cheap and a lot better than the razor scooter motor/controller setup I had laying around).

My plan, since the testing seemed to work as I thought, is to mock up a 3D model of the components and start to do testing with the setup I have.

Advantages of using the transmission is obvious like a piston combustion engine. The normal ICE has a constant force from the ignition of the fuel and compressed air. It stays in the range of the set rpm's of normally 500-8500 rpm's on standard bikes. That same range is used in different gearing ratios to achieve different speeds on the pavement. My thought process is to have that same range of rpm's but with an electric motor while using the transmission to its advantage. I haven't seen a lot of others attempt such a mod, but it seems promising so far.

I also have a few videos of the system running, crudely though!

[Crissa]

Neat!  Good luck.

-Crissa

[Csecrist12]

Update:

I took some major measurements I had of my current set up, except for the chain and sprockets. The sprockets and chain in the photo is what I'm wanting to use for the gearing ratio. Based on my current gearing ratio, I am at a 46T on the electric motor side and the crnak is at a 24T sprocket giving a 1.91 ration. So If I did my math correctly, If the electric motor runs at 3000 RPM's, approximately 70% of the max RPM it claims to have, the crankshaft would spin at 7125 RPM's. The max RPM of the motor based on the https://www.gearingcommander.com/ is 8500 RPM's so at 70% of the motor capacity, it nearly reaches the max RPM of the motor itself. Whether or not the electric motor will be able to handle the other forces inside the motor case and the forces of myself on the bike and other road conditions.

https://www.blocklayer.com/   -for the pulley calculators and many other calculators. Very Handy website.

I modeled up what I have in SolidWorks and will be ready to modify and create the blocks I need and the adapters for the sprockets.

[Say10 15FX 16FXS]

Good effort but...you're trying to turn the crank, clutch, transmission, and move the whole bike with the cam chain. This chain was only designed to turn the camshaft and about 6 light valve springs (CM400T was three valve per cylinder if I recall correctly) off of the crankshaft. I doubt it is strong enough to last very long, especially without proper lubrication and tension via the guides and tensioner. I would recommend some type of guard on top of the chain so when it does snap it doesn't fly up and rip your face off! More likely it could ball up at the bottom of the case which would likely lock the crank and rear wheel.Be ready to pull in that clutch! Wouldn't a steel plate with a couple jackshafts running in pillow block bearings be a lot lighter than the entire lower end of the engine? Good luck!

[Csecrist12]

I'm going to be replacing the cam chain with a 520 chain and sprocket set as I'm aware of how weak the cam chain itself is. I had it for testing purposes before I went all in for the modification and it not work.
The jackshafts would work, but why do that when I already have the transmission and clutch sorted out with the bottom end.
I'm in the works of creating a case for the top end along with some manual tensioners, almost like a manual CCT for this application.
Definitely going to have a safe guard in place if it does snap!

[Csecrist12]

UPDATE:

So I took some time today to make the pieces I need to secure the motor I have along with a shroud for the chain to help with lubrication and safety concerns if the chain does decide to snap. A bit of a challenge having to work around the existing holes for the bolts, but hopefully my grandfather, being a machinist, can handle the parts I have for him. There's some welding and other fabrication I'll need to do as I have made the shroud around the top sprocket out of 14 GA steel.

[Csecrist12]

Cross sectional Photo

[Frank]

Interesting concept: I don't think 2000 watts will give you much performance though.  I would downsize your motor sprocket to optimize the chain run down to the crankshaft.  2000 watts might get you 30 mph so there's no reason to try to match OEM gearing requirements. 

[Csecrist12]

Interesting concept: I don't think 2000 watts will give you much performance though.  I would downsize your motor sprocket to optimize the chain run down to the crankshaft.  2000 watts might get you 30 mph so there's no reason to try to match OEM gearing requirements.

I appreciate the feedback, but I'm trying to match the RPM's of the original motor. The 2000 Watt motor was a simple stepping stone to see if the concept will work better than the small motor I had from the Razor scooter. I'm currently doing some fabrication to case to get the clearance that I need. The motor specs says the motor can reach 4300 Peak RPM, but I based my calculations on the motor hitting 3000 RPM's to allow for any friction or other performance reducing factors of the system. If the 2000 W motor doesn't perform, but solidifies the proof of concept, I will upgrade the motor accordingly.

What motor would you recommend to get the speed at which I need with the gearing I have in the transmission?

[Frank]

I would think at least a 72V system with a controller around 500A.  I used to ride a converted Suzuki GT550 with a D&D SepEx motor and 425A Sevcon controller (at 72V) and that would have been fun with a transmission.  Most of my EV involvement has been with racing for the past 5-6 years i.e. high output systems and I'm not up-to-speed on the smaller systems.  It really depends on your goals: performance, range, etc.  The nice thing with a bigger system is that with reserve power you're not always riding around at full throttle.

(edit) I should add it depends on your terrain as well.  If you're wanting to carry a lot of battery up hills you'll need more power.

[Csecrist12]

I would think at least a 72V system with a controller around 500A.  I used to ride a converted Suzuki GT550 with a D&D SepEx motor and 425A Sevcon controller (at 72V) and that would have been fun with a transmission.  Most of my EV involvement has been with racing for the past 5-6 years i.e. high output systems and I'm not up-to-speed on the smaller systems.  It really depends on your goals: performance, range, etc.  The nice thing with a bigger system is that with reserve power you're not always riding around at full throttle.

(edit) I should add it depends on your terrain as well.  If you're wanting to carry a lot of battery up hills you'll need more power.

Would that be neccessary for this application since I am using a transmission to reduce the size of the motor needed? I guess my goal is to have a longer range and II understand the battery is the limiting factor in that aspect, but my theory is to use a transmission to prolong the battery life. I understand the mechanical losses, heat transfer and friction between the electric motor and the drive train. I figured if you used a smaller system with gearing, the gearing would compensate for the for the need of a larger system.

[Frank]

Gearing will increase torque available at the rear wheel to allow acceleration or hill climbing but cannot increase overall power.  Power is primarily consumed by rolling resistance and overcoming aerodynamic forces (plus all other sources of friction).  My e-bicycle with 48V system and 40A controller can go about 30 mph and it weighs a lot less than a motorcycle.  Of course some lightweight person might be able to go faster but not much.

I think a transmission might allow you to operate the motor in it's "sweet spot" for optimum efficiency but I don't think it would be very fast, is all.  Depending on what kind of motor (PM, series brushed, etc.) available power is generally controlled by the batteries and controller.  But don't let me discourage you!  Your project is pretty cool and as long as you're learning something it's progress.  What you're doing is a good proof of concept and you can take it from there.  Just please keep posting results to help the community.

[Csecrist12]

Gearing will increase torque available at the rear wheel to allow acceleration or hill climbing but cannot increase overall power.  Power is primarily consumed by rolling resistance and overcoming aerodynamic forces (plus all other sources of friction).  My e-bicycle with 48V system and 40A controller can go about 30 mph and it weighs a lot less than a motorcycle.  Of course some lightweight person might be able to go faster but not much.

I think a transmission might allow you to operate the motor in it's "sweet spot" for optimum efficiency but I don't think it would be very fast, is all.  Depending on what kind of motor (PM, series brushed, etc.) available power is generally controlled by the batteries and controller.  But don't let me discourage you!  Your project is pretty cool and as long as you're learning something it's progress.  What you're doing is a good proof of concept and you can take it from there.  Just please keep posting results to help the community.

I greatly appreciate your comments and inputs as it helps myself understand what I have to over come with this.

Food for thought though, doesn't a normal ICE have the same combustion at different RPM's? So couldn't an electric motor have the same power output as the combustion of fuel/air mixture with a spark thus having the transmission take care of the range and speed?

Conceptual thinking here, say the combustion of fuel/air mixture is 1000W of power, but yet that same 1000W of power can be used to run a vehicle to 80 MPH in 6th of the transmission. That's the large idea thought of this project. Regardless of the power plant you use, fuel/air mixture combustion, hydrogen combustion, LP combustion or in our case, electric motor, would be able to perform the power needed to reach that 1000W requirement. Each power plant has certian modifications to allow for the details to be sorted out, but the end of the day, each power plant is producing 1000W to turn the motor and reach a speed of 80 MPH in this example.

[gregj]

A bit late for this post, but an ICE motor does NOT have the same combustion for different rpm. It doesn't have the same combustion for the same throttle openings at the same rpm. It changes with load and air flow.
Most driving time with an ICE is done at partial throttle openings and lean mixture and sub optimal power output in favour of increased efficiency of fuel.

[Csecrist12]

A bit late for this post, but an ICE motor does NOT have the same combustion for different rpm. It doesn't have the same combustion for the same throttle openings at the same rpm. It changes with load and air flow.
Most driving time with an ICE is done at partial throttle openings and lean mixture and sub optimal power output in favour of increased efficiency of fuel.

I understand what your meaning, but my approach to is was the range an ICE motor has. In any engineering application, the main points to consider are the beginning and ends of a range. Anything in between can be neglected or assumed so to say. So in my thought process, I thought of only worrying about the range of the ICE in each gear. I'm fully aware of the irregularities in an ICE based on throttle position, amount of fuel and air mixtures, yada yada. My goal is to match the range it needs to function as a normal bike. For instance, in a specific gear, 1st, 2nd, 3rd, etc. all have the same top limit of RPM's. Normal bikes tops out around 8500 RPM's in each gear. The difference with each gear is the amount of friction it has to move in response to either in motion or a static position (starting from 0). So my thought process is if I can match the RPM's under different loads throughout a trip with an electric motor, the bike should perform the same without having to have a larger motor. I understand the energy consumption and the types of batteries and what power rating I am needing to accomplish this, but I'm not testing that aspect as I am wanting to test the theory of RPM's with an electric motor and a transmission and match the range of RPM's to the original ICE.

PROJECT UPDATE:
My grandfather is currently milling down the case of the transmission to allow for a bigger, stronger chain for the connection between the electric motor and the crankshaft. Threw out the idea of having a straight crank without the counterbalance, but would have been more intense with the fabrication of such a crank. So currently, he is modifying the case along with the crank to accept a smaller sprocket and allow for a bigger chain.