Brake..Motor kill switch.

sissonscott

New Member
Jul 8, 2008
14
0
0
Boring, Oregon
Well now that my bike is all done and running great ( Boygofast 67CC motor) , I had the chance this weekend to put some real miles on it. Every thing went great except for a small incident with a large squirrel who wanted to take a very close look at my new toy. I put the brakes on and did not have enough time to pull in the clutch, I was going 20 MPH and stopped just short of him. :eek:
I was very disappointed in my stopping distance, it was way too long !! If that had been a small child or a car backing out of a driveway it could be a big problem. I realize that I was fighting the motor to some extent during this emergency stop. :(

I gave it some thought and I came up with a very simple solution:
I took one of these water resistant “micro switches” also known in this area as “Cherry switches” they are very cheap common water resistant switches, Mine came out of an old dish washer. I would imagine that just about everyone with a shop has a few of these lying around. I built a bracket out of a small piece of aluminum scrap and secured it and the switch to the handle bar support. I made a plug out of an aluminum bar scrap and made it into a movable trip, and installed it on my front brake cable. I adjusted it so that when I applied the front brake hard the switch would close, I then wired the switch to the CDI module to kill the motor. See the pictures.

What a huge difference it makes, I tried a test stop at the same speed as before and I stopped in a third of the distance. In fact I stopped in a shorter distance than I could with the clutch pulled in. The motors compression helps stop the bike when the ignition is killed. This is great !!!! (^)

This entire upgrade took 30 Minutes to build and install, and it might save my butt someday. It is so simple that I am sure that I am not the first person to build this, But my search of the forum turned up nothing like it.

This set up could also be used to trigger a brake light.

Scott
 

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joe-craft

New Member
Aug 6, 2008
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Hey it a great idea, but im worried about the engine when that happens, wont the exess load of compression hurt the head and wont the clutch have some excess wear as well?
 

eDJ

Member
Jul 8, 2008
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Wayne National Forest
I like the idea and the resourcefulness used to bring it to the finished stage. Sweet, simple, and Cheap.

On the "cherry" switch. If any of us were hunting for a switch like it while we scavenged thru old washers or dryers, about where would one of these be found. If we purchased one new would we ask for a "cherry switch" or is there a
proper name for it ? Could you post a photo of one ?

It's just my guess on killing a 2 cycle frame motor with a 6:1 compression ratio
that the engine would endure the demand of occasional emergency stops. It is afterall just for emergency conditions. As for clutch wear resulting from slippage from such stops I'd have to let others with more experience with these motors reply to that.
 

Norman

LORD VADER Moderator
Staff member
Jan 16, 2008
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pampa texas
those are called micro switches and we use them at work on level controls to STOP compressors when the liquid gets either too low or too high. they are used in all kinds of operations I've seen them on aircraft landing gears used to keep the gear from retracting when there is weight on the gear and the gear up switch is accidnetly moved to the up position just one of the many places they are used. some are normaly open and some are normaly closed.
Norman
 

sissonscott

New Member
Jul 8, 2008
14
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0
Boring, Oregon
Look at Ebay Item #290244117019, 10 of them for 10 bucks, digikey.com sells over 5,000 different styles of these, look for snap lever switches. Any appliance parts store will carry them. All electronics supply houses will have them as well. Should be under 3 or 4 bucks if you get it locally, Get the DPDT type if you want to run a stop light as well.:)

Scott
 

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2door

Moderator
Staff member
Sep 15, 2008
16,326
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Littleton, Colorado
Very cool idea. Another approach would be to mount the kill switch directly under the brake lever on the handlebars? What I invision is a button, much like the built in kill switch on my throttle twist grip, but mounted under the brake lever so a firm squeeze would activate it. Casual braking would not move the lever far enough to press the kill button but a hard application would. I'm going to experiment with this and if it works I'll let you know. It would be our answer to a truck's "Jake Brake".
 

sissonscott

New Member
Jul 8, 2008
14
0
0
Boring, Oregon
When I was first thinking about this, I thought about putting the switch on the brake lever housing, The trouble I had with it was that it would kill the engine every time I touched the brakes. Personally I did not want that to happen, sometimes I want to be able to let up on the throttle and "Kiss" the brakes a little to slow down without killing the motor. The way I ended up doing the project, I was able to adjust the tripping barrel on the brake cable so that it would only kill the motor if I really clamped down hard on the brakes. I would love to see if anyone else build this, Please post you Pics !!!:)