Chain Drive Briggs Question....???

Im a bit of a newbie too, but will try and answer your question. If im wrong im sure ill be corrected. Im presuming you know you will need a clutch of some sort, and being as you want a direct line in drivetrain you will need a centrifugal clutch mounted to the motor. Which will widen your motor (needing more offset of motor). Also with a direct drive you will need a rather large rear sprocket (or alternitively a smaller front sprocket) as you need to reduce the ratio. If im wrong we will both be learning. Hope this helps

Hey Shorty. Sounds like a fun project. You will need a jackshaft for a number of reasons. First is the gearing. If you go directly from a clutch on your motor to your back wheel, it will be geared way too high unless you use a huge rear sprocket. Chain to frame clearance would be non existent without modifying. The 5hp Briggs in stock form will pull an overall drive ratio of around 7 to 1 quite easily, depending on your weight. Next, the motor offset for direct drive would prohibit any pedal clearance. The motor would be all on the right side of the frame. A jackshaft will allow you to put the motor in a convenient location and also pick sprockets that are more reasonable in size and readily available. Check out my threads and posts and see how I did mine. There's also many other members with quite a lot to contribute. I've been building Briggs powered bikes for over 20 years and all of mine are tilted forward. So lets have some photos of your bike and motor selection and the goodies you're going to use when you gather them up. Good luck.





Most of mine are belt drive with a Whizzer type double pulley jackshaft, but there is a multitude of different ways to go. Use your imagination and build one of a kind.

You have to realize all sprockets or pulleys will be on the left side because the engine PTO and the wheel drive are both on the left unless you eliminate the pedal chain drive. So the center pulleys/sprockets will be on the same shaft right next to each other. So when setting up the bike and before you mount the engine, start with the rear wheel drive. Then you can arrange the jackshaft and engine location. Otherwise you get everything installed and just have to redo it when the rear wheel doesn't line up. Water pump bearings are great to work with if the shaft is long enough. You will probable only use one side of the bearing and cut the other shaft off. The jackshaft mount can be welded or clamped to the seat post tube. Welding is better so it doesn't rotate. Making the mount adjustable will better accomodate belt/chain length selection. You can buy pulleys that bolt directly to the rear spokes like a Whizzer, or you can use a moped rear brake hub with a built on sprocket. Just a few ideas among hundreds.

msrfan,
You always have such good advice to give on these Briggs builds. I'll be following this thread to pick up a few more pointers.
SB

Shorty,
It is hard to beat the vintage cruisers for such a build. The cantilever Schwinn provides a lot of room, even for the 5 hsp Briggs which is a big fellow. Good luck and have fun working with your great grandfather.
SB

harry76,
I'm wondering if you're planning a similar drive train for your build with the 98cc Villiers? If I can locate the engine I think msrfan's drive setup solves a lot of problems, so I'm going to be watching for your build thread to learn from you as well.
SB

Shorty said:

-msrfan
not to get off topic, but is that your Torino in the backgroung of the red and black bike? If so, do you have a pic of it? Looks pretty cherry from what I can see man!

Click to expand...

It was a pretty clean car. Some damage to the driver side door and rear panel. It's a '69 Fairlane 500, 302 C4 in real good running condition. I have a friend who runs an impound lot and he sold it to me cheap. I bought it to chase parts in while my grandson and I got his IHC Scout going. The kid works the Pamona swap meet and when we were done with the car, some Ausies bought it and shipped it down under. Wish I still had it, it was a bomb to drive around town, but didn't have a use for another vehicle and I doubled my money.

Yeah, I can definitely see a 60's car in my future. Well, it depends on your tooth count on the rear sprocket. If your clutch is a 10 and your rear is, say a 44 or so, your jackshaft will probably be something around a 20 and a 12 for an overall drive ratio of around 7.3:1. A 5hp Briggs will pull a 7 or 8 to 1 overall ratio with a good top speed (around 40-45mph).

if you plan on going that fast on a bicycle you better make sure it can safely go that fast. my brother had a 64 impala with a 425hp 409 4 speed when he went off to vietnam i'd sneek it out! 14yrs old, neff said. now i cruze a 53 belair... 30mpg lots of smiles like our bikes!

Nice Torino.... Did u see the Torino that Jay Leno built with twin turbos. Very cool. I like the shape of Torino that you have more then Jays though.

Sorry just realised Jays build was a Toronado and not a Torino. My bad