Will the 212 Predator fit into a 50's Schwinn cantilever frame?

[silverbear]

I'm in the early stages of planning out next winter's project, a belt drive 1951 Schwinn Hornet. I'd like to do a build along the lines of msrfan's cool Briggs builds and while still considering the 5 horse Briggs I'm also considering the 6.5 Predator. Either engine has plenty of power. I know the Briggs will fit, but don't know about the Predator. Has any one done it in the Schwinn frame?

An advantage of the Briggs engine is that there are a lot of them around used, parts are readily available and it is a reliable engine made in America. On the other hand the Predator is cheap when on sale (hundred bucks) and mated to a cvt transmission would be a pretty easy build.

Assuming it fits, Do I really need to change out engine parts if I remove the governor? I have no intention of racing this bike, revving it up to the breaking point, pushing it past 35 or maybe 40 mph. As usual, I don't have a lot of money to spend. The advantage of the inexpensive Predator disappears if you end up adding hundreds of dollars of upgrade parts. I can't do it. No, I won't be winding it out, so do I really need to invest in the upgrades?

I do want an engine with some torque... raw power is nice when you want to scoot across the intersection, start out up a hill at a dead stop, add a sidecar with a passenger maybe.

So, will the Predator fit and do I have to do the internal upgrades? Or would I be better off with the Briggs? Thanks in advance for your thoughts on this.
SB

 

[sportscarpat]

Hi Silverbear,
I am not posting to tell you it can't be done, but I have messed around enough with the 200cc clones to have discovered a few things. The torque of these motors can tear a bicycle frame apart. My first concern is the forward facing rear dropouts. You could possibly pull the rear wheel out of the frame from the torque. Making the axle nuts tighter will then start to spread the drops. I use nice heavy 3/16" plate drops, 1/2" axles, proper axle adjusters. Next up is the thinner wall tubing and 50 year old condition of the Schwinn frame. Without proper engine mounts and isolation the vibration could break the frame. These items don't even address the size of the engine relative to the frame. It would be a tough squeeze. By the time your done modifying the frame to fit and survive you could have made a bigger stronger frame! It helps to have 135mm frame spacing, too. Then you can run a bigger rear hub.
Pat

 

[silverbear]

Pat,
Thank you so much for taking the time to respond with the frank heads up. I appreciate it and know that you're a busy man. I've had the feeling that the engine is too much and I suspect that even the 5 horse Briggs is taking things to the edge. I very much want to use the bike for a build since I have a nice copper gas tank Tinsmith and I made for it a couple of years ago, a Suzuki K-10 fork set aside, a couple of nice moped hubs for lacing new wheels, etc, I think I may go another whole direction and use a 147cc Jacobson 2 stroke for which there is plenty of room and also plenty of power for my needs.

I think some of us who are less savvy about motorcycles, welding , frame design and so forth get seduced by the idea that we can buy 212 Predator on sale for a hundred bucks, turn our bicycles into motorcycles on the cheap and fly down the road at 50mph without killing ourselves.

Even the 147 Jacobson will require front suspension, good brakes, strong wheels and good rubber in order to make it roadworthy.

Thank you again, Pat. You have confirmed the nagging doubts about the wisdom of what I was considering. Part of having fun is keeping it safe.
SB

 

[scotto-]

Hey there Silverbear,
Like Pat, I can't say for sure that it won't fit, but I seriously doubt that it will without some serious frame modifications. The Kawasaki 120cc 4-stroke barely fit in my friend Pat's Schwinn of almost identical frame and it's a fair bit smaller than the 212cc. I think the Brigg's would be more suitable for what you have planned.

Have fun with the build!
scotto-

 

[silverbear]

Hey Scotto,
Thanks for weighing in on this. I've decided the 212 is too much motor aside from almost certainly being too big to fit. I've pretty well decided on using a 147cc. 2 stroke Jacobson I got from Rick's Rides this winter. It has a 1950's look to it and is small enough to pass for a 50cc. So that's the plan, subject to change of course. The Briggs would be nice and I love msrfan's builds, but I have the Jacobson and it will be an adventure using something different. I want to do a belt drive to a sheave on the rear wheel. Never done that so I guess I need to.
SB

 

[dmb]

i could not find a jacobson picture so i dont know what they look like. a 147cc two stroke should be plenty powerfull even the old ones. picture please. i really like dale's bikes he truly is a artist the way he works over his bikes and does not use store bought parts like many of us do. dennis

 

[silverbear]

You can probably find one on ebay under Jacobson "Power blast". Made in Wisconin in the 1970's I believe. They were made for snow blowers. 147cc 2 stroke with a reed valve carburetor located on the bottom of the engine. Supposed to be well made. I haven't started mine up yet. Just took these photos.
SB

 

[silverbear]

In the middle of the night in between sleeps I got to wondering about how that Jacobson is going to fit in the cantilever Schwinn, so this morning I had to satisfy my worries. It is the location of the carburetor at the bottom of the engine which has thrown me some. It is an odd location and added to the height of the engine actually makes it pretty tall. I don't have a cantilever Schwinn here in Minnesota; mine is at Tinsmith's in Maryland, but I do have an older Huffy sitting around. I drug that out and laid it on the ground, set the Jacobson in place and can see that it is likely to fit the Schwinn. The geometry of the frames has to be similar. The carburetor location is not going to be a problem and the main engine mount will go on the front down tube. The pull start can be rotated one quarter turn to put it in the right position for starting the engine while seated, so that's good. The plan is to run the power through a torque converter transmission. I don't know what problems I'll run into in switching from a sprocket final drive to a pulley going to a whizzer style sheave on the rear wheel, but I'll cross that bridge when I come to it.
Anyway, the engine will fit. I think it has a nice 1950's look to it and if I make a little metal plate saying it is 47cc the bike can fly under the radar... fly fast under the radar. Ha!
SB

 

[RicksRides]

That motor looks great in there!yup fly under the radar 40+! but if you really want a 4 stroker heres a 4hp tecumseh. she's 12.5 inches tall, 11 inches wide tip of crank to outside edge of starter cup and 10 inches front to back. Its off a power washer.

 

[silverbear]

That's a nice looking motor, Rick. About how many cc's would that be?

Regarding the Jacobson, I'm wondering about vibration coming through the frame and to the handlebars. Think that will be a problem?
SB

 

[RicksRides]

my fault thats a 5 hp tecumseh not sure on cc but educated guess would be 160-170. There will be some vibration using the jacobsen , however if you use some harder rubber washers it will greatly reduce vibration. also a set of gel grips will eliminate most vibration in the bars. use both and a good comfortable seat the only place you may notice it would be in the pedals if anywhere at all.

 

[RicksRides]

as far as using a belt and a cvt you could run chain to the jack shaft and belt from there. Isnt a whizzer clutch an external part like the cvt with a driven and drive units? If so what about using the whizzer set up. Also the shaft in the driven unit of the cvt could be replaced with one that was long enough to allow a pulley to be installed on the back side of the cvt. just a few thoughts

Rick

 

[silverbear]

I may try the gel grips. I've been making my own with foam grips covered in elk hide. Pretty comfy. Good idea using the hard rubber washers. I figured if I used actual Whizzer stuff it would be pretty expensive. I can get a torque a verter set up which has everything including the jack shaft, mounting plate and cover for a reasonable amount, less than a hundred fifty. It is set up with a belt primary at the Comet torque converter clutch going to a chain final drive coming off the jack shaft. Yes, that's what I figured is that it would take a longer shaft to accommodate the pulley instead of a sprocket and also give some room for lateral adjustment to align with the sheave. Figured to make my own sheave from a 20 or 24 inch rim. Every dollar counts when there aren't very many to start with.
Would that work OK to have a centrifugal clutch at the engine shaft with chain primary to the jack shaft and then a pulley on the backside of the jack shaft to drive the sheave at the wheel? If so I already have a clutch. Just need the pulley and jack shaft which would save some bucks. What do you think?
SB

 

[RicksRides]

converting it to belt at the jackshaft would be the easiest and likely the cheapest way out, should work well. yup whizzer clutch will cost 2-3 hundred bucks. with the cvt the rpms off the cvt output shaft will be around 5000 rpm's. the pennysworth had no issues hitting 40 with plenty in reserve w/ a 145lb rider top end of 51mph if I used a cvt the top end would hit 55-56mph that with leaving the governer intact

 

[silverbear]

Thanks, Rick,
I don't have a cvt, just a centrifugal clutch from an old snow blower. Since I'm not interested in top speed and only figure to go 35 or so, tops, I think I'll give this a go and see how it is. I can always change things later if I want. So, automatic clutch at the engine and chain drive to the jack shaft... pulley at the back side of the jack shaft to the rear wheel sheave. That should keep the cost way down. Now I have to figure out how to attach the rim (sheave) to the rear wheel on the cheap.
SB

 

[RicksRides]

ill check @ the shop we should have some sheave brackets. If we do ill send you some

 

[silverbear]

You're a good guy, Rick. Much appreciated...
SB

 

[RicksRides]

Silver bear we are out of sheave clips at the shop. sorry bud

rick

 

[silverbear]

Thanks for your generous intent and for taking the time to look. Think I'll take a look to see how Harry76 made his.
SB

 

[BigBlue]

SB,

Here's a post on how harry made his. See post #17:
http://motorbicycling.com/showthread.php?t=33843&page=2

Chris
AKA: BigBlue