cylindar forward 212 preddy

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midwestmayhem

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Dec 23, 2011
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Since I'm swapping out motor and drive system on my 5hp robin build, I figured I'd make a new thread. Currently I have just about everything for the new drive sysem made. It will be similar to the old drive system but this time it will have an additional jackshaft.

Got a question some of ya might be able to help me with. I plan on bolting a plate to the side of the motor using the 4 holes around the output shaft. Plate will be holding a spring loaded tensioner and an idler. I originally planned to use 1/4" thick by roughly 9" by 8". I picked up some that is 11/32" (a tish under 3/8") because it was cheaper. I'm starting to wonder though, is 11/32" going to be too heavy for the motor to hold? More pics coming






Update-Found a jackshaft plate made by gtc that apears to be roughly the same thickness, still wondering though. http://gtcmanufacturing.com/images/view.aspx?productId=44&index=1
 
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young grease monkey

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Sep 20, 2011
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It will be quite heavy, but I don't think it will be a problem as long as you have a good, strong mount. Also, how are you going to mount the bearings? I'm doing my first 4 stroke, a 99 predy, and I'm having trouble figuring out how I will mount the bearings for the jack shaft.
 
wayne z

wayne z

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I saw someone here a while back that used a plate like this. He bolted a billet aluminum go-kart front wheel hub to the plate for his bearing mount.
 
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midwestmayhem

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Dec 23, 2011
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young grease monkey said:
It will be quite heavy, but I don't think it will be a problem as long as you have a good, strong mount. Also, how are you going to mount the bearings? I'm doing my first 4 stroke, a 99 predy, and I'm having trouble figuring out how I will mount the bearings for the jack shaft.
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It sounds like to me that your trying to run the jackshaft of of the plate that will bolt on the side of the motor. Wayne's got a good idea, You could use flange bearing also.
QUOTE=wayne z;402976]I saw someone here a while back that used a plate like this. He bolted a billet aluminum go-kart front wheel hub to the plate for his bearing mount.[/QUOTE]

My jackshaft is held be two pillow block bearings mounted on the rear motor mount of the bike. The plate is there just to hold the idler and tensioner so I can get the rotation of the engine reversed. I should have a fair bit done be this evening, I'l try to get more pics then.
 
wayne z

wayne z

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Dec 5, 2010
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run You could use flange bearing also. QUOTE=wayne z;402976 said:
I saw someone here a while back that used a plate like this. He bolted a billet aluminum go-kart front wheel hub to the plate for his bearing mount.
Click to expand...
]

A single flange bearing won't do it. Gotta have 2 bearings. That's why I thought the kart hub was a good idea, it has 2 bearings already installed.
On my tranny I used 2 plates to sandwich the primary drive, with the snap ring bearings, one inboard, one outboard, to save space and help with keeping the motor centered, with good rear chain alignment too.

You could use a single snapring or flange bearing on the plate and fab an outboard bearing carrier similar to this, instead of a full plate like my build has.
MVC-877F.JPG
 
wayne z

wayne z

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Hey Tig Yeah that's it. I'm long in tooth, short in memory LOL

CB, I looked into using 2 flange bearings like that, but they take close to 2" of shaft length each, causing pulley alignment and space issues
 
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tigmaster

Member
Jul 17, 2011
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Not a problem Wayne!LOL!...We Aint gettin' any Younger,no matter how we ACT!...Cannonball,I tossed the two flange bearing idea at My build ,but it didn't stick....LOL!....Tigmaster....
 
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midwestmayhem

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Dec 23, 2011
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Thanks for correcting me on the flange bearings. I meant two but I didn't go back and correct it cause I figured people would assume I meant two.

Not completely done with the plate. Have to recess two of the holes and trim it down a bit.
had a pic of the chain routing but it got lost somewhere..









 
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mat_man

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Jan 29, 2011
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212cc motor powering a bicycle derailleur chain? Seems scary to me.

I love the "Out of the box" design otherwise. That motor looks so much better with a forward slant and
I am sure it will it will run cooler with better airflow. Thanks for sharing.
 
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scotto-

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
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Ridin' inSane Diego, CA.
I'm not gonna ask why, but it does have me wondering a bit. I see a fair bit of power transfer loss as well as some serious additional weight added to the bike.

Don't stop now, can't wait to see how this turns out. I hope you achieve your goal on this build, you've got plenty of power to work with at least.

dnut
 
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midwestmayhem

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Dec 23, 2011
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scotto- said:
I'm not gonna ask why, but it does have me wondering a bit. I see a fair bit of power transfer loss as well as some serious additional weight added to the bike.
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I see what you mean by the wieght and power loss. A little extra wieght on a smaller 26" mountain bike might be a good thing tho :) I think I might have found the best way to route the chain to keep down the power loss.

mat_man said:
212cc motor powering a bicycle derailleur chain? Seems scary to me.
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I have a couple of ideas on how to help beef that part up. Have to wait and see tho, no point in fixing something that isn't broken. It just might hang in there (wishful thinking)

Ya the chain routing will be similar to the robin build, only changes being the idler and the output being a jackshaft instead of the bike's crank. Pic of the routing on the Robin.

 
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midwestmayhem

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Dec 23, 2011
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Hope I didn't wait too long to post an update, this thread is getting kinda far down the list :)

Got it done and riding. I don't think I lost too much by going with the idler sprocket set up. When the motor is at idle the rear wheel will start turning when lifted off the ground.

Only complaints I have- It's kinda hard to stay on when I punch the gas, might need a better seat(I wonder why :) ) and the plastic car belt tensioner makes a bit of noise, witch I think might diminish when the plastic ribs are removed. If not, it might be worth it to swap it out for an actual idler sprocket like the one mounted directly onto the metal plate.

Not sure tho. Here in S.D. it dosen't cost too much to get a title and licence ($20-$30) what sucks is they want all the reciepts of all the things I bought/used. A fair bit of it I had just laying around. Another thing is insurance. Guy I get the car insured said $300-$400 per year :( Some of the online sites said $140-$160 per year. I'd only need insurence for about 3-4 months, weather dosen't allow much more. Right know the bike's on sioux falls craigslist. If I can get a good deal I'd part with it.

Anyway, any sugestions/comments are welcome.



 
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DTFuqua

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Jul 16, 2012
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Very unique thinking. I like it. Although, I'm still thinking about just a two gear way to turn the rotation around to put the motor in the correct way. Head forward is the correct way for a non vertical single cylinder engine like the predator. Just my preference really.
 
MotorBicycleRacing

MotorBicycleRacing

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DTFuqua said:
Very unique thinking. I like it. Although, I'm still thinking about just a two gear way to turn the rotation around to put the motor in the correct way. Head forward is the correct way for a non vertical single cylinder engine like the predator. Just my preference really.
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I don't want to hijack this cool build thread but
Joker Machine is building a bike right now that
does that.

 
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midwestmayhem

New Member
Dec 23, 2011
79
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0
southeast S.D.
DTFuqua said:
Very unique thinking. I like it. Although, I'm still thinking about just a two gear way to turn the rotation around to put the motor in the correct way. Head forward is the correct way for a non vertical single cylinder engine like the predator. Just my preference really.
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thanks. Cool idea with the gears. Back when my old yz100 was just a box of parts I was thinking about somehow putting the clutch and drive gear from it onto a motor. That way a person could get the reverse rotation and a manual clutch at the same time. The problem was the clutch is/was an oil bath, I figured making a sealed box to hold it would be too difficult for me to make because I don't have any machining tools and I figure getting someone else to make it would be too much of a hassle. It would be pretty cool tho, I'd like to see it done
 
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