Genesis 29er+ Kid's ATV engine= WINNING

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KCvale

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Feb 28, 2010
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Anyone know the dimensions of these plates?
105mm OD wide.
160mm long.
30mm U edge.

That's the crappyest of the 3 4-stroke mounts I used, the Grube 4G bases were better, and the SickBikeParts 4-stroke shift kit base better still.

This a SBP shift kit base but if you look at the front mount that is the key.
Muffle clamps provide a 360 grip of the frame tubes and a flat place to mate flat steel to.



Hope that helps.
 

Motojoe2492

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Aug 18, 2014
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Hmmm that does help indeed!

The shift kit jack shaft would be perfect for my plans! I need it to line up the drive sprocket, plus I plan on putting a brake rotor on the right side as well. This would be a nice easy mount. Would that be easy even with a wider frame?
 

curtisfox

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Dec 29, 2008
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105mm OD wide.
160mm long.
30mm U edge.

That's the crappyest of the 3 4-stroke mounts I used, the Grube 4G bases were better, and the SickBikeParts 4-stroke shift kit base better still.

This a SBP shift kit base but if you look at the front mount that is the key.
Muffle clamps provide a 360 grip of the frame tubes and a flat place to mate flat steel to.



Hope that helps.
Got a shot of the other side, thats Koooool...........Curt
 

KCvale

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Feb 28, 2010
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I seeeee now that the clamps can be any size! That thing is awesome!
Now you are getting the jest ;-}

Muffler clamps the exact diameter of the tube are just a U bolt with a piece to make it a 360 grip on a tube, a flat spot to mount to, and 2 bolts coming up to just nut on to attach something.



The 4-stroke shift kit has a pair in the back for 3 total mount points.
Note you won't need a 2-piece system or an adjustable back angle.

Just cut and bend and yourself a nice solid single piece to fit your frame.

The frame will break before mounts like this will, and what I use on anything round I want to mount something flat to.
 
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Motojoe2492

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Aug 18, 2014
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That mount and jackshaft set up is perfect for what I need. Only problem is, I can find the whole kit with new bottom bracket set up, but all I actually need is the bracket/shaft part... Where could I get just that part?
 

Motojoe2492

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Aug 18, 2014
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Just to put my design ideas out there, this is the adapting plate I will be putting on the SBP bracket and jack shaft setup. This way I will have 4 mount bolts just on the bottom of the engine holding it in place :)

 

KCvale

Well-Known Member
Feb 28, 2010
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Phoenix,AZ
That mount and jackshaft set up is perfect for what I need. Only problem is, I can find the whole kit with new bottom bracket set up, but all I actually need is the bracket/shaft part... Where could I get just that part?
You haven't visited SickBikes parts page yet?
http://www.sickbikeparts.com/catalog/index.php?cPath=21&osCsid=smupt31ckp1cdqrehdgtqplho0

They have the back mount assembly, keyed 5/8" shafts, bearings, collars, everything you need to bolt a JS on to the seat post.

Just add up the parts piece meal first and compare it to a whole kit, extra parts come in handy when they are free or only a couple bucks more, especially things like nuts and bolts, various spacers, etc.
 

Motojoe2492

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I had been there but I guess I didn't search correctly. I am now finding everything I needed :D I'm excited to be able to visualize it all coming together! Thank you all for your help!
 

curtisfox

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Dec 29, 2008
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My kids think i am kind of off doing bikes at my age wait till they get older. So no gifts under the tree. Yes Marry Christmas ALL.............Curt
 

Motojoe2492

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Aug 18, 2014
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I have two overall options on my rear drive train and disk brake.

One: I COULD go with the idea of the Predyno and have a rotor on my jackshaft.

In this situation, I would have the drive chain on the right side and have the pedal drive separate from the motor drive. I would have a sprocket adapter for the hub of course.




TWO: I could also use a shift kit and replace my rear hub with a disk brake one.. At this point they would amount to about the same cost, but with the shift kit I would need to weld on a caliper mount. That could pose a problem seeing as how I have an aluminum frame... So I may lean toward the jack shaft brake for that reason.
 

Motojoe2492

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Aug 18, 2014
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As far as what I'm doing now though, I have the gasket set and piston!

Just need to get rid of the old gaskets (Which is a bit more difficult that I anticipated) And put it together. Then, on to the mounting and drive chain decisions...



 

BarelyAWake

New Member
Jul 21, 2009
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I have two overall options on my rear drive train and disk brake.

One: I COULD go with the idea of the Predyno and have a rotor on my jackshaft.

In this situation, I would have the drive chain on the right side and have the pedal drive separate from the motor drive. I would have a sprocket adapter for the hub of course...


TWO: I could also use a shift kit and replace my rear hub with a disk brake one.. At this point they would amount to about the same cost, but with the shift kit I would need to weld on a caliper mount. That could pose a problem seeing as how I have an aluminum frame... So I may lean toward the jack shaft brake for that reason.
For the motor you're thinkin' of using, I'd go with option three - a combination of both the above & likely what I'll convert to.

Jackshafting these motorized bikes has become pretty commonplace so most of the issues already known, what's less common is doing it with something other then a kit or utility engine. What's particularly interesting about these horizontal CRF clones is not only do they have substantially more HP per cc then the kit & utilities but they also already have gears - which changes the loading on the bike's dramatically.

Already borderline, with one even slightly missed shift & you could blow all the teeth off the rear cogset. Any of the inevitable derailleur hinkiness at all results in rapid wear at best & even normal long-term use, carefully well tuned as it may be - does take it's toll with hairline cracks & hammered over teeth becoming evident eventually.

This example below still only has under two thousand miles, it's (was) a decent quality cogset bought for this, not stock box store or kit stuff. I only ever missed one shift (third smallest, now missing all teeth but the one) & when I say "missed" I don't mean just the actual action of shifting, but the engine engagement. If you're freewheeled anywhere along the drivetrain you need very carefully match engine & drivetrain RPM every time you get back on the throttle or it'll spool up & essentially "neutral drop" the gears, all of the engines torque slamming into them suddenly with dire results;



...not to say it isn't doable - once bit I've never slammed them like that again, but "feathering" the throttle like that to baby the gears slows down your shifting & knowing I can sheer off all the teeth anytime with even a moment's inattention doesn't give me the warm n'fuzzies miles from home. Worse yet ALL of the other signs of wear & imminent failure in that pic have nothing to do with that one minor mistake, it's all just the wear & tear of normal, careful use... and with only a stock 49cc CRF clone;



I'd suggest the disc brake hub you were thinkin' but with a sprocket bolted to the disc mount. They make 'top hat' adapters if you wish both a disc & a sprocket or you could go with the disc on the jackshaft idea, or even just rim brakes as it's the rear... but I'm not a huge fan o'them anymore for a buncha reasons lol

Hope this helped some, lookin' forward to seein' this build :)
 

KCvale

Well-Known Member
Feb 28, 2010
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Phoenix,AZ
Already borderline, with one even slightly missed shift & you could blow all the teeth off the rear cogset.

Any of the inevitable derailleur hinkiness at all results in rapid wear at best & even normal long-term use, carefully well tuned as it may be - does take it's toll with hairline cracks & hammered over teeth becoming evident eventually.
That's why I like internal shifters, it's just one perfectly aligned #410 sprocket.
I only ever missed one shift (third smallest, now missing all teeth but the one) & when I say "missed" I don't mean just the actual action of shifting, but the engine engagement.

If you're freewheeled anywhere along the drivetrain you need very carefully match engine & drivetrain RPM every time you get back on the throttle or it'll spool up & essentially "neutral drop" the gears, all of the engines torque slamming into them suddenly with dire results.
Well said.
You won't see this happen on upshifts, you see it when you are coasting at good clip and downshift in anticipation of slow down but don't need to and don't upshift back to the right gear before you lay on the power again.

One other note for 4-strokes is like electrics, when you let off the throttle there is no engine output which really makes shifting a derailleur a problem.

If you are coasting and downshift a gear or 2 without pedaling when you hit the gas again the back wheel will get with a wallop while trying to change sprockets to boot taking out the chain and many teeth.

There is an ART to riding a shifter but it's not a steep learning curve and becomes automatic in time regardless of engine and drivetrain, and then the fun riding ensues ;-}
 
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Motojoe2492

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Aug 18, 2014
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I am into the idea of the jackshaft brake and hub with the sprocket mount. It sounds like a solid plan for what I have to work with!

I will keep the updates coming ;)
 

Motojoe2492

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Aug 18, 2014
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I am curious... I have been thinking ab9ut sprocket sizes for my jack shaft and wheel, but I don't know much about gear ratios and what the most efficient combo would be.

I'm not sure about the gearing in the engine itself, but I want it to end with decent low end torque and not need to be high rpms just to maintain 30-35mph

Any help is appreciated! :)