52cc Predator Auger Powered X-Games FS20 BMX

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16v4nrbrgr

16v4nrbrgr

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I machined up some delrin bushings I had spare from what I sell for Mercedes shifter linkages to uses as a sort of suspension for the 10mm axle I'll be putting through the bottom bracket for the standing pegs.

I might weld a nut on the drain hole on the bottom bracket for a set screw to keep the axle from turning and the pegs from spinning in an extreme situation.

I welded some fat fender washers to the bearing races in the bottom bracket, if it goes back to pedals I'll get some nice ones and new bearings. The stepped delrin bushings I made fit in the inner hole on the fender washers and will provide some damping from really hard hits, if I do this enigine mount right this bike should be okay to use on halfpipes and off jumps still.

:)
 
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16v4nrbrgr

16v4nrbrgr

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Mar 17, 2012
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Well, I was saving this joint for a special occasion, but here it is...

Once I get my work area situation dealt with, I can move forward on this frame here, which is really the only major obstacle, the rest will be little brackets, bolts, zipties, etc.

I'll have put struts to the front of the engine to stabilize it and that skid plate underneath. Should be a sweet ride, with a reliable little motor like this it will most definitely be my bottom beeyach bike for this year!
 

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d_gizzle

d_gizzle

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Would you happen to have a link to that auger? I most certainly have some frames for that. Between scooters and bmx I'm torn. But I've rode a bmx for a solid 20 years........
 
16v4nrbrgr

16v4nrbrgr

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Oh yeah it's on!

Welded up the main clamp shell for the plate that holds the frame clamps to the bottom tube. Pics later when I upload the batch.
 
BigBlue

BigBlue

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Looking good! Is this the auger and gearbox your using: http://www.harborfreight.com/15-hp-gasoline-auger-powerhead-with-4-bit-60622.html

A member Garp on the other forum made his own gearbox with a setup similar to yours, but he was not willing to share his design with the forum.
http://www.motoredbikes.com/showthread.php?29131-How-I-gave-my-motor-gears
http://www.motoredbikes.com/showthread.php?29155-How-I-mounted-my-unit-to-the-swingarm
http://www.motoredbikes.com/showthread.php?29195-Unique-gearbox-for-weedeaters
http://www.motoredbikes.com/showthread.php?29285-Electric-motor-gearbox-with-pedals

Look forward to see how your design comes along.

Thanks for sharing,

Chris
AKA: BigBlue
 
16v4nrbrgr

16v4nrbrgr

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Hi BigBlue,

Yep that's the same auger. The good news is that the motor's underrated, it's actually about 3 hp :)

That neat longitudinal gearbox looks like its from scratch, since the pedal cranks go through it and stuff. This gearbox just has a 7/8 output shaft on the left side.

Hopefully I have something to paint up tonight, step by step. I'm fabbing the components that dictate the placement of everything in the order I need them so hopefully everything will line up well first time.
 
16v4nrbrgr

16v4nrbrgr

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Thanks :)

I'm having some trouble deciding on a engine cradle design, I kinda like my original one and have been drawing lots of lines trying to figure a better one and haven't yet so I might end up going with a variation on the original paintchopped image.



It's tempting to put a lot more metal there than there needs to be, and overstylize it and just add weight. I'm using steel for this so it's fatigue resistant, so a minimal design that just ties everything together is what I need to do.
 
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16v4nrbrgr

16v4nrbrgr

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Here's a pit bike skidplate, it works out really well actually, the drain plug hole is in the right place and everything. :)

Here's where it's at so far, so many technical details with clearances and stuff. The dummy freewheel mechanism will make it so the bike won't roll backwards even off the brakes when hillclimbing, something that might be a useful trait for a trails/trials bike.
 

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16v4nrbrgr

16v4nrbrgr

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Here's what I'm gonna try and complete today.

I lucked out and found a cheap $5 14t sprocket at a local bike coop. :) Looks like I gotta tack weld it to the wheel but that's okay, if I ever replace it I'll try to get a LHD BMX freewheel hub or wheel for it, so the chain only zings around when you're gassing.
 

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16v4nrbrgr

16v4nrbrgr

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The peg sprocket's actually in front of the frame but you get the idea.

The skid plate tail will be attached to legs bolted to the old kickstand mount in between the chainstay tubes, so when you bottom it's on the frame primarily, not the engine.

I changed the design again slightly, and got the major structure fitted and tacked last night. We'll see how much I can get done, it's a reasonable thought that it might turn a wheel today! :)
 

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16v4nrbrgr

16v4nrbrgr

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You can use a four stroke on a BMX too! I was thinking someday it would be nice to make a quiet low geared four stroke bmx for hopping on the ridge trails incognito.
 
d_gizzle

d_gizzle

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Umm......huasheng 49cc 4 stroke? I'd have to have a frame modified I do believe. But if it wasn't TOO big of hit in the wallet.....
 
16v4nrbrgr

16v4nrbrgr

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Mar 17, 2012
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Yeah, that's why I don't have a HS49 in my possession yet, they are quite expensive indeed! I think one of these auger transmissions, which you can get for $100 off eBay Australia, maybe here now, would be perfect for a four stroke, it's the same pattern. The two stroke auger is nice because with a 20% off coupon you can get it for $150 together and add a service plan to it. It will make more power than the four stroke, people tend to favor these pocket bike engines over the four strokes for power and speed, but the four stroke geared to climb trees at a lesurely pace, muffled down near silent would be kinda neat I think, because pedestrians and cyclists typically don't like these things. A motorized vehicle isn't legal on the trails, but a very quiet motor assisted scooter or bicycle that doesn't ruffle feathers, well...
 
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