"finished" my backwards spinning upside down suspension "dirt" bike

StevenMain

New Member
Jul 18, 2016
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Texas
She runs, she's very fun. Been 43.8 mph which I feel I can still better. That was in 4th gear, I need more gear reduction and closer ratios. Also want to have a good air shock in the rear, and damped triple tree forks in the front.

Want to redesign a more attractive looking swingarm, and run a 24" rim in back with the tallest tire I can find. Also want to get something with an extreme low first gear. She will pop good wheelies dumping the clutch but wont keep em up.
 

ultralight01

New Member
Oct 30, 2016
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Hood River, Oregon
That is a beautiful bike and I love the plastics! I'd like to see how you mounted those. There's still work to be done but I'm pleasantly surprised to see that you made it into more than a chopped up Walmart bike. It looks great.

Those wheels though...
 

StevenMain

New Member
Jul 18, 2016
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Texas
Money is an issue lol... I have so much I could do to improve it. Id like some good double wall wheels, disk brakes, good suspension, and really really low gears.

Ill have worked nearly 100 hours this pay period when it's over, but as a flight instructor getting paid Hobbs time, I will probably only get about 20 hours of pay.
 

StevenMain

New Member
Jul 18, 2016
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Texas
Thanks, and for the plastics I bought all Honda CRF plastics, tank, and seat from ebay. Chinese copy known as "pitbikes" The tank and the seat and plastics all screw into each other, easy bolt together. For the tank I drilled two holes in the upper tube and installed aircraft Riv-Nuts. This made the tank bolt onto the frame rail. The seat is a seat post, cut off short, with a steel plate welded to the top. The seat was drilled and riv-nutted as well so it bolts onto the seat post plate. Too install you bolt your fuel tank to the frame rail. Bolt all your plastic mounting tabs to your seat bolt holes. Slide the seat and all the plastics as a single unit into the seat tube, and then install the two bolts that attach the front plastics to the fuel tank. Everything is very securely fastened, and looks professional, actually a very easy task considering the way I designed the frame.

Can possibly adapt same technique to a conventional old school frame.
 
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ZipTie

Active Member
Jan 8, 2016
750
48
28
Mpls Mn
First up side down engine I've seen. Darn creative...KUDOs man.
looks like that's one light dirt bike now. One can Lift it over downed trees or whatever. dnut
Zip
 

StevenMain

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Jul 18, 2016
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Texas
how the seats and plastics are attached. 4 10-32 machine screws into the seat via Riv-Nuts I implanted, and a seat post I welded up. All the plastics snap and screw into seat.. You slide the whole deal into the seat post, and bolt the front plastics up to the tank. Done in under a minute, secure as ****.

The exhaust does not get hot enough to melt anything, I've run it 25 miles and you can keep your hand on the chamber the entire time.. The motor is too lean though, I stopped after a hard 20 minute ride and hard 420*F cylinder head temp. Surprised she didn't cook.
.0
 
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ultralight01

New Member
Oct 30, 2016
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Hood River, Oregon
Dang, that's impressive and a perfect guide for what I want to do. I think you're the only member here to put plastics on a MB. Maybe the only MB builder, besides Motoped.
 

StevenMain

New Member
Jul 18, 2016
108
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Texas




unsure of what particularly is "horrendous" about it but "finished" is a relative term. It runs, it hauls ass, can toss you off the back in a first gear wheelie, and should be able to hit speeds of 50 mph, been 44 mph already not topped out.

Graphics on the plastics, a paint job for the frame, an improved more stylish swing arm, a dampening triple tree fork, a rear air shock, a fatty 24" rear and similiar 26" front, and disc brakes are all still in order.
 
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Feb 2, 2017
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California
No offense, I just think it's silly to make a bicycle look like a dirt bike, but to each their own. I mean, it's not bad looking, it's a pretty clean build....... but like I said, I just think putting dirt bike plastics on it look weird. With that said, if your numbers are honest and correct, that's a pretty fast effin' dirt bike, errrr I mean bicycle. :p
 

StevenMain

New Member
Jul 18, 2016
108
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Texas
the 44 is honest 43.8 to be exact, but that was my fastest speed after a romp around town and I never really got it completely topped out. 50 is a ballpark anticipation.
 

MEASURE TWICE

Well-Known Member
Jul 13, 2010
2,449
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CA
I like your creativeness.

Of all the motorized bicycles it has to have the most comfortable seat. If you could get it legal for trail riding where you are if stickers are necessary, then just one thing more would be neat. This would be having the pedals the option to both be at the same position and locked in place as foot pegs.

Going on trails for motorcycles I have limits with my suspension and the smaller tires, but it has been fun, you have to watch out. Standing up about 75 % of the time can be the norm I understand whatever seat is used.

My off road only legal bike I welded over the crank area for the pedals that were removed and traded for pegs. Just recently I swapped in place a newer used Briggs 3.5hp 4 stroke off an edger. Now I am completely realizing how much power I was limited to by a worn out engine I will be overhauling. Then it will be my extra or spare parts.

I also found that the mini bike fold up pegs are good, but when going through mud and water I'm needing to either replace with metal grate pegs, I wear all off road motorcycle gear so the boots are good for those. I might for a shot see how traction could be helped with glued on non-skid walkway stuff that is like sand paper.
 
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Tony01

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Nov 28, 2012
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sf bay area
That head tube angle seems a little far out, I bet the handling is kinda wonky. Did you sleeve the frame before you welded it? Bike looks good.
 

StevenMain

New Member
Jul 18, 2016
108
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Texas
I'm dying to get some footage of it on some off road bike trails. For one.. going 25 mph off road on a bike trail would seem insanely fast and I can hit that in a hurry.. jumping curbs and such doesn't really do it for me.

As for the caster angle on the head tube or the rake... it's perfect, everyone who rides the bike says they wouldn't change a thing, and when can they get one lol. The increased rake allows for more responsive low speed handling, and more stable high speed handling, also allows the front suspension to work better. It was 100% on purpose.
 
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Barnfresh

Member
Sep 5, 2011
202
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Nor-Cal
It sounds like an awesome custom build. I would love to see photos of this bike. All I see is X marks where the photos were. Links to pics or video would be greatly apreciated. Thanks in advance, ~BF