212cc build!

Discussion in 'Motorized Mountain Bikes and Road Bikes' started by Patchy, Dec 11, 2016.

  1. Patchy

    Patchy Member

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    Hey folks, its been awhile since I've been on the forums but I have some news! After selling my motorcycle I started a new motorbike project! My other builds were with the China Girl 2 strokes and I wanted to move up in the world so I decided on a Predator 212cc engine.

    My friend and I went balls to the wall and did as much as I could afford with the engine: new cam, connecting rod, advanced fly wheel, spark plug, springs, carburetor, governor removal, and a new exhaust.

    I wanted a fattire bike for this build and after visiting a couple local bike shops I ended up purchasing a complete bike from Sikk bikes. The frame was slightly to small for the motor so I cut away at a two spots and wrapped them in fiberglass casting tape. I'm not too worried about the structural integrity because of the wrap, but only time will tell how well it holds up.

    The 40 tooth sprocket and adapter I have is .25" to small for the rear hub of this bike so I widened with a stepped bit, it worked better than I expected the bit too. Initially the exhaust was directly over the seat tube so my friend and I bent it with MAPP torches. It took about five sessions of slow bending to get the pipe in the desired location.

    I'm typing this thread as I'm waiting for the lock tight to cure, have about four hours left until we get to take the bike for a test ride. I have more photos here everyone should check out! I'm thinking of naming her Little Red, any other name ideas? Thanks for the read y'all have a good one.

    P.s Anything else I should do to the bike besides installing lights and a rear discbrake?
     

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    #1 Patchy, Dec 11, 2016
    Last edited: Dec 11, 2016
  2. Seabass

    Seabass New Member

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    Could you have just put a shorter valve cover on, instead of cutting the frame? The hemi predator has a shorter valve cover on it too, why not that one. On the go cart sites they have tons of upgrades for the hemi too.
    Well way to be ballsy cutting the frame. i will be watching
     
  3. Patchy

    Patchy Member

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    I probably could have put a shorter cover on, but I never occurred to me to look! Oh well too late now.
     
  4. wheelbender6

    wheelbender6 Active Member

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    Great looking build. I think disk brakes and lights are good priorities.
    Will you be riding on the street legally or is it an off road bike?
     
  5. TheNecromancer13

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    Your gear ratio is way too steep, you're going to need to add a jackshaft or use a giant rear sprocket. Aim for between 8:1 and 10:1. It looks like about 4:1 right now.
     
    chmn22s likes this.
  6. Tony01

    Tony01 Member

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    There is so much wrong with this build it's not even funny.

    1. You just f****d your frame. 212 woulda fit fine if you put it vertical maybe. No amount of fiberglass tape is gonna save you. That frame is gonna crack in one of those two spots and believe me it's gonna hurt. not even sure welding is gonna save you either. You can throw the frame in the trash!
    2. No front brakes??
    3. Gear ratio too tall. This isn't a 2-stroke with a 4.1:1 internal reduction. Your bike won't even move and the engine won't rev past governor rpm so all your performance parts were for nothing. You'll fry your clutch in the first hour. Either put a 65t sprocket on the back or get a jackshaft setup
    4. I hope those are double wall rims!
     
  7. Patchy

    Patchy Member

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    I would love to ride this bike legally on the streets, but I don't know Montana's laws in regards to this. More research is required. As for the gear ratio, you are right I need to find a larger rear sprocket. I was thinking of a 58 tooth gear.
     
  8. TheNecromancer13

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    58t still won't be nearly enough. A 90t might be just barely enough. Also look at tony's post, all of his points are valid.
     
  9. Seabass

    Seabass New Member

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    I think you need allot more gear reduction than that. Check them go cart sites, for about a bill you can pick up a CVT with a bracket that mounts to your motor. That would gear it down for you. I am worried about your wrap. Nhra frames are not powder coated, painted, or covered so a crack can be seen. Id unwrap and try to weld in some gussets to sure up the frame.
     
  10. ajoh

    ajoh Member

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    that frame...............Patchy i hope your life insurance is paid up, your loved ones will likely need it.....

    that damn thing is an accident waiting to happen...........


    a smart move would be to start AGAIN with a new frame, a 212 is not a toy take it serious FFS!!.........


    breaking news, man dies/seriously hurt on halfassed motorized bicycle authorities look at harsher laws an restrictions (yet another black mark against motorized cyclists).........
     
  11. TheNecromancer13

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    Na, there won't be any breaking news about this bike, the way it is now it doesn't have enough power to move.
     
  12. Patchy

    Patchy Member

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    Thanks for the replys everyone. I have ordered a jackshaft so solve the gearing issue. As for the frame, I'll get a new one. I knew cutting the frame was risky but I didn't think it would be as big of a deal as everyone is saying it is. I definitely screwed myself over but oh well, its a learning experience! It'll be awhile before I can afford a new frame, this bike will be stuck in a garage for the winter so I'll have time to fix my wrongs before I have the opportunity to ride it.

    Any good frame recommendations?
     
  13. TheNecromancer13

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    Older models of the Trek 820. My 79cc bike is an 21" 820 from the late 80s, and there would be plenty of room for the 212 as well.
     
  14. ultralight01

    ultralight01 New Member

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    The bike will be fine as a bicycle, and probably fine with a China girl, but DEFINITELY not a predator
     
  15. Seabass

    Seabass New Member

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    Im not gonna discourage you and I'm probably gonna get hammered for it. If you sure up your frame you can still make it work, how is your welding, can you tig? Do you got a mig? Remember alot of the people discouraging you can't do either��. I'm a mechanic but I can weld. I'm not the prettiest but I can garrunty a solid weld.everything and anything is save able. Now for the double wall rims, you might be alright, the amount of tire you got should be plenty to protect the rim. Dude don't get discouraged, don't get hurt, and have fun. Screw everyone telling you that you can't do this!!!! I'm an ******* for leaving you discouraging word myself and for that I'm sorry, and so should everyone else. Ride fast take chances!!!! But be careful!!!!
     
    #15 Seabass, Dec 13, 2016
    Last edited: Dec 13, 2016
  16. scratchbuilder

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    I'm agreeing with Seabass. Take it to a welding shop,they can fix it. I would have them bend me a new downtube that would accommodate the engine lower. What discouraged me on fat wheels, are those, cotton picking thin a** spokes! If your frame is alum. Disregard the above. Make it work.
     
  17. Tony01

    Tony01 Member

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    Take one of the tires off and see if they are double wall rims. If they are then you can rebuild them into heavy duty wheels. If they are single walls then I dunno.

    I'm guessing your mods will let it spin 7k, so with that in mind you wanna run an overall ratio of around 8.5 to 9 (those of us with stock motors run a 7.5:1 to go 55).

    If ya still wanna run fat I'd either brace the **** outta that frame and stand the motor straight up, or get a new frame and lop off the rear triangle and weld the fat rear to the new one. Then get fat double wall rims from one of the many suppliers and build up with some 12g spokes. Be a bada$$ build.
     
  18. Seabass

    Seabass New Member

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    Bump!!!! Just wondering what you've been doing with this???
     
  19. ajoh

    ajoh Member

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    in regards to rims only use the best double wall rims you can get my electric mid-drive ripped a single wall rim apart (pulled the 12g spokes threw the spoke holes) i the went to a double wall it was good, lasted 7000km (4349miles)

    before i found every spoke hole cracked either side of the spoke holes .5' long
    i've since changed to a rim that has double eyelets

    1st rim as seen in pic 1. 2nd rim as seen in pic 3 3rd rim as seen in pic 5
     

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  20. xXNightRiderXx

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    I have a pair of good double walls made by Vitesse that hasn't given me any problems at all. i have a 66cc china girl driving the rear one, and even with damn near disconnected spokes (several more than two or three i might add) it never went out of true. single eyelets, 16ga spokes, and 32mm valve stems, so about a 13mm deep double wall rim. this is, of course, a 700c rim, so a 26x4.25 rim is going to need a bit more, but vitesse won't steer you wrong if you can find that size.
     

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