motor won't fit bike???? (pedal crank clearance)

Discussion in 'Frame Mounted Engines' started by dxgrenke, Dec 8, 2006.

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  1. dxgrenke

    dxgrenke Guest

    After buying one of those great looking little motors I tried to put it on a old but very good Bianchi 15 speed mountain bike.

    The problem is that the engine itself is about 1\4" too wide so I can't pedal the bike. If the motor is centered the left side hits if I uncenter it the right side will hit. Also tried it on wifes bike with same problem.

    I hesitate to buy a new cheap bike because it is diifficult to get a percise measurement between cranks and may end up with same problem.

    Any ideas???????


  2. gone_fishin

    gone_fishin Guest

    welcome, dxgrenke :)

    let's start with: what engine do you have, exactly? if you're not sure, can you post a pic?

    i suspect you have a pull-start/auto-clutch version, maybe? if that's the case, those engines require a wider crank & usually include one in the kit.
  3. Butch

    Butch Guest

    Clearance Problem

    I had the same clearance problem when trying to put a 70cc on an older Trek MTB. I have put the same motors on several Schwinn bikes with no clearance problems. You may have to spring for a new bike.
  4. gone_fishin

    gone_fishin Guest

    i didn't think the regular 50/70's would present that problem, that woulda blown my budget to have that happen. anyway let's see if we can get specific engine info from dennis.
  5. dxgrenke

    dxgrenke Guest

    What kind of motor??

    Can't find name or info. on the motor.
    In the "Gallery" it looks exactly like: "Grady Howell's Latest Build"
    "My Green Machine"
    "My Blue Junker"
  6. gone_fishin

    gone_fishin Guest

    ok, then, here's my input: since you'll have to go single-speed on the front sprocket anyway, why not consider finding an appropriate crank for the bike you already have?
  7. go to your local bike shop and ask for pedal extenders. soeone on the forums before had mentioned that such a thing exists.
  8. gone_fishin

    gone_fishin Guest

    i'm not sure the extenders are the solution, isn't it the crank-arm itself that's not clearing?
  9. srdavo

    srdavo Active Member

    Nov 4, 2006
    Likes Received:
    I had the same problem with my mt. bike. it has 3 pc. cranks. the crank arms were straight...I found some crank arms that were off-set & they worked fine. The main expense was buying a crank arm puller. works just like the sprocket puller on our lil chinese babies. your local bike shop can help you out.
    hope this helps
  10. Tom

    Tom Active Member

    Aug 4, 2006
    Likes Received:
    I dont really think you can do anything but bend the cranks if they are one-piece. And that would really screw things up.

    What I did is first buy the motor, and then bring the dang thing with me when I went to look at used bikes. There was one bike I was going to get, but it had that same problem, so I ended up not buying it.

    Everyone thought I was crazy when I would come look at their bike then bust out an engine to size up.

    Finally, I found some dude on craigslist that buys huge lots of bikes and works on them and sells them, and he was having a huge sale, so I just brought my engine down, and found the perfect bike.
  11. davidsis

    davidsis Guest

    Engine too big

    Couldn't a person just messure the distance from that center post to the engine? Or how do you messure so the engine fits?
  12. gone_fishin

    gone_fishin Guest

    what an unexpected issue, huh? well, 1-piece crank, try to find someone to sell you one from the 60cc pull start kit. 3-piece crank, dunno what to tell ya.

    base your final decision on how well the engine fits your frame, also.
  13. davidsis

    davidsis Guest

    Three piece crank

    Well, normally does a 3 piece crank have clearance issues?
  14. Edward

    Edward Guest

    Most of the time this is not an issue. For an idea of the types of bikes that can easily be fitted look at the gallery. Some require some cutting like the OCC Pacific Bicycle required a slot the length of the clutch cover to clear the pedal chain.
  15. dxgrenke

    dxgrenke Guest

    thanks to everyone, its now fixed!!!

    Took the bike to bike shop, this town so small (Kanab, UT) only has one and he just open 1 day a week, what he did was to take off my straight cranks and replaced them with new cranks that flared out. I didn't think they would fit because my bike is so old but all is now well. cost=$47.00.
    Can't wait till it stops snowing so I can get out to the garage and continue on my project.
    Thanks again for all of you that took the time to post. I appreciate it very much.