Mountain Bike viability [ frame size mounting ]

Discussion in 'Spare Parts, Tools & Product Developement' started by Demosthenese, Jul 23, 2007.

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  1. Demosthenese

    Demosthenese Guest

    hello all. i'm planning on putting an engine in a 2007 Wolverine mountain bike.

    i already know that im going to have to fabricate mounts for the engine and tank due to the tubes being oversised, and i may have to swap the back disk brake out and also perhaps a wider crankset.

    the point, however, is that there seem to be few mountain bike based builds posted, and no general consensus on their viability.

    So, anyone who has built an engine into a mountain bike, what did you think? Are you still able to go offroad over grass short distances? What kind of strength is required for the engine to hold? Is going up and down curbs a problem? Basically, is the "mountainess" of you mountain bike limited with the engine, as in confined to simple cruising?

    I'll eventually be posting my own results i suppose, just trying to get info before i start ripping apart by bike :)

  2. gone_fishin

    gone_fishin Guest

    simply the mountainbike you now own capable of doing those mountainbike-y things?

    ok, good.

    now, the real question...can it do it at speed with the added weight? i think only the highest of quality bicycle can do that. i can run around on the trails here, and for the most part, the bicycle can take it. the 3/8" bolt i call a rear axle cannot. it bent slightly and began a chain-reaction of problems i'd rather not deal with again.

    my opinion: true motored-mountainbiking is prolly best done with a full suspension rack-mount system.
  3. bamabikeguy

    bamabikeguy Active Member


    Just on a lark, I pulled up a craigslist ad in Ottowa, right at the top was a NEW Schwinn Cruiser for $150, about half price. Look at that beauty.

    He says he wants a mountain bike, I see an "even steven"....
  4. Demosthenese

    Demosthenese Guest

    thanks augi!

    i guess i should clarify. when i say "mountianbikeness" i mean the mountainbike's advantages on the road over a bike built along more classic street-bike/cruiser lines, like the ability to take bigger bumps/curbs.

    on my bike i hop curbs, go over grass and gravel at speed, basically it can handle taking the hits. I dont do downhill or jumps,i just road ride hard.

    im concerned that i'll have to go to soft on it once theres an engine in it, because though the bike is strong enough, im afraid mounts/engine wont, or that vibration over grass may be more of an issue then i anticipate (not a lot of grass riding, just getting from trail to trail in the millions of ottawa parks).

    i think the rack mount would be a case of slight overkill; this bike is single shocked and for the kind of biking i do, i dont need dual suspension, i dont ride that hard or that offroad. on the other hand, it would certainly be way safer and probably a lot less maintenance. i shall ponder.

  5. Demosthenese

    Demosthenese Guest

    damn! i missed that bike, ty! honestly, although i wouldnt trade my norco, thats a gooooood price, and i was really thinking about getting a cruiser for my first enigne project instead of ripping up the frame of my baby :)

    thanks alot for the heads up!
  6. bamabikeguy

    bamabikeguy Active Member

    If you listen to these Happy Time experts with THAT bike, you will have a winner, thats for sure !!!!

    There's been quite a few flawless, successful builds by newcomers, I hope you have one too!!!!! :lol: 8)
  7. gone_fishin

    gone_fishin Guest

    should have mentioned: not one off-road problem was ever engine-related (dax 70)
  8. I would love to have a fully suspended motoredbike and I know it can be done but there are trade offs and it seems the easy way to go would be a bike with front suspension and a shock seatpost with a comfort seat.
  9. azbill

    azbill Active Member

    that's how I ride haha :lol: 8)
  10. thatsdax

    thatsdax Guest

    I do not think...

    I do not think there is enough room for a motor to fit that bike. That is my guess. It does not look like enough room to me.
  11. HI,

    The ONLY bikes I have ever put engines on have been mountain bikes.

    I have done that since a mountain is built way beefier than your typical road bike or cruiser for that matter...Also, If you get a higher end mountain bike than can be as light as or lighter than a less expensive road oriented bike

    My 2 demo bikes (I work a full time job and hawk my "Super Cycles" at flea markets and on the downtown mall part time....It's fun to show the bikes and heck if I make a sale the $$ aren't too bad either) are a Trek 7000 and a Specialized stump Stumpjumper....I got both bikes at an auction....$70 each and ready to go except for the flats.

    I really have never off roaded them because I think the really serious trails are very slow speed twisties and hills so extreme a 44T sprocket is WAY over geared...Then engine woud be constantly lugging from the slow speeds or the clutch would be frying because of the need to constantly slip it to keep the engine from stalling...Now if I had a my machine shop friend make me a 72 T sprocket we might be able to tackle a few trails! (of course road speeds would be sooooo slooooow...So in a nut shell (for me at least) I haven't really off roaded because of gearing issues.

  12. locoWelder

    locoWelder Guest

    Re: I do not think...

    I have to agree with Daxs, it seems not to have the room in the frame for the motor
  13. bamabikeguy

    bamabikeguy Active Member

    thatsdax and Loco,

    I will apologize if I misdirect somebody, or give a bogus link, admitted out of my element re: Happy Time.

    But, I need clarification, because I've seen pix of Schwinn Cruisers fully decked out, there is one specifically (I can't find readilly), the $450 green one with the headlight on the front fender.

    Here's the Ottawa sample:


    Heres GoYouGoodThings Raliegh


    And we all have heard my complaint about my sloooooow dialup, here's mefonz's Schwinn, the only handy one I could find without an hour search:


    Why is the Ottawa Schwinn too small? Like I said, if you could point out "where" the Happy Time will have the squeeze, I'll know next time I do a quick craigslist search.

    Thanks from an ol' dog learning new tricks.

    Note, I'd like to move this over to "Bicycles/engines..." as soon as you point out how my eyesight is failing even further... :???:
  14. Demosthenese

    Demosthenese Guest

    wow, thanks for all the feedback, this forum is intense.

    just checked ups tracking from work, my engine is in ottawa being delivered (glee), so i'll know tonight about the space issue, which has been on my mind :). If it fits, it will be tight, that's for sure.

    Assuming the Norco is big enough, i think the plan is to fabricate some mounting brackets and avoid drilling the frame in any way. If it's not big enough, im probably gonna be calling that craigslist guy and mounting it stock on that.
  15. bamabikeguy

    bamabikeguy Active Member

    Well, I misunderstood, these intense guys amaze me too, know what a Norco is from memory, I thought they were saying the Schwinncruiser was too small..... psheww :???:

    No drilling the frame, you have graduated to the next level by repeating that maxim. 8) 8)

    Moving this to "Bicycles, engines"....
  16. Demosthenese

    Demosthenese Guest

    ok, so i have it, and im happy to report it JUST BARELY FITS. with the carb on and the spark plug in the spark plug wire literally touches the bar slightly. I suppose that means that changing plugs will mean unmounting the engine, but since i plan on making a good mounting plate with a double u-bolt setup i dont think it will be a problem removing the engine occasionaly. is that realistic? or will i have to be changing that thing too much to make that plan viable?

    im also gonna replace the moutning bolts that came with the engine before i run it, those things are SKETCHY as hell lol. any instances of the egine block itself braking instead of the bolts?

    im also gonna have to take swap out the back tire due to the disk brake assembly currently on there. i assumed id have to take it off, although i was hopeful there would be chain clearence. upon closer inspection, it doesnt come off! the disk part does, but the brake hub is part of the wheel hub.

    im gonna photo this thing tommorow and post a build page, but ill report on the mountain-bike question as i figure it out :)
  17. azbill

    azbill Active Member

    glad it fits :D
    I would check into mounting sprocket to disc rotor (it will be easier on your spokes for one)
    good luck and take build pics 8)
  18. Demosthenese

    Demosthenese Guest

    now theres an idea

    ty so much!
  19. Demosthenese

    Demosthenese Guest

    as a final post here, i did manage to mount my engine. the downtubes on my mb are at least 2 inches thick, but i fabricated a mounting plate and grabbed 2 u bolts, problem solved. :)

    locktite is not a suggestion lol, especially if ur planning on going over anything rougher then gravel.
  20. srdavo

    srdavo Active Member

    If you need some sparkplug clearance, try a champion CJ7Y.
    the overall length is 2 1/8"
    some more on sparkplugs, with pics here---->