29er build up in AZ

Discussion in 'Introduce Yourself' started by nrwphoto, Apr 25, 2010.

  1. nrwphoto

    nrwphoto New Member

    Hello to all, I'm Nicholas from Tempe, AZ. I have a Novara Ponderosa 29er mnt bike that I have been interested in doing a motor conversion on for awhile now. Originally was thinking of building up an old full suspension, however I think this big wheeled hard tail will make things a little easier. My plans are for a quiet 4 stroke with plenty of low end grunt. The bike will be primarily used for exploring difficult trails in the local desert and mountains. I have always seen tons of heavy used game trails and old mine roads that are to washed out to take even an ATV on. I need something that is light enough to carry over/thru difficult obstacles yet has enough power to help me up the steepest of hills. So low gearing will also be a must. Any advice would be very appreciated. I want to stay away from friction drive systems do to their poor performance in wet conditions. I also want to retain my disc brakes. Thanks and look forward to figuring this one out.

  2. azbill

    azbill Active Member

    welcome from FH :)
  3. 5-7HEAVEN

    5-7HEAVEN Guest

    Good luck on your29er build. How far along are you now?
  4. nrwphoto

    nrwphoto New Member

    Thanks. Somewhat disappointingly I have not made much progress on the motor end. The bike has been in the shop for a few months now waiting on the new Talus 29er fork from Fox to finally get in. They sent the standard length the first time. While it's in there its getting different hubs for beefier axles, stronger spokes, I upgraded to hydraulic brakes with bigger rotors front and rear, better handle bars and shifters. I need to get in there soon so the steer tube can be cut to fit me and get it all finished up from an ergonomics end. Then I can finally start trying to piece together a motor and mounting setup.

    Any recommendations on motors and power transfer? I am kinda leaning towards the Subaru Robin EHO35 engine because of overall size and weight however I would prefer something with larger displacement for more torque. Any suggestions? I saw a photo of a China made 4 stroke with electric start that was compared to the GX35 in size which would be really cool for easy of use, but don't know anything else about it.

    I am also trying to figure out a CVT or auto clutch system for it at least. That way I don't have to worry about starting and stopping the motor all the time when coming to a stop. I need this whole set up to be able to get me going up a hill from a stop, so gearing will be low, not looking for top speed from this.

    My plans are to mount it over the tire with the drive belt/chain dropping down the left side (opposite the cassette) so that I can easily remove the whole set up when I want to take it out Mnt biking without the extra gear.

    Any and all suggestions and recommendations are appreciated. Thanks
  5. 5-7HEAVEN

    5-7HEAVEN Guest

    I have had half a dozen friction drive projects and Staton chain drive on 26" frames. My frame-mount build is my favorite. It has a 5hp GP460 engine, shift kit and 8-speed cassette. I'm building two 29" frames, one an 18" Kona steel frame and an 18" Diamondback aluminum frame. Both will have 460 or tanaka 47R engines, Scooterguy in-frame mounts, shift kits and NuVinci hubs. I love 8-speed cassettes, but the weak chain is extremely undependable.

    I'd recommend the shift kit and 8-speed cassette and any low hp engines. This will supply low-end torque and can be removed, if you want.

    Keep posting with your progress.
  6. nrwphoto

    nrwphoto New Member

    Has anyone ever tried a Honda 50cc GX motor on a bike. It's only rated at 2hp but I like that it has a large cc, I would think it would have more grunt than the smaller 30cc ish engines out there.

    Also came across a Subaru engine rated at 4.3hp, a bit bigger, do you guys think it's to big/heavy or usable? http://www.homedepot.com/webapp/wcs...de=cii_16079562&locStoreNum=1950&marketID=234

    Also I have seen a few of these 50cc engine/4spd trans combos around for pit bikes and small scooter replacement. Anyone ever mess around with them? Are they to big and bulky for bikes?


  7. nrwphoto

    nrwphoto New Member

    Never mind on that Subaru 4.3hp motor, I saw in the specs it weighs 31#, that's heavier than the bike, to much weight up high I am sure.

    Also the bike is a 15" frame I do believe.... I know it's there smallest size offered in a 29er. (I'm only 5'6") so I don't think it will be possible to fit the motor in the frame being a tighter triangle do to the larger wheels as well. So that's another reason why I need to figure this out on a rear rack.

    Do they make shifter kits for rack mount applications? All the ones I see that are built seem to be in the frame and usually using jack shafts.

    Finally what is everyones opinion on belt drive applications? I saw one kit that uses a large 20" (guessing) ring on the left side of the wheel. Seems like a set up like that would allow me to keep the rear disc brake, where a chain and cog would eliminate it. However if I went the belt route I would definitely need to figure out some sort of clutch and trans up high to give me a couple gear options on the fly.
  8. 5-7HEAVEN

    5-7HEAVEN Guest

    Do research on GEBE drive systems. They bolt onto almost all engines with 76mm clutches. Also, Staton chain drve and BMP's new chain drive system.

    The Honda GX50 is an oddball. It needs an expensive adaptor and clutch before you can bolt this big engine onto GEBE, Staton, BMP, DE or any drive system.

    Hua Sheng engine is the Honda clone, but does not need the expensive adaptor/clutch.
  9. ibdennyak

    ibdennyak Guest

    At one time or another I've built one of you're examples. All have their pluses and minuses. The Gebe (with the ring on the spokes is a great system, smooth, quiet, trouble free,) but you don't have on the fly shifting. Yet. Also, it is designed to be a true *pedal assist* which means you should pedal up to a certain speed before wicking it up to preserve the belt. One of our members lowracer has done some interesting work using an extra rim. (I have one of those in the works at the moment, as well as a version using a plywood disc that ran for over 10,000 miles)

    The little horizontal 4 strokes are nice, but IMO more suited for in frame use, and can require frame modification. (Just had one of those come in last week...see how it works out :grin5:)

    I've never done a HT with shift kit, but 5-7 has tons of experience with those, as well as many other members.

    Friction drive is the simplest and most easily removed, but don't work well in wet conditions....at least for me. Then again, I live in a rain forest. 97 cc might have been too large an engine for it too. :devilish:

    The Honda 50 is a great engine, except for the clutch adaptions 5-7 mentioned. I also run the Honda clones, and am happy with the results. I have the Robin Subaru 35 on a pusher, and that engine is like a Swiss watch. Torque monster for its size too, but ya know what they say cubes is what counts. My favorite bike uses a Honda clone (Titan) into a Nu Vinci wheel. Works very well in the 1500 plus miles I have on it. Oh, for gears.....on the RS I am using a SA 3 speed hub. That works well to provide gears.

    Keep researching, and you will find what is best for you. One thing to keep in mind is that for "on road" use, legally, you are limited to 50cc and no shifting (less in some states), so another fly in your ointment.
  10. 5-7HEAVEN

    5-7HEAVEN Guest

    Hawaii Ed is the HT/shift kit guru.
  11. nrwphoto

    nrwphoto New Member

    5-7Heaven, how did your 29ers turn out? I have still to make any progress on this project. I have been working 70 hrs a week since the idea got in my head. But now I am dropping down to reasonable hours.

    The cc size issue isn't a big deal for me since this will only be used on fire roads. Which is why I want to stay away from friction drive (possible water/mud and running knobby tires). Also why I would like to have it be able to pull me up a hill from a stop. I do plan on pedaling some too, but it sure would be nice to have it pull me up a steep hill at walking speed 2-3mph rather than going 1/2mph pedaling my brains out in low gear.

    I am also short so this is a 16" frame, making the triangle pretty small, to small for an in frame mount. Mounting it over the rear tire would avoid the space issue and make it easier to remove when I want to go out for heavier duty mnt biking.

    The bike has high end wheels, hubs and deraileurs (spelling?) so I would like to keep all that as is, rather than swapping out to a 3 spd hub. I would like the gearing for the motor to be separate from the pedaling. 3 speeds would probably be enough though. Just need an extra low grunt gear for starting out and 1 or 2 higher gears for cruising the flatter areas. Everything I am finding are jack shafts, 3 speed hubs, or friction drive, and few to none that can pull from a start. I need a centrifugal/auto clutch so the engine can run while stopped with a few gears driving the wheel.

    Thanks again for the ideas.