Felt Like A Good Time To Swap Engines

Discussion in 'Photos & Bicycle Builds' started by lowracer, Feb 6, 2011.

  1. lowracer

    lowracer Member

    Here's my latest incarnation. Swapped the Subaru Robin EH035 engine for the 97cc Lifan 2.5 HP engine on the downhill MTB. It runs out strong & has more power everywhere. Too bad its over the cc & hp limit of State MB laws.
    As long as I keep it under 30 & pedal along in high gear, I might fly under the radar.
    Anybody know of a good looking readily available 49cc replacement sticker?
    -Lowracer-
     

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  2. Htown

    Htown Member

    How does front drive affect steering?
     
  3. lowracer

    lowracer Member

    Htown,
    I have gone back & forth with 2 MB's switching the engines from front rack to rear rack & putting on some miles both ways to determine which method of drive works best. I have never installed a bike engine in-frame so I can't compare to in-frame.
    I prefer front drive...
    Many people ask me what its like to have the weight of the engine out front & the best analogy I can come up with is if you were ever a newspaper boy & hooked up a plastic milk crate to your bmx handlebars with hoseclamps & loaded it up with your route full of papers.
    Just make sure to keep the extra weight closer to the headtube & as low as possible.
    I think it balances out the weight distribution on the bike better since your body is the heaviest thing on the bike & your butt on the saddle is more towards the rear of the machine.
    Adding a rear rack & engine makes the front end squirrelly. Even with low bars as I have done by flipping a set of 5" riser bars upside down and getting body weight out front & lower. It helps but still not ideal.
    Part of the fun of building these MB's for me other than riding them has always been trying to figure out new ways of making things go, using new ideas & implementing those ideas into a new build.
    Many nights I wake up brainstorming a new way to attach this, or solve that...
    I'd say, gotta give it a try (front wheel drive) for yourself to see if you like it. You can always take it apart & re-build as I have done too many times...lol
    -lowracer-
     
    Last edited: Feb 7, 2011
  4. Htown

    Htown Member

    Lowracer,

    I am definitely going to try building a front wheel drive. Been thinking about building a front wheel drive with a gates belt drive set up. Front and back. 29er
     
  5. lowracer

    lowracer Member

    Htown,
    I'd really like to see that project with lots of pics of the build in progress.
    I am also working on the 'no suspension' MB that I took the Lifan off & swapped the Suburu Robin onto. I had the BMP kit installed on the rear wheel as of yesterday, but all this talk about front drive made me take it off the back today & install it also on the front. Now I am waiting on the Cheng Shin C241 whitewalls from Niagara Cycle to arrive in the mail & she'll be ready to rock. I may need another nice saddle like the one I just got off eBay. Its a big wide honkin leather beach cruiser saddle similar to a Brooks & wonderful for long rides in the saddle. Fortunately my seatposts are all the same size on my 5 bikes so I can play hot potatoe with my saddles.
    -Lowracer-
     
    Last edited: Feb 7, 2011
  6. lowracer:

    ever seen a nuvinci hub up front? im soo stuck on full suspension bikes... at 50mph+ i feel, for safety and comforts sake, a full suspension is the only way to go and i just cant seem to part with my nuvinci... soo spoiled! I really like the rear rack mount simply for the fact i get an "out of sight, out of mind" feeling but its hard to find a soild staton gear box setup that doesnt impede with the rear swing arm travel.
     
    Last edited: Feb 8, 2011
  7. lowracer

    lowracer Member

    pickettdeblanco,
    I have read about the Nuvinci hub but haven't tried one out for myself nor know anyone with one. I run a straight ratio from pulley clutch to rim pulley attached to the spoked rim via v-belt drive. As long as I get the ratio right, I keep the engine singing in its powerband. I have done many trial & errors to get it right & think I'm close to the sweet spot.
    -lowracer
     
  8. robin bird

    robin bird Member

    On the front that thing looks like a beast !
     
  9. lowracer

    lowracer Member

    robin bird,
    The size & torque of this engine warrants itself better being on a big honkin bike like the Rocky Mountain RM7. On my other bike, it was overkill.
    -lowracer-
     
  10. lowracer

    lowracer Member

    Felt Like A Good Time To Swap Engines (Bike2)

    Here is the bike that I swapped engines onto.
    Definitely better suited to the smaller engine.
    Hope you like the pics.
    New tires are on mail order (cruiser white walls) as is the new bottom bracket that will allow me to change cranks & use a 53 tooth front chainring to a 13 tooth rear freewheel cog. I should be able to pedal along with the engine at 30+.
    -Lowracer-
     

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  11. lowracer

    lowracer Member

    I took the new Beast MB out for a spin today down to the local Mexican restaurant to grab a burrito for carry-out after riding the regular pedal bike 45 miles today.
    The Lifan 97cc 4 stroke on the RM7 (full suspension) is a really good match. I was able to cruise along at 35mph (my neighborhood speed limit) & wound it out for a few stretches closer to 45 mph. I didnt gear this one too tall like the last one & it is much more driveable in its powerband.
    I did see a few police, slowed down a bit & spun the pedals to simulate regular cycling...No Problems.
    Now I wonder what a 5-6 hp 4 stroke would be like on a full suspension Downhill MB?...Nah
    -Lowracer-
     
  12. lowracer

    lowracer Member

    I just ordered a Cag type plastic fuel tank & 7/8" handlebar clamps made to hold rear view mirrors on motorcycles. I am going to remove the ugly top mounted fuel tank on the Lifan 97cc engine & mount this smaller black plastic tank to the handlebars.
    This will make the engine look sooooo much smaller while taking some weight off the front rack.
    Take a look at the 3 pics.
    -Lowracer-
     

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    Last edited: Feb 12, 2011
  13. I'm liking the RM7 build. Reminds me of my old Norco...

    Are those Jr.T's on the front? From my experience I would have thought JR.T's would be a bit too soft with the extra weight on the front.
     
  14. lowracer

    lowracer Member

    Schwinn-Locura,
    It is a Jr.T on the front which came stock on this year RM7 (2002 I think).
    There is no extra weight on the suspension up front since the engine & rack is mounted on the fork lowers which is unsprung weight & allows the fork to react to bumps in the road.
    -Lowracer-
     
  15. True, I should have thought of that. I feel dumb now. :(
     
  16. lowracer

    lowracer Member

    BMP Front Friction on RM Flow

    I finally got the new tires in the mail today after waiting almost 3 weeks & having the wrong tires sent (which I got to keep for free). I took it out for a spin after pumping them up to 40 psi. I think I like the slight suspension effect these beach balloon tires give (especially at 30+ mph).
    -Lowracer-
     

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  17. lowracer

    lowracer Member

    Rear engine friction drive

    Did a test today w/ engine on the rear again using friction drive, a suspension fork & 5" dropped handlebars. Handles pretty good using this lightweight engine & getting my body weight low & forward.
    Here are the pics.
    -Lowracer-
     

    Attached Files:

  18. I have spent a few hours pondering the best possible MB set-up. My brand new electric bike has a front motor, but the equally heavy battery hangs out in back. My last gas bike used the GEBE drive with a RS 33.5 in back and I loved it. Hmmmmmm, I wonder what a GEBE both front and back with a pair of RS 25s would be like to ride. 2.2hp, 2 wheel drive, and at 50cc it would be legal about anywhere MBs are legal.
     
  19. katoomer

    katoomer New Member

    2WD bike on the drawing board also

    my next build is going to be a fat tired bike with front and rear engine two wheel drive. I'm going with twin Staton 7 speed chain drives. I need to sell some motorcyles to drum up some extra money for this project. I want a "Rokon" like woods trail bike. That big Pugsley bike would be exellant for this application but its really too pricey for me. I have a dual throttle adapter already that ties the throttles together. Staton's have freewheels so one engine can be shut down if I wanted to in some situations. Dual redundancy. But mostly they would be run together. I can't wait to get started on it.
     
  20. lowracer

    lowracer Member

    I'd love to see some pics of your builds in progress.
    I may be selling my Lifan 98cc engine soon & going smaller cc's again. Now which type engine to go with???
    -Lowracer-
     
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