Can I use an old lawnmower engine?

Discussion in 'Motorized Bicycle General Discussion' started by andrewjb101, May 21, 2013.

  1. andrewjb101

    andrewjb101 New Member

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    Hello,

    I'm quite new to all of this. I'd have an old bike and a lawnmower engine, I'd like to combine them and drive to work. This engine is Suffolk Type 75G14-25A

    Info here:
    http://www.oldlawnmowerclub.co.uk/technical/engines/Suffolk_Type_75G14-25A

    I will it be powerful enough to get up hills etc, and how fast do you think it could go? What are these equations to work these figures out? Thanks in advance!

    Andrew
     
  2. runnermike

    runnermike New Member

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    A pic of the engine might get some more responses, and the bike as well!!
     
  3. biknut

    biknut Active Member

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    Saca's bike in the background has a 3 1/2 hp brigs. He built it up from scratch. It weighs a ton compared to mine, but runs good.

    [​IMG]
     
  4. cumminsbayou

    cumminsbayou New Member

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    If the motor is horizontal shaft then yes you can but if its vertical like most lawn mowers it won't be worth it unless it is 2 stroke. If its 4 stroke you would have to make a friction drive on one side of the tire, and the side wall of a bike tire isn't gonna hold up to it. If its 2 stroke you can just flip it on its side and turn the carburetor around to work side ways.
     
  5. Nashville Kat

    Nashville Kat Active Member

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    Yes- it would have to horizontal shaft
    You'd probably want to use a centrifical clutch- and there are a number of issues with chain sizes and gearing-
    You'd probably have to have wide cranks or mount the motor high enough to clear the cranks- some people use shorter cranks I think
    I had a Briggs and Stratton on a Rupp mini back in the '60's- it was dependable but not all that fast, and with the small wheels

    Here are some 4 stroke motors at Harbor Freight
    http://www.harborfreight.com/engine...////Gas+Engines&RequestData=CA_CategoryExpand

    If you want a 4 stroke motor, I think I'd go with a kit myself
     
    #5 Nashville Kat, May 21, 2013
    Last edited: May 21, 2013
  6. BigBlue

    BigBlue New Member

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    O.P. is in the U.K. and I doubt that he has a Harbor Freight nearby or access to a Briggs and Stratton.

    The engine that you link to states the engine produces 1.1 hp. This isn't going to be enough to power to take off from a standing stop or go up any hills, unless you weighed about 90 lbs. You would have to pedal to help the engine along. Another issue would be finding a clutch to fit that engine or how to make it into a friction drive, not knowing what the engine shaft looks like.

    What type and size of engine depends upon how you want to mount it, your weight, 2 stroke or 4 stroke and what is your purpose - do you want the engine for pedal assist or do you want the engine to fully power the motorized bike. Many people have built friction kits with 4 stroke 35cc Honda and Robin engines. However, these engines are more powerful due to their modern designs.

    You can convert a vertical engine to run horizontal. You can also use them as friction drive, but these are bigger engines than the one you referenced.

    Here's a YouTube link how to convert a vertical to horizontal and a MySpace page of a forum member who converted a vertical engine to friction drive. i don't know if the information will help in your engine selection:
    http://www.youtube.com/watch?v=0Mba3BS1oRM
    http://www.youtube.com/watch?v=mFnZkldAwy8

    http://www.myspace.com/retiredtinkerer/photos

    Good Luck,

    Chris
    AKA: BigBlue
     
  7. fasteddy

    fasteddy Well-Known Member

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    andrewjb 101,
    Welcome to the forum. Check with your licensing people but you are going to find that the bike won't be legal. Thank the Euro people for that. I believe you are only allowed electric bikes and not more than 250w and if you don't pedal with the bike when the motor is on it won't work.

    Look up page 16 in the Board Tracker section here on the forum. Towards the bottom you will see the thread, "Villiers 98cc BTR is finished" by Harry76. He built a super nice board track bike with a Villiers 98cc mk1 lawn mower motor.

    Also my mate Silverbear is building a bike powered by the same engine. He will be back at it this summer to finish it up.

    Steve.
     
  8. andrewjb101

    andrewjb101 New Member

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    Hi everyone, I didn't except so many responses!
    I don't have any first hand photos yet but this is what I can show you for now:
    The engine:
    http://www.ebay.co.uk/itm/290916257494?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

    The engine is a 2 two stroke and very noisy. But I am in the process designing an expansion chamber exhaust using hydroforming techniques.

    The frame is a standard 20 year old mountain bike that needs a small service.

    It's a shame to hear that 1HP isn't enough to do hill starts, as I'd like it to be fully self powered.

    Hearing that it won't be legal is a big issue, I work in central London and there are a lot of police monitoring the roads. Is there a legal loop whole to work around this? I really want to build something with an engine/motor that I can drive to work!!!
     
  9. biknut

    biknut Active Member

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    Wouldn't it be a lot easier to just buy a china girl motor?
     
  10. xseler

    xseler Well-Known Member

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    I've heard that a portion of downtown London is a 'zero emission zone'.........China Girls are certainly far from 'zero emission'. Sounds like electric would be your best bet.

    Then again, I may just be talk'n outa my arse......
     
  11. andrewjb101

    andrewjb101 New Member

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    I've been thinking a lot about this project and the fact that a combustion engine is illegal to use on the roads or probably the worlds most expensive home made scooter to insure, I believe you guys are right and I'm going to go electric.

    I've been looking at some motors, I think something like this will do:
    http://www.hobbyking.com/hobbyking/..._Brushless_Outrunner_Motor_UK_Warehouse_.html
    I need to make sure that I can get the right battery and it will go more than 10 miles on full power. I'd also like to work out its maximum speed and gear ratios, does anyone know how to do that?
     

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