Monster Scooter Engine

Discussion in 'Friction Drive' started by aero07, Jul 6, 2010.

  1. aero07

    aero07 Member

    New build, I just put a BMP friction drive
    with a Monster Scooter engine on it.
    I think the engine is the same as
    the auger engine from Harbor Freight.
    After I got the carb dialed in it runs
    pretty good maybe 28-30mph on the flats
    but as for hills it doesn't seem to have much torque.
    I have a 68.5 HT that seems to have more
    bottom end than it does. Can anyone tell me
    what's the biggest motor I can get that will
    still bolt up to the BMP 78mm clutch drum
    besides the GP460 ( I read somewhere that
    the 460's bottom end is lacking too).

    Attached Files:

    Last edited: Jul 6, 2010

  2. kerf

    kerf Guest


    Is your engine broken in? Have you wiped out the cylinder plating using cheap two stroke oil (low compression)? What roller are you using?

    My experience with this engine, using a 1 1/4" roller, is that it has plenty of bottom end and hill climbing ability. From the start I now use only Red Line Full Synthetic Racing Oil. Break in takes a little longer but it keeps the engine healthy.
  3. Esteban

    Esteban Active Member

    I agree with kerf. Another thing you may want to consider,,, the full suspension bikes usually are already quite heavy before adding the kit.
  4. aero07

    aero07 Member

    I'm sure the engine isn't broken in yet,
    I've only tested it twice. Maybe a 1 1/2 tanks of fuel
    through it so far. I was just stating that it did not
    seem to be much on the bottom end. I'm using the 1.25 roller and
    I'm 220lbs. I could go to the 1 inch roller but did not want to give
    up any top end.
    I know these little engines aren't going to jerk your head back but
    I was kind of disappointed. Just wanting a little more than what
    I'm getting.
    In your opinion Kerf, would the GP460 be any better?
  5. aero07

    aero07 Member

    Again, what options do I have on different engines that will still fit
    on the BMP kit???????
  6. kerf

    kerf Guest

    The friction drive is on my wifes bike and it's running the HF engine. My chain drive is running the R460 and I had a two speed rigged up on it. When the wife was running the TLE43 with a 1 3/8", I could run off and leave her up big hills in low gear. Now with the HF and a 1 1/4", she will pull away from me.

    I'm 250# and her bike pulls me up hills just fine, so the 52cc HF seems to have great torque. Several people here have used the R460 on friction drives with mixed results. Some say it works good, others say it gobbles tires. I would not use it on a friction drive because over 7K, it gets very strong and any slippage going up hill at WOT could leave your tire on the road.

    Your engine should be hard to pull, with very noticeable resistance on the compression stroke. If not, pull the jug and see if you've scored the cylinder. Any loss of compression kills bottom end. I know because a month ago I wiped out the plating on the 460 and it wouldn't pull a sick wh**e out of b*d. A new jug, piston & ring and .005 copper cylinder gasket and I've got a brand new friend that I never knew before.
    Last edited by a moderator: Jul 6, 2010
  7. maltese guy

    maltese guy Guest

    You can use a minimoto engine,it bolts on perfectely on the bmp kit.they are powerfull engines and upgrades are easily obtained... I did it and was pleased with the performance.If you choose to go this way,take into account that you have to manufacture/modify an exhaust to fit engine and you also need a fuel tank. you can see my setup on the BMP website were it says customer photos. hope this helps
  8. Esteban

    Esteban Active Member

    Ride it a great deal more to get it broken in. A smoother tread tire is better, too.Just pedal-assist more on hills.
  9. jim_himself

    jim_himself Member

    I've used the gp460 on a friction drive and it works great for me, granted I am only 175lbs. It has worked fine with very little problems for me. I do recommend that you get a low-end performance exhaust though, i picked one up on ebay for $35, you will be amazed the difference one of these little pipes make
  10. kerf

    kerf Guest

    Tell me more about the exhaust. I've made several exhaust for my beast and am always interested in something new. The glass pack on my 460 is going to be scrapped because I'm switching to a CVT and the engine has to turn around.

    I don't want to get off topic or thread jack so feel free to PM me.
  11. Porkchop

    Porkchop Member

    I'm using the HF engine on a BMP friction drive. I have no complaints with the 1" or 1.25" roller. AS far as what's the largest engine you can use, you didn't say legal or illegal. You need to check your local laws on that one. I'll bet GP460's are illegal in all 50 states.
    Last edited by a moderator: Dec 18, 2015
  12. aero07

    aero07 Member

    Unfortunately in Alabama you would be illegal with any motor you put
    on a bicycle to drive on the streets. I was just trying to find out what the
    largest displacement engine I could get that would still bolt right up to
    my BMP friction drive unit (78mm clutch). I'm ok with the monster scooter
    49cc just wanted to know for future builds. As for as displacement goes I
    always think you can go BIGGER!!!!::idea:
    Maybe when I get this engine broken in it will be better. I have only
    went wot a couple of times and then only a few seconds, waiting to get a few more tanks run through it.
    I'm very pleased with it on the flats, its just the hills in my subdivision are kindof steep. To get up them just pedaling reguires using the lowest gears.
    Oh well these things weren't meant for mountain climbing anyway,
    but if you come across a bigger engine than the ones listed on the BMP site
    please let me know. Thanks
    Last edited by a moderator: Dec 18, 2015
  13. Whizzerd

    Whizzerd Member

    Hi Aero, my mitsi clone had been factory testrun(fuel in the primer bulb) and was very rich on the mixture. Started well and smoked alot. Not much power. After leaning the mixture a bit, the power was fine. Careful with that though, an overlean mixture on a 2 stroke denies the engine of proper lubrication and will burn it up.
  14. cycledude

    cycledude Member

    I could not get over the train, auto, overpass here while sitting and peddling, I have to stand, lean forward a little and peddle assist with low power until I feel like I can ease off the peddle assist, it's a blast, (for me anyway).
    I like going up hills now, also before you get to the hill try going a little faster until your momentum evaporates.
    Last edited by a moderator: Dec 15, 2015
  15. Were can I buy this monster scooter engine????
  16. 5-7HEAVEN

    5-7HEAVEN Guest

    I've used the GP460 engine on the BMP friction drive. It was a good starter project using the 460. I used a 1.25", then switched to a 1.375" Staton roller. I'm the one said that this engine eats tires. It also has very little torque below its narrow power band. Once the 460 drops its rpms, it REALLY drops speed riding uphill.