Help for a new guy

Discussion in 'General Questions' started by AzBigDoc, Apr 24, 2011.

  1. AzBigDoc

    AzBigDoc New Member

    Thank you Jim.
    Like just about everybody else these days I want to do a budget build, $300-350 including a inexpensive cruiser platform. I'm not biased either way in terms of 2 vs 4 strokes and by what I've read all over this forum it can get pretty heated. I would like to hear from folks in the 300lb club who have first hand experience with all types of builds ie. friction or chain drive, rear or center mount, various motors manufacturers etc. as well as what to look out for.
    Thanks in advance - Doc

  2. KilroyCD

    KilroyCD Active Member

    Doc, I'm Jim's brother, so I'm the other XXXL rider he spoke of. I have three 2-stroke bikes and two 4-strokes. All are frame-mount, so I have no experience with rack mount or friction drive bikes. Wait, I forgot that I did briefly ride a friend's front-engined friction drive bike several years ago (a BumbleBike), but I really cannot remember much about riding it except that I didn't really care for the thumb lever throttle.
    I have built two 2-stroke bikes using 48cc GruBee engines. Both of these are chain-drive and have the standard 50-tooth rear sprocket that came with the kits. I don't know if 50-tooth sprockets now come with them, as I got my kits in 2003 and 2005. They might now come with a different size, as I rarely hear anyone speak of 50-tooth sprockets anymore. With the torque the little 48cc engine has, the 50-tooth sprocket works well with my weight.
    However, that is not the case with my 4-stroke build. I have a bike with a 49cc HuaSheng engine with the EZMotorbike Q-Matic drive, and I couldn't even get up to speed with the 50-tooth mounted (the final drive ratio was too tall). I now have a 64-tooth sprocket mounted, and I get up hills nicely as well as having good performance on the flats. In fact, a 260lb friend was riding that bike the other day and I was on my Whizzer, which is a 138c belt-drive bike that has had some performance mods done to it and he walked me going up hill!
    The frame-mount 48cc 2-strokes can take me to a little over 30mph on the flats. I can get to almost 40mph with the 4-stroke bike (and over 40 with the Whizzer) on the flats. I don't think that's too bad for a 300lb rider.
    In short, with chain final drives I'd suggest staying with larger diameter sprockets in both 2-stroke and 4-stroke applications.
    As to the choice of engine, I'm partial to 4-strokes. Not to say that I don't like my 2-strokes, but the 4-stroke doesn't vibrate as much and I think will offer better longevity.
  3. JunkyardDog

    JunkyardDog Active Member

    I'm a bit on the heavy side, have had both a 2 stroke and a 4 stroke. The 2 stroke made so much noise the bike was unridable in town, and even out on the road without earplugs, though I understand this is not a problem with all 2 strokes. the 2 stroke crapped out after under 1000 miles. I really can't say I was sad to see it go. I got a new 4 stroke setup, and so far I love it, it has gone well over 1000 miles, and still runs like new. Both were rack mount friction drives.

    The biggest problem I have had has not been with the engine (I'm pretty sure the 2 stroke was junk to begin with) but with rear wheels. I have broken several. And it is not because of the engine. If you are heavy, you need a super heavy duty rear wheel, and keep your tires inflated to the pressure stated on the sidewall. Most of my wheel failures were from broken spokes, I replaced them with better ones, and finally they started pulling through the rim and elongating the holes in the hub. Rather than get a Chinese made wheel "designed" for a motorized bike, I recommend having a wheel built by a bike shop, specifically for a downhill mountain bike. They are as strong as it gets, though not cheap.

    As for the engine, I definitely recommend a 4 stroke, even though I love 2 strokes, and have owned many 2 stroke motorcycles and scooters and mopeds. 4 strokes just seem to be better suited for bicycle use.
  4. Porkchop

    Porkchop Member

    I have personal experience only with friction drive from BMP. I have used both Honda GX35, 4 stroke1.6HP and the 2 stroke from Harbor Freight's auger, 2 stroke rated at 52cc and 2.2HP. The Honda is definitely a sweeter engine but the 2 stroke has WAYYYYYY more power. Just remember, .5 horse power will make a huge difference in these small engines. I've been well pleased with my build. As everyone will tell you friction drives are useless in wet weather. The wider the tire and the smoother the tread pattern, the better performance and wear you will get out of them. I have an unused Grubee Starfire 50cc engine, sitting on the bench now for 2 years. I read so much bad junk about them I decided no to use it. I ordered my friction kit while the Grubee was in delivery transit. Might use it one day, or I might sell it one day. Who knows ? Good luck and be safety smart !
    Last edited by a moderator: Dec 15, 2015