weight limit on 80cc engine

butchatron · #1 07-27-2009, 05:48 PM

hey guys! I'm looking to build an MB- 80cc on a cruiser frame. I have one question: how much can these motors pull? I'm a heavy guy (350+) despite that, I'm in pretty good shape and have no difficulty peddling my bike around town (I have the bike rigged with heavy-duty components to support my big butt) I just want a motor 'cause I think they're really cool. So if anyone can give me some info, I'd be greatful.

Cabinfever1977 · #2 07-27-2009, 05:52 PM

48cc will pull 120kg or 265lbs
58cc will pull 140kg or 309lbs
70cc(80) will pull 170kg or 375lbs

butchatron · #3 07-27-2009, 06:02 PM

thanks CF! I guess I'm making the right choice going with the 80cc.

Norco John · #4 07-28-2009, 06:34 AM

I weigh 310 and my "80" pulls me up to 30MPH on the flats and can get me up a hill that I would normally get off and walk on if I'm pedalling.

city of angels · #5 07-28-2009, 10:13 AM

you could also go to sickbikeparts.com i get one of their shift kit if you need more pulling
i heard really good things about it

butchatron · #6 07-30-2009, 04:33 PM

Norco John,

That's very reasurring! I was weary about going to the trouble and expence of building a MB only to find that it couldn't pull me.

City of Angles,

I'll look into that.

Thanks to the both of you!

MikeJ · #7 07-30-2009, 11:46 PM

I second the recommendation to get a shifter kit from Sick Bike Parts. I installed mine only two weeks ago. I weigh 245 lbs. A test hill I chose is 250 feet vertical climb in about half a mile. Another factor is the hill altitude is almost 7000 feet air density above sea level on a normal day. The air is thin. On a hot day, the air density can reach an equivalent of 9000 feet above sea level. Some people from sea level have a hard time breathing in a brisk walk. Any naturally aspirated engine here puts out only 3/4 of what it can produce at sea level. My 80 cc engine can't make the entire hill by itself even in first gear. So when I am under 10 mph, I throttle back a bit and pedal. On flat highway, cruise at 30 mph in 4th gear and only 80% of redline rpm. 35 mph on declines. Only because I know it has good brakes! The engine had only 75 miles on it at hill test time. It is not fully broken in yet. I expect performance to get better at lower altitudes, in colder temperatures, and with another 100 miles on the engine.

butchatron · #8 07-31-2009, 12:08 AM

I looked into the shiftkit, but I don't think I'll get it. I don't deal with multi-speed bikes. The platform for my bike will be a single speed cruiser, and I want it to be as simple as possible. Really, I don't like the idea of putting a front brake on it, but I don't wanna die. I just wanna make sure it can pull me, but I'm not trying to build a speed machine, I just want something I can put around town with.

Junster · #9 07-31-2009, 12:22 AM

Having brakes on both ends is an absolute must. Your going from crusing at 10mph to at least 25mph. If you don't think you'll be going that fast it's only because you haven't had the ability too. Once your on the motorized bike it's only a matter of time till 25-30 is common place for you. This is really fun. Getting a little extra speed brings the kid back out of everyone.

butchatron · #10 07-31-2009, 12:37 AM

yeah, I wanna go as fast as I can, but I have a very specific look I'm going for, very stripped down, very old school. I've ridden/worked on bikes all my life and I love beach cruisers for their simplicity- no cables or gears to muck-up the look. At first I was against the idea of a motorbike simply because of all the wires and cables running all over the place. IMHO these can ruin an otherwise beautiful cruiser. But after looking at several pics of other peoples bikes, particularly Venice Motor Bikes models, I decided ratbikes are the way to go. But still, I want it as clean as possible, only what it takes to make it go.