what would be the max weight i can pull with a 48 cc and a 66cc motor?

gill vanderwerf

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Sep 9, 2019
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i am building a bicycle teardrop trailer from foam and canvas..and its just a bed to sleep in and storage for my trips food spare parts and so .....can anyone give me a rough idea how much weight i can pull on either of those motors?
 

LR Jerry

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Dec 19, 2011
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That can be hard to say how much weight you can pull without knowing a few important pieces of information.

1) What kind of set up are you going to be using? Shift kit; internal geared hub (3 or 5 speed); free hub (cassette or freewheel)??? Left side rear wheel sprocket (high or low geared)???

2) Over all weight (your body weight, the build's weight)?

3) The terrain, what percent grade hills will you be climbing? (The two steepest paved streets in the world Canton Ave and Baldwin St are a 37% grade.) I live in Tennessee where there's 30% grade hills. My bike and I overall weight is 350 lbs. In order for the bike and me to go up 30% grade hills with no pedal assist a minimum of 88 ft/lbs of torque is needed.

4) Are you just wanting to use 2 strokes? Bigger 4 strokes can generate a lot more torque which would be helpful with pulling.
 
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LR Jerry

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using my 2 stroke
That still isn't a lot of information. The 2 stroke 48cc or 66cc, size matters. The 48cc should be able to carry 350 lbs overall weight up a 30% grade hill with a 50:1 reduction and no pedal assist. The 66cc should be able to carry 350 lbs over all weight up a 30% grade hill with a 45:1 reduction.
 

gill vanderwerf

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i am around 220lb and the weight of the trailer would be loaded up around 200lb + is my guess but around the time i would take first road trip i should be around 180lb again.
 

LR Jerry

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i am around 220lb and the weight of the trailer would be loaded up around 200lb + is my guess but around the time i would take first road trip i should be around 180lb again.
If you reach your desired weight of 180 lbs; I'm going to give the build a minimum of 60 lbs and the load of 200 lbs. That'll total 440 lbs. The next big question is, are there any really steep hills along the route you plan to take? This will determine whether you can do a single ratio build or if you need a shifter bike.
 

LR Jerry

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Well you're definitely going to be encountering steep hills. Unless you're talking about a Florida east coast to west coast. Doing a USA coast to coast while pulling a load is going to require a really good shifter build. A China girl engine probably isn't the best choice of engines for doing that.

I'm not trying to discourage you but a build capable of doing a USA coast to coast is only half the issue. You're going to encounter legal issues. Some states could care less about your bike as long as you're obeying all the traffic laws; other states will treat self built motorized bicycles like they're the most dangerous vehicles ever put on their roadways.

If you still want to do the trip with a 2 stroke engine while pulling a load I'll tell you more on how to set up a shift kit.
 
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gill vanderwerf

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yeah that is a issue i been wondering about how they will treat you i am in process of making the bike complete street legal for pa, lights, turn signals all this is not necessary front light good back light mirrors and horn . my thought is the less they can find to pull you over the better it is so far none of the riders that i know here in pa ever had a problem
 

curtisfox

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Dec 29, 2008
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yeah that is a issue i been wondering about how they will treat you i am in process of making the bike complete street legal for pa, lights, turn signals all this is not necessary front light good back light mirrors and horn . my thought is the less they can find to pull you over the better it is so far none of the riders that i know here in pa ever had a problem
If you are going to be legal in your state, you shouldn't have any problem, unless you run into a state that bans motor bikes. I would say to copy and bring the law with you, just in case. You normally have like 60 days to comply to there law of getting new license, should also apply to your bike. You should also have a bike that is well broke in, and malfunctions all worked out, and go through your bike every day check all nuts and bolts. Somewhere on this forum there was a guy that went on a long trip and did good, a few years ago. Search and see if you can find, also can search for the laws in each state can be of help. ...........Curt
 

LR Jerry

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Dec 19, 2011
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So are you asking about the two different size 2 strokes because the smaller one is being carried as a spare engine?

Other things would be using 2" wide road tires, front suspension and a suspension seat post. This will give you a much more comfortable ride. Comfort is a must when riding long distances.

You should also use double walled rims and disc brakes. They come in very handy when having to bump brake going down steep hills especially with a 200 lbs load behind you.

With the shift kit use a cassette hub instead of a freewheel hub. The FW hubs axles are prone to bending. As for the cassette use a 8 speed 34-13. I'd set the high limiting screw on the rear derailleur to exclude the 13t sprocket. This'll then be the same as having a 7 speed 34-15 cassette.

I'd contact David Staton of Staton Inc about one of his shift kits. With the SI shift kit it uses a double freewheel system. It can hold 3 chainrings instead of one unlike the Sick Bike Parts shift kit. In my SI shift kit I had double White Industries Trails freewheels installed. It comes with a 28t chain ring and I'd suggest adding a 36t and 44t steel 4 bolt chainrings. The SI SK engine drive sprocket is a 44t.

This setup gives you a 3x7 drive system. The shift pattern will work like this: 1(1-3), 2(3-5), 3(5-7). Hill climbing 1(1-3); level ground cruising 2(3-5); down hill or level high speeds 3(5-7). Center the wheel to where 2(4) puts the chain in a straight alignment. With this set up the lateral stress on the chain will be greatly reduced thus reducing chain failure. Get a good chain like a Sram 870.

The shifters put them on the left handlebar. Use a 7 speed twist shifter for the cassette and a thumb shifter for the chainrings. A little trick I did on my late brother's build was was to engrave a line down beside the shifter numbers on the twist shifter and engraved a dot beside the numbers on the thumb shifter. Then I painted the dot beside CR1 red, CR2 yellow and CR3 green. Next on the line on the twist shifter paint (1-3) red, (3-5) yellow and (5-7) green. This way you'll keep the red rear cogs on the red front chainring, the yellow sprockets on the yellow chainring and the green sprockets on the green chainring.

Get a techometer/hour counter then be in a gear where the rpm stays around 6000 at full throttle. Use starting gears; be in 1(1) before stopping on stops going up hill. All other stops use 2(3).

Finally for the engine get a pull start. You don't want to bump start trying to pull a load. This'll also mean installing a centrifugal clutch. Then there's a few options on how to get the primary reduction going into the shift kit. I personally suggest using a double jackshaft system. In your 1(1) 28:34 you'll need a reduction of at least 60:1. A single jack shaft means having to use a small sprocket 9t and a large sprocket 52t. This can put a lot of strain on the small sprocket. Then a 15t sprocket to drive the 44t shift kit sprocket.

If you want to use a double jackshaft system let me know.
 

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