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Motorized Bicycle General Discussion All topics regarding bicycles with engines.

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  #671  
Old 02-11-2013, 07:22 AM
JTona23 JTona23 is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Hi, I'm a year 12 student that is completing a research project. I have chosen to motorize a bicycle using a 80cc, 2 stroke engine. i am looking at ways in which i can modify the bike to optimize its efficiency. I have considered the following:
- fuel type
- tire pressure
- Temperature
- Spark plug
- fairing

further advice on the list above, or any new ideas would be much appreciated. Thanks!
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  #672  
Old 02-11-2013, 07:35 AM
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Ludwig II Ludwig II is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

From my involvement in cheap motorcycle racing, the very first thing to be done is to rebuild the engine the way it was designed, not how the factory built it on a Friday afternoon.

The people here who know the engine will run you through the steps required, so you'll be in safe hands.

There's a job called blueprinting, which means that any unwanted steps or roughnesses in areas where gases flow through the engine are removed. The barrel sits on the crankcase, and there can be edges of the metal of either protruding into the transfer ports and slowing up gas flow. The same point applies to the carburettor and manifold. You will need guiding through those stages.

Then the reassembly of the engine. Bolts and studs need to be tightened to the appropriate degree and in the correct sequence to avoid leakages and distortions that can reduce the engine's efficiency.

My team won it's class last year on a "shouldn't have" bike, which had little money spent on fast parts, but hours and hours on fitting and assembly.
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  #673  
Old 02-11-2013, 09:00 AM
Wally Wally is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Research? I wonder what field! I have yet to see a 80cc motor. One normal measures the swept volume not the total volume which is what the Chinese like to do. Sounds better. Yes I agree with you LudwigII except Blueprinting is "get it closer to the drawing" One blue prints a standard engine for performance (Racing?) Also I get the impression he wants us to do the research for him :-) Why do I say that? There is a tremendous amount of info on these sites (plural) I didn't need to ask any questions with respect to my first build I just read and digested it all. But then again I have been working on cars, bikes and things mechanical for 50 odd years and I am still learning.

.
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  #674  
Old 02-11-2013, 09:45 AM
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Ludwig II Ludwig II is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Another question which needs to be asked is what sort of efficiency are we looking for? Fuel efficiency and greatest mpg, or efficient use of fuel for maximum power?
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  #675  
Old 02-12-2013, 01:32 AM
Yankphan Yankphan is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Do the cops bother you ?
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  #676  
Old 02-12-2013, 04:17 AM
Wally Wally is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

In Cape Town South Africa, No, they look but don't get out of their car. But again I don't ride like a manic and pedestrians have right-of-way I ride mainly on sidewalks, we have quite a few bicycle friendly paths. Although the cyclists are NOT friendly to me. :-)
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  #677  
Old 02-17-2013, 05:22 PM
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SuperDave SuperDave is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Okay, here's my 2 cents worth of "advice".

I've read through 68 pages of tips & tricks & no one has mentioned this:

1) That cheap plastic insert that shims the carb to the intake manifold? Pretty much worthless and a potential air leak if you don't get the carb seated firmly against the O-ring. Solution? I used a 5/8 heater hose (about 1/2 an inch worth), trimmed it as straight & flat as I could (where it butts against the carb), inserted it into the carb, and then press onto the manifold. Mine was a VERY snug fit, had to dab a bit of grease on the manifold to get it to go in. Once mounted it was very tight and leak free.

2) I live in an area that is INFESTED with sand spurs, a.k.a. goat head stickers. With a normal el-cheapo inner tube you'll get a flat in under a mile. So this is what I did: I got a pair of extra thick Slime brand inner tubes. The package claims it's 5 times thicker than the regular kind. I dunno if that's true, but they also come prefilled with self sealing goo. As if that were not enough, I used the original tubes, cut them down the middle (where the rim is) and used that as a liner between the tire & the Slime tubes. Haven't had a flat since. I got mine at my local bike store, and I've notice Wally-World now carries them too. If they're not available in your area, you can try here: http://www.pricepoint.com/detail/16528-345_SLIST7-3-Parts-74-Tubes/Slime-Super-Thick-Smart-Tube.htm

3) On my aluminum bike, I was a little concerned about the seatpost tube cracking where the motor mounts against it, so I got an extra seat tube, cut the tapered end off (where the seat mount grips it) and sunk it into the bottom of the seatpost tube. Then I added my 1st seat tube on top of it. Had to trim off a little of the bottom to get the seat adjusted for my height, but the added insert helps to reinforce the aluminum frame where the motor clamps onto it, so I feel better about it.

4) If your handlebars vibrates so much that objects in your mirror appear as blurs, this tip is for you: I took a caulk gun and inserted the tip all the way into the ends and squirted enough to create a stoppage. I let it sit overnight and the next day I filled the ends with sand up to a half an inch from the ends. Squirt with more caulk to seal it in and tape it up with masking tape. Flip it over and do the same with the other end. Give it another day to dry. (Might be best for days you're not gonna ride it, such as wintertime or rainy days)

5) Replace all the screws and fasteners that come with the motor with American made Grade 8 hardware. I went with black allen bolts, I think they just plain look better. Go to an auto parts store and get Locktite Threadlock BLUE (not red). Dab just a drop on each bolt and let dry overnight before using on the motor. I've had some of the factory bolts loosen on me and once lost my magneto cover, luckily I was able to find it and reuse it. My motor originally came with phillips head screws on all of the motor, they are made cheap, they strip out too easily, and if the heads are that soft, how much better are the threads? Lowe's Hardware in my town carries the largest selection of all the big box stores so I recommend you shop there 1st. Also, the nyloc nuts are no good after the 2nd time installed/removed, so if you have had to remove them more than once, replace them. Chinagirls vibrate something fierce, and weak nuts will back off on their own.

6) My motor's stock muffler cap came loose on it's maiden voyage and fell off completely before it burnt through the 1st tank of fuel. I suggest a second jam nut over the 1st nut if you intend on running the original exhaust for any length of time.

Hope this helps someone.
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  #678  
Old 02-19-2013, 09:30 AM
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Wickedest1 Wickedest1 is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

First let me apologize if this has already been posted, but the crappy front mount u bolt sux...I've swapped that fur an exhaust clamp from the auto parts store...best 2 bucks I spent on this...i could lose my rear mount completely and it wouldn't fall off...mount the ubolt so the clamping bar is beneath your down tube...

As for me, after every 15-20 rides, I remove the spark plug and dump 2 ounces of motor oil into the engine, let sit about 20 minutes, then with the plug out and a paper towel over the hole, push the bike around to work all the oil into anywhere that may not be lubed enough, then replace the plug, start the motor and let idle for 5 minutes or more...shes gonna smoke like a tire fire but you will be well lubed...
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  #679  
Old 02-20-2013, 03:09 AM
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Russ McClay Russ McClay is offline
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Default Re: Motorized Bicycle Take a Tip...Leave a Tip

Hi Wickedest --

Quote:
Originally Posted by Wickedest1 View Post
As for me, after every 15-20 rides, I remove the spark plug and dump 2 ounces of motor oil into the engine, let sit about 20 minutes, then with the plug out and a paper towel over the hole, push the bike around to work all the oil into anywhere that may not be lubed enough, then replace the plug, start the motor and let idle for 5 minutes or more...shes gonna smoke like a tire fire but you will be well lubed...
This is a very interesting tip that I haven't heard before. Does anyone else do this?

Russ
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  #680  
Old 02-20-2013, 04:12 AM
Wally Wally is offline
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I am surprised with the lack of comment for or against. Me personally I don't like it dueto the amount of carbon build up from burning motor oil. 2-stroke oil has been designed to mix with petrol (Gasoline) and burn in a conbustion chamber. A fair amount of carbon is produced which is why an exhaust pipe get blocked up. I personally won't do it.
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