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  #151  
Old 07-07-2014, 04:46 PM
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Otero Otero is offline
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Talking Re: Reasons for riding Motorized Bicycle

20 mph! Terrifying! 16 mph is plenty.
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  #152  
Old 07-07-2014, 05:10 PM
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Default Re: Reasons for riding Motorized Bicycle

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20 mph! Terrifying! 16 mph is plenty.
I'm living on the edge man!!!lol
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  #153  
Old 07-07-2014, 05:29 PM
Big G Big G is offline
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I'm living on the edge man!!!lol
Come on now, I'm just trying to get a crude little motor to run as smooth as possible.The one in question will do about 48mph. Thanks to Arrow Motor Bikes ported cylinder. rechambered head and expansion chamber. The Delorta SHA 15/15 didn't add any speed but it does run a lot smoother at top end. It's the bottom end that was giving me trouble. I went up a few teeth on the rear sproket, increased the idle rpm and it doesn't buck until I get below 15mph and that's all I wanted.
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  #154  
Old 07-07-2014, 05:40 PM
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The one in question will do about 48mph.
Well gosh...now I feel like I am living on the edge of a very tiny hill.
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  #155  
Old 07-08-2014, 12:27 PM
Big G Big G is offline
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Default Re: Reasons for riding Motorized Bicycle

I don't know what the small cliff line meant but, as far as your comments go about growing up and wanting a moped go I really know what you mean. As a kid I always wanted one. We were the average family in Western Pa. in the 50's. We got along ok but no extra money. The poorest family in the neighbor hood was headed up by a long haul truck driver. He worked on his own truck a lot. and had every tool you could think of. His three sons, each a year apart we all pretty good with tools and engines. One took a 6.5 horse power tracktor motor and made an awsome motorized bike. Another took the motor out of a wrecked Sears mo ped and made his own chopper and the third had an old wizzer that he had rebuilt. When the three of them came down the street together, they sounded like a mechanized army unit coming. Man I wanted one. When I was 64 I noticed the Grubee kit on line. Of course I ordered one right away and I built the first one on a Huffy beach cruiser. I was hooked. That was several 2 stroke builds ago. My next project is a four stroke. Do you know of one larger than 50 cc that I can adapt?
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  #156  
Old 07-08-2014, 02:04 PM
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Default Re: Reasons for riding Motorized Bicycle

Big G

As far a 4 strokes go....the Harbor Freight Predator 99cc and 212cc are fairly popular builds. For $99 for a 212cc Predator...you can't hardly beat that price for an experimental engine. I have even mounted them on my racing gokart after the governor has been removed, rejetted , hi-flow filter and hedder and spin them up on the track all day long at 5800 rpm just for fun. For a $99 cheap china engine....they are tough as nails. Might even get lucky and find a new "hemi" 212cc Predator. Drop in a 1:3 ratio rocker on the intake, remove governor, install 22 lb valve springs and a Mod 2 cam as well as a K&N type filter and Super Snake hedder and you will have one spooky fast ride. Way too much for a bike, but a great conversation piece if nothing else.LOL

Being the practical guy I am..I would probably take a look at the 99cc Harbor Freight Predator. Would be fairly easy to adapt I would think and I am sure there are many threads to be found where that particular engine is used. I havn't really researched the 4 strokes for bike use. My heart lies with the heart breaking, crude little 2 stroke china girls. Why this is....I don't know.
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  #157  
Old 07-09-2014, 01:42 AM
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BarelyAWake BarelyAWake is offline
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Default Re: Reasons for riding Motorized Bicycle

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...My next project is a four stroke. Do you know of one larger than 50 cc that I can adapt?
The Harbor Freight Predator 99cc and 212cc are "fairly popular" builds, however they are also prime examples of the fallacy behind the saying "there's no replacement for displacement" as they've remarkably poor preformance for their size & weight, the $99 price tag is also somewhat deceptive as this ofc doesn't include the aforementioned preformance mods, nor the redrive system needed.

Simple & straightforward - utility engines can be fun, practical and reliable motors... but if economical preformance is desired they're not all they seem at first. For example the HF 99cc is 2.5hp at a max 3600rpm, whereas your typical moped engine either two or four stroke make that same hp with a mere 49cc, such as this example: http://tboltusa.com/store/50cc-moped...ls-p-1301.html

Granted, that example is $200 more then the HF99 - but consider it makes the same power stock as the HF twice it's size, comes included with it's own actual, integral transmission (other models offer 3, 4 & 5sp w/auto/semiauto or manual clutches) & even has electric start & full charging system... should you modify a HF to emulate this, it will most likely cost significantly more. Best yet if hopup mods & overall preformance is your game, as it's a Honda CRF50 clone has an extremely vast selection of common, even inexpensive aftermarket parts & upgrades from innumerable suppliers - opposed to the somewhat limited selection of parts & vendors for our motorized bicycles with utility engines.

Admittedly, another problem is fitting such a horizontal in your typical bicycle frame... yet I suspect if you've the wherewithal to make a utility motor work, then this would also be achievable, if you like choppers - it may not be a problem at all: http://motorbicycling.com/showthread.php?t=18970 or, for inspiration the motoped;




The utility engines are indeed fine motors and they can be an inexpensive way to get started in custom building motorized bicycles, it's just there's many other engines to choose from as well - which one suits your overall needs best only you can decide, but as with anything it's somewhat more complicated then it seems, it's more then price & displacement alone

Last edited by BarelyAWake; 07-09-2014 at 01:52 AM.
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  #158  
Old 07-09-2014, 02:24 AM
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Default Re: Reasons for riding Motorized Bicycle

Dang, BA. I too, was gonna suggest the HFs. (i own a few and really like em)

But you make some great points. Most importantly, re-purposing an engine that is meant to drive a small vehicle. Honestly, using a replacement engine for a snow-thrower to drive a motorized bicycle is kinda counter productive. Carb is meant to run at a steady, governed. Huge and just not meant for a MB.

When I hit lotto, gonna have the GY6 recast so as to fit a bicycle.
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  #159  
Old 07-09-2014, 02:51 AM
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BarelyAWake BarelyAWake is offline
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Default Re: Reasons for riding Motorized Bicycle

The utility motors are very likeable engines & I considered them myself, but they can paint ya into a corner if you'd like much more then the most basic build & I worry those that see the "good deal" price without further research, the redrive in particular as even the addition of just a TAV2 cvt will put you about $50 shy of the CRF50 clones, with S&H it's so close to the same, add in a good carb and it is... except ofc the limited modification potential, the multiple speed transmission, the charging system & etc.

Again tho - nothing wrong with the utility motors if no more then a basic custom is desired, if ya have one kickin' anyway or jus' wanna play with one - then again that can be said for jus' about any engine lol, I do like 'em all


...although I'll admit I really really despise recoil starters, but that's an almost unjustified personal bias based on 40 below temps, crappy chainsaws & me own wonky shoulders (of which are ofc my fault)

Last edited by BarelyAWake; 07-09-2014 at 02:56 AM.
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  #160  
Old 07-09-2014, 03:18 AM
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Default Re: Reasons for riding Motorized Bicycle

Truly valid point. Pull starters are the first failures. Always. Even when treated gingerly and used as the manual suggests, they fail.

IMVHO, the greatest weakness of most 4 smokes. .
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Last edited by Dan; 07-09-2014 at 03:25 AM.
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