New aluminum frame build

old motorbike

old motorbike

New Member
I haven't been posting in a while as I've had many projects. I started with a newer alum. framed bike and switched my china girl from my old store bike. I couldn't accept the vibration and decided to switch to a pocket bike motor. 49cc smooth, hi-rev, centrifugal clutch,pull start and gear reduction. The motor is light and inexpensive. Even wider there is still room to pedal easy. Should only need 1 gear with these rpms. Uses a different size (smaller) chain. Hand made an engine cradle and currently waiting for a gas tank. Have no idea how gearing (or anything) will work yet.
I assembled the old bike back together to keep it for a comparison.(and nostalgia)
 

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Great Build. How Many Teeth On Chain Box Tranny Sprocket ? You May Already Know, The Box Is 3.25 : 1. About 18 To 1 Final Ratio Will Work Good. Ron
 
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Motorbike, That Is A Very Neat , Clean Diy Install. I Have Several Of That Very Same Eng. Did You See My Recent Diy Cvt Belt Drive Build?? I Started With That Eng. It Worked Very Well. I Had The Same Engine As Yours On A Friction Drive, But It Has The Big Bore Kit (52cc ). My Plan Was To Switch Engines, Which I Have Done. The Kit Sells Around 50 Bucks. It Changes The Engine Into A Mean Machine. Much More Compression, More Instant Power And A Different Sound. I Think You Will Like Your Build As Is. Your Rear Sprocket Appears Small. I Think You Need About 18;1 Final Ratio. Thanks For Sharing Ron
 

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Your build has inspired me. I'm looking to build a bike with a pocketbike engine now! I just can't see getting a HappyTime, when a PocketBike engine costs similar, and it has a centrifugal clutch, and most likely MUCH more reliable!
 
I Am Very Pleased With The Cvt Belt Drive. I`m From Wisconsin = Snowmobile Country. They Have The Belt Drive Perfected On The Snowmobiles. Pretty Much Trouble Free And High Speeeeed. The China Girls Do Look Cool. Jims New Engine Should Save Them. The Cvt Mount Is Easy To Make, I Can Post More Pics. Have Not Had To Adjust Drive Chain. On Post 21 Of Thread "engine Rpm To Cruising Speed" I Stated To Large Fillipino That He Would Like The Cvt On A 4 Wheeler so his dog could sit beside him instead of the rear dog box. Also a front wheel cvt freewheel build, I will use the salad fork first and then the hydralic fork. I See He Has A Cvt Belt Build Almost Finished On His Trike. I Just Watched His Video, He Is A Happy Camper For Sure. The Sbp Kit And The Cvt Is A Great Option, And Nu Vinci Of Course. If I Can Help, Let Me Know. Ron
 
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GRR, just when I thought I was close to having a plan for my first build.. I had to find this post and get a wrench thrown in my spokes.. grummble.

Nice bike, very interested in hearing how it runs.
 
Thanks fo0r the great comments. Neat times, you have a great collection and some innovative ideas. I'm waiting for parts, pull start and gearing. This is why I keep my old China Girl.
 

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ZnsaneRyder said:
Your build has inspired me. I'm looking to build a bike with a pocketbike engine now! I just can't see getting a HappyTime, when a PocketBike engine costs similar, and it has a centrifugal clutch, and most likely MUCH more reliable!
Click to expand...

I have being having simmilar thoughts, but then I dont know iff I want to go any faster on a pushbike.
 
old motorbike said:
I haven't been posting in a while as I've had many projects. I started with a newer alum. framed bike and switched my china girl from my old store bike. I couldn't accept the vibration and decided to switch to a pocket bike motor. 49cc smooth, hi-rev, centrifugal clutch,pull start and gear reduction. The motor is light and inexpensive. Even wider there is still room to pedal easy. Should only need 1 gear with these rpms. Uses a different size (smaller) chain. Hand made an engine cradle and currently waiting for a gas tank. Have no idea how gearing (or anything) will work yet.
I assembled the old bike back together to keep it for a comparison.(and nostalgia)
Click to expand...

BEAUTIFUL JOB !!!xct2
 
I finally had time and some parts to experiment trying to make a functional gear ratio for this bike.
Taking the trans apart I machined out the bigger of the 3:1 sprockets. (don't ask how) and welded in a 60 tooth sprocket. Making that small chain fit and Cutting open the rear of the housing for clearance. This made a 7:1 ratio. Enough to get it in range, added to the 4:1 in the rear. It worked out almost perfect and seems to go about 35mph with ease. It does vibrate the bars and tingle the hands, but twist the throttle and go fast.
There are many upgrades to do, but that is the fun.
The little engine just screams with power and the pipe sounds great. The rains came and had to put it away.
 

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Did a gps yesterday and it only did a 32 mph. I could gear it up a little.
The chain I use is for pocket bikes and is like a necklace. Like to make bigger, but can't find interchangeable sprockets, etc.
Want to do some videos, but need a helmet cam.
 
Hi Motorbike, Again, Your Build Is A First To My Knowledge. Very Good Thinking. What Pitch Chain Are You Running Now On The Secondary #25, #35, Or 8mm? And What Is The Tooth Count? Dont Tell Me 32, Then I Will Know You Have False Teeth! Lol. I Think I Know Of A $5. Sprocket To Get You To 1/2" Pitch X 1/8" Bmx Chain(seconddary Chain). I Have Some Of Those Transmissions (3.25ratio). Was Planing Doing A Build Just Like Yours Except , It Would Be A Rack Drive. The Same Rack Mount As My Diy Cvt Belt Drive, But Drive Off The Left Side. I Hope You Don`t Mind If I Copy Your Set Up! The In Frame Looks Much Neater. A Free Wheel On The Rear Axle Is A Real Pleasure To Ride. I Had A Left Hand Thread Die Manuactured, Now I Cut Left Hand Theads On The Left Side Of Rear Hubs For Free Wheel Sprockets And Adapters. You Can Buy The Hubs, But Then You Have To Pay Sh, And Get Them Restrung Etc, It All Adds Up To Us Funds. 32 Mph , How Much Faster Do You Want To Go?? Thanks For Sharing. Ron
 
NEAT TIMES said:
Hi Motorbike, Again, Your Build Is A First To My Knowledge. Very Good Thinking. What Pitch Chain Are You Running Now On The Secondary #25, #35, Or 8mm? And What Is The Tooth Count? Dont Tell Me 32, Then I Will Know You Have False Teeth! Lol. I Think I Know Of A $5. Sprocket To Get You To 1/2" Pitch X 1/8" Bmx Chain(seconddary Chain). I Have Some Of Those Transmissions (3.25ratio). Was Planing Doing A Build Just Like Yours Except , It Would Be A Rack Drive. The Same Rack Mount As My Diy Cvt Belt Drive, But Drive Off The Left Side. I Hope You Don`t Mind If I Copy Your Set Up! The In Frame Looks Much Neater. A Free Wheel On The Rear Axle Is A Real Pleasure To Ride. I Had A Left Hand Thread Die Manuactured, Now I Cut Left Hand Theads On The Left Side Of Rear Hubs For Free Wheel Sprockets And Adapters. You Can Buy The Hubs, But Then You Have To Pay Sh, And Get Them Restrung Etc, It All Adds Up To Us Funds. 32 Mph , How Much Faster Do You Want To Go?? Thanks For Sharing. Ron
Click to expand...

Thanks, neat times. The chain in the (transmission ia a 25s?) about 6mm long links between teeth on sprocket. The front sprocket in trans has 8 teeth and about the size of a nickel. the rear, went from a 29 to 60 teeth. about 7:1. Thru the case is another sprocket size ..05t chain. the size is about 8mm between teeth. That's a 14 tooth sprocket that goes to a 55 in the rear. the rear mounted to a disc mount, with the 3 holes being enlarged.
I want to make another trans for the mb size chain aand can get bigger sprockets for a motorized bicycle size chain.
A rack mount would be better as these engines have a higher frequency vibration that goes thru the bars and grips rather numbingly. but they do have way more power and engineering than the China girl.
Good fortune with it and keep us informed. there is another guy doing these on this board, but I forget who right now.
 
Old Motor Bike, By My Figures You Have A Final Ratio Of 28:1. Thats Is Great For Starting Out. It Would Seem That You Are Doing Some Serious Rpm. I Am Hoping To Get A 'tiny Tac' So I Can Compare Rpm At Various Speeds. You Might Try A 8mm 20 Tooth On The 6 Spline Shaft Running The 55 Tooth On The Rear Wheel. That Would Give You A Final Ratio Of 19.5 To 1. That Should Cruise Nice And Help With The Vibs. I Had One Of The Motors Like Yours On My Cvt Belt Drive And It Worked Fine. It Starts At About 32 To 1 Ratio And Shifts To 14 To 1 ( My Guess). Now I Have The Same Motor With The 52cc Up Grade, Seems "gooder". Lol I Just Got The Bid For A Morini Motor, It Will Be Here Next Week. I Don`t Know When I Will Get It Mounted. Roncvlt1
 
NEAT TIMES said:
Old Motor Bike, By My Figures You Have A Final Ratio Of 28:1. Thats Is Great For Starting Out. It Would Seem That You Are Doing Some Serious Rpm. I Am Hoping To Get A 'tiny Tac' So I Can Compare Rpm At Various Speeds. You Might Try A 8mm 20 Tooth On The 6 Spline Shaft Running The 55 Tooth On The Rear Wheel. That Would Give You A Final Ratio Of 19.5 To 1. That Should Cruise Nice And Help With The Vibs. I Had One Of The Motors Like Yours On My Cvt Belt Drive And It Worked Fine. It Starts At About 32 To 1 Ratio And Shifts To 14 To 1 ( My Guess). Now I Have The Same Motor With The 52cc Up Grade, Seems "gooder". Lol I Just Got The Bid For A Morini Motor, It Will Be Here Next Week. I Don`t Know When I Will Get It Mounted. Roncvlt1
Click to expand...

Thanks, neat times Yes, I have a 19 tooth, I think will work better (maybe) to keep below the vibration zone. I needed to get a longer chain though as it wouldn't fit. I wanted to go with a 415 chain for this to be stronger, if I can find some sprockets to adapt.
 
Old Motorbike, Yeah, That 19 Tooth Will Work Nicely. Nothing Wrong With The 8mm Chain. If It Were Me, I Would Order A Couple Master Links And A Chain And See How It Works. My 8mm Chain Seems To Be Good. I Have Not Had To Adjust The Chain Since I Assembled The Unit. I Do Not Have A Chain Adjuster. I Used The Slotted Rear Supports. "parts Left Out Never Break". Thats My Motto And I`m Sticking To It. Lol. Roncvlt1
 
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