interesting experiance, trying to blow up a china girl motorized bicycle !!

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rogergendron1

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Sep 18, 2013
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Re: interesting experiance, trying to blow up a china girl !!

just checked my bike over and damn it .!!! my rear hub is worn bad !!! lol its catching in a spot and gripping the tire so it wont spin freely and there is drag on it all the time , but not enough to make it so i cant pedal it it just makes it hard to pedal and is prob limiting my speed .

i may get a new air filter and swap my rear tire out to a free wheel or just swap the motor on to my diamond back mt bike until i get a new hub

i guess a cheap wal mart 100$ beach cruiser hub cant stand up to 30 - 40 mph speeds for weeks strait ! ROFLAO !!!!

i think the break syst inside is compleatly worn to sht and gripping the hub

man she sounded like she was crying lol

well i am going to ride it no air filter and worn hub and all until it blows lol !!!


had it up to 36 mph and 8,556 rpms with no filter and a hub thats locking up !!!!

man she sounded like she was crying lol
 
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rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

alright guys i pulled the chain off to see if it was just the motor catching via unadjusted clutch.....

nope lol the hub is DESTROYED !!!!

i cant even spin it by hand in some spots ! it will spin by hand hard in some spots then catch and i need a mule to free it !!! i cant believe i got the bike up to 36 mph with that mutch friction holding it back !!!!! i took a video of me spinning the hub and i am up loading it now also i am taking pics of the new bike its going on.
 

rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

video of the damage to my rear hub, the motor chain is disconected

https://www.youtube.com/watch?v=_RAERghxXX4


https://www.youtube.com/watch?v=yOok9OCKVNw


lol the bike is blowing up before the china girl !

ok i am srsly starting to doubt most peoples speed claims here on the forum, lol it seems like a lot of people claim 40 mile an hour out the box with a stock motor or even that there x,y,z brand engine does 9,000 rpms stock lol well i srsly doubt that because in order for a stock motor and sprocket to reach 40 mile an hour on a 26 in bike it would have tobe powerfull enough to turn at 9,000 pluss rpms !!! i highly doubt that any stock motor will send you down the road at 40 mile and hour and 9,000 rpms on a 44t rear !!!

i mean i have MAJOR port work and nearly 13 to 1 comp with a modded piston, a 16mm carb and perfectly port matched intake and exhaust and a custom x chamber and 40 mile an hour is at the verry top of my speed margine here, i call fubar on those claims ! my bike is nearly 3 times more powerfull than it was stock and there is no way those guys would keep up with me on a stock motor !!! NO WAY !!!

i mean i am trying to break this thing by reving it to the max and holding it there and my speed is 36 -42 depending on the weather, heat, and road !
 
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rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

ok here is my piston ... you can see how its running and the port ramps i made, also you can see the skirt cut 1/4 in on the intake. it has been holding up to this abuse quite well i would say .

also the puch head, it has some carbon build up but seems just fine and the plug looks good.
 

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rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

ok here is my port work and jug

you can see the intake has been ground to a D shape and hogged out as far as i dare

the exhaust is ... well ... just huge lol.

i ground it out to an offset D shape and i can fit my thumb through it !

the cylinder wall is pretty good considering the abuse i have put it through for the last 3 weeks lol some glazing and a lil bit of scoring but still useable

the piston has some blow by where the rings close together and where the exhaust port is but thats to be expected espesialy with sutch a large exhaust port.

its all going back together and on another bike untill i get my trike rear end and new hub
 

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rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

the new bike its going on is a diamond back outlook 26in 27 speed mt bike with IRC Advantage Pro tires (sort of like a 2in version of the maxis hookworm)and shimanno Paraliax hubs and shimanno derailers with cantilever breaks, strait aluminum bars and aluminum goosneck and clamp with aluminum break levers.
 

MotorBicycleRacing

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Re: interesting experiance, trying to blow up a china girl !!

ok i am srsly starting to doubt most peoples speed claims here on the forum, lol

it seems like a lot of people claim 40 mile an hour out the box with a stock motor or even that there x,y,z brand engine does 9,000 rpms stock

lol well i srsly doubt that because in order for a stock motor and sprocket to reach 40 mile an hour on a 26 in bike it would have tobe powerfull enough to turn at 9,000 pluss rpms !!!

i highly doubt that any stock motor will send you down the road at 40 mile and hour and 9,000 rpms on a 44t rear !!!
No kidding!
 

rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

ok i did some transfer port modding to try aand open her up to getting more fuel at higher rpms .

i was looking at high rpm chainsaw motors and thought i would copy the designe.....

thought i would give the open transfer port a go ! this way there is no restriction at all, the port opening is the same size as stock so i did not alter the timing but the opening is bigger than stock and will flow a lot better this is because the stock transfers have a 2 step casting at the opening. they have the opening for the correct timing then it steps down with sharp 90 deg angles to the actual port and then goes down a skinny triangulare shapped tube with ruff edges to a miss matched case opening. now my motor has a wide open transfer so the skinny tube through the jug is all gone and there is zero restriction getting to the top of the piston and the steps are gone and a nice clean ramp angled up is in its place, i also took the liberty to angle them tords the middle of the chamber and back tords the intake. the piston is ramped to open the port even more, so hopefully i will be looking at some serious rpms and top end power ! i dont care how much low end i may or may not have lost i am looking for all out high rpms to try to blow this thing up !!!!

my goal is to get to 45mph and or over 10,000 rpm's before it blows ! all on a stock 44t rear sprocket and 26 in wheels.

here is a video of the mod


https://www.youtube.com/watch?v=SGLouFs15jM



in the video i say 93,000 rpm lol i meant 9,300 rpms
 

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rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

ok here are some more views of the ports i hope to get high enough rpm's to blow my motor with .

as you can see the transfers are much larger than stock, as in deeper and wider and thicker even though the opening is the same size. this is because the side wall is gone and all the space it took up is now available for fuel flow leaving only the side of the piston itself as a restriction and even that has been minimized and smoothed out by cutting raamps for flow.

the timing is set so the intake is open almost .4 in before the exhaust is fully closed, this is due to the massive cut in the skirt coupled with the deep porting on the bottom of the intake port itself. i am hopeing that opening the intake as soon as possable will help suck as mutch fuel in as possabl. why open it before the exhaust is closed ? well the upward stroke of the piston at high rpms creates a suction that can start to draw fuel in even before the exhaust closes of and it works much better with an exhaust tunned for this. though it cant work if the skirt is in the way lol.
 

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rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

i just made it to work and good god the rpms are insane ! She will def ho pretty soon lol i lost all botom end but my god the top end ! The top end is limitless !!! Lol

Well i cant say too much yet i ran her to work using a cut piece of sock as an air filter lol its super restrictive and causes boging when i twist the throttle but if i turn it slow i can get uo ti speed real quicj and she screems now ! .

I dont think she will hold up to thease rps for to much longer
 

Intrepid Wheelwoman

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Re: interesting experiance, trying to blow up a china girl !!

I dont think she will hold up to these rpms for too much longer
!st April, 2045.
Today the emergency services had to intervene when an elderly man with a long white beard made an attempt to ride an old motorised bicycle that according to the neighbours he had dragged out of his garage that morning.
When questioned the elderly man would only say, 'She's gunna blow, she's gunna blow......'
 

rogergendron1

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Re: interesting experiance, trying to blow up a china girl !!

vid of the rpms i have been riding at or close too for the last few weeks lol it sounds like a chain saw at WOT !

https://www.youtube.com/watch?v=IE_OAqeAGW8



i have yet to make a vid of me riding but i cant quite figure out how to video, ride, and show speed, all at once lol
 
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FFV8

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Oct 29, 2013
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Re: interesting experiance, trying to blow up a china girl !!

I WANT TO SEE THIS THING BLOW !
you guys have any ideas to get her to blow ?
like riding up hill wot, or down hill wot ?
no change of fuel mix though, i want to be fair ! keeping her at 93oct 40:1 mix with 1.5oz of lucas oil upper cylinder lube mixed per half gallon


mabey even riding in a strait line at wot as fast as i can go and keep her there for as long as it takes ? 10 miles 15 miles who know lol i will have to recored it !!! i know she will do a full 2.5 miles at WOT as fast as possable then slow to a intersection and then right back to WOT for another 2.5 miles again without a prob

i just can not believe this cheap motor is still taking the abuse !!! srsly i need to document this !!!

how many rpms do race motors turn ? how many rpms are concidered safe for the china girl ? because i am dead shure i am turning well over 8,000rpm's ever ride and keeping her over 8,000 for 99% OF THE RIDE
With your mix at 21:1 they can be hard to hurt.

You are making 40:1 fuel by adding 3.2 ounces of oil per gallon. Then you are adding 1.5 ounces of high grade synthetic (Lucas) per half gallon, which brings the blend up to 6.2 ounces of oil per gallon, or 20.64:1

High performance Karting engines run between 16:1 ~ 24:1 Plenty of oil will keep a 2 stroke alive under very harsh conditions. A chainsaw of similar stroke will turn 13,000 rpm @ WOT for most of it's service life.

.
 

Russ McClay

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16v4nrbrgr

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No, the higher octane gas would lose power and last longer, it burns slower and has tetra ethyl lead in it. If you really want to give your engine a spectacular ending, try adding some nitromethane RC gas into your premix. It will feel like a motoGP bike until it pops or melts down at high nitro levels!