| | | Motorized Bicycle General Discussion Topics on bicycle engine kits, help articles, repair and modifications for your motorized bicycles | lost top speed Discussion at Motorized Bicycle Engine Kit Forum in the Motorized Bicycle General Discussion forum. Hi
I have lost top speed ever since I have got a new carby. It very strong and takes off ...  | 
10-04-2008, 12:48 AM
|  | Motorized Bicycle Senior Member | | Join Date: Aug 2008 Location: Coffs Harbour, Australia
Posts: 69
| | lost top speed Hi
I have lost top speed ever since I have got a new carby. It very strong and takes off great but it seems like it doesn't hit top speed. Once it hits top speed it feels like the clutch is on. The clutch is not covering the air hole and the trottle does not cover it too.
So can you thing of a reason why it has lost top speed??? | 
10-04-2008, 01:20 AM
| | Motorized Bicycle Senior Member | | Join Date: Aug 2008
Posts: 51
| | Re: lost top speed Quote:
Originally Posted by 4wdingman Hi
I have lost top speed ever since I have got a new carby. It very strong and takes off great but it seems like it doesn't hit top speed. Once it hits top speed it feels like the clutch is on. The clutch is not covering the air hole and the trottle does not cover it too.
So can you thing of a reason why it has lost top speed??? | Check to see if the screen in the Tank petcock valve is dirty.
cheers
Bob | 
10-04-2008, 02:09 AM
|  | Motorized Bicycle Elite Member | | Join Date: Sep 2008 Location: Seattle
Posts: 442
| | Re: lost top speed If your float level is too low it could cause this. When you stop your using less gas so you would have enough to start out good, but you could be,in affect running out of gas at higher rpms. | 
10-04-2008, 05:54 AM
|  | Godfather of Motorized Bicycles | | Join Date: Jan 2008 Location: Ashtabula county, Ohio
Posts: 7,121
| | Re: lost top speed Check your plug first....see what color it is. Shouldn't be white or light grey. Should be tan to chocolate brown or a slightly oily black. If you are running too lean it will seem weak and get hot quick, too rich and it will have a good pull, but when you hit cruise or WOT it could "4 cycle".
Now, what do you mean "The clutch is not covering the air hole and the throttle does not cover it too."?
__________________ If it ain't broke, and you mess with it long enough, it will be. | 
10-04-2008, 08:45 PM
|  | Motorized Bicycle Senior Member | | Join Date: Aug 2008 Location: Coffs Harbour, Australia
Posts: 69
| | Re: lost top speed sorry i meant the choke any way i will check my plug and check the float | 
10-04-2008, 09:28 PM
|  | Motorized Bicycle Elite Member | | Join Date: Sep 2008 Location: Lima, Peru
Posts: 123
| | Re: lost top speed Hi
My mb has great start too (clean sounding engine)
But when sustaining mid rpms kind of 4cycles
And when flooring it pulls slow
Mb has a 'vibration' speed limiter...
Plug is dark brown
Should I lean the mixture?
Thanks in advance | 
10-04-2008, 11:00 PM
|  | Motorized Bicycle Elite Member | | Join Date: May 2008 Location: Corpus Christi, Texas
Posts: 823
| | Re: lost top speed Jose, Check your carb for torque against the manifold. They come loose and make an air leak sometimes. No we need more info like mix ratio, plug type, ect.
__________________
Only Bikers know why dogs love to stick their heads out of car windows, | 
10-04-2008, 11:16 PM
|  | Motorized Bicycle Elite Member | | Join Date: Sep 2008 Location: Lima, Peru
Posts: 123
| | Re: lost top speed Hi
I sealed the carb-intake tube joint with grey silicon
Mix is 30:1
Plug is ngk b6hs
Needle clip is in the second notch from top
Tire press is 40 psi (jk)
Thanks in advance | 
10-05-2008, 07:10 PM
|  | Motorized Bicycle Senior Member | | Join Date: Aug 2008 Location: Coffs Harbour, Australia
Posts: 69
| | Re: lost top speed thanks everyone
I switched the jet and the float leveler from my old carby to my new one and it works great i can get top speed...
thanks everyone | | Thread Tools | | | | Display Modes | Linear Mode |
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