40mph?????

S

SJCASEY1110

New Member
I had my bike with an 80cc engine for a little while and I get up to about 27mph. Does anyone know of any adjustments to make to make it go faster LOL. It says they go 40mph and up, but Id be happy to go over 30mph.


(c) - Shawn
 
Hi,
You can optimize the engine as much as you like BUT the stock gearing on most engine kits is too low to allow for high cruising speeds...The cheapest way to make the bike go faster is to install a smaller rear sprocket....I run a Dax 70 with a 36T and and can max out at about 34.4 MPH...if you want sustained cruise over 30 you may want to go even a little higher (smaller sprocket) since at 34 MPH my engine is screaming pretty high....Of course gearing depends on other factors too like rider weight, terrain and altitude above sea lever etc...
Hope this helps you.
Andrew
 
i would be scared to death on my motorized bicycle to do 40 :eek: i wouldnt mind trying it though. :D
 
SJCASEY1110 said:
I had my bike with an 80cc engine for a little while and I get up to about 27mph. Does anyone know of any adjustments to make to make it go faster LOL. It says they go 40mph and up, but Id be happy to go over 30mph.


(c) - Shawn
Click to expand...

Andrew and Ilikeabikea have it down it's in the gears - but also there are some things you can do. First break the engine in. Always have a good plug - I think the NGK B5HS is about perfect. Good wire and boot. (you don't want to miss a cycle at all).

Next tune the carb as best you can. Or just buy a NEW carb - research the options. Then get a new head gasket and pull the head (and cylinder) per Norms posts. Do the wet sand lap job. You can get a better seal and slightly better compression ratio.

Use the highest octane gas you can buy. Use a synthetic race oil 25:1 or so. (I won't say add a little Castor oil yet)


Just a few things....read more in the speed forum!
 
Re: Pablo why do you adopt the style of another site

Your post---- Next tune the carb as best you can. Or just buy a NEW carb - research the options--- why not POST the brand of carb you bought.

research the options.?

Amsoil is a fine synthetic oil.
Castor oil flows towards heat.
The mix of synthetic oil plus castor works better than either one alone.
 
My replacement carb is just a $22 China carb.....I think we are finding out there is more than one manufacturer in China though......

In theory you are correct about the oils, but hesitate to recommend it until I try it with these engines.
 
hello,

maybe my suggestions are the wrong kind of advise you're looking for as they are not engine related but,

why dont you try using thinner non-knobby tires.

if your frame allows use thinner larger wheels

regrease and check that the axles spin freely

use a lighter frame.

try taking out the exhaust baffle all together (faster but also louder)


I use road bikes and both my bicycles can make 40+. I use cyclocomputer so not sure how accurate it is. I do keep up with cars though (I usually don't try it makes them mad). its dependent on different variables though, an altitude too high or too big a hill and I dont make those speeds.
 
I don't know much about these things but I did learn the carb does have a large impact on it's speed. Try adjusting the cable that goes into the carb. Bring it up or down till u find the sweet spot.
 
Yeah... I found that my bike runs best "LEAN" with the needle all the way down, (c-clip at the top)
I also "port matched" the intake manifold & exaust pipe to the cyinder ports for better flow.
Try a 36-T rear sprocket.
 
To adjust the cable- Unscrew the cable housing adjuster lock nut at the top of the carb almost all the way, turn the cable housing adjuster in until there is a little freeplay in between the cable housing and the cable housing adjuster.

Gently unscrew the cable housing adjuster until it makes contact with the cable housing and then screw down and lock the cable housing adjuster lock nut.

Adjust idle with idle adjustment screw.
 
VENICE BOY said:
Yeah... I found that my bike runs best "LEAN" with the needle all the way down, (c-clip at the top)
I also "port matched" the intake manifold & exaust pipe to the cyinder ports for better flow.
Try a 36-T rear sprocket.
Click to expand...


These carbs definitely give some room to fine tune your running.

I ran mine both lean for awhile, and I liked the way it ran smooth in the mid range. It just seemed to be a little too lean when under load or at 3/4 or higher throttle. I was worried I smoke something, so I went back to "a little too rich" which is where these engines were designed to be run.

If you do run lean, I would suggest a castor or castor blend oil fo' sho'.
 
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