Unsatisfactory Power Output

GoldenMotor.com

fishingluvr

New Member
May 13, 2012
3
0
0
Milwaukee
Me and my dad recently put a 66cc kit together and I'm using it to ride around my neighborhood to save gas. The problem is the thing only goes about 20mph. I know its a small motor but i hear ppl getting 40mph on these things. I heard about the upgrade for the carb and the exhaust which im going to do...and the boost bottle....Im just wondering if those are going to get me +20mph...it seems at 20mph the engines revs are pretty high and idk what to do to get 40 out of it...also im still in the semi-break in period which im running gas at 25:1. When i go 40:1 is it gonna improve performance that much. I just seem a little disappointed in the performance.
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
Welcome to the forum!
All the engines are somewhat weak until fully broken in.
Many other factors can also cause poor performance too.
Did you do the proper pre-installation stuff?
http://motorbicycling.com/showthread.php?t=31010

How is the engine tuned?
Do you have any air leaks?
What oil ratio are you running?
Does the clutch slip at all?
How well is the bicycle tuned?

These kits are not a "slap it on and ride" affair.
They need proper feeding and care before, during, and after assembly.
A good maintenance routine will give them a longer lifespan too.
If you really want it to last, replace all the cheap Chinese bearings with good Japanese bearings before the Chinese ones blow up. This takes mechanical skill and patience though.
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
Welcome aboard!

Chinagirl? Well, get used to disappointment! :)
...but she's a cheap date!

it's probably just running too rich.
You will need to read the threads on re-jetting your carb.

40mph?
NOT gonna happen without a whole bunch of expensive parts.

It will do thirty on level ground if you don't weigh as much as I do...
..well, soon as you get it running on 40:1 and re-jetted.

an Xchamber is the BEST improvement you can make to any two stroke.

Best improvement to a chinagirl kit is a clamshell sprocket adapter.

IMO
rc
 

Joel G.

New Member
May 2, 2012
16
0
0
Guam
I got mine up to 41 mph with some wind at my back and some down hill with ZERO extra parts, just what came in the kit.. I just hit my 200 mile mark and am still running it at 20:1 fuel/oil mix with the needle completely on the rich side. After about 5 minutes of letting it warm up, I easily cruise around 32 mph. The only changes I made were- drilled small hole on the inside of the fuel tank cap to let gravity help the flow of fuel making it faster, and I purchased heavy duty gasket material for the intake and exhaust.. I was thinking possible lack of compression due to head gasket leak or loose head bolts, or fuel flow..
 

Greg58

Well-Known Member
May 1, 2011
5,353
2,575
113
65
Newnan,Georgia
All of the above advice is true, don't worry about speed just yet because most engines run much better after breakin. Most all will tell you to get the plug color correct, light brown and if it idles ok just ride. You will have to retune after breaking it in, around 300 miles is where mine started gaining power.
 

Sidewinder Jerry

Well-Known Member
Dec 19, 2011
1,996
928
113
61
Rockwood, TN
If you're seeking more power and speed because you don't want to run full throttle to do your legal speed limit that is a good thing. If you're off roading or race on a track go to the high performance section here. You should lookup and read your local laws as to what is required to operate on the public roadways. If you're not in compliance with the laws then surely you don't want to draw attention to yourself by doing 40+ mph.
 
Last edited:

fishingluvr

New Member
May 13, 2012
3
0
0
Milwaukee
ok well thanks for the info....im gonna wait until i get the gas to oil ratio up then start making some upgrades....where do i buy an xpipe or the x style exhaust mentioned...do one of the motorized bike online stores have them?...or is the expansion chambert a good option?
 

maintenancenazi

New Member
Oct 22, 2011
157
0
0
Asheville
Well, my 2 pennies. You should think about getting a smaller tooth count rear sprocket. I currently run a 32 tooth. Even though I weigh around 225 lbs, it still pulls my large A$# around town and up hills nicely ( you will have to peddle some ) The best thing about it is the increased mileage, and lower cruse RPMs. My bike will cruse at about 20 mph with the throttle just cracked open above idle! Your results may vary of course..

Peace, James

Edit, I also run a SPB X chamber, and some porting mods....
 
Last edited:

zaviii

New Member
Oct 17, 2008
65
0
0
Chico, Ca
Make sure your brake shoes are not rubbing the rims, mine did and I couldn't' figure out why my bike would not go beyond 22 mph, despite the high rpm.