80cc vs 60cc

Gulu73

Gulu73

New Member
I have a 80cc MTB and My Friend Has a 60cc MTB ! He goes faster then me in a smooth road and even in a hill ! And He is heavier then me ! Why is this ?

My 80cc -
Standard 80cc Engine
Z4C Spark Plug
Standard Carburetor
36 Tooth Rear Sprocket
Standard Muffler
24" Bike

My Friend's 60cc -
Slanting Head 60cc Engine
BR6HS Spark Plug
Standard Carburetor
44 Tooth Rear Sprocket
Standard Muffler
24" Bike

Any Suggestions how can i go faster then him ?
 
Well, first off - there's no such thing as an "80cc" in-frame Chinese two stroke kit, here's a quote from a retailer;

China bike engine factories have always advertised their biggest engine as 80cc. However, the bore and stroke of an 80cc being 47x38mm only equals 66cc. Therefore there is no such thing as an 80cc bike motor and it truly does not exist.
Click to expand...

...so odds are you've both the same displacement.

The quickest & easiest mod, the one that'll getcha the most "bang" for the buck? It's w/o a doubt an expansion chamber exhaust - a critical component for any performance two stroke, left outa the kits as a cost saving measure ;)

ofc... then he'll jus' get one too when ya start dustin' him - let the modification race commence :D
 
I'd like to adjust my carburetor. But i don't know how D: ? Any Suggestions on how to set the best way ?
 
he has a 44 tooth sprocket and you have a 36, his is able to rev out faster than yours, it takes a good running engine to pull a 36 tooth sprocket, most will actually go slower with the 36.
 
And by moving the clip needle up what does it mean ? And by moving the needle down what does it mean ? Sorry for being a Noob
 
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Forget the motors! Look at drive line loss and make it as efficient as possible.Make sure your brakes aren't dragging. make sure your wheel brearings are good and lubed and not over tightened. Look at tire design and pressure.get smooth high pressure tires ,skinny is faster. Move your chain tensioner to the pedal chain and don't over tighten your chain( I gained a few mph just by doing that). make sure everything is perfectly lined up and you have no tight links in your chain. Cam lifter is right about the sprockets. Try a 40 tooth it's a good all around size. He's got a slant head so he's got higher compression so he's going to have more mid range power. Get a Pirate head or a slant head. Clean up your ports and match your gaskets, his might have cleaner castings than yours. When you move the needle clip up or down and read your plug. Make sure your thottle slide is opening all the way. Put a good plug wire and NGK plug in both available at sbp for cheap. Always do the cheap easy stuff first.
 
Cheapest and easyest mod for any noob to do is port match the intake. Followed by the exhaust. This is JUST dremeling your manifold (or exhaust header) to match the size/shape of the ports on your engine. And then making new gaskets to match. (Stock gaskets are often mismatched to the port as well!)
This gained me an estimated 15~20% power by my ass-o-meter just by doing the intake, maybe another 10% for the exhaust.

Expansion chamber will gain you at least 30% IMO, maybe 50%. Could even be a little more. But then, they cost more then port matching too :)

Tuning your carb, if you are 4 stroken a lot, Can gain you another 30% depending on how much its 4 stroken. You can basicly feel a kick in the ass when it goes from 4 to 2 stroking. The carbs needle E-clip usally needs to be moved for stock muffler, And the jet itself will also need to be changed of you go to expansion muffler. (You can buy new jets for about $4 each)

As for what direction to move the e-clip... Well, Use the old ass-o-meter to tell. Find a big hill and see how fast you can make it up, or judge your acceleration (And sound) on a flat.
 
Even when he climbs a hill ! My friends 60cc engine keeps on reving and my 80cc/66cc will be going to choke !
 
camlifter said:
he has a 44 tooth sprocket and you have a 36, his is able to rev out faster than yours, it takes a good running engine to pull a 36 tooth sprocket, most will actually go slower with the 36.
Click to expand...

I agree cam, get a 44 t and you will prob beat him or go just as fast. I run a 48t and its quicker and just as fast as with the 44t
 
idunno what you guys are saying, my last bike with a 44t hit 50kph max and that was revved to ****, my current bike has a 36t and i can hit 50 with very nice rpms, i cant get much above 50 due to lack of power but i know it will rev higher, perhaps once its broken in and i lean it out, otherwise i will need to start looking for more upgrades, i would like to pull atleast 60kph
 
The 36T sprocket isn't your problem in my opinion, I have one bike with a 41T and another with the 36T, they will actually top out about the same at 37-38MPH this was checked by GPS so it is correct, the 41T bike will pull hills maybe just a tad better but the 36T bike will run @ 30-32MPH almost vibration free for miles and miles, when on the other hand the bike with the 41T will shake you to death at 32MPH and only cruises comfortably @ about 26-28MPH max before the vibration gets outa hand.

You likely just need some fine tuning and and do as it was mentioned earlier and make sure everything in your drive system is smooth and well lubed with nothing too tight.

If you have the stock exhaust, I would remove the internal baffle and drill 4-5 extra holes in the very bottom so you can get the exhaust out of the engine quicker, this can make a big difference in how it accelerates and pulls hills.

Best wishes, Peace
 
Check gour plug for colar, I bet your plug is dark and maybe oily, if so your getting to much gas, by raising the c-clip it will lower the pin and give you less gas, a 40t is a good all around gearl I got a 36t and its slow coming out of the hole, till I get going about 15-18 mph then it starts to climb and reve up to higher speeds more quickleyr.ly.
 
speaking of sprocket size, these things r easily over geared by using 2 small a sprocket, thus not allowing them 2 reach max rpm. Pick a sprocket that, along with rear wheel size allows ur motor 2 just b able 2 wind out 2 maximum rpm (without laboring), so u get the most out of it. A smaller sprocket doesnt mean higher speed if the motor doesnt have the torque 2 turn full rpm (over geared). Cheers
 
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