More speed/power from a China engine?

[Lice]

Hey guys!

So I bought one of these:
http://www.ebay.com.au/itm/New-80cc...824464?hash=item41992e5410:g:sl8AAOSweW5U874m

I don't think its 80cc... But anyways, top speed I've achieved so far is 35km/h (about 21.75mph). Is this low? How can i improve the top end? Is it normal to not be able to take off from a standing start with these? (have to pedal before letting clutch out to move). Am i just too fat for it? (180lbs) It says "Speed: 55Km/Hr. Depending On weight" but that's probably just advertising.. I'd love to get to 55 on it..

I'll measure the tires tommorow and count the teeth if need be - it's dark out at the moment.

Cheers,
Troy.

Mods - i accidentally submitted this same post thinking i was logged in when i wasnt, sorry!

 

[DangerNoodle323]

What # of teeth do you have in the rear sprocket? The less the teeth, the faster. 38T or a 36T should guarantee you 30+mph

 

[AquaManAndy]

Upgrade it, I'm 240 lbs (108 kg) and I can hit 35 mph (56 kph) with a 44 tooth sprocket. torque pipe, ngk iridium spark plug, lightning cdi coil, properly jetted carburetor. your bike will thank you for it

 

[Lice]

Hey guys,

Thanks for the replies! I'll look into the forum for how to do those upgrades mentioned. (I may look into a bigger bike too as this one is a bit small).

Anyone know if it's possible to take off with these engines using just clutch/motor? I've tried and it needs to get pedalled to take off or just stalls. Maybe the upgrades listed above this post will make it doable.

 

[AquaManAndy]

Hey guys,

Thanks for the replies! I'll look into the forum for how to do those upgrades mentioned. (I may look into a bigger bike too as this one is a bit small).

Anyone know if it's possible to take off with these engines using just clutch/motor? I've tried and it needs to get pedalled to take off or just stalls. Maybe the upgrades listed above this post will make it doable.

you will always need to pedal to take off from a stop, unless your bike is rolling already.

 

[FurryOnTheInside]

You can but you would have to get a jackshaft system to use the gears on the bike (presuming that your bike has gears) like the Sick Bike Parts Shift Kit that I'm saving up for (or trying to) lol.

http://sickbikeparts.com

 

[Steve Best]

With a little bit of fine-tuning you can make it so that it will start away with just the clutch. Keep the 44 tooth sprocket. It will let you do 55 kph an hour. Let the engine break in that it works it's smoothest. Then read or ask for some advice on tuning tips to get more power out of it.

 

[AquaManAndy]

You can but you would have to get a jackshaft system to use the gears on the bike (presuming that your bike has gears) like the Sick Bike Parts Shift Kit that I'm saving up for (or trying to) lol.

http://sickbikeparts.com

I had a shift kit from sbp on my first 2 stroke bike, I liked the idea of having a transmission but in practice it was unreliable. The bicycle chain would break under torque from the engine, granted I was using walmart chains after the first chain broke. My most recent build I went with the single speed sprocket and could not be happier. That was just my personal experience and probable bad luck with it though.

 

[Steve Best]

I didn't have problems with chains breaking. My problem was getting it started was awkward. Eventually I stripped the one way clutch. Like you, I found joy in returning to single speed. 50 km/h is fast enough, and I have no problem starting away and getting up hills even with a 48cc.

I think too it's a question of different goals. I am biased towards lightness, simplicity, and reliability.

 

[Arty]

I agree with Steve - it's a question of goals and expectations. I started off with single speed, and enjoyed the simplicity, and relative lack of maintenance, but I did switch to a shift kit (7 speed).
The trouble with me is - as much as I try not to, every time I get on my bike, I seem to revert to "road race" mode, always wanting the engine to be on the sweet spot regardless of what speed I'm travelling at. It's not a "show off" thing, but it's just too damn much fun not to.
I agree, it took a while before I got my setup reliable, but with good chains, proper alignment etc., my setup is pretty bulletproof - - (but I never ride without some tools, and a rag).