2 stroke motorized bicycle top speed

the only stock bike i ever built did a whopping 34mph in a full tuck. it wasn't straight out of the box, though. i match ported the intake manifold and the exhaust flange.

the first bike i built i had a 35t sprocket and a stock motor. speed on that was 38mph.

sea level, flat ground. 66cc Grubee GT4

 

I don't know. Never held it wide open to check.

The vibration was so bad I thought it unsafe.

I can tell you it would go faster than 25.

But I wouldn't -

 

I have to know... what tires/wheels do you have? That's really impressive speed without a shift-kit or chamber or any other mods. Bet it pulls out from the stops really nicely =) I don't recognize the carb either. Did you just port it and that's it?

My top speed out of the box was 24/25, after a proper jet it was 28. Switching to a 36t from a 44t only got me up to 29-- but removing my muffler cap got me up to 34. Going down a 30 grade hill at WOT only gets me up to 35. I know I have some significant drag somewhere I just don't know where. I'm guessing it's my wheel hubs/40psi tubes.

The stock exhaust I had was really, really, really restrictive. Nothing I did made a more significant improvement than removing that cap. Of course it's too loud without it, that's why I'm putting an SBP chamber on it. But with the cap on, it takes a full 30 seconds (timed!) to get up to top speed. Without it I accelerate faster than most cars.

 

Xeno, his Ford Ranger was going 75, and his bike was strapped to the back of it. It was a joke, lol. The bike itself didnt actually go 75. Tom (2door) was being funny.

 

'Fresh out of the box' in stock condition should go between 25-30 MPH if you have experience with building the bike properly. (every engine runs a little different though).

 

Hahahaah! Oh, I am gullible... >.>

 

My bone-stock BGF kit with a couple hundred miles on it went 32 on level gravel road and tucked in, REALLY vibrating. Have had ZERO problems with it, about 800 miles on it now, have not had the spark plug out of this engine since I installed it! I rarely run over 25mph now, more concerned with making it last than setting records.

 

"out of the box" is hard, because kits and bikes vary-

But a little faster than several yerars ago- even comparing 66 kits, which now have either usually a 66 Speed carb or CNS- for more power

and often a smaller than 44 sprocket-

I voted 25-26 which in hindsight is maybe what my cruiser did with beach tires, a 44 sprock and old 50 cc NT standard carb and intake

I get a good 30 cruise with narrow wheels, billet intake, Speed carb and 34 sprock. It will exceed 35 but I haven't pushed it there- and that's with 8 inch rise BMX bars, sitting normally. That's confirmed on the analog speedo which might be reading low for 26" tires and not the 27 wheels I have on.

But I've drafted a semi truck at 60mph on 250 gram seta sew-up tires, so it is niente....

 

My newest 66cc Z80 HT with a 41 tooth sprocket and my 230lb heaping pile of a$$ onboard will do a blazing fast 32mph on the flat according to Garmin. However.... it really cruises nice and comfortable at a not so blistering pace of 20-24mph.

 

My bike has a puch head and dellorto SHA carb. Its has a MEAN load of torque and acceleraties well. As soon as I Hit 27 mph it hits a wall though, because I have to work out my jetting. It also feels like Im running out of gear. Im gonna get a 71 jet + 39 tooth sprocket and she'll rip! I wouldn't be surprised if she hits 32-33. Ps my intake and exhaust are part matched too.

 

Or was it?

 

I squeaked out a 31 mph with a GPS before I swapped to a 36T.

I LOL'ed. I almost made a bumper sticker with [picture of bike] + [picture of truck] = Averaging 67 MPG, take that Prius!

 

Before swapping out my head and exhaust, my RB80 with only and SBP HD air filter and 36T sprocket could squeak out 38.2 MPH, but was pretty happy around 32 MPH. I never ran the original air filter or 44T sprocket, but figure they probably would have been good for a max of ~30.

 

I blew up my first one back in 2006 trying to hit 30. After that I never went over 28MPH with a 44T.

I voted 27 to 28.

 

I tried for months now to hit 40 MPH, the best I got was 39.7. BUT, over about 35 - 36 MPH she sounded/felt very unhealthy. Recently I have been sticking to cruising in her sweet spot around 32 MPH and she seems much happier. 30 - 32 is where my girl sings, it is funny how her vibes smooth out right there, so I figure that is where she wants to cruise.

 

had 40 in 8th gear loved it but 30 t0 35 perfect
GARY

 

I have a port-matched, tuned up HT with an NGK plug and performance air cleaner, and 38T sprocket. While I have no speedometer mounted as yet, I have left a 49cc Ruckus behind me, chokin' on my dust and failin' to catch up. (Dude made some kind of comment related to "old man".)