Chinese Scooter Club

alfa1972 · Tue Jun 17, 2008 8:08 am top speed

Hi guys I have a yiben hurricane 125 with the ubiquitus 152qmi engine in it, I am a few miles shy of the end of my running in period so I thought I'd open her up fully for a few seconds to see what she'd do, but I was disapointed, she took an eternity to reach 50mph and that was with the throttle against it's stop, went from 40-45 quick enough but that extra 5 mph took for ever, I was expecting 55-60 mph, once it's had it's first service will it be better or is there something I will have to do or ask the dealer to do in order to acheive that top end speed I've heard talk of cutting some pink wire which is a restrictor can anyone help either with the top end speed or the pink wire, would changing roller weights help, saying that not a clue what the current weights are?
Cheers guys in advance hope you can help me?[/I]

Aerostudent · Tue Jun 17, 2008 8:36 am

I assume that it is a brand new bike? If so, then you should gain a few mph as the engine breaks in (500-1000miles). That said, 50 mph doesn't seem all that bad for a stock, brand new. 125cc scooter. My 150cc scoot would only do 56mph stock after broken in, so 50mph isn't all that bad. 60mph is hard to reach on a stock scooter, ESPECIALLY on a stock 125 chinascooter. The only 125 I know of capable of 60 mph stock is the Buddy 125.

Also, there shouldn't be a rectrictor (pink wire, etc.) on anything over 50cc's. If there were a restrictor, you wouldn't be doing over 30ish. Rollers will improve your acceleration, but I wouldn't worry about doing anything to it brand-new. Let it break in some, then if you need more speed :D we can talk about it in a couple hundred miles.

It never hurts to ask the dealer!

Aero

Fox · Tue Jun 17, 2008 10:01 am

50 mph is pretty good on a flat for a 125. I suspect if you were to lean into the wind you might see a little more speed. Lighter weights will help with acceleration. I would say drop the weight by 2 or 3 grams from your current rollers and you will see a good increase in acceleration. The only way to know for sure what size weights you have in there now is to take them out and weigh them all at once then divide that by 6.

Maybe an up-jet and a free flow filter will get you up to 55 ish. :?:

Maybe it's running rich as it is, and you just need more air. :?:

Pull the plug and check the color. Black means rich. Greyish brown is good, and white or yellowish means lean.

Dave

RX8Marc · Wed Jun 18, 2008 8:58 pm My stock 125cc will do 63mph

My 125cc, will do 63mph on the flat, this was measured on my dads dyno machine! not using the "oh so accurate" chinese speedo!! :lol:

But it didnt really achieve this until the engine had its first service, has got 1100km on the clock now, acceleration has improved loads.

My bike is totally stock GY6 stuff!
I would say give it time to run in and make sure has a good service!

Aerostudent · Thu Jun 19, 2008 12:13 am

Keep one thing in mind that the dynos tend to be a little high, as they lack the ability to add in wind resistance to their calculations. As much as 25% of your power goes to JUST fighting wind resistance, so that 63 could be as low as about 47mph with wind resistance, though you are probably in the area of low to mid 50's with your performance exhuast (not bone stock ;) ). The only real way to test top speed accurately is to find a flat road, with little to no wind, and do a run with a GPS.

Aero

JumpSteady555 · Thu Jun 19, 2008 6:42 am

I'm hitting like 52 mph on my 150 so sounds about right for 125. I can push 55 out of it mabe 60 down a hill. Wind does make a big difference, I lost a few mph when I installed my large trunk.

Fox · Thu Jun 19, 2008 6:46 am Re: My stock 125cc will do 63mph

RX8Marc wrote: My 125cc, will do 63mph on the flat, this was measured on my dads dyno machine!

You factor in wind resistance and you are down to 55 tops@! ROFL

RX8Marc · Thu Jun 19, 2008 9:40 pm 125cc Top Speed

Oh yeah you are absolutely right regarding wind resistance! when your a fairly big bloke pearched on a scoot you do tend to have the aerodynamics of a brick! I did ride it to work when we had bad gales, with a head wind (strong!!) chinometer was reading about 50, not bad really! did 26 miles in 34 minutes, so works out about right! :roll:

Aerostudent · Fri Jun 20, 2008 4:57 am

It's not even the rider that makes that much of a difference, but bikes in general have very poor aerodynamics. It is said that most motorcycles (cruisers and crotch-rockets alike) have aerodynamics on the same level as a brick, and that is literally, not just a figure of speech. The coefficient of drag of your average red brick is roughly 2.0, and motorcycles vary from 1.8-2.0, while the average car is around 0.30. So you are perfectly correct in saying that a bike is as aerodynamic as a brick lol

Aero