General Dirt Chat - speed dylan9302 - May 10, 2006 - 09:09 PM Post subject: speed
if you have a 50 cc dirt bike will it go 50 km/hr and an 80 80km/hr and so on
The_Wheelman - May 11, 2006 - 03:47 PM Post subject: RE: speed
Yes a 50 cc bike can go 50km/hr if you give it enough gas, etc.
dylan9302 - May 11, 2006 - 06:16 PM Post subject:
but could bigger ones like 250s go 250
JR_Greenhorn - Nov 12, 2006 - 01:20 AM Post subject:
I think I see what you're getting at, and you have the wrong idea. Bigger bikes go faster only because they have bigger enignes that make more power, but there isn't any direct way of knowing how fast a certain size will go. You should take a look at oceanpalms' thread called "Help!!!!" for an explanation of what cc's are.
50km/hr (or kph) is really moving for a 50cc bike, and most 50cc dirt bikes would never go that fast. A friend of mine has a modified XR50 pit bike. With a 130lb rider, it will do about 50-60 kph (GPS-measured). However, the bike has a 88cc kit, and enough mods that it needs high-octane race gas to run (13.5:1 compression).
A stock 90cc bike could probably be capable of 40 kph, but it would depend on gearing. It's just too hard to say with 50-90cc bikes, because they are primarily designed as youth bikes. A lot of youth bikes, especially 50s, are factory limited to 11-16 kph.
Bigger bikes can go much faster, maybe 100-110 kph, but not many can go much faster than about 130 kph. The fastest dirt bike ever tested to this day was the legendary 1981 KTM 495. A magazine at the time clocked it at 123.75 mph (or just about 200 kph), but they had to change the gear ratio of 5th gear, swap for a different rear wheel to fit different sprockets, and change the compression ratio to get it to go that fast.
Most sportbikes ("crotch rockets") can reach 250kph, but these bikes usually have at least 100+ hp, while a 250 motocrosser makes maybe 35-40 hp.
DanE - Oct 20, 2007 - 09:00 PM Post subject:
Yeah, I had a friend that though his bike went 50(Honda Z50R), but a 1000cc street bike dosnt go 1000k/m or m/h.