Thumper Club Forum

Club House => Chatter => Topic started by: tommy on May 27, 2017, 10:19:31 PM

Title: gn 250 top speed
Post by: tommy on May 27, 2017, 10:19:31 PM
hi lads i just got a gn 250 maybe to sell  on but its a nice clean one so i might keep it for a run about bike
question is what  is the top end speed on one of these ,its very lively up to about 60 mph and the struggles to go much quicker 70 tops its a  1988 us import  ,ta tommy
Title: Re: gn 250 top speed
Post by: timbo on May 29, 2017, 07:41:39 PM
Sounds pretty darn quick to me Tommy, for a 250 commuter bike IMHO  ;)
Title: Re: gn 250 top speed
Post by: guest2083 on May 30, 2017, 09:28:01 PM
Sounds about right for one of these, although no doubt road testers managed to get a few more mph out of one.  My RS's will cruise at 70 most times, and road testers apparently got 90 or so, but I have never managed more than 80 and not often, but then I'm no lightweight myself.
Title: Re: gn 250 top speed
Post by: tommy on May 30, 2017, 10:19:10 PM
i was out for a bit of a spin on the gn  this evening on the back roads,(round donard way ) strong motor its a nice little thumper ,maybe i will keep it for a bit ,i was supposed to sell in on  :-\ tommy
Title: Re: gn 250 top speed
Post by: Propellor on May 31, 2017, 05:35:16 AM
Sounds a bit low for a 250 but then again I don't know what power these things kick out. Does it have a rev counter?
Title: Re: gn 250 top speed
Post by: Propellor on May 31, 2017, 05:48:49 AM
Have a bit of fun playing around with this

http://www.wallaceracing.com/Calculate%20HP%20For%20Speed.php

One thing it does show up is how a small change in the frontal area really hits top speed.

The internet has the power of the gn at 22hp. I dunno if the collective agree but I'd say that'd get you to around 80/85 mph?

If it has a rev counter you could see what revs it tops out at and compare with max power rpm.

Sounds like a decent little bike regardless, but you did ask!
Title: Re: gn 250 top speed
Post by: CrazyFrog on May 31, 2017, 08:19:54 PM
Mz 250 is about 21bhp and can manage about 80 to 85 on the flat...
Title: Re: gn 250 top speed
Post by: tommy on May 31, 2017, 09:10:26 PM
no rev counter on it as its a us import, i am wondering now if the us ones were restricted theres no way it will go near 80mph  but it takes off pretty lively ,maybe i will get joolz to build me a supercharger for it  :) tommy
Title: Re: gn 250 top speed
Post by: Propellor on June 01, 2017, 06:06:29 AM
Nah. A sprinkle of covfefe should do the trick.
Title: Re: gn 250 top speed
Post by: CrazyFrog on June 01, 2017, 07:50:46 AM
theres no way it will go near 80mph  but it takes off pretty lively

Has somebody been messing with the gearing then? Worth counting the teeth on the counter shaft and rear sprockets to make sure they are standard which is 15/41 I think.
Title: Re: gn 250 top speed
Post by: Moto63 on June 01, 2017, 08:33:34 AM
My thoughts exactly Pete, does sound like the gearing has been altered 🔧🔧🏍🤔
Title: Re: gn 250 top speed
Post by: manxie on June 01, 2017, 10:51:51 AM
Where`s Spooky?? He`s the man that would be able to tell you as he has one!  ;)
Title: Re: gn 250 top speed
Post by: iansoady on June 01, 2017, 02:29:50 PM
Nah. A sprinkle of covfefe should do the trick.

There's a man keeping up with the news......
Title: Re: gn 250 top speed
Post by: tommy on June 01, 2017, 09:06:53 PM
i taught that about the gearing but its standard ,but i  think i will mess about with a different sprocket  ,but overall i,m happy with the gn
Title: Re: gn 250 top speed
Post by: tommy on June 01, 2017, 09:12:30 PM
Nah. A sprinkle of covfefe should do the trick.
??? i had to google that one propellor  tommy
Title: Re: gn 250 top speed
Post by: Propellor on June 02, 2017, 04:51:47 AM
Nah. A sprinkle of covfefe should do the trick.
??? i had to google that one propellor  tommy

Hee hee.
Title: Re: gn 250 top speed
Post by: timbo on June 05, 2017, 09:19:05 AM
Aye, Spooky is the man for this one, as he's owned a fair few GNs and is our resident guru. However, he's very selfishly cleared off to France for seven weeks  ;)
Title: Re: gn 250 top speed
Post by: Moto63 on June 05, 2017, 04:54:11 PM
FRANCE, France ya say. But Ain't that where the French live 🤐🤐