Top speed on gz250

[Skunkhome]

I have been searching but must be using the wrong search criteria. I am a big guy (250lbs but loosing) and am generally happy with what I believe to be a Stock GZ250. Performance seems to be fine as it keeps up well with surface street traffic (well actually can run off and leave most autos in traffic if I have a mind to do so.) but I am curious as to just what sort of top speed is typical of a stock bike with a lard bucket like me onboard. What is the benefit of adding a 16T front sprocket. I realize that it woud move my shift points up by 6-7% but other than that would it improve my top speed or just reduce the maximum RPM in overdrive (5th gear). I am quite pleased with the amount torque the bike has now and am concerned that the 16t sprocket might reduce the torque significantly. Another issue is that i do not want to adversly effect my gas mileage. Can the 16T sprocket be installed with the stock chain ?

[minieggroll]

I am 5' 8" and 140 lb. I can get up to 65 and even 70 if you give me a couple minutes lol. However, 65 on this bike isn't the most comforting speed in the world to be at imo. By the way, for your sprocket question, I refer you to this thread.

viewtopic.php?f=9&t=4505 (http://www.gz250bike.com/forum/viewtopic.php?f=9&t=4505)

There have been many other threads discussing the pros/cons.

[blaine]

The 16t lowers your Rpm,the down side is you loose any usable torque for hills and wind It works well in town as it makes 1st gear much more useable.It worked well for me,but I'm only 150 Lbs wet.You can use the stock chain.So if you try it & don't like it,it's only a few minutes to shift back.
:) :cool:

[jonathan180iq]

Out of the box, the GZ can touch +/-80mph.

With proper tuning and favorable conditions, it can do just a little more. But not only it is restricted here by power, you're also looking at redline with the factory gearing. The 16T sprocket increases the gearing of the final drive, theoretically giving you room to go faster. But the limited power then cannot overcome the taller gear to use it. There have been some guys who spent a lot of time trying to increase power along with the higher gearing. What's the magical new top speed you ask? ......+/-80mph.

The bike is what it is.

I loved the 16T sprocket because it gave more around-town smoothness to the shifts and I think is just so pleasurable for back country roads. My max speed dropped down to around 75 or so but that still let me cruise on the interstates between different parts of town. What is 5 mph anyway when we're never really on the highway to begin with?

To answer your question, at your size, you should still push 70. More with a tail wind.

[Skunkhome]

I am not dissatisfied with the performance just curious about what is possible.

My stats are as follows:
Driver weight: 240 + lbs
Local elevation: 23-25 ft above sea level.
Fuel: unleaded 87 pump octane
Fuel economy: average 75.6 mpg until last fillup that was 66 mpg with exclusive city driving.
Top speed thus far: 70 mph

[Water Warrior 2]

I am not dissatisfied with the performance just curious about what is possible.

My stats are as follows:
Driver weight: 240 + lbs
Local elevation: 23-25 ft above sea level.
Fuel: unleaded 87 pump octane
Fuel economy: average 75.6 mpg until last fillup that was 66 mpg with exclusive city driving.
Top speed thus far: 70 mph
Sounds like a GZ doing what it was meant to do.

[jonathan180iq]

It seems like what you are getting is about what is standard.

I averaged just over 68 mpg for the life of the bike. And I was able to pull a faster top speed with 5/6th throttle. Absolute full twist would slow me down just a bit. That little bit of information right there shows you the importance of proper jetting. ;)

Anything other than 87 octane is a waste on this bike.

[Jvacustoms]

I am not dissatisfied with the performance just curious about what is possible.

My stats are as follows:
Driver weight: 240 + lbs
Local elevation: 23-25 ft above sea level.
Fuel: unleaded 87 pump octane
Fuel economy: average 75.6 mpg until last fillup that was 66 mpg with exclusive city driving.
Top speed thus far: 70 mph

Only thing I can suggest to make this bike go any faster is to loose weight and tuck yourself like you are on a crotch rocket, loose the windshield and keep your knees in. Use non-ethanol fuel. add roots blower or some other forced induction. However without major modifications to the engine you will not peak 85mph I only ever achieved 83 mph down hill drafting a truck on the interstate tucked in with non ethanol fuel, no windscreen and fresh tires.

P.s. I weight 245, not picking on you just saying that it is over average intended rider spec. :rawk:

I have went from 250 to 1200 and i love every bit of it. I lost about 12 mpg but with performance and weight that happens... my bike pushes 95 hp form factory that is alot more than a gz and it still wont peak 130mph at any configuration without major modifications. 1984 Gl1200 Goldwing Custom(Naked)

[Skunkhome]

Not loosing the windshield just got it to where I can ride and keep my head out of the airstream. The wind noise was deafening.

[PimpS]

Mine went 120 km/h, thats 74 mph. It was strong back wind, otherwise it goes 115 kmph, thats about 71 mph...
Otherwise i'm a happy camper at 55mph...

[Water Warrior 2]

Lynda's GZ hit 80 mph once while on a flat road with no headwind. Windshield and bags on too. This was after figuring in the speedo inaccuracy. Can't for the life of me remember why we were riding that fast. She didn't like it much and never tried again.

[gypsyspit]

I've had my GZ for about a month now. I just got the M on my license Saturday. I just started taking it on the highway in short doses. And to my surprise it actually accells quickly. No mods made to it at all. And vie managed to get a top speed of 75. Haha it's not the safest feeling. But I feel like if I had a straight away and no wind it could push 80. But I'm also 130lbs and don't carry anything on the bike that I can't keep in my pockets

[davesisk]

Hey guys...I've ridden my lady friend's GZ-250 to test it out, and I can only get it up to about 52 - 53 mph in 5th gear. Based on what I read here, it should be able to get up to at least 65-70 or so. (I weight about 170 lbs, so I don't think my weight is the issue.) It's a 1999, and seems to run well, start easily, and generally be in pretty good shape. It does seem to burn just a little bit of oil...maybe 1/4 quart every couple hundred miles. I don't know all the details of the stock exhaust, but there is the one stock opening in the cone-shaped muffler and looks like two additional 1/2" or so holes have been drilled into the back plate of the muffler. (I'm a Suzuki S40 owner, and drilling holes in the back of the S40 stock exhaust is a pretty common mod, so I wouldn't be surprised to find a similarly common mod on the GZ250). So, maybe if the exhaust has been drilled, then adjusting the fuel-air mixture to be a bit more rich would give it a bit more power? Just guessing here (the S40's run lean stock, so adjustment the fuel mixture to a bit richer is another common mod for the S40's...again I wouldn't be surprised if the GZ250 wasn't the same given they are both "thumpers".).

That said, any other ideas on what might be limiting it's top speed so much?

TIA,
Dave

[Jvacustoms]

Have been running the bike too lean probably drilled holes and never adjusted the mixture. Might start by checking the plug it will tell you the mixture. If it is lean as i suspect you might shim the needle and replace the main jet.

Sent from my DROID RAZR using Tapatalk 2

[davesisk]

...Might start by checking the plug it will tell you the mixture...

OK. White plug tip means rich...I don't recall what indicates lean or just right?

Dave

[blaine]

Welcome.White tip means extremely lean,black is rich.light tan is right on the money.You need to increase the size of the MJ & shim the needle.
:) :cool:

[davesisk]

Ah, OK...so a little more than just adjusting the fuel/air mix then, eh? I assume there's probably some stuff in the How-To section on how to do this...I'll give it a look.

Thanks guys!
Dave

[mrgz250]

I was going to go to a 16 tooth sprocket but think about it take a good look at the
aftermarket ones its a solid piece of steel the factory has a rubber damper in it to lessen
the stress on the chain that rubber is there for one thing only 4me my gz is happy with factory new parts

[raul10141964]

I am 220 lb
my settings
2.5 turns on the pilot
shim needle
140 main jet
16T
top speed 80+
cruse 70-75 (to fast for my taste )
63MPG city

[Water Warrior 2]

I was going to go to a 16 tooth sprocket but think about it take a good look at the
aftermarket ones its a solid piece of steel the factory has a rubber damper in it to lessen
the stress on the chain that rubber is there for one thing only 4me my gz is happy with factory new parts
The rubber dampner does not lesson stress. It is supposed to lesson the chain noise but I have never noticed a difference.

[Glewis950@gmail.com]

I did it the 16 tooth sprocket and I love it. Less shifting and less viberation. When turning from a stop at an intersection I can at least get through the turn before shifting to second. I have found it easier to maintain top speeds (70+) when I take the RPMs up well into the power band before shifting to fifth.
(Comfort) something that helped make my bike fit me better I raised the front of the seat an inch and placed a 1 inch thick foam pad in the lowest part of the seat causing me to sit up and back a bit. More comfortable seating, shifting and braking. P.S. I weigh 215 lbs, 30 in. Inseam and 76 years young.

[09GZ250]

I got mine to 87mph when I did a top speed run flat road. I weighed 107 at the time.