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Old 05-21-2008, 05:25 PM   #11
Easy Rider
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Quote:
Originally Posted by Arcade
Huge improvement in top speed
Right!

I encourage you to repeat whatever tests you did to come to that conclusion.

If it turns out to be true, you will be the only person in the history of the world to get any significant change from the mods that you listed.

Oops, I'm sorry. There was ONE other person who posted results like that here.......along with some other rather..mmmm...dubious claims and then vanished.
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Old 05-22-2008, 12:27 PM   #12
Arcade
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All I've got is personal experience. I went from barely reaching 60 going downhill with a tail wind and fully open throttle to 65-68 on a flat road with a little bit of throttle left. I haven't done anything else to the bike except remove the front fender and the rear seat.
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Old 05-22-2008, 12:53 PM   #13
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Here's the thing. If anything, removing that little deflector from the air filter opening would actually slightly lean the air/fuel mixture. Less gas and more air equals a less complete explosion, resulting in less power. Simply rotating it from front to back doesn't change the flow characteristics at all. The air filters sucks it air from behind the plastic side cover. So, you aren't getting any RAM effect either.

It's more likely that the atmospheric conditions on any given day were different. As such, a variation of 5 mph here or there is not unheard of.

When I first got my bike, I could ride at 80mph all day long. Then, it started slowing down to maxing out around 70-75. I attribute this to the engine breaking in and loosening up a bit. I haven't seen 80 in months and that was in the draft of a transfer trailer.
My new top speed doesn't really count as I have a different gear ratio. Still, there are days when I can't get the bike above 60 and days when I can still hit 70 and I gave up on "power" increases a long time ago. I rarely ever need to go faster than 55 and that is a speed that this bike is really made for.



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Old 05-22-2008, 02:16 PM   #14
Arcade
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I'm not a mechanic, but it seems to me that if you help with the airflow, from intake to output, even a little better air flow might help things out. Releasing the backpressure in the muffler means less restricited air flow, add in allowing better airflow through the airfilter by turning it around. There is no practical way (for me) to measure the increased airflow through the filter since it is under the side cover but even minute pressure from outside forcing (a strong word that I am using to illustrate a point, in actuallity its probably a little closer to the drips from a faucet when you don't shut it off tight enough) air in causes the engine to work less hard. Anything you can do to decrease the workload on the engine is good, as far as I am concerned. 5 mph in a car or larger bike isn't much of a difference, granted, but for me, 5 mph constitutes a huge improvement on this bike.

I'm from S. Georgia, atmospheric conditions dont change THAT much on any given day down here. From mid/late spring to late fall you can expect 80-95% humidity, 75-95 degrees, and rain just about everyday, when we're not in a drought. Barmeteric pressures stay relatively the same except just before and just after a big storm (which we haven't had many of recently, hence the drought).

I would LOVE to get 70-75 mph on my bike. It just aint gonna happen unless I put a big bore kit on or perhaps swap the muffle out and rejet. I am seriously considering the 16T front sproket if i can find one.

One thing I have noticed from reading over the boards, everybodies bike is a little different. It even seems the "stock" bikes achieve different speed ranges. I don't know the why's or werefore's or the why not's for that matter. All i can say is what I've done to mine and what improvements (or lack of) that I've seen. If i had dyno'd it before and after and had some real empiricle evidence that could be repeated over and over, then there would be something to argue over. As it is, all I've got is my observations. Take it for what's it worth, love it or leave it, opinions are like a certain body part, everyons got one and they all stink, (add whatever cliche you want here).
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Old 05-22-2008, 03:19 PM   #15
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You're right. You are certainly entitled to your opinoin and if you are getting an extra 5 mph and attribute that putting holes in your muffler and moving a plastic lid from the right to the left, then so be it.

I will go ahead and tell you that the 16T sprocket will not make your bike any faster. It will, however, lower your cruising speed RPMs and make the bike feel not so "buzzy" at faster speeds. I'll never go back.

On a simple carbuerated engine changing the airflow and letting the bike breath better will, indeed, increase some power output. However, an increase in airflow on a carbed engine will result in a decrease in power if you don't properyl adjust the fuel flow, also known as "jetting" at the same time.
That being said, it is possible that the generic jetting from the factory tended to be a little rich (higher fuel ratio than is ideal (14.7:1) and in doing so your adjustments slightly leaned the mixture and you are actually realizing an incrase in power output. That's possible. It's just not common. The factory setting tends to be fairly lean.

One last thing, there is no big bore kit for this bike. Don't get your hopes up. Does that mean that you can't spend tons of money have something retro-fitted? No. But, if you spent $1000 on something that might increase your power output by 10%, it still won't really be worth it.



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Old 05-22-2008, 04:44 PM   #16
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Quote:
Originally Posted by Arcade
I haven't done anything else to the bike ***EXCEPT*** remove the front fender and the rear seat.
(Emphasis added)

Just removing the LARGE front fender might get you 5 mph on the top end. Lots of wind resistance gone.

Quote:
Originally Posted by Arcade
I'm not a mechanic, but it seems to me that if you help with the airflow, from intake to output, even a little better air flow might help things out.
Well, if it was that simple and all it took to make more power was more air.............then everybody would be a mechanic. Alas, it isn't that simple. You gotta add more gas WITH the air or it's counter-productive.

Don't believe me? Just take the (very restrictive) air cleaner element OUT and go for a short test drive. Don't get out in traffic though because it will run like CRAP and you might get squashed. We've pretty much beat this topic to death in the past 18 months or so.

Want to do another test?
Put the front fender back on and see what happens to your top speed.

Quote:
Originally Posted by Arcade
It just aint gonna happen unless I put a big bore kit on .....
That sounds familiar. Are you sure you haven't been here before ??? :??:
(Just kidding!)
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Old 05-22-2008, 06:44 PM   #17
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Go for a ride in the rain with no front fender. The fender is there to protect you and the bike from anything the tire kicks up.
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Old 05-23-2008, 06:50 AM   #18
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That's like asking a pony to carry the horse's load. :roll: The GZ I ride tops out in the mid 70's, but it is most comfortable to ride at about 60 mph. The GZ is a commuter bike made for urban riding, and back roads. It can be used for many purposes though. I have put 1500 miles on mine in about 2 months most of them on back roads and 2 lane highways. The best way I know to ride any faster would be to get a larger bike, or one that is made for speed like Kawasaki's Ninja 250 it will run about 100 mph and doesn't cost much more than the GZ. As for myself I'll just keep cruising :rawk:
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Old 06-06-2008, 01:29 AM   #19
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i have a crappy 99 gz

that had been sitting for 6 years. i had it up to 66ish the other day before hitting fifth gear and all ive done was a few holes and took the hood and rear seat off. im 6 ft, 240, and i have a moped tag on my bike just for fun ( i used to have a pagsta...). ive done wheelies on it (albeit not big or long ones, but hey, you take what you can get) and love this thing. mine seems to have a little bit of a rumble in the exhaust now, not annoying but more than youd expect. i did drill a hole on the right side and hit the second plate, i drilled through it too. maybe that was a big help, who knows. anyone really going to dyno one of these? hell an dyno run would cost more than i paid for the bike. actually, the new tires and chain cost more than the bike...
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Old 06-06-2008, 09:50 PM   #20
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OK here is where I am now

I cut open the filter to allow more air in
then I put in a new larger main jet
then I shimmed the needle, (although I don't know if this did anything
then I adjusted the pilot jet
then the exhaust

the exhaust was rattling, what was rattling, who knows
so we removed the whole exhaust
cut the pipe in front of the muffler
and out fell a 6 inch long 1/2 inch sttel rod with a sharp point on the end
we figured someones "friend" knew how to make the bike sound better
only when he tried to punch a whole in the baffle he knocked his home made punch right into the muffler and could not get it out
anyway
welded the muffler back on and drilled a few holes in the back plate of the muffler to allow the increased air and gas mixture to flow out as well.
I will try to post some pictures when I can.
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