64 tooth working out well!

48rob

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Sep 26, 2010
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I have a bike that came with a 44 tooth sprocket.
I installed a 4 stroke/Q-matic kit.

<img src="http://images.yuku.com/image/pjpeg/6c836d854f3b53285d8c450938fa0d22caa210c7.jpg"><P>
<img src="http://images.yuku.com/image/pjpeg/64726b84d05a35b04073a705249603656eb509a2.jpg"><P>

The 44 tooth just didn't have any low end power, top speed was 34mph.
After talking to Lee about it, and discovering his kit was designed for a 56 tooth, I changed it out and gave it a try.
Worked much better! But, it still seemed to labor too much taking off, and I wanted to have more hill climbing capacity.
Top speed was 33 mph.

I picked up a 64 tooth sprocket and had it machined to fit.
Top speed dropped to just 30 mph.
It climbs hills much better now!
<img src="http://images.yuku.com/image/pjpeg/ad416b485e59453d09828452188a2c7d828f27af.jpg"><P>

I've been riding a 2 stroke for several years now, but really liked the idea of an automatic.
On my 2 stroke, I overcame the cheap chain tensioner by building my own from a skate wheel.
On this bike, thanks to tips picked up while reading the board, I threw the tensioner in the trash and learned how to set it up so it isn't needed.
Thanks!

I'm 180 pounds, and take the bike camping, where there are always a lot of steep hills.
I'm far more interested in hill climbing ability than a high top speed...though 30mph is about as slow as I want to get.
Anyone have any hill climbing tips, or mods to reduce pedaling on the really steep ones?
Though the "hills" here in the midwest aren't much more than bumps compared to mountain states, surely those with real hills have found the right combination of gearing and power?
(I realize a much bigger engine would do it, but I want to stay legal, or close to it so I won't have problems in different states while out cruising).
There is a hill here, that if I can conquer without having to pedal, I'll have reached my goal...

This is the hill;
<img src="http://upload.wikimedia.org/wikipedia/commons/thumb/1/17/Newport%2C_Indiana_hill_2009.png/600px-Newport%2C_Indiana_hill_2009.png"><P>

It doesn't look like much, but it is 140' tall, with 1800' from the bottom to the top.
My bike made it about 2/3rds or so up the hill before needing pedal help.

Rob
 
I have a tip for you. Replace the stock exhaust with a flex pipe and you will see a noticeable difference. Just ask sliverbear. He made the change and is very happy with it. Lee can help you out with that too. BTW nice bike!

Jim
 
Last edited:
Thanks Jim!

The bike is a GT-2.
Overall, pretty good right out of the box.

Thanks for the tip.
I've got a couple 1" straight through muffler inserts ordered that I want to try.
The general idea was to lengthen the system a bit, adding the straight through muffler, then bringing the exhaust tip up high and straight back to help reduce the volume and keep the sound from skipping so much, like it does when mounted low.
I'm torn on the straight pipe idea.
I want/need more power for hill climbing, yet most of the time those hills are in campgrounds and parks, and bothering all the other people with a loud bike isn't something I want to do.
Maybe an exhaust cutout valve...hmmm.


Rob
 
A lot of testing was done to determine the correct length for the flex pipe. The big difference in the smooth wall you want to use and the flex pipe is the flex pipe is not perfectly smooth like the pipe. The testing done found that an exact length of flex provided the right mix of back pressure and free flow. I don't remember the length off hand but Lee can answer that question too.
Good luck
Jim
 
The flex pipe was tested on several DYNOs and the best overall powerband was determined. If you choke the system with too much length, or incorrect flow muffler you will reduce the power. It is important to select the correct I.D. and length. The Flex pipe kit uses real automotive pipe and the interior is very smooth compaired other choices.


NICE BIKE!

Have fun,
 
Hi Quenton,

Thanks for the tips!
Is the testing info available on the Internet?

If the flex pipe system gives the most power, does anyone know how much power the stock pipe/system that comes with it takes away?

The goal is to have power and be reasonably quiet.
Actually, very quiet would be better...

Some people like Harleys and the super loud wake the dead "look at me" pipes, and thats okay for them, but I want to be able to ride my bike in parks and residential neighborhoods without having everyone wish I'd go away.

Maybe in time, the market will support research for a quiet motorized bike.
I realize it will cost more, but in the end, it will be good for the hobby, as if we all zoom around irritating our neighbors and public officials, we could discover that they'll use the power we gave them to end OUR enjoyment...

I really like the automatic, smooth, easy, fun!
Good job!

Rob
 
Hi Rob,

The testing and research on the flex pipe was conducted on several different DYNOs and the data varied greatly. In all cases the flex pipe indicated an increase of 18% or more HP, and the torque peak was also slightly higher. The most important information gathered was the torque curve had relocated it's peak about 600 RPMs lower [slightly more bottom end grunt].

One motor tested [Honda GXH50] went from 1.90 HP to 2.45 HP with the pipe exchange. The motor had the original "box" type muffler and then the tuned flex pipe.


The data isn't on the EZM site because EZM didn't conduct the tests [I did] and it certainly won't pass EPA standards. The flex pipe kit isn't actually available from EZM,
but from Simpson Motorbikes, or myself.

It is also important to note the design helps reduce the noise as well as supply the necessary back pressure for good overall performance. It is louder than the "box" or kit pipe, but not as loud as you would expect. Nothing like the pipes on a HD or any straight pipe. Most think it has a nice low mellow tone and most like the ease of installation and the increase in power.


Hope I answered your questions,

Have fun,
Quenton
 
Quenton,

Thank you.
Yes, you've answered my questions very well.
18 percent is impressive...
I may contact you to give one a try.
What do you think about a split system, a cutout that would allow peak performance when desired, and as little noise as possible when needed?
I suppose the toughest part would be finding a cutout that small...

On another note, I'd like to change/fine tune the gearing further and would appreciate your thoughts.
The large sprocket on the rear has me where I want to be for no pedal starts and decent hill climbing, but the front sprocket, clutch and or pulleys are of interest.

Currently, I can cruise at about 12-15mph before the rpm's drop so much that the clutch disengages.
I'd like to be able to cruise slightly slower, say around 10mph.
As it is, at 12-15 because of the required rpm's for the cluch, it sounds/feels like the engine is racing (not slipping, just really fast and loud for the speed).
Can that be adjusted so the engine doesn't turn so fast at a lower speed?

Thanks for the help, I appreciate you taking the time to explain all this!

Rob
 
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