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Heads and Cylinders All about your porting, compression, rings, cylinder and piston modifications to your bicycles engine

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  #1  
Old 08-12-2016, 12:15 AM
StevenMain StevenMain is offline
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Default 34 tooth swap, down hill, new personal best!

90 degree oat, 49% humidity, Density Altitude 3,000 feet
Going down a moderately sloped hill but unsure of the grade.
GPS logged on "speedometer gps" android app.

51.45 mph! I fixed the high rpm surge, the carb needed to be mounted more level and I adjusted float height. The 34 tooth sprocket is way too much though since the bike still could have gone faster I just ran out of hill. On level ground it will sustain 44 mph.

Next I need to do some quality mag wheels and a fairing of some sort.
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  #2  
Old 08-12-2016, 06:11 AM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Post script. .
I was wondering if there have been many people to hit 50mph on level ground? Or if it's even possible?

Stuffed case
Balanced bottom end
Fully ported Jug with 3rd Transfer port
Ported lower block halves
Windowed piston
Arrow style reed block
Keihin 20mm slide carb
Custom x pipe.
HD cdi ignition.
Milled stock head
NGK pkug

I would be happy with the performance the 44 tooth offered but I can't get the engine to continue pulling over 9700 rpms maybe try a different x pipe I've run out of ideas.
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  #3  
Old 08-12-2016, 10:02 AM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

This bike clocked 56.4 MPH on flat...

Keep in mind that this was on a real good day! (It will do 53-54 every day).

It has a 30T sprocket & tons of internal engine work.
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Last edited by Venice Motor Bikes; 08-12-2016 at 10:08 AM.
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  #4  
Old 08-12-2016, 10:33 AM
0megaMan 0megaMan is offline
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Default Re: 34 tooth swap, down hill, new personal best!

That's fast on a bicycle!
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  #5  
Old 08-12-2016, 01:51 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

I'm wondering what a better chamber and head will do for me. I'm skeptical on the head but I feel I've taken the jug to the absolute max .
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Old 08-12-2016, 05:09 PM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Post a pic of you bike so we can see what you've got
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Old 08-12-2016, 06:09 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Hope these links work. My stuff is worn out and I can probably go a bit faster on a fresh piston and jug and now I know what it likes for porting ill spend more time on the next jug.


This one is just to show the windowed piston, I have since ported the intake as pictured above.
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  #8  
Old 08-12-2016, 10:02 PM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default Re: 34 tooth swap, down hill, new personal best!

What's going on with that boost port cut in the cylinder???
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Old 08-12-2016, 10:27 PM
StevenMain StevenMain is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Just been experimenting, thinking a small jet or air and fuel could help induce swirl and gain a bit on the low end. It performs very well but obviously not 54mph on level ground like you. I don't know what you have done to get that kind of performance! I've tried about 5 different cylinder variations on porting so far and this one has the best top end and better than stock low to mid range.

I have yet to try a cr machine head but I don't know how it could possibly boost any performance. I have piston interference with one head gasket so I run two. I have a very very tight squish band.
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Old 08-13-2016, 12:41 AM
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sbest sbest is offline
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Default Re: 34 tooth swap, down hill, new personal best!

Quote:
Originally Posted by StevenMain View Post
<SNIP> I have piston interference with one head gasket so I run two. I have a very very tight squish band.
Try running 2 base gaskets and removing one of the head gaskets.
If that works well, run 3 base gaskets and use a twisted rope of teflon plumbers tape for a head gasket.

Steve
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