Victoria! Zeke's CB175 Build

Difference between the opening of the intake valve and the closing of the exhaust valve. It's the number of degrees of rotation where both are open.
 
LSA is the angle between the two peak lift numbers - not the IO and EC times. Changing LSA also changes overlap and by definition changes exhaust open and close times in relation to inlet open/close times. In general it is said that wide LSA makes for better low end and tighter LSA generally helps top end - especially on a motor that doesn't breathe well.

In a motor where there is a mismatch between intake and exhaust flows, focus on improving the flow that is restricting power.

Where is this mind torture leading? More Compression is generally good, and it really helps the bottom end with a lumpy cam. More duration and lift ( don't forget lift) helps at higher revs by providing more time to get gas in or out. Stock cams are great for going to the corner store for milk or for commuting, but they restrict top end.

Too much valve timing/lift leads to lower gas velocities and lower VE numbers. Lucky and Vicky are different bikes and in theory, Lucky should make a great street bike where Vicky should be a racey little minx. Next step with Victoria is to see if compression can be raised a little. 11:1 would be a good place to start if the squish bands are right and with low crown pistons and U4.4 anything is possible.

http://www.tildentechnologies.com/Cams/CamBasics.html

http://www.hughesengines.com/TechArticles/2choosingacam.php

http://www.chevytalk.org/fusionbb/showtopic.php?tid/243852

And let';s keep in mind that cranking compression doesn't tell us much of anything about one motor compared to another. Our 175 (181cc) makes 21hp on a good day and cranking compression is not high. That motor is easy to ride and revs well too.

And lest we forget, we are dealing with a sixties motor design and not a current model high CR 4 valve design, so old school theories will tend to apply.
 
"Where is this mind torture leading?" lol...yes back to the word optimization and understanding hopefully. You know it is like you have always been told the world is flat and then you discover it is round. I never once took into consideration how a cam impacts compression. I thought if the valves opened and closed then a 9:1 compression engine would have less dynamic compression than say a 12:1 engine. I never realized they could have the same compression based upon cam selection.

So now my world is round. :)

We selected the cam because of a wise ones experience but we didn't have his knowledge.

So we go to the Dyno without checking our compression numbers and we make 21hp on t4 and 23 on U4.4 and so we never bothered to check our compression.

Victoria runs like a bat out of hades compared to Lucky so I never worried about it.

So then we pulled out the compression gages (3) of them because I couldn't believe my eyes. A HF that was new was bad , one we used before that turns out to have a bad schrader valve, and now the one on loan from Oreilly's.


https://vimeo.com/116774415


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Early GSXR motors (oil-boilers ;) ) had LSA of 104 degrees with idle speed somewhere around 2,000+ and red line around 10,500~11,000
Some of the race cams were 102~103 LSA
Low rpm motors (automotive, max rpm around 6K) will have LSA around 110~114 degrees)
 
crazypj said:
Early GSXR motors (oil-boilers ;) ) had LSA of 104 degrees with idle speed somewhere around 2,000+ and red line around 10,500~11,000
Some of the race cams were 102~103 LSA
Low rpm motors (automotive, max rpm around 6K) will have LSA around 110~114 degrees)
Click to expand...
this cam is 100 intake and 105 exhaust.


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and don't forget on victimoria being a sohc is fixed,ground into the cam wheras the dohc has the advantage of being able to actually play with that
 
Yep, I know LSA is ground into the cam, point is, you may not want it to be too close to the 100 mark but also don't want it over 110 for a high rpm motor
 
xb33bsa said:
and don't forget on victimoria being a sohc is fixed,ground into the cam wheras the dohc has the advantage of being able to actually play with that
Click to expand...
victimoria lol ur funny


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Did you have to make a tach adapter for the tach? Its electric right?

I had to make an adapter for mine since it was meant for automotive use. It dwells slower than yours and i think my resistance calculation was wrong when I read some instructions online. The lowest setting was two cylinders the adapter cuts it in half. I'm not sure how accurate my tach is. Looks great Tex.
 
acm177 said:
Did you have to make a tach adapter for the tach? Its electric right?

I had to make an adapter for mine since it was meant for automotive use. It dwells slower than yours and i think my resistance calculation was wrong when I read some instructions online. The lowest setting was two cylinders the adapter cuts it in half. I'm not sure how accurate my tach is. Looks great Tex.
Click to expand...
no adapter...Teazer sent us that tach and it is wired to the coil. Victoria has survive one ride at redline on that tach since I didn't tell Benjamin what the redline was...lol


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So the more the RPMs increased the cylinder pressure increased and I removed the carb like you suggested XB :)


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Now will will start it on the left side and test it with just the Cl, then on one cylinder @4000k and increase the revs and see what happens


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That's about as high as it will ever get so you know your good to add a bit more.
Maybe skim head and re-profile combustion chamber
Thinner head and base gaskets (copper as you'll probably be pulling it apart a few more times ;) )
 
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