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  #11  
Old 12-13-2005, 06:57 PM
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Default Re: Racer's Edge Performance (REP)

     

Quote:
Originally Posted by Aus_Rider_22
Andrew, you've outdone yourself!

Invaluable info in this thread!

I vote this to be put into the knowledge base forum.
I second that motion!
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  #12  
Old 12-13-2005, 07:27 PM
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Re: Racer's Edge Performance (REP)

Well I am impressed . I am moving this to the Knowledge base forum. This took me back to engineering physics classes and labs. I think I'll print it out for my personal use too.

Faded you are a valuable person for this site. Thanks for contribuiting so much

Bill
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  #13  
Old 12-13-2005, 07:32 PM
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Default Re: Racer's Edge Performance (REP)

Thanks for that Bill
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  #14  
Old 12-14-2005, 04:51 PM
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Default Re: Racer's Edge Performance (REP)

Thank you. This is for those that are interested in getting more out of there motor for not much dough. The manufacturing tolerances really start to stack up in production and the compression ratio and squish clearance that your bike ends up with can be a bit off from the design and published specs. By tightening things up it will run as designed and the end user (you) benefits.
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  #15  
Old 12-15-2005, 12:21 AM
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Default Re: Racer's Edge Performance (REP)

I renamed this and put it in the two stroke section.

Edited.

Actually, I moved it back to the two stroke forum so I don't have to approve every post. When this has run its course, we'll move it then.

Last edited by Woody_393; 12-15-2005 at 12:24 AM.
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  #16  
Old 12-15-2005, 04:46 AM
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Default Re: Calculating Head Squish Measurements - (REP)

Thanks Jonathan

Hopefully, soon as I get my stuff together, I can follow Andrew's instructions and report back with photos
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  #17  
Old 12-19-2005, 12:42 AM
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Default Re: Racer's Edge Performance (REP)

Great post Andrew.

First of all, you know that I have a great deal of respect for you.

And, based on part of your post, I might offer a bit of feedback that you may want to add further clarification on. I dunno, we may just be using different language but the statement below seems off just a bit.

Quote:
Originally Posted by Faded
......... Measuring the squish height and head gasket thickness will help you determine what the deck height is (height from top of cylinder to top of piston, can be + or - or even 0)........
First. Deck height is actually the measurement from the centerline of the crank to the top of the cylinder bore. (need special tools to get this exact measurement)

Second. The measurement of how far the piston is in the hole (below deck height) or out of the hole (above deck height is) is called deck clearance. Expressed as + or - and then the measurement or .00x in the hole or .00x out of the hole. Deck clearance can be determined a few ways. If you have flat top pistons you can use a deck bridge and a dial indicator, or you can add the stated stroke, stated rod length and the stated compression height of the piston and subtract this from the "known" (measured) deck height. The "Actual" deck height is what seems to vary the most in maufacturing. You'd usually do this with domed pistons. You'd still have to cc the dome to help determine the combustion chamber volume.

Third. Measuring the height of the squish band in the head (above the gasket surface of the head) and adding it to the gasket thickness does not tell you a thing about the deck height (relation of piston top to the top of the cylinder). It tells you part of the total Quench or squish as we commonly call it.

A more accurate statement would be "Measuring the head's squish band height and head gasket thickness will help you determine some of the total quench or squish."
or
Measuring from the centerline of the crank to the top of the cylinder will determine the deck height."

Which of these did you mean?


If you measure the height of the squish band in the head, add the measurement of the compressed head gasket and add the + or - deck clearance, now you have your total quench or squish.

Am I off hear at all?

Ride safe.

Ian

Edit: changed "stated" deck height to "measured"

Last edited by E-man811; 12-19-2005 at 09:43 AM.
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  #18  
Old 12-19-2005, 12:58 AM
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Default Re: Calculating Head Squish Measurements - (REP)

Oh, and I'll add this thought.

The tighter you start to make the compression in your engine, the more important it becomes to have the proper quench. There's a balance that the builders could tell you more about.

This is how a lower compression engine can sometimes be more prone to detonation than a high compression engine with the proper quench.

Ride safe.

Ian
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  #19  
Old 12-19-2005, 09:48 AM
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Default Re: Racer's Edge Performance (REP)

Quote:
Originally Posted by E-man811
First. Deck height is actually the measurement from the centerline of the crank to the top of the cylinder bore. (need special tools to get this exact measurement)

Second. The measurement of how far the piston is in the hole (below deck height) or out of the hole (above deck height is) is called deck clearance. Expressed as + or - and then the measurement or .00x in the hole or .00x out of the hole. Deck clearance can be determined a few ways. If you have flat top pistons you can use a deck bridge and a dial indicator, or you can add the stated stroke, stated rod length and the stated compression height of the piston. You'd usually do this with domed pistons. You'd still have to cc the dome to help determine the combustion chamber volume.

Third. Measuring the height of the squish band in the head (above the gasket surface of the head) and adding it to the gasket thickness does not tell you a thing about the deck height (relation of piston top to the top of the cylinder). It tells you part of the total Quench or squish as we commonly call it.
No arguments here, just a wording difference/mis-use on my part. I will edit my original post to clarify.


Quote:
Originally Posted by E-man811
A more accurate statement would be "Measuring the head's squish band height and head gasket thickness will help you determine some of the total quench or squish."
or
Measuring from the centerline of the crank to the top of the cylinder will determine the deck height."

Which of these did you mean?
Explained below.


Quote:
Originally Posted by E-man811
If you measure the height of the squish band in the head, add the measurement of the compressed head gasket and add the + or - deck clearance, now you have your total quench or squish.

Am I off hear at all?
You're not off at all. Since deck height/clearance is not easily determined by the average DIYer without the proper tools I've tried to supply an alternative method albiet a little more confusing at first.

If you measure total squish first (first step in my post) prior to pulling off the head then you have a number to work from. After pulling off the head you can measure the squish height in the head and the head gasket's compressed thickness. By adding these two numbers together and subtracting them from your total squish you can get a fairly good idea of deck clearance. Not the most precise way to do it, but close enough without having to buy costly equipment. I hope this clarifies things a bit.
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  #20  
Old 12-19-2005, 11:14 AM
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Re: Calculating Head Squish Measurements - (REP)

Faded and Eman,
Thank you both for taking time to explain this topic so well. I hope y'all will finish it out with some fine tuning and answer a few member's questions. I am going to duplicate this in the KB soon so it is in here for all to use. You guys rock!

BTW, Faded, according to your profile you are 86. You look good in your profile picture for an old guy.

Bill

Last edited by Florida 393; 12-19-2005 at 11:29 AM.
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