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Cool head question for a stock bike?


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I have an '01 with T-6 pipes, recently bored .030 over with Wiseco pistons and top end kit. I am looking at purchasing a "cool head", but not sure what size of domes to run in a relatively stock bike. I have no port work done and the crank is stock and NOT welded. I want the bike to be dependable relatively fast, should I consider putting a cool head on it or leave the stock head??

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I have an '01 with T-6 pipes, recently bored .030 over with Wiseco pistons and top end kit. I am looking at purchasing a "cool head", but not sure what size of domes to run in a relatively stock bike. I have no port work done and the crank is stock and NOT welded. I want the bike to be dependable relatively fast, should I consider putting a cool head on it or leave the stock head??

 

 

whats your elevation and what gas will/do you run ?

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Can someone explain the number that coensides with the domes like for example: 21 cc domes, what does the "21" mean? I have 130 lbs of pressure in each cylinder after the bore if that helps. How much will 20 or 21 cc domes increase my cylinder pressure? Will it add more horsepower to the motor? Will I need to have the crank welded with a 20 or 21cc domes? I know its a lot of questions, but I truely do not know and I am wanting to learn and I truely appreciate all the input fella's.

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Can someone explain the number that coensides with the domes like for example: 21 cc domes, what does the "21" mean? I have 130 lbs of pressure in each cylinder after the bore if that helps. How much will 20 or 21 cc domes increase my cylinder pressure? Will it add more horsepower to the motor? Will I need to have the crank welded with a 20 or 21cc domes? I know its a lot of questions, but I truely do not know and I am wanting to learn and I truely appreciate all the input fella's.

 

 

Well 21cc is a measurment in cubic centimeters the lower the number as 21cc the higher the compression. For a motor with 21cc cool heads wont put out as much horsepower as a motor with 18cc, but a rule of thumb is when changing to a lower cc dome you might have to use a higher octane fuel depending how low you go in the cc ratio. Going lower on your domes will increase your compression thus giving you a stronger motor. Ive seen friends run 18cc dome with 91octain fuel but again every bike is somewhat different. You also have to look into the future as if you plan on adding more HP to your engine yes you will need your crank welded but if this is as far as your going then no. I would have it welded it if you have the cash, just my .02

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So if I'm reading this correctly, lower number (18cc)=higher compression? 21cc = a little bit lower compression. With 21cc domes, I could still run 91 octane fuel and be ok? Do you know exactly how much of a compression bump it would be with 21cc domes? Will it be enuff of a compression boost to have to weld the crank?

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around 20-25 psi with 21cc domes from standard which are 22cc.

yeh the smaller the cc the more the compression due to the air/fuel mix being compressed into a smaller area.

 

i would have thought on 91 pump that 145-150psi would be a tad high, especially if your going to up the timing.

Edited by dirtydownunder
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around 20-25 psi with 21cc domes from standard which are 22cc.

yeh the smaller the cc the more the compression due to the air/fuel mix being compressed into a smaller area.

 

i would have thought on 91 pump that 145-150psi would be a tad high, especially if your going to up the timing.

 

The timing is getting advanced with a conservative 4 degrees actually this week., Would 145-150 psi be to high on a "non-welded" crank?

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