"CNC racing cylinder head" big joke

Clats97

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Aug 17, 2019
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Ok so I pulled the "CNC racing cinder head" off of an extra GT5 Pro Racing engine I had laying around... I wanted to experiment with "high compression" outside of shaving the head, which from my perspective did nothing good (or bad) to the engine.

Expecting some kind of power gain, I was left extremely ly dissapointed. Not only was there no power gain anywhere, I lost 15kmh of top end minimum. It takes me about 15 seconds to get to 35 and that's it....

So in short I have slower acceleration and worse performance throughout the rpm range or power band.

I assume the gt5 engine is built differently. Should I put the gt5 engine on to reap the benefits of high compression?

Wat is going on. I'm pissed again
 


gary55

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Nov 27, 2012
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How many cc's is the head? Some advertise as high comp. performance head when they are really a 8 cc chamber. That is lower then stock, and needs milling at the jug for any real benefit other then cooling.
 

Clats97

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Aug 17, 2019
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How many cc's is the head? Some advertise as high comp. performance head when they are really a 8 cc chamber. That is lower then stock, and needs milling at the jug for any real benefit other then cooling.
I don't know. From what I saw online it's supposed to be 6cc
 

gary55

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I don't know. From what I saw online it's supposed to be 6cc
If it's really a 6cc head it should show some improvement over stock. You may not have gotten a good seal at the head. Is the plug tight? Does the plug reach all the way into the chamber?
 

The_Aleman

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Nice thread title. Looks inspired by FUD.

The "big joke" here is that you blindly threw on a "pro racing" cylinder head from a different engine and got "pissed again" because it didn't work. Some of these engines are quite different from eachother, despite their looks. Swap em back if that's a problem, what's the problem?

It went from running beautifully and maxing out at 65kmh to running like sh*t
I'm surprised if you're surprised.
 

Clats97

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Aug 17, 2019
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Nice thread title. Looks inspired by FUD.

The "big joke" here is that you blindly threw on a "pro racing" cylinder head from a different engine and got "pissed again" because it didn't work. Some of these engines are quite different from eachother, despite their looks. Swap em back if that's a problem, what's the problem?



I'm surprised if you're surprised.
The cylinder head is an upgraded piece available ob bike berry. Specifications say it is compatible with my engine. Not sure how that's blind but anyways. I am not experienced enough to know whether or not the "CNC pro racing head" is defective or whatnot. Hence me asking for opinions
 

Clats97

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Joined
Aug 17, 2019
Messages
36
Nice thread title. Looks inspired by FUD.

The "big joke" here is that you blindly threw on a "pro racing" cylinder head from a different engine and got "pissed again" because it didn't work. Some of these engines are quite different from eachother, despite their looks. Swap em back if that's a problem, what's the problem?



I'm surprised if you're surprised.
The cylinder head is an upgraded piece available ob bike berry. Specifications say it is compatible with my engine. Not sure how that's blind but anyways. I am not experienced enough to know whether or not the "CNC pro racing head" is defective or whatnot. Hence me asking
If it's really a 6cc head it should show some improvement over stock. You may not have gotten a good seal at the head. Is the plug tight? Does the plug reach all the way into the chamber?
Everything seems fine to me. I am thinking that, although this is sold as a seperate performance part, what comes stock with the gt5 probably has different measurements. Reason why I think this is because I am under the impression that the crank shaft on the gt5 is different than most HT engines. It stands to reason that it coukd be different. But again... This part is supposed to be compatible with my engine
 

FNTPuck

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Jul 2, 2018
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650
I had the same head from a GT7 kit and it was fine for cooling, but no more performance than stock since it wasn't really "high compression". Actually cc'd at slightly lower compression than stock.

That being said, it wouldn't HURT your motor and sure as heck wouldn't be that dramatic of a performance drop unless something else went wrong. If you reused the head gasket, it is likely leaking since the stock head and the aftermarket will have different crush ring sizes and locations. You can get away with reusing a head gasket once or twice if its the same head removed and reinstalled, but if you switch heads you need a new gasket.

Alternately, the spark plug might be shrouded since some heads have too deep threads and the plug doesn't stick all the way in the chamber. In that case, a longer plug or projected tip plug would be needed.
 
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