Fred Head Cylinder Questions

[panmines]

So I am in the market for a high compression cylinder head and have a few questions to ask before I choose a specific type. Basically, I want a high compression head not for a power increase but instead for the mass amount of surface area the fins provide for engine cooling. I have recently jackshafted my bike down to some really low gear ratios, so the engine will be spinning at higher RPMs without as much air flow moving between the fins. I am considering three heads, all CR Machine “Fred Heads”: the single, strait plug 5.0 cc variant, the single strait plug “stage two” 6 cc variant, and the single strait plug “stage 2” 7 cc variant. I am leaning toward the 7 cc version because it has lower compression and in its description it states it is “designed for highly advanced engines using normal pump fuel.” Since I am using the stock CDI (highly advanced ignition) and I use normal pump fuel, am I correct to say this is the head I am looking for? I am not confident with this because the description states the head is for engines with 47 mm pistons and 8mm studs. Would this still work on a stock engine?

My second concern is the thread pitch. The website gives me the option to choose between fine or coarse threaded head nuts. Does anyone know what the stock head studs are?

Also, I was wondering about the heads with a compression release. The site warned that a compression release shouldn’t be used with a “shift kit or any other type of spring loaded tensioning device.”. Does anyone know why?

 

[Deleted member 12676]

aren't these questions that should be directed to Fred?

 

[gus.]

I think Fred don't care about answers to customers. I written 2email to him no look.
And he said in the contact area he loves to hear about us. LOL.

 

[butre]

7cc will suit you well

the engines can come with either one, you'll have to eyeball the thread pitch on your own. if you get it wrong you can reuse the stock head nuts.

I don't know what the issue with compression releases and spring tensioners is, but I can ask him later. I'll keep you posted on that. I imagine it's a shock loading issue but don't quote me on that

he spends most of his time in his shop so he doesn't get much time to use the computer or answer the phone. it's a one man operation, it's either he answers every single question that people have or he makes the parts that people order.

 

[panmines]

You guys are right: I guess Fred would have to know. Thanks for the input Butre and you don't have to ask him on my behalf, unless you are curious your self.

 

[45u]

This is the head I am going to run on build two. Matt that sells them is a great persons and will answer questions by phone not like most others. This head is made in the USA and is 6cc and I would not go any less. Matt is a great person always willing to help. I have called left messages for him to call back and he always has. He cares about his customers after the sale not like most.
https://bicyclemotorworks.com/product/6cc-billet-high-compression-head/

 

[45u]

I think Fred don't care about answers to customers. I written 2email to him no look.
And he said in the contact area he loves to hear about us. LOL.

If he does not care about the customer or answering questions I sure would not buy from him!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I only deal with good sellers that care about the customer and to hell with the others!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! With all the problems you seem to have you might be better just to leave it stock.

 

[gus.]

No I can't buy from vendors if not respond.

 

[panmines]

This is the head I am going to run on build two.

That is a good looking head and it was my second or third choice, alongside the diamond head that Jake's sells:

I ended up going with the Fred head because I found a lot more information and testimony from people who used them. In fact, it arrived the the mail today and I had just enough time to test it out. It meet my expectations with maintaining low compression. For some reason the stock slant head that came with my original kit gave 175 psi while my 7cc fred head gave around 120 psi, which is right around optimal for these engines using the stock CDI. I also tested how well it is at cooling by letting the engine idle. It reached a max temp. of 215 fahrenheit in 15 min. and before it only took 5 min. to reach the same tempature. Overall I am really satisfied.

 

[Deleted member 12676]

Is that the 6cc or 7cc head?