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Discussion Starter #1
Did a search and couldn't find any info on this.

1. Anyone ever used cometic head gasket on the cbr f3? How good are they?

2. Is it suppose to label 67mm bore on the f3 gasket case? Thought f3 would label 65mm according to the bore size?

3. Why is it that when I searched eBay for cbr f3 and cbr f4i head gasket they are both marked 67mm?

4. Is it OK to use that cometic f3 gasket marked 67mm bored cause at the moment am rebuilding the engine with new bearings and crankshaft.

Thanks in advance for any help I can receive.
 

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If I were you I would not use a 67mm head gasket on a 65mm bore. Only if you bored your cylinders to 67mm you would use the 67mm gasket. F2's and F3's are 65mm stock bore. F4's and F4i's are 67mm stock bore. F4i pistons in a F2 or F3 engine is a bargain big bore kit, if you ever need to bore your stock cylinders. You can also use F4i intake cam and move you F3 intake cam to the exhaust side, for a cheap cam upgrade, but you would need adjustable cam sprockets.
 

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Discussion Starter #3
That's what have me puzzled. Was asking a mechanic and he was saying as long as it's labeled f3 it's OK but I know f3s are 65mm bore. I plan on doing the piston swap but where can I get adjustable cam gears?
 

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I wouldnt do the piston swap unless you had to. Dont do just for the fun of it. Wait until you scar your cylinders or something like that. And then it would be a complete rebuild gaskets, bearings etc = $$$! Try the "CBR Zone" for adjustable cam sprockets. Go to an OEM supplier for the proper 65mm head gasket.
 

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Discussion Starter #5
Well actually it's a definite rebuild because crank that was in there before got damaged and blew a rod. So all main bearings have got to be changed along with rod bearings. So got another crankshaft along with bearings. So thinking about doing the f4i pistons since the engine is already split in pieces waiting to be rebuilt. Just makes sense getting it done now Instead of tearing it back down later. Will the f4i piston build do any harm?
 

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Make sure you get someone who knows what their doing when boring motorcycle cylinders. I heard its a little different than doing a car engine but important. From what I heard theres a taper from top to bottom. I think. Search 637 big bore on this site. It will give you a little insight of things to come.
 
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