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Discussion Starter #1
Hi guys,

after some advice on cams. have an 02 FXD, with zippers 107 kit, cnc heads,657 red shift cams, etc, add fueling oil pump and lifters,S& roller rockers. swapped out the G2 carb a few months ago for a 48mm Mukni, goes a lot better. As with having it like this four a while , i wan to up grade it a bit and was looking at a cam swap. i spoke to Bob woods, he said that the 68G would go in as is. but is biggere better? I scored a set if 72G of ebay, new. with the comperssion for thoses Bob said you need 11-1. my 107 is 10.5 (i think zipper said), so will .5 down on the compression be ok? I know that I have to swap out the springs for a bigger set as well.
Thanks for the help...

Kiwihdrace
:thanks:
 

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Cams

I would think that a minimum of 11:1 cr would be required to run those grinds in that engine. May need a piston to get there, but once you are locked and loaded, you will certainly be able to fire for effect.
Scott
 

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kiwihdracer said:
Hi guys,

Bob said you need 11-1. my 107 is 10.5 (i think zipper said), so will .5 down on the compression be ok?

NO NO NO It won't be ok............


{salute( :spank: {salute(
 

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IronButt
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Well you need to first know if the psrings in the heads you have will be able to handle the 72 cam. And every cam has a compression that it works best at. Running a cam low on compression will have the lower rpm range suffering. So as Scott said you may need a piston to raise the compression and then you will need to check the valve springs with that cam and then check TDC height for piston to valve. and valve to valve. ( I do not know what set zippers is running in that head at this time).
 

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may have to clearance the cam chest some more also.

i had tw72's in a 120" deuce that i had. It hauled some a$$ but sucked around town. Was a chugger til the cam turned on. If i hadnt sold it, a cam swap would have been first on the list to make it more rider friendly.
 

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Cam

It is certainly not a plug and play set-up.
This needs to be looked at and checked to insure that the end result is what and where it should.
Scott
 

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If you are dedicated to the 72's then you best get your comp up or she will be dog lazy on the bottom end. To be honest with you, there are other street cams that will serve you better than the 72's. Don't get me wrong when that cam hits, it HITS! But getting there can take some time while winding up the powerband.
 

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Discussion Starter #8
72g

Thanks Guys, it seems that the 72 may be too big for my use as my local bike shop said 10.5 (10.7) the most we can go here in New Zealand. we have 95 octane gas with 98 at some stations.zippers said that the heads will take up to 700 lift with the spring in there, so may be a 68G is what I'll have to go to. they should drop in, with checking pistion to valve etc.
I thought that the bigger cam would ( like in a V8) just loose a bit down low and give it a bit more top end? in saying that you could run more compression because of the over lap and when the cam comes on thecompression goes up to the normal ( say 11-1), are v-twins the same?
thanks for the input, here in NZ its hard to get any info as not too many bigger motors around so the shops here are no help.

cheers Kiwi
 

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kiwihdracer said:
Thanks Guys, it seems that the 72 may be too big for my use as my local bike shop said 10.5 (10.7) the most we can go here in New Zealand. we have 95 octane gas with 98 at some stations.zippers said that the heads will take up to 700 lift with the spring in there, so may be a 68G is what I'll have to go to. they should drop in, with checking pistion to valve etc.
I thought that the bigger cam would ( like in a V8) just loose a bit down low and give it a bit more top end? in saying that you could run more compression because of the over lap and when the cam comes on thecompression goes up to the normal ( say 11-1), are v-twins the same?
thanks for the input, here in NZ its hard to get any info as not too many bigger motors around so the shops here are no help.

cheers Kiwi
It would seem that a 68G in a 107 should be plenty in a street build. 10.5:1 still seems kind of marginal for even a 68G. Got a good friend running 68Gs with Baisley 1.7:1 rockers in a 117" with 13:1 compression and R&R oval port billet heads and it is a sick ride. Of course, his gas comes to the house in barrels from VP. I am at almost 12:1 and run 100 octane with TR-725Gs with no pinging. Little soft on the bottom, but my heads and pipe contribute to that. I like the way it rides, though.
 
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