Comp difference front to rear
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Cruiser
Joined: Nov 2017
Posts: 201
Likes: 104
From: Ohio
Comp difference front to rear
I put woods TW 7H cams in my 2012 FLHTCU with the heads milled .025 and Cometic .030 head gaskets. Now I can hear a distinct difference in the exhaust from side to side (Rinehart true duals). So I did a comp test and have 165 in the front cylinder and 125 in the rear. This is with the engine warm and the throttle held wide open (does it even really open if the bike is not running?) Any ideas? It has Power Vision with a tune from Fuelmoto that is not really for my combo but it was as close as they have. I also have the Target Tune and wide band O2 sensors. The bike runs strong except for a very noticeable miss or surge with a popping in the exhaust from 2700-3000 rpm that I can only feel if I try to cruise at that RPM. If I roll on it, it runs right thru that range with no issues.
HDF Community Team
Joined: Jun 2006
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From: san antonio
A leak down test should follow to see where the lost compression is going. If the leak down results are good, cam timing would explain the lost compression. Being off one tooth will allow the motor to start and run (not as well as it should) but will show the compression variance you are seeing. 
Seasoned HDF Member
Joined: Dec 2005
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From: poway
One of the things to note is that if the cam timing is off, it would have to be off on both inner and outer cam chains assuming that the 165 is what you are expecting. I'd oil the rear cylinder and and see if it comes up. Your popping on the 3K is more than likely tune. If you ran it for some time with a bad tune, you likely hurt the rear cylinder.
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Cruiser
Joined: Nov 2017
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Likes: 104
From: Ohio
Thanks
One of the things to note is that if the cam timing is off, it would have to be off on both inner and outer cam chains assuming that the 165 is what you are expecting. I'd oil the rear cylinder and and see if it comes up. Your popping on the 3K is more than likely tune. If you ran it for some time with a bad tune, you likely hurt the rear cylinder.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,894
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From: poway
I would say if you changed cams or set them up on a SBC, you'd get it right. The manual makes it pretty simple. It's not like you are trying to set the cam timing on a worn out Honda CB450.. 
Acr
could be. on my Pv I could disable the acrs. On a tbw bike the throttle will not open full throttle while cranking.
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