4 in crank or stock 4.375 ?
#1
07-30-2009, 11:31 AM
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4 in crank or stock 4.375 ?
I have 07' fatboy and this winter i plan on doing my build. The past couple of weeks i've seen some threads on builds with a lot of people saying the 4 inch crank and all bore is the way to go. I just got the s&s 106 bolt on kit for my 4.375 crank a few weeks ago. I plan on splitting the cases for the timken install what do i need to do to make the 4 inch crank work on my bike or should i even bother? I also plan on doing my heads with t-man stage 3, dark horse crank work and 590 gear cams. I'm spending a lot of money to do it right so need some opinions. Do i go with 4 in crank all bore,case boring to go bigger or stay with my s&s 106 bolt on. Keep in mind i ride 15,000 a year and ride like i stole it!
#3
07-30-2009, 04:45 PM
You know my stance. An all bore engine is the way to go. The twin cam engine was designed around a 4" crank as a 95" engine to begin with(the Moco before release shrunk the bore on factory bikes to an 88" for emission purposes and made an optional "95 inch BB kit" as an aftermarket/SE add on/upgrade). By going all bore with a 4" crank, with either a 107"(4.125" piston)combo or a 114"(4.25" piston)combo, you gain engine displacement, while keeping side loading, piston speed, and general engine wear to a minimum, while gaining in the process a naturally smoother running engine(via and oversquare engine setup)in the process. For a street engine this is optimal. I'd take a 107" or 114" oversquare design with the 4" crank any day of the week over say a 106/107", 110" or 113" that utilizes a 4 3/8th crank with a smaller bore.
Last edited by GunmetalBlueNT; 07-30-2009 at 04:47 PM.
#4
07-30-2009, 06:05 PM
You know my stance. An all bore engine is the way to go. The twin cam engine was designed around a 4" crank as a 95" engine to begin with(the Moco before release shrunk the bore on factory bikes to an 88" for emission purposes and made an optional "95 inch BB kit" as an aftermarket/SE add on/upgrade). By going all bore with a 4" crank, with either a 107"(4.125" piston)combo or a 114"(4.25" piston)combo, you gain engine displacement, while keeping side loading, piston speed, and general engine wear to a minimum, while gaining in the process a naturally smoother running engine(via and oversquare engine setup)in the process. For a street engine this is optimal. I'd take a 107" or 114" oversquare design with the 4" crank any day of the week over say a 106/107", 110" or 113" that utilizes a 4 3/8th crank with a smaller bore.
Bore that Biotch! send in the crank!
Last edited by PaleRearEnd; 07-30-2009 at 06:16 PM.
#5
07-30-2009, 07:01 PM
R.I.P. BROTHER
As much as I honestly cant stand this creepy Gunnie guy....That was a heckuva good post.
Fvcken' weirdo makes me want an all bore 107" so bad....I can tell a difference between the way my bike revs Vs' a buddy of mines 96 stage 1 bike. Its not just the cams and headwork. Mine snaps when his digs deep and grunts.
At least thats how I feel it.
Fvcken' weirdo makes me want an all bore 107" so bad....I can tell a difference between the way my bike revs Vs' a buddy of mines 96 stage 1 bike. Its not just the cams and headwork. Mine snaps when his digs deep and grunts.
At least thats how I feel it.
#6
07-30-2009, 07:13 PM
i like the 43/8 crank better as once it is Darkhorsed and timkin done at 107 if he decides to up the cubic inches later all he will have eto do is bore the ecases again and axtell cylinders and then he will have a 117.
i am running a 41/2 in crank and have absoluty no issues with it at all. if he lived in NJ i would let him ride mine.
i am running a 41/2 in crank and have absoluty no issues with it at all. if he lived in NJ i would let him ride mine.
#7
07-30-2009, 07:14 PM
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#8
07-30-2009, 08:36 PM
R.I.P. BROTHER
i like the 43/8 crank better as once it is Darkhorsed and timkin done at 107 if he decides to up the cubic inches later all he will have eto do is bore the ecases again and axtell cylinders and then he will have a 117.
i am running a 41/2 in crank and have absoluty no issues with it at all. if he lived in NJ i would let him ride mine.
i am running a 41/2 in crank and have absoluty no issues with it at all. if he lived in NJ i would let him ride mine.
That must be bezerkoe insane snappy on that 4" stroke eh?
#9
07-31-2009, 01:44 AM
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I would really like to go with the 4 inch crank and the axtell 114 kit but it's going to cost a lot more than going with the axtell 117 with my own crank! Is the wear and tear with the 4 3/8 crank really that bad! Also nobody has told me what it will take to modify or adapt the 4 inch crank. In other words i know it's not a straight bolt in unit. I want to know because it will help me determine which way i go with my build. My 106 kit i can sell on ebay or craigslist so no worries there.I have 4500 now to spend and another 2500 by early spring for a total of 7 grand to work with.My shopping list goes like this t-man heads,t-man 590 gear cams,s&s gear drive conversion,hpi 51mm throttle body,fueling cam plate,fueling oil pump,s&s roller rocker arms,woods rocker arm support,d&d fatcat big bore qt and dark horse work with timken/case bore.If you guys can think of any thing else please do tell.
#10
07-31-2009, 02:44 AM
I would really like to go with the 4 inch crank and the axtell 114 kit but it's going to cost a lot more than going with the axtell 117 with my own crank! Is the wear and tear with the 4 3/8 crank really that bad! Also nobody has told me what it will take to modify or adapt the 4 inch crank. In other words i know it's not a straight bolt in unit. I want to know because it will help me determine which way i go with my build. My 106 kit i can sell on ebay or craigslist so no worries there.I have 4500 now to spend and another 2500 by early spring for a total of 7 grand to work with.My shopping list goes like this t-man heads,t-man 590 gear cams,s&s gear drive conversion,hpi 51mm throttle body,fueling cam plate,fueling oil pump,s&s roller rocker arms,woods rocker arm support,d&d fatcat big bore qt and dark horse work with timken/case bore.If you guys can think of any thing else please do tell.
Lets see on the budget:
A. Timken bearing conversion and case boring: $600
B. Plug,tig and true from Darkhorse $150 I believe, add $400 for static balancing(not needed)if you want to go the extra mile.
C. Axtell 114" lite kit $1400 retail(there are places you can get it for a grand even)
D. Tman heads: $1300
So for the base and most expensive items were at $3500. Probably less if you shop smartly.
You have 7 grand to work with plus I assume the price of the 106 kit if you Ebay it. You can easily pull off a 114" setup to be within your budget if your smart take your time and shop around.
And to add, I did a 114" for a friend who was on a budget of $3000. He bullitproofed the bottom end, did a MILD bolt in cam, mild inexpensive work to the heads to let em breath better and he put down 110hp/130tq numbers. It was an absolute stump puller. In less than 2 years time he has put almost 50k on the build. Runs flawlessly.
Last edited by GunmetalBlueNT; 07-31-2009 at 02:59 AM.