Head work question
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Tourer
Joined: Jun 2010
Posts: 411
Likes: 23
From: Alabama
Head work question
Getting everything ready to change my 96 to 103.Will mild port work and larger valves help a lot or will it move th HP to the higher RPM range?Its a touring bike Ultra and I want the HP and torque in the low RPM range.Thanks
Road Warrior
Joined: Jun 2008
Posts: 1,437
Likes: 80
From: currently an Okie
Headwork
A lot here will tell you the headwork will make a big difference.
From the before and after dyno sheets I've seen, I'd have to say there is little difference below 5K.
That being said, I would go ahead and do it just for S&G's.
From the before and after dyno sheets I've seen, I'd have to say there is little difference below 5K.
That being said, I would go ahead and do it just for S&G's.
I'm not an expert, but every dyno I've seen the HP peaks toward the end of the scale, I believe Torque is what you are looking for, the cam seems to have an awful lot to do as to when that happens. Search the threads and call Dragos, Fuel Moto, and others, plenty of free and informative information.
Last edited by dbell66253; Dec 2, 2011 at 05:03 PM. Reason: spelling
From what I've seen on dyno charts and from personal experience porting and larger valves when used in conjunction with the proper cam will usually increase the torque somewhat. What they really do is extend the range the torque is maintained which is what gives you an increase in horsepower. If you look at the FM 555 charts in which the builds are all basically the same you will see that with head work there is a slight increase in torque, but a big increase in HP. If all you are looking for is low end then the head work may not be worth the money to you.
Outstanding HDF Member
Joined: Apr 2009
Posts: 2,523
Likes: 3
From: Illinois
I had Jamie do the Woods 6-6 cams in my bike and dyno it before and afterwards. (I also have the Stage 1). From completely stock to my current set-up I gained 25 Pound feet of torque and about the same in HP, and I don't need to be in the higher rpm's to have the torque available. You could port your heads, that's up to you and will most likely help your situation, just don't know if it's necessary for what you're looking for. Your cam is the biggest determining factor in where and how much torque you want.
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If you and your head porter talk about what your goals are, he can set up your heads for the power band you want to ride in. Porting for velocity will generally help torque production at the lower end. Running bigger valves will increase capacity, but will generally shift the bias towards the upper end. If your porter has a one-size-fits-all approach to head porting, you need to find another machine shop.
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