I have just recently installed the andrews 57h cams and I'm starting to concider going to the next step. After installing the cams I've lost about 8lbs of ccp according to the big boyz calculator which seems realistic. In an effort to recover my lost compression im either wanting to have head work done or simply install a .030" or a .027" head gaskets. The .027" gaskets should put my ccp about 1psi higher than it was stock, the .030" fall about 1psi short of stock. Either would be fine but I'm not sure of tolarances if I were to use the .027" (input please). As far as having motor work done it only makes sense to tear it down once and do headwork and a 107" at the same time if possible. With that said im not sure that I want to spend that much right now and to be honest I have no idea how much runout my crank has becouse I didn't have a tool to measure it while doing my cams. I was installing chain drive cams so I just didn't worry about it, ignorance is bliss I guess. So with all that said what type of gains could I expect with just using gaskets to get my compression back up vs. having head work done? And how would those compare to going 107". When I say "headwork" I refuring to a vee twin street port or hillside job.

 

You are not going to "feel" an increase of 8psi of CCP; exhaust tone might change a bit but I doubt the change will register on the butt dyno. Pulling the heads to install a thinner head gasket just isn't worth the effort and expense IMHO.

If you pull the heads, have them worked and setup for the 57 cams and a .030" head gasket; that will register on the butt dyno. Should be good for at least 10TQ/HP with a good tune.

 

Ok, if the desired compression is reached through headwork/.030" gasket then how much power can be gained from the 4 cubic inches of a 107"? 5hp/tq?

 

even mild headwork with 1.900/1.630 valves + setting the compression will give it a good kick

 

I agree

But I guess my question to the OP is;

What exactly are you trying to accomplish?

 

There's no simple answer to that question IMHO! Adding a 107" kit to a near stock engine adds a few cubic inches, but normally also comes with increased CR and cams, reworked heads, plus hopefully a suitable exhaust system. If you just mix those parts taken from here and there, the results may not be as near as impressive as buying a kit of proven matching parts from a high profile tuning shop. From what you have said so far I suggest you pick up the phone and talk to one of our experts - including the above! You'll get excellent results......

 

The same thing you are ultra, I'm trying to keep the wrenches turning and keep the smile on my face!!!.... Lol in all seriousness im wanting to achieve my bike running as best as it can without getting into the bottom end. Seems that for $1000 I can go 107" and have my heads worked over. That seems reasonable, plus I'm just the kind of guy that enjoys working in the garage. I grew up riding fast bikes "crotch rockets". I know my Harley will never run like they do, nor would I want it to but the more power it makes the more fun it is to ride in my book. What I don't want to do is spend more on my Harley motor than it's worth. I read on here where guys have $5k in there Harley engine which is fine but why not just buy a bigger better motor?

 

**EDIT**
disregard my previous question. didn't read properly.

Ok so here's what I see with you and is the same thing I saw when doing my own. Also keep in mind without actually measuring it, you should assume with stock HD setup, pistons as being .005 in the hole front and rear. It's usually in the range of .000 to .008, but assume .005 for good measure.

So with that said. Here's what you're looking at with your current build, stock build, and headwork.

STOCK


Andrews 57H


Andrews 57H w .030 Head Gasket


Andrews 57H w .030 HG and 82cc Headwork



Now what you're seeing here is simply 2 facts and 1 I want to point out to you.

1. You want to keep your CCP under 200 or at least pretty close to it. If you don't you'll have a great running bike on 92 octane and then it will run like **** on 87 octane if you run into that problem where 92 is not available. You want a bike that will run both without knocking and pinging you to death.

Fact 1. Changing cams doesn't change your static compression, only corrected and CCP

Fact 2. Doing headwork or changing head gaskets changes all 3, static - corrected - and CCP.

Now another thing to point out. Don't believe all you see about charts on this or any other site. Those charts are to be used for comparative purposes only and I woulnd't use any of those as assumed results from doing what they did. Look at the curves and look at the AFR on these charts. This tells you where your peak HP and peak TQ are going to be made and usually when trying to sell something a vendor will throw up 6th gear WOT runs as that's where they are going to show the best information. Now thing think about where you ride. You're not riding in 6th gear at WOT EVER! So I'll say it again as I've done many times before and my word is not gospel, only educated enough to know the difference:

Determine FROM YOUR RIDING STYLE what you want to achieve and build from there. If you want to chase peak HP and TQ numbers you're going to wind up with a bike that's not a whole lot of fun to ride.

Personally I think going from a 103 to a 107 kit is a total waste of time and $. I achieved with 82cc heads, a good head pipe, a good set of mufflers, 57H cams, and good A/C the same or better results than some of these 107 kits I'm seeing posted all over hell's-half-acre and at 1/2 or less the cost. The extra 2 - 3 HP and 2 - 4 TQ you're going to gain are never going to be realized by you, your riding style, or your seat of the pants dyno. If you're going to go through all that, you might as well go to 117 or 120 and attend to your bottom end while you're at it. I'm no expert by any means, but listening to those that are I won't move a 103 to anything higher than a 107 without bottom-end being done.. That's just me. I don't want people coming back to me with problems later on down the road.


That's my .02

 

oh yeah, 1 more thing. I'd sure like to know where you can go the 107 route with head work for $1000. That's awfully cheap IMO

 

Thanks for the input ultra, I have been using the big boyz calculator also except I was basing my charts off of 87cc heads as a stock number as suggested try other members. My statement about being able to go to a 107" with headwork is curtesy of vee twin who you are familiar with. $499 for bore and cp Pistons, $425 for a street port including head gasket. Of course the are other small expenses involved such as rocker box gaskets, base gaskets(o-rings), fluids, ect. ect. However it seems pretty reasonable to tear it down and do the top end all at once.