Top End Rebuild on 2006 117 (got tips/suggestions?)
- Thread starter SMCT
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SMCT
Active Member
No one had it thought out. In speaking with S&S, they never factored in that the rocker arms would load to one side.
Any rocker that has an offset, will load to one side. In our industry we see what's called "straight on" rockers which have no side load, we also see .050, .080, .100, .150, .180, .250 and even up to .750 offsets. These S&S engines have offset rockers that are 3.000 and greater, and they will produce load onto one side. When you are working with an engine that has offset rockers, there is a lot of fatigue on the rocker and the rocker box that holds it.
S&S is well aware of the design flaw issues, and has no comment on the flaw. It is a design, and a poor one at that, that saves them money but causes the consumer much grief.
Any rocker that has an offset, will load to one side. In our industry we see what's called "straight on" rockers which have no side load, we also see .050, .080, .100, .150, .180, .250 and even up to .750 offsets. These S&S engines have offset rockers that are 3.000 and greater, and they will produce load onto one side. When you are working with an engine that has offset rockers, there is a lot of fatigue on the rocker and the rocker box that holds it.
S&S is well aware of the design flaw issues, and has no comment on the flaw. It is a design, and a poor one at that, that saves them money but causes the consumer much grief.
Nice work sir, Love watching this stuff. Thanks.
what does this thrust bearing look like?
If washer is. 062...im guessing you checked rocker end play as well which was within tolerance? I suspect this could be a good time to tighten up that end play to the lower end of the tolerance spec of 0.001" - 0.012"? As the chances of less wear over time now with what I assume is a harder material?
I have heard of people doing a similar mod and inserting a shim of washer to return rocker end play to within spec.
Someone had also patented something called a "Rocker Locker" which is just a brass fitting which helps prevent movement of the rocker arm shaft itself. I don't have any experience with it, but the idea makes sense. I believe it was designed for stock Harley not sure if S&S has similar design flaw?
http://www.dkcustomproducts.com/Roc...Davidson-Big-Twin-Evo-1984-2000-DK-RL-BTE.htm
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I assumed S&S had tighter tolerances...ive really only heard of folks using them In stock Harley engines.
Just figured I'd throw something else out there.
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TapioK
Well-Known Member
Friend bought those for his Twin Cam with 80.000 miles. I looked at the arm/shaft. It was tight, no need for those at least not in that engine. What I didn't look was the box end...
SMCT
Active Member
Thrashing away and as of tonight I am up to this point. Just something to note or point out: Apparently Big Dog or S&S had missed calculated the length of one (1) of the 1/4-20 socket head screws (per each rocker stand). The allen screws provided was to short and I could see that many could strip the aluminum threads out of the head from not having enough engagement. I replaced it with a 1/4-20 that was .250 longer and it seems fine.
Next is a new clutch cable and then the exhaust will go on.
Next is a new clutch cable and then the exhaust will go on.
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SMCT
Active Member
Started it up today. I can honestly say that the rocker boxes are significantly and noticeably different. There is absolutely no sound at all coming from the top of the engine. You can set your ear on the rocker box cover and nothing. I knew right away, that if I could cure the binding in the rocker box, then it's for the better mechanically, although I never would have thought that it would go completely silent. I am very, very pleased with how this came out. It's 22 degrees here today and I ran it in my garage and then was able just to take it down my block and back. Once getting back into the garage, it started snowing. Well, that's a wrap and I appreciate anyone who has been following my progress throughout this build. Thanks.
I appreciate you taking us along for the ride! Your a true craftsmen sir. I wish I could do what ya do..
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chubs
Guru
Between you, and Marky Marc , we're just liable to learn something here !
good write up and great pics 
.
SMCT
Active Member
It's just a little smaller of an engine then what I build day to day. This one went to a race team in Florida. It runs 0 to 160 in 4.3 seconds, normally aspirated with no power adders.
You just think to yourself, that since this is something that I have been doing for 33 years, something that is small and only has 2 cylinders, should be a breeze. The complexity was learning as I go and applying just common sense to this little engine as I have been doing with the big v8's that I typically build. The curve ball was the additional time it took to learn about the parts availability and get an understanding of them. If I was to go back into it, once again, I would have taken the guides out and installed bronze ones as well as design a much better intake and exhaust valve. These valves are very heavy and unnecessary, and it could be made significantly better which would be easier on the springs, rocker arms, pushrods and lifters. There is only so much time in a day/week/month that I just had to make decisions on where to draw the line. I am most likely going to pull the heads once more next winter and design some valves and put those bronze guides in. For me, it's not about the power, it's about the mechanical reliability, and from mechanical reliability you create power naturally. It's the side effect of mechanical reliability. Case in point, chevrolets ls engine design.
You just think to yourself, that since this is something that I have been doing for 33 years, something that is small and only has 2 cylinders, should be a breeze. The complexity was learning as I go and applying just common sense to this little engine as I have been doing with the big v8's that I typically build. The curve ball was the additional time it took to learn about the parts availability and get an understanding of them. If I was to go back into it, once again, I would have taken the guides out and installed bronze ones as well as design a much better intake and exhaust valve. These valves are very heavy and unnecessary, and it could be made significantly better which would be easier on the springs, rocker arms, pushrods and lifters. There is only so much time in a day/week/month that I just had to make decisions on where to draw the line. I am most likely going to pull the heads once more next winter and design some valves and put those bronze guides in. For me, it's not about the power, it's about the mechanical reliability, and from mechanical reliability you create power naturally. It's the side effect of mechanical reliability. Case in point, chevrolets ls engine design.
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Dragonslave
Active Member
I want to be like you when I grow up! In all seriousness though you sharing this has really made me question the way my bike is running. I am handy with a wrench but you sir take it to another level, almost scientific. I know you have heard this many times but you are a true master of your craft and if you ever plan on selling this bike you will have no problems especially if you post on this forum. Thank you for sharing this on the forum. More members are needed like you.
