The S&S stroker 106cui. kit is what I'm running in my bike for the last couple years. If I had it to do over again, I would not use this kit. Not because I have anything "bad" to say about the kit though...

Since the cases need to come apart anyways, and since you might need a new crank regardless, I would look into getting a crank directly from Darkhorse already welded, plugged, balanced, etc. You can pick your poison with any stroke available. You can also go with a bigger bore than the 3.875" that the S&S kit uses with your stock cylinders. Boring the cases can easily be done at this point because you're already there with it all being tore down for the crank. You'll have alittle more $$$ in it with the price of the cylinders and case boring, but not much!!

Do it once, do it right... 117", 120", 124"...


K.

 

All have given some good advise. Stock heads are the platform that most shops use to end up with performance heads for street bikes until you start getting into some really big bucks and exotic builds. Do your research, ask others that have experience with a particular build or kit and then select a package based on recommendations of the builder. Headquarters, Tman, Hillside, GMR all produce total packages and all are just a bit diffirent, but all produce respectable results. I prefer Headquarters as the results are repeatable build after build. All can also provide a package that is reliable, just sold my 120" Ultra with 40k on the build and it was still rock solid so dont worry about that end of it. Decide what your riding needs are, do the research and pull the trigger. Nothing like a well tuned 103/107 compared to stock.

 

I am thinking that the 106 kit isn't really for me with this bike. I spent about 2 hours with the mechanic, and we are looking at a 100 inch kit- square motor, stock 4 inch stroke, and 4 inch bore. A new stock stroke crank from Darkhorse, rework the stock heads, 585G cam. He says he will be able to have the cam matched to the heads. The jury is still out on which carb to go with- he is not crazy about the screamin eagle carb, he would prefer S&S, but says the stock cover can be made to fit but isn't really right. I want to keep the stock cover for the 100th aniversary stuff. This way is a bit easier on the bank account, and looks like it should do what I want.

I know its kind of a roller coaster from one idea to the next, but this way really makes more sense to me.

 

Ok... So if you're buying a Darkhorse preped crank, you're buying pistons/cylinders, you're boring the cases for the 4.00" bore, etc... Why stop at 100cui., when for the same money in parts & labor you could go bigger??


K.

 

I don't know... How big can you really go with this method? If you go too big don't you have to move the bolts for the jugs around? I don't want to weaken things if I can help it- I don't want cylinders that are bored to the maximum- I would rather have some extra cylinder wall left... I can spend some more time with the mechanic- Just hard to get everything figured out in one sitting- its a busy little shop.

 

3.875" bore has been the most common, which takes a 88cui. to a 95cui. with the stock 4.00" stroke. 3.927" bore has become more common in the last couple years which yields 97/98cui. with the same stroke. The 3.927" bore is what most consider the maximum the oem cylinders can be bored for. After that you're looking at aftermarket cylinders.

With the oem cases, you can bore them to accept 4.125" cylinders, safely. Some have gone as large as 4.250".

Again... In my opinion, the more you're having to buy the more it makes sense to go larger.


K.

 

So, if I were to go with a 4 inch stroke and 4.125 bore, that would get me between 103 and 104 right? And then my case would be just about maxed out? Well I am not calling this a bad idea by any means, but my thinking is that I can build it to the 100 inch mark with 4 inch stroke and 4 inch bore, and still have room left for a future build after I wear this one out... This build will be a daily driver for a few years yet, but the next one I can go a little crazy with because it probably won't get so many miles packed on.

 

If you're having to buy a crank why stay with the stock 4.00" stroke when you have other options? 4.375", 4.500", 4.625" can all be had from Darkhorse as well.

The oem case wouldn't be "maxed" out at 4.125", and it's not a wear item that would need replacement in the future. There are lots of bikes represented on these forums with many miles using these configurations.

I'm not trying to tell you what to do, but I've been there with my bike. First a stock 88cui., then a 95cui. big bore, and now the 106cui. I wish I would have gone that little extra step when it was all tore down and added the 4.125" bore.

If you "over build" it for what you want, keep the compression in check, don't go crazy on the cams/valvetrain, good tune, etc. you'll have many, many miles ahead of you.

Just trying to throw ideas at you,

K.

 

4.125" x 4.00" is 107" displacement. Can't argue with those that suggest that if you case bore, go to 4.125" but remember that once you do that, you can't go back.

You are looking at $5K-$6K for a new 4" flywheel assembly, balance/true/weld, case boring, Timken coversion, 107" pistons/cylinders, cams, heads/headwork, new cam drive, pushrods/tubes, ignition, carb, gaskets/oil/filters and tune.

You can save about $1000 if you limit displacement to 98" and eliminat case boring and the cost of 107' pistons/cylinders; just bore yours to 3.927" and fit to a good set of pistons. There are several places you can have that done and know that fitment is good; I can think of two on this forum.

I am aware of a 4.375" SE flywheel assembly that is sitting at Hoban's shop now and is for sale for $400. The guy has changed his build plan and does not need the parts any longer;at least that was the case a couple of weeks ago. You would still incur the cost of the true/balance work and the Timken conversion but you could avoid case boring and set displacement at 96" or 103" with your stock cylinders and a new set of pistons. This should save you about $1500 should the parts still be available. PM me if you want to pursue the SE core.

No reflection on your mechanic but there are too many other options that will provide very predictable results as opposed to trusting your mechanic to "match the heads to the cams". There are the obvious guys like HQ, TMan, Bob Woods, etc. that can provide you with a set of heads and their cams that will produce better results. There are forum members that have proven combinations as well. You need to be talking to someone besides your mecanic about heads/cams. What was his basis for selecting the 585G? Are you sure you want gear drives when the new hydro tensioner/roller chain upgrade with better oil pump is an option?

Like NCTURBOS, not trying to tell you what to do but throwing ideas out there. I have been down this road several times and have learned that the key to satisfactory results is knowing how you want the bike to perform and putting together a kit of parts that will deliver. Some of us can do it on our own and some cannot; those that cannot need to talk to to those that can, learn and make the decisions rather than turn the decision making process over to a local wrench. At the end of the day, you will have to live with the results.

 

Well, if for the same money I could go to 107 I will consider it. You are right on with your price- we came up with a price of about $5300 including a guess of $450 for a carb, and labor for him to handle all of it.

I will ask further about heads, and mention that I may want to handle getting that stuff- he doesn't care, he will do whatever I want- but I do think he has built enough to have a fair deal of knowledge about the heads and cams.

I asked why the 585, and he said it was a good wide range cam that comes on very early- I am not much for high revving, I prefer a good throttle response from just a twist at 3000, rather then downshifting. I won't be racing, or speeding all that much, I just want good acceleration. I don't know much about fuel pumps, but he will install a better one, and I had gear drive put in a couple years ago, so the kit is already installed(read "paid for")...

Flip side of dealing with the local wrench work is that if I am not happy, or something doesn't cough up the numbers he says it will, I can just go over there to deal with it, instead of phone calls and shipping pieces of the engine here and there...

All this being said, keep the advise and observations coming, I read it all and consider it all.

NCTURBOS: I am avoiding the stroke end of it for comfort and heat- it makes sense to me that the longer stroke will make more heat and wear, and also increase vibration- those are two things I want to avoid- I will look at the 107 option with 4.125 bore and stock stroke. It seems that as I read through, the reviews of the various stroker configurations are mixed about 50/50- some love it, some hate it, some swear its big problems, some don't... I am on the side of making sure I don't build something I won't like.