This is just a hypothetical brainstorm. I know S & S make Evo engines and they go from 80" to 124". So since they are both Evo's technically but by different companies, I started thinking. I began to wonder if its possible to take the 124" jugs and put them in a stock lower end. Basically making a 124" Half stock Evo.
Almost seems theoretically possible. If it is possible, I know the pistons and rings with have to be changed to match the larger size. Not sure what else though.

So the question is it possible in fact that it can happen or is the fact that the 2 engine manufactures differences make them incompatible? Any possible drawback or problems with this idea?

 

There is a point where when the bore exceeds a certain size, you have to bore the cases. The large bore engines have reinforced cases. If you exceed a certain bore size on a stock HD case, it becomes weak. In my opinion it is ok to go a little larger on a stock case, but then after that, if the intention is to stay with a stock case, your efforts are better spent on better flow in and out, better fuel system, etc to get the most out of the displacement you have.

Generally a longer stroke engine will turn less rpm's but will have more low end torque. That principle is what Harley engines, especially shovelheads and Evo's are designed on.

Japanese bikes, especially crotchety rockets use very short strokes with a larger bore. They have five digit redlines. They tend to produce more high end horsepower and less low end torque.

I may be wrong, but I think TC88's use a larger bore and shorter stroke than Evo 80". That is part of why they lost the characteristic sound and feel different. The TC96 and TC103 may have rectified that but I am unsure.

 

No...max safe bore on stock EVO cases is 3 5/8" and some year cases you can't do that...124" bore is 4 1/8"

 

Joe, I spent a lot of effort some years ago looking into the ways I might improve the performance of my bike. Although you are right about an S&S Evo being similar to a genuine Harley one, they ain't identical by a country mile! There are Evos available up to 175", but the way they achieve that size is by expanding the crankcase size away from the drive-side crankshaft bearing. In other words the only thing a larger engine has in common with a stock one is where the primary drive layout is located. An S&S 124" engine will be wider and it's centre-line moved towards the right of the bike, to get in the larger cylinder bores.

In the case of my own investigations there were companies that made replacement crankcases at the time that could take a stroker crank plus larger bores, to give 106"/107", but the costs of a rebuild were pretty high. Do as I and some of the rest of us have done and buy a fresh bullet-proof engine from S&S. I made do with a 107", they currently make a 111", plus of course a 124".

S&S make 'V' Evo engines, also 'T' twincam engines that will fit our bikes. The twincam 124" is available in a low compression version for use as a touring engine, which I find especially appealing - if I can only find that darned lottery ticket........

 

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For someone on a limited budget you sure are trying to spend a shitload of money.
As for above I'm not sure what a case and jugs will do for you without all the other parts.
If you do get a 124" you will need a bigger starter and a better clutch at least.
I think you will also need some bigger diameter pipes so the thing can breath.


Here is some serious no **** advice.
Get your bike and just ride it for a while to see what you think.
DO NOT go sinking a bunch of money into a bike you might not like in the long run. You will never get that money back.

 

Find an Evo bike that already has a large displacment motor. Would probably only be 2 or 3 k above what it would cost you to do yours. I thing the S&S 111 is almost 7k and thats without factoring in a clutch, starter and a carb.

 

It was just hypothetical dude nothing serious.

 

If your serious here's a start.

http://harleytechtalk.org/htt/index....topicseen.html

 

Joe, the best advice I have mirrors thc's. You really need to just get a bike and ride it. You won't know what you want to change until you actually have something to change. We realize you're excited about getting your first Harley in 8 months, but all the hypothetical threads you start here and other places on the forum are a bit much.