How big is to big to bore EVO cases : V-Twin Forum: Harley Davidson Forums

Breeze_tsmc · 10-04-2009, 01:40 PM

I guess I put the cart before the horse here and now I'm looking for some reassurance.

I have a 92 FXDC and this year I broke the Crank pin resulting with very minor damage to the inside of the cases.
After several choices, I decided to spend allot now in hopes that I won't spend in the future.
I was told that S&S came out with a new hot set up called the FLS&S96 hot set up.
I was told that (I think anyway) that I would not have to have my cases bored for this set up. After reading ALOT of threads here about boring cases on EVO'S I still don't have a good idea/feeling that my 92 case is strong enough.

Does anyone have any info on problems with the 92 style cases?

Breeze

1949shoebox · 10-04-2009, 03:31 PM

if you want to go to twin cam barrels (4") you need to replace the case totally, boring your existing cases to fit the bigger barrels may blow out , not worth it ! jp cycles sells complete kits since i see theres been damage to yours.

wfolarry · 10-04-2009, 04:23 PM

That's a 3 5/8 bore. Boring the cases isn't the problem. It's how well they hold up to the added power. Seen it go both ways. If your cases are in good shape go for it.

baggersport · 10-04-2009, 04:57 PM

I've seen a couple cases crack....stock and big bore....in that year. Earlier cases, like the '85-'88 appeared to hold up much better, and it seems the later model years of Evo cases may also take it better. You may be better to get stronger cases for the 96"...or consider stopping with an 89"

.

springer- · 10-04-2009, 07:30 PM

This might help as well ... http://www.v-twinforum.com/forums/ev...ighlight=cases

Breeze_tsmc · 10-04-2009, 09:34 PM

After reading all of this I am really hopeing that this kit doesn't require boreing the cases!!

Springer, That post is right on point and I plan on printing it out and taking it to my wrench and HOPEFULLY he is aware of what you pointed out!!

I think that is an important tool in finding the right wrench, There are so many that know more than I do and can sound like a very reliable wrench. By bring this up I should be able to check his knowledge and hopefully feel better about spending all my cash.

I really hope that my pinion shaft didn't break because of some of these case issues. I will get sick of I break this motor!! I ride very hard on my bikes and really need a peace of mind to know that i spent my money wisely!!

Shoebox, Are you describing a evo bottom twincam top end? I have heard talk (from BS artist) that this a pretty easy and reliable combo?

Thanks to everyone's input. This site is a valuble tool!!!

Hillside · 10-05-2009, 06:48 AM

Quote:

Originally Posted by Breeze_tsmc

I guess I put the cart before the horse here and now I'm looking for some reassurance.

I have a 92 FXDC and this year I broke the Crank pin resulting with very minor damage to the inside of the cases.
After several choices, I decided to spend allot now in hopes that I won't spend in the future.
I was told that S&S came out with a new hot set up called the FLS&S96 hot set up.
I was told that (I think anyway) that I would not have to have my cases bored for this set up. After reading ALOT of threads here about boring cases on EVO'S I still don't have a good idea/feeling that my 92 case is strong enough.

Does anyone have any info on problems with the 92 style cases?

Breeze

Axtell also offers an all-bore 97" cylinder kit that easliy shows 95-100 hp and 105-110 ft/lbs with something as simple as as a Wood 6 cam or an Andrews 27, slip-on mufflers, and OEM carb. The S&S kit will be VERY similar set-up that way, also.
A couple years, the Moco's cases were prone to crack in behind the rear tappet block, on that 90* machined surface, even without opening up the spigot holes.
Your's in one of them.

Scott

baggersport · 10-05-2009, 07:54 AM

Quote:

Originally Posted by Breeze_tsmc

I really hope that my pinion shaft didn't break because of some of these case issues. I will get sick of I break this motor!! I ride very hard on my bikes and really need a peace of mind to know that i spent my money wisely!!

I've seen this happen with improper (for a H-D) downshifting..............??

.

Hillside · 10-05-2009, 10:07 AM

The breaking of those year pinion shafts is due to improper design.
On flywheel sets that allow the replacement of the pinion shaft, a 2-key pinion shaft is used with a pinion gear conversion that corrects the shortcomings of the later design.
S&S never offered that, as they know of the ill fate that is possible.
Scott

wfolarry · 10-05-2009, 07:53 PM

Buy a complete motor from S&S & you're done. Some guys rework the stuff they have but if you ride it that hard & you don't think it will hold up replace the whole thing.

I did a 92 this year with an 89" kit. Beat the hell out of it tearing up the trans but the motor is still holding together.

While I won't argue that some years are worse than others the fact is that aftermarket cases are stronger than the stockers. It's all in how much you want to spend. If you got the $$$ go for it.

Hillside · 10-05-2009, 08:29 PM

Larry is right on, as an S&S case manufactured from 356-T6 aluminum is waaaaaaaaaay stronger than anything the Moco ever even thought of offering.
Scott

Breeze_tsmc · 10-06-2009, 04:28 PM

ok well I called my shop and we decided to go with the 89 kit to be safe. it seems like I can save 2000 and only drop about 20foot pounds of torque. I think I will be able to live with that since I have a weak foundation. Thanks to everyone for the help.

I am still a little concerned as I do like to beat on it. Replaced the gears with a stock set out of a twin cam softail last year so Hopfully The motor will hold together.

blackjackcustms · 10-08-2009, 07:34 PM

1992 is right in the weakest spot for cases and cranks. I would'nt big bore anything but pre-'89 or post '95 stock cases. That being said, A big bore CAN be more reliable than a stroker, and is likely to make more high rpm power. Moving the bore out lets the air flow in better, and the shorter stroke winds up quicker. For a budget fix, the 89" is probably your cheapest way out, but a big bore with better cases will be a better motor IMHO.
I'm running a 103" in stock (replaced) cases. When you replace your cases through a dealer they give you the latest greatest design with your number on 'em. My motor is 4 5/8 stroke by 3 3/4" bore. Very meaty mid range, but less happy when it tachs up. Plenty of fun though.