Here's the deal. I have some exp with an old Sporty 1000 and my Buell 1203. I do not have much exp with shovels though! I picked up a built 1979 FXS that was supposed to have a rebuilt bored over 80", with a cam blah blah blah! It was having some problems that lead me to pull the top end off to discover it was pretty stock as far as pistons and cylinders go.

3 31/32" stroke
3 7/16" bore .010 over (JCC pistons)

What I am looking for is input on what componants and displacements have worked good for others. I am not a speed demon, we just cruise so I do not need 100 HP or anything. How big a displacement is possible with out case work and losing reliability? (budget build)

Also what is "common" wear on shovel pistons. I was thinking about just honing and re-ringing it if possible. There are some light surface scares on the skirts. I would not consider it heavy at all. But then again I do not know what is normal.

I will try to attach a picture to show the wear.

Thank you,
Tom

[IMG]local://upfiles/56234/286732E22C4944D88FAC25D003903783.jpg[/IMG]

 

hi Tom and welcome to the HDForum,
you will probably get as many different suggestions on what to do as there are combinations to go with as options are limitless.
I would determine first if the pistons are cast or forged {look cast but need to be sure} and have clearance checked by a machinist if you don't have the measuring devices to do so.
Are you planning on going in to the bottom end?
Another thing to know is what you have to start with as far as carburetor, cam specs type of exhaust ect.
What were your problems to have to take the engine apart?

 

I picked the bike up and had put about 1000 miles on it. All of a sudden one day it was difficult to start more than normal anyways. (not turning over) It started I just kind of dismissed it as it had sat for a week or so. Went on a ride about 50 miles and it died, almost like it lost power. On the side of the road I could not even get it to kick. Like it was froze.

I got it home and put a new starter, relay, solenoid and charged the battery still nothing and could still not kick it over. So I pulled the top end with no heads I stood on the kicker and still stuck then bounced a little and it freed up. Since it is apart to this point I figured why not at the very least do rings and hone if not more.

I agree I believe them to be cast. I assume most are going with forged pistons now.

I am running a S&S Super E carb, supposedly a mild cam (specs not known) and a Thunderheader. It ran good and had decent power prior to tear down.

I am hoping to get by with a clean and inspection on the bottom end. However I am one of those people that say whats another couple hundred when it is town appart. For all I know this may end up completly rebuilt by the time I am done.

Thank you for your welcoming and input. Keep it coming!

Tom

 

So I am guessing the bottom rolls over now that the jugs are removed?
it should be pretty obvious the pistons and or rings seized to the cylinder.
if thats the case find out why this happed
the piston to wall clearance according my trusty on HD manual is .001 .002 loose.
thats at the skirt measuring top middle and bottom of jug.
I've cleaned up bores in chain saws and dirt bikes before and ran same pistons but if it were my Harley I would at least buy now pistons... if they did seize the may not be round any more or damage to the ring lands or both.
it would be interesting to know if you can find out how long ago the bottom end was rebuilt.
The top end for that matter, if it hadn't been that many miles maybe the thing was never broken in properly and got hot right from the git go. I've seen that happen a lot.
New pistons, rings, clean up the bore and back on the road again.
going to post some images of the bike for us to see?

 

Thanks pretty much what I was thinking. Have the cylinders honed then get new pistons, rings and get her back together.

Here is a picture.


[IMG]local://upfiles/56234/206EC6ACFE9546858D7BA7CA71744E29.jpg[/IMG]

 

nice custom!!
good luck
I've installed the keith black pistons and have had good results with them.

 

So I understand that 80" and 74" used the same cylinders. Does that mean I can bore my cylinders out to accommodate 80" pistons?

Is it just that easy, or is the stroke different as well?

Thanks,
Tom

 

74 cu in is 3 7/16 bore size
80 cu in is 3 .50

as far as I know you can run 80 barrels I had my 74 out to .060 I think which is close to max. over size the cyl walls getting a little thin .080 over is max which makes it an 80 cu in I think?

I would rather go 80 cu in std bore instead of .080 over 74 bore.

 

I did a little more research and found this out.
74" = 3 31/32" stroke
80" = 4 1/4" stroke

So my plan is out the window. Looks like it will be high compression 74" bored .010 to .030

Thank you,
Tom

 

oh yes now I find the specs in my book as well
4.250 for the 80
3.968 for the 74
been a long time since I compaired the numbers
when I was running my 74 against my buddies 80 I could keep up with him just fine until we were running full throttle top end at speeds we shouldn't have been riding any way.
nothing wrong with a tuned 74 at all..
good luck hope it all works out for you Tom.
keeps us posted