Compression Ratio

I am working on my 95" 2002 Fat Boy and can't find these Screamin' Eagle pistons in the catalog. I have to believe they were superseded by a newer design and given a new part number. I need to buy new pistons but must know what the ratio was on the old ones. Don't want to re-map again. Is anyone able to help with the compression ratio on the part #22862-00 & 22863-00 pistons?

If you call the dealership and give them those numbers they should be able to tell you the new part number or what the compression ratio for them is...

I gotta tell ya, I have an '05 95 cu in Fatboy and it was factory built (ordered new) and I can't get info from dealers on the inards!! Lots of assumptions. The ordering dealer says that its got screaming eagle guts (cams, pistons) but he's now outta business. I do know that I can take some stock 103's.

I called Arias with the part numbers. That's the company that was making Screamin' Eagle pistons for H-D. They gave me H-D's new part number and they are the 9.6:1 pistons. Local dealer doesn't stock them but, could order them. I might just order from Arias though.

Probably will save the motor company "tax".

10,000 miles after the "95 build the Fueling oil pump broke. Lifter noise got my attention and I saw the oil light was on so, I towed it home. And, the pressure relief valve seized in the cam plate. I ordered Fueling's cam plate and oil pump. Crank runout measured at .003 so, I flushed the tank and lines and centered the new pump. I left the return line loose in a can to flush more of the motor. When I connected the line, topped off the oil tank and started up the driveway I heard a tink tink tink from the rear jug. Back in the garage I tore in further. Rockers looked OK so, off with it's head... and jugs. Pistons were galled. The rear worse then the front. So, here I am shopping for pistons. Found that Mahle has some with a nice coating on the skirt. If they have them for my bike is yet unknown. Sent 'em an after hours email. Tom Stahl in Chula Vista CA is gonna bore n hone the jugs for me soon as I get the new cans. Well, that's the long n short of it Cowboy. Wudda ya tink? Am I on the right track?

Yup. Think I'll try n sidestep the stealer... errr... I mean the dealer and their mark-up if I can. Ya know SE pipes are made for H-D by V&H. And SE pistons by piston makers (probably the ones with the lowest bids).

Thanks Cowboy. Words of encouragement give me confidence of light at the end of the tunnel. I'm an 'ol fender mender. Body n Paint. Frame straightening, collision repair 28+ years. Not much gear head type motor wrenchin' experience. But, so far it don't seem like rocket science. OK, bad analogy because I do want it to go like a rocket. 96hp & 102lbs torque is what I had. Not exactly brain surgery then. If I knew now what I didn't then, I could've of saved a ton of dough and done that "95 inch build myself instead of taking it to a performance shop. They could've just dialed it in for me on their dyno.

no gumba you cant take 103 the bore is the same as 95 but the piston pin height will be incorrect your piston will be i 3/8 of an inch incorrect . stroke of the 103 is longer so the pin is in a diffrent spot higher setting towards the ring land.

Dough! Yer fergot Nooow Yoooork eese! interpretation: I beat stock 103's.

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Gotcha

Those PNs are obsolete. 22863-00 is a 3.875" piston with an 8cc dome but no longer available; not sure about 22862-00 but assume the same. Your piston choices are those that are available in the 2013 catalog.

22868-00A, forged 3.875" bore for 4" stroke with a 6cc dome.
22661-99A, cast 3.875" bore for 4" stroke with 11cc dome.
22851-99A, cast 3.875" bore for 4" stroke with flat top.

Just because the piston is advertises as 9.6:1 piston doesn't necessarily mean your static compression will be 9.6:1. I have seen TC heads that are supposed to be 85cc-86cc measure anywhere from 83cc to 89cc. You need to cc your head chambers and figure out what compression ratio you want from there.

Most builders given the choice between domed pistons and flat tops will opt for flat tops. I will always opt for H-D pistons and cylinders if I can achieve the displacement. Nothing against the aftermarket pistons as I have used JE and CP and both are very good quality. However, I have pulled down too many TC88 top ends with many miles and the coating on the pistons looks like new and the hone marks in the cylinders are still visible. The MoCo has got the metallurgy and fitment of pistons to cylinders down; they just work.

You can "bypass" the dealer by purchasing from an online discount H-D dealer like New Castle and save 20% and local taxes. Of course, you have to pay shipping but ordering from an online dealer will save some $$.

Thanks for all the info bro. I got some 22870-00A forged SE 3.885's (22868-00A + .010) coming. The shop that did my 95" build 10K miles back were able to help me out by offering to get them for me at their cost. ARAIS was making the one with the 8cc dome for Screamin' H-D but I don't know who makes the new ones. Hope 2 cc's of dome doesn't make much of a difference. The shop precision dyno tuned it with a TTS tuner and she ran from the gate right along with my bro's '07 SE 110 before. ARIAS could send me a set but, it would take a week or 2 to put it together because they aren't making them for H-D SE anymore. Plus, I'd be paying some for shipping costs and a few $ is a big factor right now.

You can offset the reduction in compression by shaving .020" off the heads. Don't know what cams you are running but getting the corrected and cranking compression in the sweet spot is usually easier done with flat tops. You could take more off the heads but be cognizant of piston to valve clearance. You didn't mention headwork but if the heads have been worked and a larger intake valve installed, I would be mocking those pistons up to check the piston to valve clearance at the valve relief; they will be deep enough but may need to be opened up toward the perimeter of the piston.