DJL, I called KB, the dome vol is 6.7cc including valve reliefs. They list theirs as negative numbers if using their calculator, +6.7 on BigBoyz, both are almost the same, static=9.94 to 9.95, dynamic=9.29 to 9.30, ccc=189 to 193. The cyl's I was going to use were takeoffs (by H-d warranty) from my brother's 09 103" w/ 600 mi. but they were not round when torqued & needed .010 to clean them up so I had him bore other cyl to fit my std pistons. My build is a 95" not 103". Do I need to replace the cyl studs w/ the SE studs with this c/r? I'm assuming the deck ht will be .000 but I'll check it. If less do I need to set it to 0 using gaskets instead of the o'rings?

 

OK, my bad, when you referred to 103 cylinders, I got tunnelvision and forgot that you are working on an ealier model; that's the disconnect on the compression numbers. But I got my head out of my *** now and understand the numbers.

I hope you have decided to install compression releases. CRs will extend your battery and starter life; CCR greater than 190 is pretty hard on batteries and starters and could result in a heat soaked restart kick back and those can be nasty.

I am pretty sure your deck height is no 0.00" and expect it is more like .003"-.005". I have never seen negative deck height in TC88 cylinders. I not saying it doesn't happen; just that I have not seen it. Deck height would have to be negative to require the use of base gaskets to bring it back to 0.00" or a positive deck height. The thinnest base gasket available is .010", so unless deck height is -.010" or greater, you can't adjust with base gaskets anyway. It is unlikely that you will be faced with this situation. However, if the piston does sit "proud", or above the deck, I would most certainly mock up the top end and clay the piston to valve clearance.

If the SE studs make you feel better, use them but they are not necessary.

 

And if a piston is proud, say .003-.005", we grab the piston in the oil control ring groove, with a set of aluminum soft jaws, in one of or lathes, and trim as needed.
This works with flat-top pistons, and if using a domed unit, then we reach for the piston vise, and modify as needed in a milling machine.
More that one way to skin a cat.
Scott

 

Thanks for all input. Since this is an older post, I'll recap. I've got all the parts & jumping on it real soon. Wife’s 04' Fatboy, carb, 120 lb rider. Going w/ 95" KB-905c pistons, 6.7cc dome, ported 04 heads w/ 87cc, 1.94 intake, 1.61 ex, high lift springs, comp releases, .030 Cometic HG, SE-203 cams, SE street Legal 6200 Ignition, V&H Long Shots w/ Thunder Monster baffles. Calc comp s/b 9.95 stat, 9.3 corr, 193 psi. I used BigBoyz calculator to get these numbers. It's now Stock 88 w/ SE203 cams, 40k, s/b 160 PSI. Rocker boxes never opened up. I wanted a baseline test so I borrowed my pro auto mechanic friends Mac Tools compression gauge & it tested 180 PSI hot @ WOT. Off the subject but I then tested my '10 96" StreetGlide 20k, stock except pipe & SE-AC & it pumped 210 PSI on rear & 205 front. My SG warranty just recently replaced the compensator & I had them replace w/ the SE comp. I also said I was having blowby out the AC, it failed the leakdown test & compression was low (didn't tell me the numbers) so H-D had dealer hone the cyls, new rings, & said they checked the heads? It now hesitates when starting kinda like too much compression, not bad but noticeable, especially for colder weather. Are these comp. numbers possible or maybe gauge wrong?

 

You got 180psi from the above bike? Any calculator will show that combination between 155psi-160psi, depending on the condition of the top end.

The above should test about 170psi.

So one bike calculates to 160psi but registers 180psi on the guage and another bike calculates 170psi but registers 200+psi on the guage. Sounds like the guage to me; I would try again with another guage. No way should there be that much variance between calculated and tested compression. JMHO

 

djl, When I pulled the heads off, I bolted the original cyl down with the 1/2" pvc couplers, cleaned the carbon off the pistons & checked the deck ht. It was .000. I'm installing the new pistons & cyl now & the new ones are .006 frt, haven't got to the rear yet. this calcs to 9.90:1 static, 9.25:1 corrected, 188.2 PSI @ 650' elev Using Cometic .030 head gaskets. Is it ok to torque them down to chk valve/piston clearance & then reuse that gasket or do I need to replace the gasket?

 

V-RoyD, Im just outside of Muskogee. Moritz Machine on Admiral will cut your pistons if you need.

 

Just use a stock .045 gasket and do a clay check then subtract 15 thou if youre using a .030 MLS. You wont want to reuse a MLS that has been compressed. Also if you drill the small holes under the umbrella valves out a little, it will probably stop having blow by.

 

1931, I put the frt. cyl. together & torqued head to Cometic specs, 42 fp. Then when I took the rear off, I saw the o-ring on the case dowel which I didn't know was there on the front. (It stuck to the bottom of the frt. cyl and I didn't see it). Dumb A$$ mistake but glad I saw it before getting it all back together. So I will not be able to re-use the MLS gasket? Crap, that's another $30 & 1 week wasted since I gotta order that. Looks like I'll at least have 1 spare gasket since they come in pairs.

 

Also I'm replacing the rocker boxes with 2 piece Total Performance Machine that have a different breather system so hope I won't have any blow by issues.