Sometime this winter, I'm going to take my bike in and have the dealer put on my last cosmetic upgrade (no, really), black cylinder head covers. As you can see in my signature, I have some engine upgrades (cam, exhaust, air cleaner, etc), and was starting to entertain the idea of having the heads shipped off to Big Boyz for port/polish and bigger intake valves, and maybe even mill them in anticipation of going Fuel Moto 107 in the future. I just don't have the budget to do it all right now, but may be able to swing the headwork, which would really give a boost to my 555's. What do you all think, given that I can't do it all now, but not much of a reach to take the heads off once the dealer is in changing out the head covers? Thanks for input.

TedMan

 

I would definately have the headwork done. I would mill the heads to set corrected comp for your current cams, or whatever cam you choose when the heads go back on, and a .030" head gasket to set proper squish. As many have stated on this forum, it is very important to maintain corrected compression somewhere in the range of 9.2 - 9.6:1 . It could be a little lower, but certainly not higher. In a light bike like yours, you just may be happy with it.

 

With out Stage II Heads, 107", 555 cams, OE t/body, and Rhineharts, Fuel Moto showed 109 hp, and 127 ft/lbs, all in by 3400.
You would really want to do it all at once, as there will not be any labor/gaskets being doubled-up on, at a later date.
FWIW, a 58 S/E t/body, with cylinder head port match, should pull more hp, and broaden the torque curve as well.
Scott

 

I hear ya, Scott, and always take your input seriously. I just don't have the budget to do it all, so seems I should wait until I can.

At the risk of hijaking my own thread, I have a follow-up question. I was on the Big Boyz site using their calculator for compression and cams. I used the Woods 6-6 (close enough to 555), .03 Head Gasket, and flat top pistons. Then, I chose both 107 and 103 bore to see what the differences were, shooting for something close to 10.4-10.5 uncorrected compression, and about 9.6 max corrected (600 ft altitude). The 107 got me there without milling the chambers, but the 103 needed an 83 cc chamber, so milling required. I know many reputable builders on this site say don't sweat going with the 107, and seems OK, but I can't help but think that about 50,000 miles down the road when I have to rebuild the top end, there will be nothing left after boring out to 107, but with a 103, I got more material to work with. Can the seat of pants be that great between the two builds, with only 4 ci, to justify having to buy a whole new set of jugs/cylinders down the road instead of the cheaper overbore I could do if I chose the 103? More input/opinions welcomed.

TedMan

 

Don't worry about 50K miles down the road; there aren't any over sized pistons for the 3.927" bore anyway. Cylinders are cheap; toss the 107" cylinders and start over with new pistons. Overboring from 95" to 97", IMHO, is a waste of time and money. However, if starting from 88" 0r 96", boring to 97" or 103" makes sense to me. Get the most for your money now.

 

Thanks all for input. I've decided to wait and do it all together, and just install the new covers myself.

TedMan