Piston Choice With SE Heads & mods : V-Twin Forum: Harley Davidson Forums

Ron99 · 05-30-2009, 08:59 AM

I have a 99 EVO with SE heads. Currently running weisco's at about 9.5 CR with a EV27 cam. Looking to do a woods W6 cam this fall. Would like to bump the CR. What pistons to use? If I bore the cases and go with a bigger jug from Axtel same question.
Ultimately I'd like to use the W6H but I believe the springs will need to be changed to accomidate the increased lift. How would the added lift effect piston choices? Thanks

wfolarry · 05-30-2009, 11:38 AM

You have to use a piston made for those heads if you want to increase compression that way. If you bore the cases & go with bigger cylinders your compression should be right with a flat top. I have the 3 5/8 bore jugs with flattops & my compression is a tad over 10:1 with the SE heads.

Ron99 · 05-31-2009, 08:49 AM

Is HD the only source for pistions for these heads? I've looked at some other mfg and can't seem to find. Are you using compression releases? At what CR should you with a stock starter? Any opinion on the head points?

It seems that worked stock heads are easier than the SE.

Thanks for the input.

93 FXR · 05-31-2009, 10:16 AM

Sounds like we have a similar set up.
I went with Keith Black pistons, flat tops, 8.5:1
Stock jugs bored .020 over. That combo yielded 9.5:1 approx. w/ SE Heads.
SE heads were polished and decked to achieve an
approx. 10:1 compression.
Really a nice combination so far, and came to me
highly reccomended from my local wrench, who has built
his share of V-twin monsters. I've found this to be a
very good streetable bike with a suprising amount of power,
which is exactly what I wanted...
Also, might want to double check this, but I think that SE heads
will accept a .600 lift cam without modification???
Not sure, but I think I read that somewhere in the Harley
SE catalog. Maybe someone else might chime in with
more specifics....

1997bagger · 06-01-2009, 10:05 PM

Ron99, one of the best SE heads specialist posted in the #2 slot, a call to his shop might open some options for you.

Some of the SE heads are 585 lift, beehive valve springs would be a possiblity for the Woods cam if rated at 585, upgraded valve seals should be in the picture if your pulling your heads.

Another option is to do as 93FXR did, save the money on pistons and bore and have a SE head specialist work the ports and do some milling to get compression needed for that W6H to run. SE heads need a little port work to be efficiant and can get some good HP numbers in the right hands.

Just ideas to keep you awake at night