10-03-2009, 11:11 PM #1
Ok, so my 1300 munched last week.. Put it together the same way? How boring.. We must experiment..
Whats up with those big holes in the side of the pistons?
And why is the intake piston skirt so much shorter than the exhaust skirt?
Hmmmm, will theory and reality walk hand in hand on this, or will they have a fistfight?
We will find out soon...
10-10-2009, 09:22 PM #2
Veeeery interesting.... Will be interesting to see what she does!
10-10-2009, 10:42 PM #3
Found some areas to do some lightening of the pistons also... Its all back together but cant make it to the water with it till next weekend. Maybe it wont be so friggin hot next weekend also.. 108 heat index today. Oppressive heat!
Oversize holes in the skirt will allow more intake charge under the piston dome at BDC and will help keep the piston cooler.
Machining the piston skirt to match the machined/ported cylinder skirt on the intake side will simply open the door a little more for the incoming charge at BDC once again, as well as taking some reciprocating mass off also.
Hope it doesnt take any low and midrange power away. Pretty sure it will add power on the top but concerned about the low and mid.
10-11-2009, 07:33 PM #4
- Join Date
- Jul 2005
- Central North Carolina
Ross, here a tec tip for you! Your short skirt piston should work fine. The only problem is you will get a lot of piston rock ( slapping) at low rpm's idle to 2500 rpm's. for best service life try NOT to let the enging idle a lot and when ever possible when ridding slow try to keep the rpm's up to a min of 2000-2500 when going slow. Best of luck with your new design! Tommy Jordan
10-13-2009, 06:35 PM #5
The gains are very small, but every little bit adds up.
10-13-2009, 10:26 PM #6
After checking out some of the new piston designs i concluded these GPR skirts are still on the huge side.. Of course you cant do much with the exhaust side or you uncover the port at BDC, but when comparing mine to some of wisecos new designs, wisecos have the REAL miniskirts..
Should have coated them, but didnt..
Started it today, runs fine, will do some cruising on it this weekend..
Check out these wiseco miniskirt designs..
10-13-2009, 10:31 PM #7
10-14-2009, 12:15 PM #8
10-25-2009, 03:59 PM #9
Ok guys, lets just say i took one for the greenhulk team on this experiment.
It did not work. Do not cut the PISTON skirts.. HAha.
Lets just say its very ugly.. Piston rocked too much in the bore and dug into the exhaust side port, all 3 the same.. Bad... Cylinders need re-nikd also now...3 hours on engine....
Oh well... Next.....
10-25-2009, 04:03 PM #10
Ross, do you have any pics for us to view
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