No need for stronger springs with just the higher compression.  If using an aggresive cam with the highercompression you may need stronger springs to compensate for the cam (so much lift can wear stockers and cause flutter) I was just suggesting an answer to wanting stronger springs.  Ross must be working from stock figures, they just ask about any mods we've made, (pistons should work fine with stock cam, better with regrind).  I gave the 8mm deck clearance figure from our last piston post, and the fella seemed surprised, maybe that is not the stock clearance? i would like a positive measurement on this also before we order...  anyone know the deck height for sure?

the 4mm deck height seems more probable, i can't find the stock figures anywhere, (but then, i have no clymers).  If that's the case we can still go 2-4mm heigher with the piston without entering the combustion chamber, with valve pockets cut down to within .03 of the original piston height at tdc we should be safe, and we'll definately be able to get to 10:1.  I think the valve pockets raise the piston price by about 20 bucks. so with rings and pins about 157 a peice. That's getting a little steep but i'm still in....  hopefully that 8mm figure is correct....

yeah, Au is gold, Al is aluminum...  

and I get to put another   as stronger valve springs are for agrerssive cams... (wasn't thinking, just typing...) stock springs should be fine for mild cams...

oh here was my thought train:

anything over 10.5:1 or so needs an aggressive cam to ge thte most out of it, then we'd need the stonger springs... now that makes sense.  


and for what it's worth, my understanding is that stock weight pistons are the way to go if possible.

We'll definately get everything figured out before an order, just looking for interest until then.  If we can get 4 folks agreeing on the same numbers, looking to order within the next month or so we can figure out exactly what we need to do to the pistons to reach those goals.  I'm ready as soon as we have deck height figures.
97mm
10:1 compression
we need two more.

96mm 9.5:1 and I'll take 2 -  

wiseco makes 3 95mm/96mm/97mm - interchangable with the dr650 up through 1995 - the specs on the 4597MO9600 (96mm) with a +1 on compression is all I'd really be comfortable with in these road bikes

96mm 9.5:1 and I'm in also.  96mm is boreing about .07 over, not real extreme with the thickness of our cylinder, we'll get about 1 horse per mm overbore, nothing serious, but worthwhile with changes in carb and cam.  With the bore tech carbide coating i wouldn't worry much about longevity, as someone else on here mentioned, ceramic bores rarely need rebore or resleave work, the strength is pretty serious.  The only concern left is valve clearance, but since the wiseco order was for 9.5:1 CR it must fit, we still need the numbers, but i'm sure it will work.  There are three spoken for now, at leats 1 more person and i will make another call to ross to set up the order.

Oh yeah, if we went with 95mm it comes to 666cc, make for a neat theme anyway..

Okay... Now that you guys are talking more reasonable for street use, and not max bore and compression, I'm "Interested." I'll buy in for one at a reasonable price @ 96mm and 9.5:1 That gets us 680cc right? And I think people will be surprised what a slight increase in the compression ratio will do to the power. (1)

I don't care anything about making the piston lighter; modifying the skirt, or any trick coating on the piston itself. Just a good forged piston with no interference, and the possibility of adding a performance cam (like Lancer's).

One concern... Ross mentions "racing rings" which are a different animal from normal use rings. But then they also continue to describe multi-part rings like street bikes use. I want to be sure we are getting a ring set that will hold up for a long time, and isn't made to be changed after every few "races!"

Provided of course that one size fits all... I noticed that the Wisco 96mm says years 1986-1995. Is there a difference after that? I'm wanting the piston for my newly aquired 1999 that has 27k miles on it. I know the head has supposedly been "done" (what was done I don't know). I have no idea what might have been done to the cylinder at that time. As told to me, only the head was re-worked.

(1) Back in the early 90s, I owned an old 70s Savage 250cc Enduro bike. It looked and rode good, but was smokin' and a bit down on power. I was going to hone and ring it, and went to a local Suzuki Guru who used to own the biggest dealership in the area. As an old man, he had lost the dealership, and now ran a cycle salvage. When I went to see him for a set of rings, he went into the back of one of his old sheds, and came out with this NOS piston for some Suzuki 250cc MX bike, and nonchalantly said "drop this into her and see what happens." I did, and the tame little Savage was instantly turned into a fire breathing beast that would wheelie at will on throttle twist all the way up through third gear! Fourth gear only required that you help jerk it up a bit!  My point: I learned a big lesson from the old man. A little compression change can go a long way. I know the two Savages are very different bikes, and I wouldn't expect that kind of change out of our street Savage, but I still think some folks will be surprised what the difference between 8.5 and 9.5 might do.