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Message started by baker87 on 03/31/12 at 18:57:55

Title: larger pistons
Post by baker87 on 03/31/12 at 18:57:55

what pistons will work with a savage? and what is the largest overbore we can do? ;D

Title: Re: larger pistons
Post by Oldfeller on 03/31/12 at 19:45:30


97mm -- going bigger would require a new sleeve and new stud locations (a host of issues too big to consider)

Title: Re: larger pistons
Post by MMRanch on 03/31/12 at 20:52:12

Baker

I put a 95mm in and can't tell a lot of difference but then I put a larger front pully (23 to 25) on at the same time too ....

One time I put a 160 main jet in the carb.   ...   That made a big power difference .   But gas millage went to the low 40's.   That was hard to live with after being used to near 60 mpg.   So it was back to the 145 main.

Title: Re: larger pistons
Post by LANCER on 04/01/12 at 16:11:30

BORE vs DISPLACEMENT

94 mm = 652 cc

95 mm = 665 cc

96 mm = 680 cc

97 mm = 694 cc

100 mm = 740 cc .... hmmmm  8-)

Title: Re: larger pistons
Post by justin_o_guy2 on 04/02/12 at 03:10:58

13, 15,14,16 cc increase as piston size goes up..

Title: Re: larger pistons
Post by Oldfeller on 04/02/12 at 03:18:22

 
Lancer, have you ever looked at Subaru pistons?   Same 23mm wrist pin size as the Savage and the stock bore size ranges go from 92mm to 99.5 mm as bone stock (lots of different bore sizes in the same block = all the different stock Subaru engine displacements).  

On Ebay right now there are sets of four for $130 (aftermarket) and periodically folks sell used but nearly new sets for a lot less (they upbored for more power or turbo'd and went to a lower compression piston accordingly)

If they could be made to work (shaved down or thick base gasket or whatever) that would be a OS Savage piston for around $45 which would be a good thing, I think.

Title: Re: larger pistons
Post by LANCER on 04/02/12 at 05:15:05


7D5E5654575E5E5740320 wrote:
 
Lancer, have you ever looked at Subaru pistons?   Same 23mm wrist pin size as the Savage and the stock bore size ranges go from 92mm to 99.5 mm as bone stock (lots of different bore sizes in the same block = all the different stock Subaru engine displacements).  

On Ebay right now there are sets of four for $130 (aftermarket) and periodically folks sell used but nearly new sets for a lot less (they upbored for more power or turbo'd and went to a lower compression piston accordingly)

If they could be made to work (shaved down or thick base gasket or whatever) that would be a OS Savage piston for around $45 which would be a good thing, I think.


I will take a look; sounds interesting.
Any idea what the skirts look like ?

Title: Re: larger pistons
Post by Oldfeller on 04/02/12 at 10:32:13

 
Stock pistons look normal enough with a high compression relieved center top (some actually have a raised outer ring to form a squish pocket) on some of them.  They vary, in other words.

The weisco after market hot performance pistons look just like the aftermarket ones we use now.   The stock units vary stock from flat tops to normal valve relief cuts to things that look like diesel compression ring tops.  

The only way to see what it would actually do for us is to get your hands on one -- mebbe one of the ebone people (shop workers at Subaru shops most likely) can send you a burned one for shipping just so you could check it out.

If you want to experiment, sell some quarter shares on a four piston buy (after you check out which model would most closely be able to fit in our sleeve envelope).  I'd kick in $35 on an at risk purchase just to see if it can be made to work as the distance between $35 and $145 for a piston is considerable.
 
Just for example -- not the one we'd want to buy


NOT THIS 99.5mm PISTON, you'd have to resleeve the jug to use this little puppy.  But you get the idea.  BTW, at 99.5 I think you <might> be able to resleeve without having to move the studs any.

http://www.ebay.com/itm/Subaru-2-5L-EJ25-SOHC-16-Valves-new-Pistons-w-Rings-/260695098541?pt=Motors_Car_Truck_Parts_Accessories&fits=Make%3ASubaru&hash=item3cb2a384ad&vxp=mtr

http://mizumoauto.com/ebay/mizumo/PS9009_image3.jpg

Title: Re: larger pistons
Post by LANCER on 04/09/12 at 13:46:03

The '96 and later DR650 has a stock bore/piston size of 100mm and uses the same wrist pin.
Raised area on piston head; cuts for the valves... Doesn't that sound fun ?
Would not leave much on the liner wall though. :-?

Title: Re: larger pistons
Post by justin_o_guy2 on 04/09/12 at 19:09:02

Riding around on a hand grenade is one thing,, riding around on one with the pin out? Ill pass,, thanks,..

Title: Re: larger pistons
Post by LANCER on 04/10/12 at 11:48:41


312E282F32350434043C2E22695B0 wrote:
Riding around on a hand grenade is one thing,, riding around on one with the pin out? Ill pass,, thanks,..


Pin out ???

Title: Re: larger pistons
Post by verslagen1 on 04/10/12 at 11:55:39


565B54595F48080D3A0 wrote:
[quote author=312E282F32350434043C2E22695B0 link=1333245475/0#9 date=1334023742]Riding around on a hand grenade is one thing,, riding around on one with the pin out? Ill pass,, thanks,..


Pin out ???[/quote]
A pinned grenade (safe?) or an un pinned grenade (hand holding the spoon, ready to toss)
Like having a verslavy vs. the stock cam chain adjuster.

Title: Re: larger pistons
Post by Oldfeller on 04/10/12 at 13:05:34


Here is the rub with re-sleeving to a larger sleeve and larger bore.

You have to machine the cases out to the new larger sleeve OD -- and then you find out just how much the counter-balancer mass swings into that same space .....

:(

And you find out you have to cut away part of your new sleeve ....

Title: Re: larger pistons
Post by justin_o_guy2 on 04/10/12 at 13:15:07

& just How is it you know all this? Hmmmm?

Title: Re: larger pistons
Post by Oldfeller on 04/10/12 at 13:31:58

 
You are asking this of a guy who kept a engine on his computer table for like a year and a half until he finished rebuilding it?

If you look at your jug right now it has a cutaway for the swinging mass of the counter balancer that leaves just a thin lip of metal at the bottom of the jug.

Go much past 97mm and that cutaway can become a short notch in the jug -- start sleeving it out for 100mm bore size and the notch gets deeper (and you start fighting with two of the studs for real estate space).

"Rational, real world" power from a Savage comes from cam, carb, compression, intake/exhaust flow and then only a minor additional boost can come from displacement before that gets too too complicated.

REAL pony power  (25% or more) would be nitrous, turbo or supercharger.   And then you start breaking stuff inside the engine ....

And no, Justin, nobody really knows what all I did to my two engines.  My bike is a mountain sleeper, looks like me -- jest sorta old and decrepit.  

:D   It is supposed to look that way.


Title: Re: larger pistons
Post by justin_o_guy2 on 04/10/12 at 16:16:32

Keep em off guard, dude,, Thanks for the "How its built" explanation.
Some things just arent worth doin,, Massagin these things is one thing, re-engineerin them is quite another.

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