I'm reminded of the table in the student union building where the geeks with slide rules, pocket protectors and Dungeon and Dragon game pieces in their pockets congregated.

Actually, the benefit from increasing compression height (wrist pin centerline to top of piston), would be establishment of an actual quench zone.  With the current design, there really isn't a quench zone (tight clearance between the overhanging head surfaces and the top of the piston).  Reports on this forum state that there is something on the order of .160"+ between piston top and cylinder head when the piston is at TDC.  It should be .040" or less.  If the piston compression height were increased to establish .040" quench, and the pop-top removed (i.e. flat top piston) you end up with increased compression ratio plus a reasonable quench clearance.

So how do we go about getting these flat top pistons with increased compression height?

So on the original version of my engine when I had the head shaved .015”  and the cylinder shaved .025” for a total of .040” with 94.5” bore and a Suzuki flat top piston, Compression would be brought up to ..... ??

It did run very well with the original Stage 1 cam and 36 VM.

This would leave the quench zone intact.
My cam chain was not just flopping around, there did not seem to be any noticeable change in the chain tension.  The tensioner may have been out ever so slightly more, but for a change of just o.o4” ... REALLY ?
I have a hard time seeing any issues with the chain.

Lancer, the stock head is 57cc when the stock quench is added ,total volume comes to 87cc. Your removal of .040 would reduce that to about 80cc ,using the formula for compression  that would work out to; 80+652/80 =9.15 :1 .but this doesn't take into account the reduction caused by a domed piston ,use of the domed DR piston would drive compression higher .and reduce chamber volume .If someone could determine the displacement of just the domed area of the DR piston we could subtract that from 80 and get a hint of what the actual compression is in our bikes using it.
  The problem with the cam chain isn't that it's flopping around ,its that the slack caused by your .040 reduction is really seen as .080 for the double sided chain ,and all of that is taken up on the back side by the cam chain adjuster. How much does that retard valve timing? has the chain ages it becomes worse. how does this affect performance?

justin_o_guy2 wrote on 12/06/18 at 08:53:13:


It was Armen.

I have linked the thread a time or two....I don't know where that thread is at the moment - it would take some searching to find it.  It involves the fact that the number of splines where the crank sprocket mounts is different than the number of teeth - so by turning the sprocket on the crank and moving the chain on the teeth, you can advance/retard the timing in pretty small increments.

Found it!

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1476554649

batman wrote on 12/06/18 at 08:01:44:



So you are saying that the extra slack in the chain caused by the reduction causes the timing to be retarded ?
If that is the case then why is the timing not retarded when the chain just naturally stretches ?  Isn't that the same thing ?  Both create extra slack.  I thought the chain would have to slip a notch to do such a thing, or a new pin hole created to manually shift the sprocket position.
The timing is held in place by the bottom drive sprocket and the cam sprocket on top (the chain is in tension on this front side) and that does not change regardless of the amount of slack on the back side.

Am I missing something here ?