I just completed an upper end renovation of an S-40 engine with some changes.
The big change was a 96mm Wiseco piston that brings out the displacement to 680cc. When I weighed the old piston and pin it was 510 grams. the new Wiseco was 477 grams. I was concerned about possible vibration from unbalance. To make them weigh the same, I machined two half slugs of aluminum to fit into the ends of the wrist pin. The outer ends are tapered to match the inside of the new pin. A hole was drilled in each and threads cut in one end. An allen screw was fitted after generously filling the threads with JB weld so that the screw will never come loose. (see the photo) this made the piston assemblies weigh the same.
Valves were hand lapped to insure a good seal.
One of Mysterious Johns' copper colored cam chains was installed, I worry a bit about this as the pin diameter of this chain is a tiny bit smaller than the stock one but at least it is new.
The apply proper tension to the chain, I installed my modified tensioning device. This will be the first on the road test of this thing.
( see the photo)
When taking the engine apart, I noticed the horizontal position of the timing marks on the starboard end of the cam. (see Photo)
At this position TDC, a center punch dot was noticed at the BOTTOM of the starboard end of the crankshaft. This can be used to set the crank at TDC during reassembly, no need to open the port side cover to see the mark indicated on the alternator as the book says.
I replaced all gaskets involved and replaced all four copper crush washers under the nuts of the head bolts.
Upon disassembly of the clutch,( I had bought a full set of friction discs), I miked each friction disc and found that only two of them were actually less than the new ones so I only replaced two discs.
NOTE one of these discs is deliberately thicker than the rest. Note the position of this disc upon reassembly.
When all this goes into the bike, it will exhale through a new fishtail muffler that should give less restriction.
I have already installed a 152 and a half main jet in a new carb to feed the beast.
I will give more results after I have put some miles on this engine and dare to open it up to compare  hill climbing speeds with those I have noted in the past on some local roads.





Additional photos show milling the valve spring compressor tool,
and the piston pin removal tool I made from threaded rod and plastic pipe.

T Mack 1 - FSO wrote on 04/19/09 at 15:49:27:


I already threw out the packing trash, but not to worry, If it is satisfactory I will be getting another for the engine that Will come out of the  bike this week.
If you are in a bigger hurry, Google to get Wisecos' site but you will have to look under dirt bike parts to find it.
The Dr 650s of pre 1996 use the same piston as the LS 650.
There are three sizes available. 95mm, 96mm, and 97mm.
The 97mm will bring it out to almost 700cc, BUTT, the cylinder liner wall will be marginally enough barely.
I spoke with one of their techys and he said that absolute minimum liner wall thickness is .080.
The skirt of my cylinder liner measured 101mm. I bought the 96mm piston. That only leaves 5mm difference. divide by two gives wall thickness of 2.5mm.  Do the math and you will see how close this is.
This engine is only an expirement. It is testing the big piston, the port relieving job, Mysterious Johns' cam chain, and my modified tensioner.
If any of it fails, I will build the next one differently.
If the breakin goes well, I expect to be on the road for 4,000 to 8,000 miles before returning home. That should be a good proving test of the unknowns.
I would like to find a service that will stroke the crank 6mm for me and do the rod shortening to match. That should give somewhere around 725cc. A really good sidecar puller.

Phelonius

Back when Powroll was out on Tumalo Falls Road, I had them stroke a crank for my XL350.  They did a fine job and I was duely impressed.
I called them a couple of months ago and they said that they didn't do Suzukis.  Maybe I should talk to them some more.

Phelonius

LANCER wrote on 04/21/09 at 19:35:39:


There ain't many dudes on Savages bigger than me. Uglier maybe.

Phelonius