Finally getting my newly purchased S40 back together.  Did chain tensioner mod changed out oil and sat or cover.  The problem I'm having is starter won't turn.  I have a new battery, manually actuate the decomp, I have 12 VDC at one of the large terminal at the relay but when I try to start the bike it only has 4.3 on the other side.  I have tried jumping directly from the positive to the starter and it doesn't turn seems likes if I held the wire it would weld in place...same if I try to jump the large starter solenoid terminals.  Any ideas would be great.

Engines don't tighten up just because you drained oil, and 4.3 volts won't make your starter turn.  You won't have any luck turning the engine over manually to run oil through the engine....you won't be able to spin it fast or long enough...at less than 1,000 rpm the engine doesn't pump much oil up to the head....and at speeds less than that the oil will just flow to the bearings on the crank.

Sounds like you have a battery issue.  Is the ground wire for the battery tight to the engine case?  Sealed batteries can go bad in an instant.....and without warning...even new ones.  I had one fail that was only 2 weeks old.

Dave

Same issue I'm having with mine. Battery, starter,  starter relay or connections. Generic starter relays are cheap on ebay maybe $10. Starters can be disassembled and cleaned serviced with videos on youtube. Check frame connection from negative side on battery. Im not sure I like the AGM sealed batteries yet. I went thru 3 the past two days before I think I finally got a good one. I never had this kind of trouble before with batteries. I think I perfer the old lead acid type battery but they dont fit the battery box.
Good luck.

No it's not working yet but its at my storage facility and thats where I work on it. Plan to check a few other things today, like connections and I charged the battery for 5 hours last night. Battery reads 12.8 vdc this morning. Should be fully charged now.

yes I did have the cover off, the old one was all beat and had crack in it, I replaced it and swapped over all parts  I'm thinking what you are about to tell me won't be good news

I was able to push it and pop the clutch engine rolled,  what on earth could be stuck?  I think you may be on to something because the wire to the starter was getting warm but I didn't mess with the starter or gears at all when I took the stator cover off

I guessing the stator cover needs to be removed again to pull the starter?  I noticed one washer which I put back on the top right gear from memory, maybe I didn't notice the other one

thanks so much for all the help, I'll won't get a chance to take a look at it until Thursday but I feel confident your long distance diagnosis is correct