Hi all, another st1050 starting issue. I cranked my bike to start it the other day, it is normally a bit hard to start, however takes about two 3 sec cranks to start when cold. On about the 2nd or 3rd crank, the starter Motor changed pitch, sort of like 2 pistons were cranking instead of 3, and the bike would not fire. It did a couple of coughs and that was about it after many attempts.
The bike is a 2006 st, 60000 km on clock.
I pulled it apart thinking maybe it dropped a piston, but looking down spark plug holes all pistons appeared to be going up and down normally when cranking, looking into air cleaner ports, valves were also all working. I found that the 3 core plug from recently fitted cmos rr was all charred from poor connection, so did resistance check on rr and all appeared normal. I cut out plugs and reconnected wires with new spade terminals and tapped these all up to keep moisture out. No change to starter pitch or starting.
My thoughts were that the rr would not cause a change in starter pitch etc anyway as battery was fully charged.
I have fitted a new battery only a few weeks prior to this issue, so know that is all good.
About 12 months ago I changed starter cogs near sprag as the 16t one was stripped and a couple of teeth from the large one were smashed off. I recovered all teeth, so this repair was successful and have done about 10,000km since then.
I note that the bike has already had the sprag clutch upgrade to the heavy duty one, and this seemed to be okay when turning by hand etc.
I have just pulled the starter apart and it was a bit dirty, but brushes etc all in good condition and seems to operate normally when operating starter switch.
Not sure what to check next?
Any ideas would be appreciated.