I was given an old Jonsered 525 chainsaw. There were a few problems most of which have now been sorted out. The problem that I have now is that it is very difficult to start the saw it appears that the compression of the engine is very high, pulling on the starter cord it is very tight. If the spark plug is removed the engine is very easy to turn on the pull cord. Any idea what could be causing this?
Jonsered 525- Starting Problem.
- Thread starter jazzman
- Start date
Sounds like you might have a timing issue and possibly it has been caused by a sheared key on the flywheel. Flywheel has moved on the crank (keyway position keeps the timing correct- the nut torqued down holds that position) and the timing is out- might be firing at TDC and not just before.
Or it could be carbon build up on top of the piston and on the squish band of the cylinder, reducing the air space and thus increasing the compression.
Or it could be carbon build up on top of the piston and on the squish band of the cylinder, reducing the air space and thus increasing the compression.
Yes, as it would if caused by carbon build up as well.
No spark in a sealed combustion chamber is much the same as mistimed spark- you are trying to over compress a gaseous semi fluid in a sealed chamber.
Like pulling the plunger back in a syringe, placing your thumb over the outlet tube (no needle fitted!) and trying to compress the plunger- if the air cannot get out- the plunger will only travel so far.