iainscot

hi


i have an old os fs 40 four stroke engine its about 15-20 years old and it hasnt been run in a while and the push rods were all gummed up so i had to take them out and clean them and the cam and the little things the push rods sit in ( sorry i forget the name).

so i had to take the cam out which has lost the timeing so it needs timed now

however i found a thing on the net on retiming os 4 strokes it says to find the timing mark on the cam gear side and point it upwards inline with the push rods but my cam gear doesnt have a mark on the side

can anyone help out or show me some pictures on how the cam gear should be when the piston is top dead centre?

thanks

donkey doctor

Hello; I have never seen an OS cam without the timing mark. It is a punch mark on one side of the gear. I could understand you not noticeing it through the rust and detrious build-up. I would take a bit of emery cloth, or sand paper, and shine up the side of the gear, both sides, until you see the punch mark. Then assemble it lined up with the pushrods whild you hold the crank at TDC. The gear is helical cut, so it will turn as you insert it. Just make sure that when it is all the way in, the punch mark lines up with the pushrod and lifter(that's what the thing is called that rides on the cam).

Hope this helps.

iainscot

yea i found it a while after posting this

i wiped all the old fuel and oil build up off it and i couldnt see it so i took it inside and gave it a scrub with a brush and i found it

its not timed and i have just ran a tank through it and it ran sweet as a nut

thanks for you help

phbiggles

Hello,
I also have an old O.S. FS-40 in need of the pressure adaptor for the exhaust. Do you know if the new O.S. 40 exhausts fit or will I have to get one specially made? The original exhaust had a pipe with a retaining nut. The new ones seem to have a male end on the pipe and a locking nut. I guess it is a matter of whether the threads and size are the same.
Thanks,
Pete

loughbd

sweet as a nut?

jaka

Hi!
Why use pressure on the old OS FS .40?? It's not needed! The OS runs equally good without pressure.

Regards!
Jan K