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S2 kickback

Posted:
Thu Mar 12, 2015 2:57 pm
by monument7
Why would my newly rebuilt S2 engine " kickback" so fiercely it rammed the pedal back up to the stop and put me on the sick for a week ouch.
Kickstart shaft moved and caught something ?
Re: S2 kickback

Posted:
Thu Mar 12, 2015 3:17 pm
by drivera
what have you done to the engine ?
Re: S2 kickback

Posted:
Thu Mar 12, 2015 3:20 pm
by monument7
new bearings, seals and a 190 kit, no new internals other than crank and 12v
Re: S2 kickback

Posted:
Thu Mar 12, 2015 3:50 pm
by drivera
Sounds like high compression , my 225 Rapido does the same !!
Re: S2 kickback

Posted:
Thu Mar 12, 2015 4:18 pm
by Digger
+1

Re: S2 kickback

Posted:
Thu Mar 12, 2015 6:16 pm
by johnnyXS
or spark timing off ?

sounds like you may have it too aggressively advanced . Try backing it off a couple of degrees
It helps to kick the engine over firmly and quickly without any hesitation so that the momentum carries the stoke through rather than the engine reversing when the spark ignites toO early BTDC
Re: S2 kickback

Posted:
Thu Mar 12, 2015 6:39 pm
by dickie
Aye, that's usually caused by ignition being too advanced. High compression can exacerbate it, but i doubt it's the root cause.
What 12v system have you fitted? Did Phil persuade you to get a varitronic?
Re: S2 kickback

Posted:
Thu Mar 12, 2015 7:17 pm
by Wack
For anyone who struggles to kick start a motor I would recommend a Kytronic from MB's. They retard the timing at kick over speed making it easy to start a hi comp motor.
Re: S2 kickback

Posted:
Thu Mar 12, 2015 11:33 pm
by monument7
Phil set the timing up and the engine had been starting / running sweet until Sunday. Don't think timing has moved and the kickback seemed more mechanical than compression. I wasn't messing about kicking it over and it seemed as if the kickstart was mechanically pushed back.
Phil called in today and it did the same to him but luckily just caught his toes / ball. Mine was on the arch of the foot so took the full hit. He has been building engines for many years and said it wasn't compression.
Could the kickstart shaft have caught something. Side case has got to come off anyway to check just thought it was an idea to ask first.
Re: S2 kickback

Posted:
Thu Mar 12, 2015 11:50 pm
by dickie
Does Phil only have one ball?
Re: S2 kickback

Posted:
Thu Mar 12, 2015 11:54 pm
by johnnyXS
well you asked and then you dismiss all the replies ??????
If the engine is turning in the correct rotation it shouldn't be possible to get kickback because the kickstart mechanism is based on pawl type engagement ie one way only .otherwise if your passenger inadvertently pushed the kickstart down whilst you were riding ,the kickstart would engage and lock the engine up whilst you are travelling along .
I suppose something could have come loose or out of position or jammed etc ??? I guess you are going to have to remove the cover to check everything is ok under there.
Re: S2 kickback

Posted:
Fri Mar 13, 2015 12:05 am
by monument7
I have dismissed the replies I didn't think were relevant
Re: S2 kickback

Posted:
Fri Mar 13, 2015 12:09 am
by monument7
dickie wrote:Does Phil only have one ball?
ha has now
Re: S2 kickback

Posted:
Fri Mar 13, 2015 12:09 am
by johnnyXS
Re: S2 kickback

Posted:
Fri Mar 13, 2015 12:17 am
by monument7
Bollocks to you as well

Re: S2 kickback

Posted:
Fri Mar 13, 2015 12:28 am
by dickie
At work last week someone said to me that "team" stands for: Together Everyone Achieves More.
I thought quietly about this for a moment then said "f#ck Off".
Re: S2 kickback

Posted:
Fri Mar 13, 2015 12:56 am
by monument7

sorta sums it up