S2 kickback

[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 ?

[drivera]

what have you done to the engine ?

[monument7]

new bearings, seals and a 190 kit, no new internals other than crank and 12v

[drivera]

Sounds like high compression , my 225 Rapido does the same !!

[Digger]

+1

[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

[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?

[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.

[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.

[dickie]

Does Phil only have one ball?

[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.

[monument7]

I have dismissed the replies I didn't think were relevant

[monument7]

Does Phil only have one ball?

ha has now

[johnnyXS]

well I guess you're going to have to sort it yourself then

[monument7]

Bollocks to you as well

[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".

[monument7]

sorta sums it up