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Post by baldmeister on Apr 18, 2013 7:11:05 GMT
hi all,
i have been told that as i have put a dr180 on my px 125 i should retard the ignition by 1 degree .
can someone explain why and what effect this should have.
thanks
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Post by sbwnik on Apr 19, 2013 2:01:01 GMT
It'll fire slightly earlier, giving the flame a better chance to expand.
Or something like that, I always struggle with advance and retard, it's why I have it drawn on my garage wall!
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Post by kru251 on Apr 19, 2013 10:27:24 GMT
It'll fire slightly earlier, giving the flame a better chance to expand. Or something like that, I always struggle with advance and retard, it's why I have it drawn on my garage wall! Retarding the ignition actually has the spark firing LATER in the rotating cycle (i.e. nearer TDC) so less chance of the flame front trying to bang the piston back down the wrong way leading to pre-ignition/pinking/hole in piston. |
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Post by pxguru on Apr 19, 2013 15:11:15 GMT
Something to keep in mind is far too much timing advance causes detonation and melted pistons. Far too much timing retard causes the flame to continue burning in the exhaust, the oil to burn off the piston and then heat seize!  Where you want to set the timing is, as far advanced as possible but never, ever, detonates no matter how much you thrash the life out of it. |
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Post by baldmeister on Apr 19, 2013 16:59:44 GMT
so what would you suggest for a px 125 (2011) with a 180 dr kit?
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Post by sbwnik on Apr 19, 2013 18:08:02 GMT
See, I told you I always have problems with this..... I should have gone into the garage to check  Who gave you the advice? I'd check with a scooter shop TBH. |
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Post by bryno on Apr 22, 2013 8:13:38 GMT
What do the fitting instructions tell you? I would go with exactly what DR suggest and not play trial and error.. If they suggest retarding the timing and you don't, as said, you risk detonation (pinking) and melting the crown of the piston, generally considered to be a bad thing!  |
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Post by pxguru on Apr 22, 2013 11:35:31 GMT
Don't feel the urge to retard it a bit extra to be on the safe side to stop pinking, as this might be enough to increase the exhaust temperature to the point it will heat seize!
Be sure to use a timing light, as the stator marks are plus or minus a few degrees depending on your engine.
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