Could a too far advanced timing cause a engine size?

[kidda]

Been messing with the timing today advancing it a touch,went out for a run no problems then gave it a touch it seemed to be struggling not as quick as normal,took it up to 55mph it wouldn't go nomore,stuck at this for say 1/4 mile then died and wheel locked up,pulled clutch in sharpish and stopped,left it for a bit and managed get it going and limped home,after investigation the pins to the barrel had come loose a fraction and had a soft seize by the looks of the barrel,plug looks a nice colour so I'm at a loss at why????any ideas folks?sudden intake of air?plug firing to close to the piston making it overheat?cheers

[me]

Yes - put simple - over advanced igniton can casue it to over heat...

Ive writen about this in the past - on this forum i think - its all to do with what is known as the "flame speed" - this is a constant - the petrol/air mix always burns at the same rate and for it combust completely thoughout the combustuion chamber.

If you can imagine the piston is rising in the bore towards the head compressing the petrol into the head and a certain point the spark plug fires and ignites the petrol as the piston is rising - for maximum force on the piston the pressure wave formed when the petrol is burnt needs to push on the piston as it reaches TDC and then the pressure wave pushes the piston back down - - this is why lots of bikes have a auto advance and retard system - as the revs rise the amount of time the pressure wave has to act on the piston is reduced - but the rate of burn is the same - now getting to your question - - put very simply - if the ignition has too much advance the piston is trying to compress the pertol explosion as its trying to expand downwards this can make excesive heat build up and casue a heat sieze.....

Hope it makes sense...

[kidda]

Makes alot of sense because that's what I was thinking,been thinking aswell
I've a faulty stator even though relatively new because having alot of problems setting the timing also the problem with struggling over 50mph,also the power surge not long ago that blew my bulbs,wondering if it's a 120w stator and not compatible with my non battery scoot,put an old stator on and kicks up and dunna sound 2bad think I've been lucky,going take her 4a run see what she goes like and upjet aswell be on the safe side

[pxguru]

How much did you advance it? Usually any of the normal set ups can be plus or minus a few degrees and not have any issue (just set to where the lower rpm power pulls best) but when the timing is changed the jetting needs to be re-checked completely, from the start. The jetting will always be affected in some way by an ignition timing change. It takes time for the plug to colour and may not give instant feedback.
To go fast the jetting needs to be as near to dangerous as you dare Lack of performance can mean it is too weak or too rich.

[henri]

slightly advanced timing an slightly lean jetting=seize (4 corner heat seize)in my experience .really over advanced timing =holing in top or pitting of piston crown .as guru says check ya jetting after re-setting timing .H

[kidda]

To be honest I couldn't tell what degree it was I just tweaked it a touch,no pinking and started 1st kick I'm trying to solve the hesitant 50-55mph issue.im thinking the stator is faulty how can I check it's OK?the reason I'm thinking it's faulty or the wrong one is because I've advanced/retarded and re-strobed and it has made little or no difference to my original timing marks???i put an old stator on slightly advanced it it will not start do this to the other one no change starts 1st kick????also had a power surge that blew all my bulbs,going see how it runs with this old stator on and upjet.

[vespasco]

all true

also, the cylinder stud coming lose probably didn't help much either

check your regulator too if all your bulbs blew

[0105]

Did you ever find a solution to your 50mph issue as I'm having the same issues on mine