Timing feckery

[DaveTomo]

Just done the winter overhaul on the engine,changed the barrel over,new rings etc.Engine back in the frame,checked the timing using the positive stop method ,line the stator up with the 2 marks on the flywheel and the white line in the pick up, got it to a guesstimate 17BTDC. Anyway fired up 3rd kick - chuffed .strobed the timing when on tickover marks line up on the mag housing and the stator, revved it up suddenly couldn't see the arrow on the flywheel! Moved the strobe gun around the arrow on the flywheel is about 90 degrees BTDC (or about quarter to 3 if you imagine a clock).

The stator ( a SIL) was one I fitted last year on the side of the road after my original SIL stator packed in (after 6-7 years good service).Just fitted where the markings were for the original,carried on on my way - got me to the IoW and back and a few other places after but never strobed it till now.

Any ideas? - would the piston in the wrong way round cause this? I'm on paranoid overdrive at the moment

[Adam_Winstone]

No, piston would make no difference, whether upside down or not.

This probably wasn't happening before (last ride) so it might be worth thinking through all that has changed. It sounds like something breaking down under load. First common check is to take the loom's green off at the CDI, keeping the one from the stator connected, to see if the problem goes away when you strobe it. Taking this 2nd green of at the CDI means that you will not be able to control ON/OFF by the key or kill switch and the ignition should always be live (you should be able to use the choke to stall it off).

If this does not bypass it, then I'd start looking at CDI, stator, etc. issues and or pickup alignment (this is the ignition trigger). What flywheel are you using?

Best of luck.

Adam

[Monty]

May be worth checking the woodruff key is still intact

[Adam_Winstone]

^... yep, good shout, especially if the timing marks do not go back to the correct position when the revs drop.

I went to strobe a scoot for a mate recently and almost instantly sheared the woodruff key, which it turned out was manufactured too tall so that the flywheel was tightening down on the top of the key, rather than the crank taper. That put a rather quick end to strobing the bike as he didn't have another key

[eden]

pickup f@@ked. ive had that several times!

[DaveTomo]

Thank you chaps,much appreciated.Given me something to go at, I'll be honest freaked me out a bit when I saw it! I'll go through it all methodically as per your suggestions & if all else fails another stator plate. Thank you all for helping.
PS Adam its a medium weight flywheel

[lambro]

pickup f@@ked. ive had that several times!

+1, just had it on a PX.
Marks were fine on tickover, rev it and the marks vanished to the opposite end of the scale
And that was a new stator :-/

New pick up and all good.

[DaveTomo]

Just to tidy up the thread - checked again today- woodruff key OK, still the same with a different (known working) CDI ,green off the ignition, still the same.Changed the Stator (again for a known working one) checked the timing - spot on! pick up fecked on the original one as suggested,thank you lads appreciate your help