SEM IGNITION TIMING, HOW DO I SET TIMING CORRECTLY PLEASE ?

[mudmonkey]

can some one confirm or point me to how to correctly time a SEM ignition please?
ive seen the pin in the above post but my SEM doesn't seem to have a hole in the flywheel or stator plate for it to locate into ?
im currently using the DTI method then adjusting the stator plate to give 15 deg on the pointer cast into the flywheel window.
does that sound correct, bike starts fine & rides well.
ive put a timing light on the ignition but its got me confused, light indicates its firing 45 deg atdc at just above idle speed.
the timing cant be that retarded as it rides so well !
got me scratching my head anyway ha ha !!!

bike is an 87 400lc

 

[fran...k.]

Since you have a timing light and it is giving you a reading take the spark plug out and put something like the eraser end of a pencil in, turn engine and determine top center. Make mark on rotor near something perhaps one of the bolt holes for the cover. Figure out how much angle different for advance you want. I think 18 degrees is what it calls for , I use 12 to almost eliminate kick back. Mine has the mini 6 not the sem. Warning those screws can loosen up and the stator shift take what preventative measures you choose. You are probably doing fine if it rides good and does not kick back.

 

[PEZBerq]

The owners manual explains the procedure. The arrow should point to the zero position when the piston is at the correct mm before top dead center. Sounds like you have it pointing to 15 instead of zero.

 

[mudmonkey]

sorted it out now.

the replacement main shaft i fitted to the crank on rebuild has the woodruff key way in a different position.

drilled some extra holes in the intermediate stator plate, pulled the wiring through abit more, now timed up fine.

 

[visiteur1948]

 

[visiteur1948]

 

[Bigbill]

Isn't there a measurement from btdc while the piston is coming up to tdc. But we need the head removed.

 

[ajcmbrown]

No need to remove the head Bill, a dial gauge will tell you exactly when the piston is in the correct position.

 

[Bigbill]

I set the ignition as I assemble the engine while doing crank bearings and seals.

When I disassemble a engine I scribe a line from the stator bracket to the block before tear down. I recheck it anyway.

 

[justintendo]

I set the ignition as I assemble the engine while doing crank bearings and seals.

thats great, but you also need a dial indicator to set it whether you do it head on or off...i certainly wouldnt pull the head off to set ignition timing, that sounds like a waste of time. i just use a dial indicator as shown above whether an ignition is replaced, swapped to another machine, adjusted for tuning, or doing diagnostic work..do you pull the head off every time? doing a new build i still set timing with motor in frame, head on.

 

[ajcmbrown]

I set the ignition as I assemble the engine while doing crank bearings and seals.

When I disassemble a engine I scribe a line from the stator bracket to the block before tear down. I recheck it anyway.

My apologies if I sounded like I was criticising your method, that wasn't my intention, your method is accurate. Lifting the head on an air-cooled bike is easy and inexpensive, LC head gaskets are much more expensive and best left in place.

 

[justintendo]

My apologies if I sounded like I was criticising your method, that wasn't my intention, your method is accurate. Lifting the head on an air-cooled bike is easy and inexpensive, LC head gaskets are much more expensive and best left in place.

damn right those gaskets are expensive. i dont even bother scribing crap, its so easy to check with a mic. its kinda rare to pull the entire ignition off regardless.