Motorcycle Repair: Yamaha IT-490, timing advancer, stihl chainsaw


Question
Which way do I turn the timing plate to advance the timing and how much should I advance it?  Also shouldn't the reeds on a 2 stroke keep it from backfiring?  Are my reeds bad maybe?
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The text above is a follow-up to ...

-----Question-----
Will using a shot of starting fluid on the air filter cause it to kickback?  When I tried to get the old bike started, it tried to start on the first kick, but didn't catch.  Then on the second kick it slammed the kickstarter back at me, broke 3 teeth off the kick idle gear, and sheared off the return spring where it goes through the starter shaft.
It never did that before, but I've never used starting fluid on it before.
Also, the service manual says to mix the oil at 20:1.  That seems like too much oil.  My Stihl chainsaw uses 40:1 and all my outboards use 50:1.
-----Answer-----
Hi Bill.

First, always trust the manual.  It was written by the engineers who designed the machine.

Second; what you experienced may have been a backcompression stroke or a backfire.  They can be pretty dramatic.  I recall some of the old Harley guys talking about watching guys get launched over the handlebars with one of those, while trying to kickstart their bikes.

What you experienced, while not catastrophic, was definitely extreme.

Make sure that all of the engine settings are set correctly.  If the bike has a timing advancer, then try advancing it just a bit.

Good luck and ride safe.
FALCON

Answer
Hi Bill.

 If the reeds are clean and undamaged, then they are most likely good.

 As far as which way to turn the timing plate, refer to your repair manual for the specifics.  The direction that you need to turn it depends on which side of the bike the plate is on.  For example, a clockwise turn (to advance) on a plate that is on the high side of the bike is a counterclockwise turn for a bike with the plate on the low side.  Again, I suggest referring to the repair manual for the details and specifics for your bike.

Good luck and ride safe.
FALCON