Will it still spark?

[speed20]

If a motor is 180 degrees out of time....it will still spark, but at the wrong time, Correct?

[Macs]

it will spark when engine is at the bottom of the stroke.

[200Xtreme]

I disagree, If the timing were 180 deg. off, it would fire the plug when the piston was at the top, but on the exhaust stroke, instead of the compression stroke.

[ATCnut]

You are both right. It depends if it is 180 deg out on the crank or the cam.

83-85 200x have the cdi pickup on the cam, so 180 out will make it fire at the top of the compression stroke.

350X has the pickup on the flywheel, so 180 out there would make it fire at the bottom of the stroke. 350X fires both at the top of the compression stroke and the top of the exhaust stroke (I think).

[speed20]

If it was 180 out, it would fire when the piston was and BDC (bottom dead center) i figured out what it was...the CDI (on the motor) was 180 off...theres 2 positions it can be at.... the line can be at the top when the timing is correct, or at the bottom, throwing the timing or spark off)

[Howdy]

The only way for it to fire with the piston at BDC is if the timing is off 90 degrees. If it was off 180 degrees it would fire as 200Xtreme said "with the piston at the top on the exhaust stroke".

Why do I say that? On a 4 stroke the crank turns 2 times for every one of the cam. On the 83-85 200x's, they have the CDI pick up on the cam. Thus it only generates spark once every time the cam turns a complete turn ( 360 degrees ). We know 1 full turn is 360 degrees. We also know the crank turns 2 complete revolutions ( 360 degrees x 2 ) for every 1 turn of the cam shaft ( 360 degrees ).
So, if the crank turns 180 degrees ( piston is at the bottom of the cylinder ) the cam has only turned 90 degrees ( re: the cam only turns 1/2 as fast as the crank ).

If the timing is off 180 degrees ( cam turned 1/2 a turn ) the crank will have turned 1 complete time, thus the piston would be back up to the top of the cylinder not at the bottom.

Now on 86-87 200x's , 350x's and similar motor designs the CDI pickup is mounted beside the flywheel. Thus it sparks every time the motor turns 1 complete revolution ( 360 degrees ). If the timing is off on this style motor you got some serious work to be done. lol

Howdy

[350x'inNY]

As a math teacher, very good mathematical explanation Howdy!!!! ;)

Bruce

[200Xtreme]

Thanks howdy, When I read ATCNUT's post, I thought I was going to have to go into that. Then I saw your post, and you did an excellent job explaining it. thanks again.

[ATCnut]

Thanks Howdy, that's what I was trying to say. Just did not use enough words

[krizo88]

great explanation Howdy!