Setting Points Gap

[AdkStihl]

Can someone tell me what the proper points gap is for a Jonsereds 49SP?

Thanks
Jeremy

[chet]

Been a long time, but if memory serves me it was .3mm to .4mm for points and air gap was .30mm. Timing was 2mm BTDC.

[sawguy21]

.015" should work for most two strokes.

[Al_Smith]

I'd guess about 12 thou air gap and 16-20 thou on the points .You could check it with a timing wheel and a continuity meter for somewhere around 26-30 degrees advance before top dead center on the ignition .FWIW most McCullochs are set at 27 advance while Stihl is at 28 .

[AdkStihl]

No timing wheel. Up until this point I had never messed with anything except electronic ignitions.
So excuse me for sounding inexperienced, but how do I set the timing advance?

[ladylake]

With a smaller gap points will open sooner advancing the timing, wider retards the timing.  Steve

[Al_Smith]

You have to take the flywheel off of course .Set the timing wheel up in the normal method so it's marked at top dead center .

You just set the points so they open at what ever amount of advance you want .Where the points open and you loose continity to ground with a tester is where the coil fires .Try for say 27-28 advance and see how it goes .Setting the points closer slightly retards the spark,farther apart more advance .Probabley at best without moving the coil you might have a 5 degree window to work with .

[Al_Smith]

With a smaller gap points will open sooner advancing the timing, wider retards the timing.  Steve

Sorry to act like a butt hole but you have it backwards .Think about it now .

If it's set wider the cam in the crankshaft opens the points sooner in rotation .Closer it's farther up on the lobe and thus later in rotation .

[chet]

Rotate base plate to set timing.

[chet]

Dug threw some of my old stuff and found an old 49SP op manual. 

Ignition system
Breaker point gap adjustment
Remove the starter assembly, the magneto flywheel, and
the cover over the breaker point assembly. Fit the flywheel
nut and turn the crankshaft until the breaker points are
at their widest distance apart. The gap should then be
0.016 inch (0.4 mm). If not, adjust the position of the
fixed point.
Ignition timing
The ignition timing is set at the factory to 0.080 inch
(2 mm) before TDC. Turn the magneto mounting plate
against the crankshaft's normal direction of rotation to
advance the ignition timing. To retard the timing, turn
the plate in the same direction as that or the crankshaft.
The distance between the flywheel and the ignition coil
core should be 0.012 to inch (0.30 mm).

[Al_Smith]

Does that model in fact have a base plate like a power products AH -47 for example ? It's a question because I really don't know on that model .

Brings up an interesting event on another web forum I no longer visit regarding an AH-47 engine nobody actually knew how to time one except by the method recommended which gave reference to distance before top dead center using a depth micrometer .

I just grinned and put the proceedure on another  forum . ;D

[Al_Smith]

Well alrighty then it does have a stater base of sorts .Nice job of research .

[ladylake]

With a smaller gap points will open sooner advancing the timing, wider retards the timing.  Steve

Sorry to act like a butt hole but you have it backwards .Think about it now .

If it's set wider the cam in the crankshaft opens the points sooner in rotation .Closer it's farther up on the lobe and thus later in rotation .

  Al   Thanks for straightening me out, one of those days.    Steve

[Al_Smith]

It's easy enough to get screwed up .On a chainsaw the "cam " is an indent in the crankshaft .It almost acts like it's backwards as compaired to a regular cam .

If you tinker with the timing via the points two things you have to remember .First the points have to completley close for it to work .In addition the points have to open some place within the window of the magnets aligning with the stater pieces on the coil .

 

[Al_Smith]

As usual the forum software shuts me off before I'm through .So if it's 50 posts to get a point accross so be it .

Back to points .About the magnet alignment .In addition to playing with the points just like a solid state coil an offset key will realign things if need be .Generally speaking though as a rule you won't change the timing by much because we aren't talking extremely high RPMs or relatively low compression ratios .

[thecfarm]

Al are you a slow typer?   :D   I have been doing a post,than the wife will need something done,I come back to the post and all is fine.

[Al_Smith]

I could double my speed if I could just learn to use two fingers instead of one .In addition to that my phat phingers can hit three keys at once .I'm just a mechanic I'd never make a secretary although I've known a few in another life so to speak . ;)

[Al_Smith]

I got to thinking about something .Now I know exactly how ignitions systems work but knowing and explaining are not one in the same .

A good research source is here ,Fox Valley Karting in Indiana .Not only on just ignitions but  engines in general .Check it out .http://www.foxvalleykart.com/timing1.html

[AdkStihl]

Great info guys!! Thanks

I'm just gonna have to guess on the ignition advance, I have no way of knowing where to set the points plate. I understand that by rotating the plate in a counter clockwise motion I am advancing the ignition and vice versa for retarding.

And I did pay attention to where the plate was sitting before I took the old one off.
It was fully advanced in the adj slots.

[beenthere]

As usual the forum software shuts me off before I'm through .

Sounds more like you are not signing in right. Been so long since I've signed in, but is seems like there is a time limit box to check or uncheck.

[Al_Smith]

I'm on automatic no need to sign in .I don't know why it gets a pain in the buttocks after the post goes over about three paragraphs .If there is an option I'm not sure where it might be at .No big deal I'll just make a zillion posts if that's what it takes to get a point across .

[Oliver1655]

That is weird Al. I haven't had a problem with making longer posts - knock on wood.

[AdkStihl]

Thanks for all the info guys!
Houston.........we have ignition!!

[Al_Smith]

I'm curious to hear how it does .J-Red was never a front runner here due to no dealer support .In my lifetime I've only worked on three .I think a 620,630 and some 49 cc model 235 maybe?

The little one had a surprising amount of zip for a 3 cuber .

[AdkStihl]

Heading to get some fuel hose @ lunch break.
Maybe fire it up next weekend.