ignition timing

[disonny]

Does anyone know the timing for 82 430wr with a SEM ignition? I have a manual but it doesn't show any technical info.

 

[grouty]

2.18mm BTDC or 17 degrees.

As quoted in the Husqvarna updates. This figure is the same for WR & CR with SEM or Motoplat.

 

[Kartwheel68]

Yes, I think stock spec is 2.2mm but I always retard mine slightly and run 2.0mm.

 

[jo360]

What is the best technique given an aircooled motor with the exhaust on, would it be to mark the flywheel and then mark the case area with a mark(a) at the point where the piston stops going up when rotated and then mark (b) where the piston starts to drop, with the mark on the flywheel between a and b set the timing plate to 17 degrees?. Dont have a special tool just a pencil to stick down the plug hole.have used a threaded rod in the past using the threads as markers but found the exhaust interfered with an accurate measure.

 

[grouty]

I use a dial gauge down the plug hole on my 78. Not sure if the plug is vertical on your 430. Failing that buy a degree wheel. They are cheap enough.

 

[justintendo]

i like using a dial indicator threaded in the plug hole.

 

[fran...k.]

I have used a dial indicator in the plug hole and it is really sensitive as the piston is not moving much at all as the crank goes past the top. Kind of surprising how repeatable it was though. The angled plug might be complicating or in danger of damaging the tool I do not recall doing one of those with the head on at least not right now.

I did see a video on another site about another kind of two cycle product. It pertained to port timing the guy put a degree wheel on the crank and a maleable wire to something on the engine. Instead of measuring the top he measured the same thing rotating the engine around through the bottom. This may well be a more precise way. I do not really recall how he stopped rotating probably screwed a stop in the spark plug hole. On second thought I think he put a light in the spark plug hole and watched the exhaust port. Bend the maleable wire pointer until you get the same thing from both sides.

 

[justintendo]

physically measuring timing at the flywheel could be more accurate as you take bearing play and such out of the equation. i just like the ease and consistence of the dial indicator. nice small tool to go in along with the other instruments.

 

[84scrambler]

Not positive on this but , I don't think all plug hole dial indicators are the same length and width . Meaning one that will fit a liquid cooled bike may not fit in a air cooled bike. Maybe some one will chime in and sum it up.

 

[justintendo]

dial indicators themselves are pretty universal, they just have different ranges..there are different holders, with a set screw to slide the actual dial indicator up and down to "re-zero" for different chamber and head designs. a holder designed to work for the "normal" 2 stroke i.e. bikes that take the es series ngk plugs, work for any bike that has a spark plug with those depth threads. for the most part.
the holder for mine is a bit tall in order to clear fins, so it will work on pretty much any 2 stroke. i can take a pic if anyone would really like to see.

 

[84scrambler]

That would be cool because I think the one I have only fits liquid head. I think mine hits the fins on the 79. Maybe I just need a different holder ?

 

[jo360]

My head has the angled plug hole and the cap touches the pipe when on the plug, actually deformed the exhaust to give more clearance and also the same to clear the decompression valve.i have not bought or tried the dial but was chasing opinions on the accuracy of the above method.

 

[justintendo]

i was always under the assumption checking ignition timing via measuring piston travel before top dead was quite accepted. the factory workshop manual gives the spec for it, and if you think about it i cant really come up with a reason to not trust it. it is quite repeatable as well.

 

[fran...k.]

i was always under the assumption checking ignition timing via measuring piston travel before top dead was quite accepted. the factory workshop manual gives the spec for it, and if you think about it i cant really come up with a reason to not trust it. it is quite repeatable as well.

Measuring the difference between the highest point and a dimension lower is pretty reliable compared to finding top center with the dial indicator. The one I used is to ten thousands and I had to unscrew the tip on it to reach. It isn't a motorcycle one. There are (assumption) screw in extensions though I don't have any. For an angled plug I would think a skinny part that could be positioned vertical and held some how would be easier than using the sin/cosine correction factor and hoping the gague doesn't bind. I kind of do like to use a timing light just to see if the pin really puts the spark where it is desired. If one was to thread the inside of a spark plug and run in a bolt with rounded end as a stop the top could be quite accurately determined by approaching from both directions and splitting the difference.

 

[Kartwheel68]

I also use a dial indicator, some bikes I put it through the plug hole, some bikes I take the head off if the plug hole is not in the center. I have also used a degree wheel on the crank but I prefer using piston travel to set timing.

 

[justintendo]

heres my pics...of an old ass suzuki setup, sadly missing its clear lens. really easy to use and leaves the flywheel area open and uncluttered for adjustments.

here it is taken down...you can see the lockscrew where it can be slid up, down, or rotated some. also my motoplat pin!

heres a close up of the face..this old girl has served me well and has worked well on any 2 stroke ive tried it on. much like any dial indicator the outer ring rotates to set the zero wherever.


hope this clears up questions for anyone thinking about purchasing one!

 

[justintendo]

Measuring the difference between the highest point and a dimension lower is pretty reliable compared to finding top center with the dial indicator. The one I used is to ten thousands and I had to unscrew the tip on it to reach. It isn't a motorcycle one. There are (assumption) screw in extensions though I don't have any. For an angled plug I would think a skinny part that could be positioned vertical and held some how would be easier than using the sin/cosine correction factor and hoping the gague doesn't bind. I kind of do like to use a timing light just to see if the pin really puts the spark where it is desired. If one was to thread the inside of a spark plug and run in a bolt with rounded end as a stop the top could be quite accurately determined by approaching from both directions and splitting the difference.

im not understanding how watching the movement indicator rise and fall at the top of the dial indicator is any more or less reliable? to be clear im not against using a degree wheel, just seems a pia to me..a degree wheel would be handy for portwork, setting up port opening/closing timing

 

[jo360]

Looks like a quality item but wouldn't clear my exhaust, going to set mine at 15 degrees seal it and put in a vent for summer.

 

[disonny]

Thanks guys for the response. Grouty, my plug is at a small angle. The tool I have is similar to the handle of a micrometer. it screws into the plug hole. There is a floating shaft thru the center with a thumb screw to lock it in place once you find TDC. 1 rotation equals 1mm. The reason I ask about the timing is that had to seal the flange that holds the crank seal behind the mag. The bike ran great before I did the repair. I marked the backing plate when I removed it. But now the bike seems sluggish since I got it back together. The only thing that could have changed is the timing.
So, there are timing marks on the mag, a mark that should line up at 2.2mm. Then there are marks that appear to be every .5mm. My question is this. When advancing the timing is that having the ignition fire earlier than the 2.2mm? I'm just trying to see how it works in my mind.

 

[justintendo]

Looks like a quality item but wouldn't clear my exhaust, going to set mine at 15 degrees seal it and put in a vent for summer.

certainly a good idea using a vent. when i still had my 79 250 i had loosen the bolt holding the exhaust and remove the springs and it would give me enough room. same for my other air cooled bikes. everything else cleared well.