I have been having an issue of occasional hard starting and then a massive backfire. I was out riding today and ran by the indie shop. I talked to the mechanic and told him what was going on. He said, well, it sounds like your ignition timing has too much advance. He said I can't look at it today and hell, I can't see through those little sight glass windows either anymore. He said go home, pull the sending unit cover off and mark the current setting with a sharpie. Then retard it a little and give it a try.

So, I did as he suggested. He said that a good place to start if you don't have the timing light or otherwise can't see through the little window is to just set the plate in the middle of the settings and start from there. What I did was retard the timing just a little. Now it does seem to do everything better. I haven't tried a cold start yet but, I'm real happy with the hot starts. Much more predictable and no backfires or kicking back. Fingers crossed.

 

Timing lights are $20, and you don't need the little window plug thing if you don't mind a little oil mist blowing at you.

However, if it is running well now, whatever. There used to be the "timing with a hammer" method of setting the timing on hot rods. You leave the dizzy hold down a little loose, drive it, stop, tap the dizzy one way or the other, drive it, compare, tap, etc., until it ran good.

 

You can eliminate the oil blow with a little forethought next time you're in the primary.
When you have the primary open next time, pull the plugs and get something to make some scribe marks on the rotor. I have actually used my old lady's fingernail polish and it lasted a long time on there to highlight the scribe marks.

You want to mark the rotor at exactly 3 o'clock for each timing mark on the flywheels and have them correspond to a mark on the inner primary. The old oil spout on shovels worked awesome as a timing mark locator as it was right at 3 o'clock inside by the rotor.

Once you have spun it over to all marks you can close it up and now you can shoot the timing light thru the inspection cover and see the marks as they align with the inner cover mark. Lots cleaner this way.

If you have to pull the rotor, you need to index it with the sprocket or you'll have to re-do the markings.

Griz

 

I need pictures of a dizzy for this one Doc.

 

Sure thing:

 

Thanks, Darn thing looks just like one of those spark adjusters.

 

I've never tried it but a properly sized piece of PVC pipe in the timing hole should cut down on most of the oil mist. I tried a clear plastic plug once but I couldn't see a mark well enough.

Now that I have an ignition with a static timing LED I don't need a timing light. My motor isn't stock so there is no reason to expect a timing mark to be useful.
I time my ignition by looking at the dip switches or using Dynatek software.

Performance dictates the proper timing on modified motors, not the factory timing mark.

 

Tried a cold start.. Started first time. For a cold start on an 80 degree day that's not unusual. For a cold start on a 49 degree that's highly unusual. I read someplace that people intentionally advance their timing to get more torque. Even if that's true it doesn't seem to be a good deal considering the negative aspects. Anyway, the overall performance seems a lot better now.

 

Just feel like I need to say that this bike has never run as good as it does right now. Starts first time every time hot or cold. Runs wonderfully out on the highway. The sound from the mufflers is a shade quieter. It's a cinch to get the carb set. I wish I had discovered this a long time ago.

 

timing and backfire
Can the air and fuel mixture cause the problem or even the excellarater pump because I'm having the same issue