WR400 ignition timing

[Quiggs66]

Hi everyone. I went to check the timing on my 84 WR400, expecting the magneto to sit in or around 17 degrees BTDC.  But using my timing light the marks lined up at 0. (actually this mark appears to show a '1' and not a 0).  This is clearly not firing at TDC as the thing makes a lot of power. So I wonder if the mark doesn't refer to degrees BTDC, but refers to degrees from correct timing (ie degrees from 17 BTDC).

Another thing I found unexpected is that the timing doesn't advance with increased revs. Just stays at the same zero mark.

Anyone out there who can make sense of these??

[Tony.Brown]

Which ignition does it have SEM or Motoplat? The timing procedure is different for both.
If you don't have a dial guage, you should get one or risk a kickback cracking the clutch cover and even the crankcase if too much advance is used.
If you do have one, it's best to be at about 1.8-2.0mm btdc. From memory the factory setting is 2.2mm btdc.
These ignitions do not have an advance curve, they stay static throughout the rev range.
Tony.

[PEZBerq]

The WR is likely to have the SEM ignition. Swedish Electrical Mystery.

17 degrees BTDC sounds right.

Yes no advance as Tony said. Static timing.

[Quiggs66]

I think it's a SEM magneto.

So shouldn't the timing marks reflect a '17' when using a timing light?

When you do static timing, how do you know the points are at the point of opening?

[grouty]

There are no points. What you have is a "trigger point". The position at which the spark is sent.
As Tony said, time it using a dial gauge at 1.8 - 2.0mm BTDC.
I run my 390WR at 1.9mm BTDC and the Auto at 1.65mm BTDC.
They run so much better. Probably due to the crap they put in modern petrol.

[bigk]

What are you up to Paul? That bike is a pearler & runs as it should, it actually goes pretty damn well, very strong everywhere in the power curve, I would not tinker with it. My suggestion is to leave it alone & just ride it.
K