Strobe Timing with Trisspark

I see there are many posts about this but I'm still confused (easy to do) of what to look for with the timing light.

This started when I asked AI why the engine stalls if a crank the throttle as fast as i can but if I go a bit slower it revs right up. Among other carb things it told me to check timing with a strobe at 3500 and make sure its 31 deg BTDC. Everything else I see says 28btdc. AI refuses to back down on this spec. Any insight on which it is?

"This started when I asked AI why the engine stalls if a crank the throttle as fast as i can but if I go a bit slower it revs right up. "

Low vacuum.

Manu said:

I see there are many posts about this but I'm still confused (easy to do) of what to look for with the timing light.

This started when I asked AI why the engine stalls if a crank the throttle as fast as i can but if I go a bit slower it revs right up. Among other carb things it told me to check timing with a strobe at 3500 and make sure its 31 deg BTDC. Everything else I see says 28btdc. AI refuses to back down on this spec. Any insight on which it is?

Click to expand...

Tri Spark manual says to set at 29 btdc. Mine's at 30 because I thought close enough when I checked it. I doubt you will notice much difference between 28-31.

That's what I thought. Just rechecked mine and its ~30. Fires right up and idles fine. It does cough/backfire slightly every once in a while when i kick it but usually not.

I'm at 6k+ ft. altitude so been trying to dial it in. Other than the stall on fast-full-throttle it seems to be running fine.

Maybe it thinks it's a Triumph and wants 38?
That 10 degrees difference says so much about the difference in efficiency, or otherwise, of the respective combustion chambers, doesn't it?

Keep in mind that recomended advance is always given at sea level. For every 4- 500 m up, add 1° .

When you say it backfires sometimes when you kick it, it this cold or hot start?

I think that your throttle opening lag problem might be mixture.
If so, the question is whether it is low end mixture or higher end.

If it were my bike (and I have a single Mikuni - you may have 2 carbs), I would richen the low end mixture by turning in the low end
air mixture screw one turn (to richen) and test bike. If no change, 1 1/2 turns. After that, put back to
where they originally were (ie I set for maximum hot idle speed)

If the above does not work, I would raise jet needle (two noeedles in your case?) two notches (ie the most possible)
and see if problems go away. Should carbs have to come off to do this, I would do a big clean while they are off

Dennis

At 6000 ft you've got problems. It will never run as well as at sea level. If you are often changing elevations then you should stay close to stock jetting. I used a hotter plug at 6000 feet just to get some plug life and then change to the stock plugs when going to lower elevations.
Buy an 8 pack of plugs. Check often. Replace when they get black. Do NOT be concerned with plug life.