Does sync effect pilot mixture?

I've searched like crazy, but haven't found anything.

Actually, I started read the XJ chat forum starting at page 213.....heading back to page 1. I'm on 191 right now.

Anyway, can carb sync effect idle/pilot mixture?

 

I will be corrected if I'm wrong.
You have 4 carb's trying to feed 4 pistons fuel, if one of the carb's was not sending enough fuel to one piston while the others are racing away then there will be drag and the motor is not in sync and trying to pull against itself.
You may already know that part, but.

If there is improper burning of the fuel due to a carb out of sync then you may well see your spark plug foul quickly as well as other tell tale signs it's not running right.

If they are not synced then you won't be able to set the mixture consistently so i think yes but only indirectly.

 

Yes. But not horribly.

 

Some of the air for the pilot mixtures comes in past the butterflies.
When you sync the carbs, butterfly position changes, and therefore the pilot mixture changes (less air flow past the butterflies = richer mixture). Adjusting the idle knob has some effect on the mixture as well.

Once you get the carbs balanced, check the mixture (colortune or spark plug color, whichever). Adjust, then check everything again. The Colortune plug makes the job go a LOT faster...

 

I'm just wondering if that's the case with my SECA.......since plug 3 is richer then the rest?

 

One rich cylinder doesn't mean you're out of sync... You might just need to adjust the #3 pilot mixture screw in a bit.

The only way to find out for sure whether your bike is out of sync is to hook up a manometer (the home made kind, gauges, sticks, whatever) to the carbs... On YICS bikes, you'll also need to block off the YICS passage to get an accurate reading.

 

Sync adjustments will throw off the mixtures; mixture adjustments WON'T change the sync but do affect how the motor runs. Once they're correctly sync'ed then we fiddle with mixtures; but not until then.

Check your sync before tweaking the mixture screws. Your Seca isn't a YICS bike so that part's not a concern.

 

Checked the sync, and my bench sync was pretty darn close.
Is it normal for small flames to come up the sync tubes?

Did a colortune test, and the mixture screws did not effect anything.
All 4 were lean (pale blue). I could hear the RPMs rise when I backed the screws way out.....but no change in color.

I did a check with carb cleaner on the throttle shafts, but didn't hear any change.

I've got to have an air leak to be running this lean.

Not sure where to go from here?

 

I don't think the flames are normal. You should definitely not see any flames on the intake side of the engine, unless it's severely out of time or the intake valves are blowing by... 8O

What RPM did you sync/colortune at?

 

Valve clearances have been checked, and are correct?

 

The blue flame in the vacuum tubes were only visible when I first started the bike. I had to choke at first.....sat for 10 mins after I took it for a ride.

I sync and colortuned at around 1500 rpm.


Mikey, I did check the valve shim clearances....ended up replacing two.
They all appear to be within spec now.