Pilot screw settings.... How many turns out?

[muaymendez1]

so i ordered the larger pilot jets but just needed to see if I could find the screws and do the idle drop test to see if any of the pilots would not make a difference in rpm when turning them in.

They all worked and it seemed that they were turned just about 2 1/2 turns from seated. i turned them out 1 full turn and re synched the carbs. they were off a bit.

Felt better but tommorow morning will be the real test when starting from cold.

 

how many turns out worked for you, did you eventually go with the larger pilots.

with the larger pilots what setting should I used.

how many turns out?

[RSTDdog]

Pilot screw adjustment is best (ideally) done with an EGA Exhaust Gas analyzer. While every good shop should have one, most don't and neither do most mechanics. There is typically no "set number of turns out". When tuned with an EGA you will find that none of the screws will be set the same. Yamaha provides threaded ports on eac of the exhaust head pipes to insert EGA probes. The options for adjusting mixture I am aware of are 1. EGA. 2 Lean Drop method. 3 Color tune product. I am not familiar with the Color tune product but a search will turn up discussion of it. 2 to 2 1/2 turns out is a good starting point for mixture screws.

 

Prior to EGA's the lean drop method was typically described for setting mixture if the original settings were out. You will need a good tachometer (not the one on your bike if you have added one) to see small changes in rpm. Some people also do this procedure "by ear".

 

I'm working from memory, but generally this is how its done. FIrst you start the bike and warm it up to operating temperature and set the idle speed to spec first. Then turn one mixture screw slowly in or out as necessary untill the maximum idle speed reading is obtained Changes (increases) of 100 to 200 rpm are not uncommon.

 

Once the maximum idle speed is obtained ( whatever that happens to be) on that cylinders adjustment turn the pilot screw in to drop the rpm by 50 (So if you started at 1000 rpm, turned the screw until you got to 1150, turn mixture screw in until it drops to 1100) Now reset to the spec idle speed with the idle speed screw and move on to the next cylinder and repeat.

 

After completing the above on all cylinders, re check the sync. You can use your sync stick while doing the above procedure as well since typically the max vacuum in a cylinder will also be when you are at max rpm. The sync stick readings should change while you are adjusting the mixture as that cylinder starts burning more (or less) efficiently. I would not resync between each mixture adjustment though, just use for a visual tool to see changes if by ear is not your thing.

 

If you have a good shop nearby with an EGA I would pay them shop time to do it with an EGA. If not the above will get it pretty close.

 

RSTDdog

Edited August 21, 2011 by RSTDdog

[Lil Venturous]

While I have not tryed it on the venture yet. (first gen) I used to set my needles with a vacuum gauge, you will see vacuum increase as you get closer to being right. But I have not tried on this bike yet so the pulse of the system might be to jumpy to notice any difference.

 

Now I do know they left the factory set at all kinds of turn out. This 86 of mine still had the factory block plugs in the carbs when I got it. One was completely screwed in tight and one was neary three out.