Airscrew Adjustment to fix off-idle stumble and Throttle Body Sync - w/ pigtails

[Yamaguy55]

Mercury is a very poor choice of liquid for three reasons:

At 13+ times the density of water, and even more times the density of oil or ATF it has 13 or more times less sensitivity. for instance if you can reliably discern a 5 mm difference in fliud levels in your manometer that 5 mm will correspond to more than ten times the difference in pressure with mercury than it will with water or a less dense fluid. Another way of putting it: The height difference in your column will be greater the less dense your liquid is. The height difference (sensitivity) is proportional to the density of the liquid.

Mercury destroys aluminum, even very small amounts of mercury can damage aluminum.

Mercury is toxic, both to the touch and the vapor from open mercury. If it get's loose, you will never get it all collected again, and will be getting exposed to small amounts. It is not advisable to use something toxic when a non-toxic or low-toxic alternative is available.

No doubt this is true, which is one of the reasons I'm hiding from Greenpeace right now. However, I have owned this for quite a while ( since the mid 80s), and I'm very familiar with it. When it finally stops working, I'll replace it. I take great care to be sure the Hg doesn't get near the tops of the tubes, let alone the actual hoses to the engine.

I am very aware of the hazards of Hg. Most of the toxic nature is when it is in a vapor form. Which is why I question the alleged environmentalists that claim the CFL to be a reasonable replacement for incandescent lights. LEDs yes, CFLs, no. But this isn't that forum.

Just like everything else, it needs care in handling and use. I'm not interested in an electronic device to take its place. I work with electronics and test equipment every day, all day. I've done so since the 70s. I have not found that everything electronic is automatically better than some of the older mechanical and analog devices. If I find that I will never need to sync more than a twin, I'll buy the factory analog gauge tool.

I agree with all of your statements about mercury. But right now, it works and is good enough.

 

[Koinz]

Last week we did the airscrew adjustment and the engine seemed to run well except... when normally accelerating in 1st gear @ approx 3,000 RPMs the engine RPM would increase quickly. I have not ridden it for three days and needed to ride. Tonight 6pm the engine seemed to run well and smooth except for the 1st gear acceleration increase. I rode into cool darkness and hills. The engine started to stumble like it was running lean or rich. Then I thought affected by long downhills. Stopped for a burger at In & Out Burger. When leaving I realized the engine was running poorly overall. Final 20 miles were on the freeway at a constant 3500 RPMs and the engine ran inconsistantly. Filled up at 141 miles and averaged 43.85 MPG which is less than the usual 48 MPG. When I get a chance I will check for vacuum leaks and the balance of the throttle bodies. I have not set the CO levels to +6 though have plans to do this.

Suggestions! Advice! Appreciated!

This happened to me. Not from the adjustment but from the additional vacuum tubes. I even got an engine light on deceleration and hesitation on acceleration. I removed the addition plumbing and it ran perfectly. I don't know if the sensor that is T'd off is sensitive to changes in vacuum, but if it ain't broke, I'm keeping my paws off of it.

 

[tomatocity]

This happened to me. Not from the adjustment but from the additional vacuum tubes. I even got an engine light on deceleration and hesitation on acceleration. I removed the addition plumbing and it ran perfectly. I don't know if the sensor that is T'd off is sensitive to changes in vacuum, but if it ain't broke, I'm keeping my paws off of it.

Thanks Koinz. I will try removing the pigtails before anything else. I am also getting a Engine Trouble Warning Light on deceleration and when I turn the key on. There has to be a vacuum leak somewhere.

 

[colorider]

Thanks Koinz. I will try removing the pigtails before anything else. I am also getting a Engine Trouble Warning Light on deceleration and when I turn the key on. There has to be a vacuum leak somewhere.

Did each of you use the spring clamps on the extra plumbing that Devin suggested? Possible cause?

 

[Koinz]

I couldn't find any that small. I did try to clamp off with a plastic tie strap, but apparently didn't work. I was able to remove the plumbing with my 10 inch needle nose pliers and the tank installed. It was like surgery.

 

[tomatocity]

Did each of you use the spring clamps on the extra plumbing that Devin suggested? Possible cause?

I did not. The hardware store did not have any and the vacuum lines seemed to fit tightly. Guess not. Need to find some of the clamps but I need to ride out of town on Wednesday and don't want to have any problems.

 

[colorider]

I couldn't find any that small. I did try to clamp off with a plastic tie strap, but apparently didn't work. I was able to remove the plumbing with my 10 inch needle nose pliers and the tank installed. It was like surgery.

I found some at Lowes that seemed to work. Had a real hard time getting in there to "spring" them. I'll try a ride today to see if I get any errors or similar.

 

[SpeedStar]

As I mentioned, I had the check engine light too on decel and found it to be a vacuum leak. It was fine after the spring clamps. Although, I just pull mine off with needle-nose pliers and put them back the same way if I need to make an adjustment with the tank on.

 

[jajpko]

I bought some 7/64" vacuum tubing at Auto Zone with 1/8" connectors. I think this will work better. Have not tried it yet.
Also they had some 1/8 band spring clamps in an assortment. Kinda pricey, so will look at the dealer today.

 

[SpeedStar]

Jim, I think you might be right. 5/32 was all I could find, but if you look at the ID of the stock left side tube, it is smaller than the 5/32 tubing. Let us know how the 7/64 tubing works out.

 

[jajpko]

Jim, I think you might be right. 5/32 was all I could find, but if you look at the ID of the stock left side tube, it is smaller than the 5/32 tubing. Let us know how the 7/64 tubing works out.

Devin, you may have to ask for it. I asked for 1/8 and the answer was no. So, I asked for something smaller and low and behold, 7/64. ::025::

 

[colorider]

Devin, you may have to ask for it. I asked for 1/8 and the answer was no. So, I asked for something smaller and low and behold, 7/64. ::025::

Ha! Same question I asked at AutoZone - but I failed to ask for anything smaller!!
::026::

 

[3putt]

I found the 5/32" at Pepboys, it was in the windshield wiper (vacuum) area and 6' length in a plastic box about 6" square.

I got to ride the bike this morning first time since I did the mods. Got CEL on acceleration above 4k rpm but would go off when cruising or never come on till you pushed it. So, I stopped and changed my CO settings to +3 (backed up 3), no more CEL after that under any conditions. 62F this morning, the bike runs VERY strong in Sport, jeeze! ;D

 

[Yamaguy55]

Devin, you may have to ask for it. I asked for 1/8 and the answer was no. So, I asked for something smaller and low and behold, 7/64. ::025::

That's the stuff I have. It is slightly less than 1/8 inch. A tight fit is always good on vacuum lines. I think it works out to 2.7 or 2.8mm size.

 

[slipangle]

I'm curious as to what is happening with the left side throttle body. Does anyone know the purpose of the sensor that the vacuum line ties into?

It concerns me because I don't have a factory manual yet, and ended up winging the throttle body synchronization today with my newly acquired Harmonizer. I didn't make the pigtails like SpeedStar did, so I ended up just pulling the vacuum line off of the mystery sensor in order to connect the harmonizer to the left side throttle body, leaving the sensor disconnected from the engine's vacuum. Would leaving the sensor out of the loop negatively affect the adjustments that I made?

Everything seemed okay during my test ride afterwards. Before synchronizing, I adjusted the CO setting by +6 via the diagnostic mode, and then made the 270 degree adjustment to both of the air screws. I was suprised by how much I had to tweak the left side throttle body in order to sync it with the painted right side. While the Harmonizer only showed it as being 6 millibars out of adjustment, both before and after the 270 degree adjstment, I ended up having to close the unpainted screw about 180 degrees in order to get it to zero, making me suspicious that my leaving the mystery sensor out of the vacuum system has thrown off the adjustment.

I apologize in advance if quoting myself is against the CoC, but I ended up answering my own question, and wanted to throw it out there in case anyone else runs into it.

The mystery sensor turned out to be an "intake air pressure sensor". I acquired a service manual, and therein observed that Yamaha felt it was important enough to include the sensor in the throttle body synchronization that they had assembled a special tool that essentially duplicated SpeedStar's pigtail setup. So, feeling silly for not having done it the first time around, I set off to the local auto parts store and assembled one of my own.

After hooking it all up, the Harmonizer showed that leaving the sensor out yesterday only threw the synchronization out of adjustment by 3 millibar.

In sum, unless you're going to leave it hooked up for easier adjustments later, I wouldn't bother with including the sensor.

 

[Scoop47501]

I have been reading this thread with interest.
As I posted in my introduction I bought a demo with 2000 miles on it a week ago. Well I get an E-Mail from the owner of the dealership asking me to bring in the bike for "adjustments". I'm thinking "what the" ? Anyway , so I take it in yesterday and he orders this adjustment and TBS right away while I chat with the owner in his office. Tech is done in short order and there was no charge. He told the tech to write it up as owner complaint of stumble off idle . I don't know if there is a tech bulliton on this but the way I got it mother Yamaha will pick up the tab on this. I do know it cost me nothing as it should not with the bike new and all.
My point is if you don't like to mess with your own bike and have a reliable dealer they should take of this for you free of charge.
Hope this helps
Scooper

 

[Kevhunts]

To those who have already mastered the CO & SYNC proceedures, where are the home made training videos? ::017::

 

[3putt]

I did this mod last week, and just returned from trip Eureka Springs, Ar (about 985 miles for me). Did a lot of twisties and found that I had CEL on engine braking plus stumble on acceleration right after. I suspected the "T" fitting or pigtail on left cylinder to be leaking. I did not put any wire/spring or anything on the pigtail to "T" when I did the mod.

I pulled the pigtail but left the "T" and put a rubber cap on it with ziptie real tight. Fixed, no more problems. I also changed my CO settings to +6 again. So, beware that the sensor on the left cylinder vacuum line is very sensitive to any vacuum leaks.

 

[Koinz]

::015::

I did this mod last week, and just returned from trip Eureka Springs, Ar (about 985 miles for me). Did a lot of twisties and found that I had CEL on engine braking plus stumble on acceleration right after. I suspected the "T" fitting or pigtail on left cylinder to be leaking. I did not put any wire/spring or anything on the pigtail to "T" when I did the mod.

I pulled the pigtail but left the "T" and put a rubber cap on it with ziptie real tight. Fixed, no more problems. I also changed my CO settings to +6 again. So, beware that the sensor on the left cylinder vacuum line is very sensitive to any vacuum leaks.

Tiger, thanks for checking this again. I might also suggest that the air sensor may also be affected by the length of the pigtail. In another life I worked as a tune-up and emissions specialist at a Ford dealer. Some sensors are very sensitive to vacuum signals and the extended length and vacuum pulses through the tube could be the cause. I haven't had a chance to try the smaller tubes, but I just wanted to offer an alternate cause. Ford was very specific regarding the length and routing of vacuum lines.

 

[~TABASCO~]

::015::
Tiger, thanks for checking this again. I might also suggest that the air sensor may also be affected by the length of the pigtail. In another life I worked as a tune-up and emissions specialist at a Ford dealer. Some sensors are very sensitive to vacuum signals and the extended length and vacuum pulses through the tube could be the cause. I haven't had a chance to try the smaller tubes, but I just wanted to offer an alternate cause. Ford was very specific regarding the length and routing of vacuum lines.

True, Ive encountered this in the past aswell... I did the sync and put it back the way it came.. The adjustment is not something that needs to be done that often...