Throttle body sync--feeling guilty, should I?

[Dr. Strangelove]

I am sprucing up Stella! for our prime riding season down south. Checked valves and they were fine, diagnosed a faltering stick coil on the right--had a spare, and after a ride today set up a TB sync.
I decided what harm would there be in just checking the sync prior to turning both BBSs.

Hooked her up and the sync wasn't so bad. Turned the screw on the right and balanced my columns (about a quarter turn open ) and balance was pretty darn close. Checked at 1500. 2000. 3000 and still close, very close. I left it there.

I am using the homemade manometer with ATF fluid, so I am thinking that because it is lighter than oil and certainly Hg, pretty darn close, maybe an inch or closer, is a pretty sensitive reading and the enemy of good is better.

I left it at that.

Anybody else do that? Just hook up your manometer to see how close your adjustment is before you go through all the rigamarolle of a TB sync? I have never seen in any of the descriptions of TB sync to check it first, you may be just fine.

John

[MIXR]

A very valid check taught to me long ago in my aviation days. You should never just jump in and start adjusting until you have checked the current state of play. It will serve two purposes. One (as you discovered) is that you may need to adjust nothing. The second is that it confirms you are set up to adjust the right things.

Now that I do my own valves, I always check current clearance to see what might have moved. Last time, it was nothing! It also confirms that I've set the intake or exhaust at the right place if I'm not using the timing marks (plenty of overlap) as the feeler will be pretty close even if it has opened or closed the gap a little. It just gives you added confidence that you are set up right and adjusting the right thing to the right clearance.

I reckon you are spot on John and agree wholeheartedly with the approach.

[garr2]

There's always a slight risk when doing a TB synch that you will damage the soft metal threads on the adjuster on the RHS throttle body. If you check the synch prior to doing an adjustment and find as you have that they don't need adjusting, you can avoid that slight risk of damaging the adjustment mechanism

[CycleRob]

I do not remember anyone instructing us to loosen up things before checking the adjustments. Mechanics never do that. That would be wasteful and too often unnecessary when the correct measurement is present. Doing a mileage due valve adjustment or TB Synch is scheduled to keep the engine in a desirable near perfect tune for smoothness, quietness, efficiency and to prevent damage such as burnt valves caused by (long neglected) insufficient valve clearances. Sure, you can check the TB and ignore an "adjustment needed" reading or valves that are too tight or too loose -but- if you've gone as far as either taking the valve cover off -or- hooking up a Manometer -and- you are doing and can do the work . . . . Why Not do it?
BTW, throttle cables do not "stretch". The inside curve of the curved route cable's housing minutely wears out, effectively making the cable's length appear longer.

"I am using the homemade manometer with ATF fluid . . ."
No good. BTDT. The oil is so viscous it responds much too slowly to be considered an accurate indicator as it approaches "zero". You have to wait too long while the engine runs if you are not using a big fan or 2. Advise that you drain the oil out, solvent rinse it clean, then replace it with premixed, dyed water and ~10% of volume being Isopropyl (70%) alcohol (to prevent bacteria growth). You'll be amazed at the faster reading, immediate stabilization and better accuracy with water. My Manometer's hose ends are plugged during non use to prevent evaporation but it still needs a purge-n-replace every 5--6 years or so.

Thumbnails below take you to the pics of my 48" version with green tinted water. If anyone is making one from scratch, make the board 6 feet (72") long and use 20 feet of tubing, so the larger synch errors have less chance of sucking out the water. Click Thumbnail. Click big pic for full size if available:


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Now, something new for when the synch is either known to be "Off" by the uneven sputtering/burbling sounds or because the cables and/or the BigBrassAirScrews were removed. A very low cost home made device that indicates and deals with a LARGE Synch error without getting the tinted liquid suctioned into the intake port by those errors. Just fill one bottle to 80% full using suction on 1 hose with the other dunked in your 3rd bottle that is near full. Because the Bubbling H20/Isopropyl will evaporate out of solution during extended use, you can use the same technique to add new Alcohol to the full bottle using the empty bottles hose. These pics show the basic construction of the necessary parts using similar screw top Wine Bottles as taller is better than wider. They do not have to exactly match as you're just concerned with similar height and volume, not the exact size/volume. This is so much fun to watch and SO easy to use when you are stuck with a really screwed-up TB Synch:


EDIT: To change photo host from PhotoBucket to the faster, less intrusive Postimage.org -and- add LargeSynchErrorTool pic.

[Dr. Strangelove]

Thanks to all.

It seems to respond pretty fast though, Rob. The alcohol will evaporate, but the lighter weight will respond much more sensitively for sure. Next time, next sync, I'll try it.


John

[iowabeakster]

You should absolutely not feel guilty. I also believe that non-adjustment is ideal. Not out of laziness, but because that means the bike was tuned accurately the last time. Once those cables are done stretching (early in the bike's lifetime), adjustments should be getting smaller and smaller... appraoching the point of just wasting time.

As was said above, I also have "adjusted" my valves without doing anything other that sticking the feeler gauges in the gaps.

Done and done.

[Sunbeemer]

That procedure makes perfect sense to me...common sense.
If it's right, it's right. I don't fix it if it ain't broke!

...you can avoid that slight risk of damaging the adjustment mechanism

First, do no harm!

[Dr. Strangelove]

agree fully with recs.

It always is a sphincter tightening experience tightening that cable bolt. If I can avoid that then fine.

yes, Rich, primum non nocere, and a corollary to that: Always go with the most conservative member of the team.