throttle body sync- high speed adjustment rpm?

I've read in several places differing thoughts on what is the proper RPM to use for high speed TB sync adjustment. 1500 rpm's, 2500 rpm's, and 4000 rpm's are the numbers I've been seeing. I'm looking to sync TB's on my 2000 R1100RT.

Too bad I can't be at the rally (stinking work commitments!) to ask Mr. Glaves, Mr. Smith, or others at the oilhead tech sessions directly.

Guidance please!

Personally, I sync mine to smooth out the engine as much as possible, and I want it to be smooth at highway speed. So, 4500 rpm for me.

My suggestion is to go for a ride and figure out what speed you want it to run the smoothest at and sync it at that rpm. Being carefull to keep air flowing over the cylinders so you don't overheat it of course....

What he said!!
The trend is to set the high speed adjustment at about 4K RPM as that tends to be the range for most legal speeds.
Good luck with the adjustments!

4000 it is. Thanks for the replies.

If you have a TwinMAx...

I'd suggest that you do your final sync while riding...

at low throttle opening....

it's the first off-stop adjustment that determines the right adjustment of the TB's

wide-open throttle adjustment is not an issue since minor balance issues do not matter....

I do mind in second gear at 3-4,000 rkpm....

this adjustment makes a big difference....from those done at stand still where even a small crack of the throttle produces a high rpm response...

JimBud said:

I'd suggest that you do your final sync while riding...

at low throttle opening....

it's the first off-stop adjustment that determines the right adjustment of the TB's

wide-open throttle adjustment is not an issue since minor balance issues do not matter....

I do mind in second gear at 3-4,000 rkpm....

this adjustment makes a big difference....from those done at stand still where even a small crack of the throttle produces a high rpm response...

Click to expand...

+1. Taping the TwinMax to the tank makes fine tuning under load easy....

I do mine at 1800-2000 rpm. That was recommended by Paul Glaves a few years ago in the Owner's News.

While riding? I think I'd like a picture of that operation!

It's a lot easier than you think...

tomrogers said:

While riding? I think I'd like a picture of that operation!

Click to expand...

adjust, ride, observe, stop, adjust...and repeat as needed....

the difference is worth the few minutes it takes....

If you are trying to exactly equalize throttle plate angles, any difference will show up asa vacuum change when the throttle plates are as closed as they can be while still pulled by the cable. In other words just off idle. The percentage difference in the throttle plate angle will be the greatest and the percentage difference in the vacuum will also be the greatest. For smoothness a little higher will work.

If then, when you increase the RPM to 3,000 or 4,000 and see the balance change you have something other than throttle plate angle causing the differences. Such things can be deposits in the intake tract or on the valves, compression differences (ie leaky rings), etc.

You may make it "smoother" by unbalancing the throttle plate angles to accomodate for these other mechanical differences but you have not synchronized the throttle bodies really.

And, it may change on you suddenly as those deposits on the valve heads or stems wear off or burn off.

Boy, Oh, Boy......I love my new cables...

I just put new throttle cables on my '01 1150Gs....and it's like a new bike....after 40,000 miles...

If your bike is more than three years old, you should do this....

TB sync

" (Quote) You may make it "smoother" by unbalancing the throttle plate angles to accomodate for these other mechanical differences but you have not synchronized the throttle bodies really.

As Mr Glaves said other frorces may influence your adjustment, I had a bad Primary Coil that caused me to adjust the TB's numerous times. Under warranty the dealer replaced the coil and Readjusted the TB's, she now runs like a cat (not the diesel) ahhh like a Beemer should. (10k and still in sync)
I adjust for low speed with two fans running on high in front of the jugs for cooling, and usually the top-side (sync) is correct, <ususlly>.

If it does not stay in sync for long, look at other items in the food chain.

later