jammess
Well-known member
I searched but can't find out if this question has been asked already but can the "completely unauthorized throttle body sync" be performed using a two port Harmonizer?
unauthorized throttle body sync with Harmonizer
- Thread starter jammess
- Start date
Help Support Yamaha FJR Motorcycle Forum:
It could, but won't be as easy.
I have a TwinMax electronic vacuum differential meter that I bought when I owned a BMW oil-head, which I imagine is pretty similar to the Harmonizer. Here's how I would go about it:
1) Close down all 4 air screws fully to lightly seated. You will have to slightly hold the throttle open to get the engine to idle with the air bypass screws all the way in. Use a throttle lock or a ty-wrap around the throttle and brake lever to hold the throttle.
2) Hook the meter up to ports for #2 and #3 (caps on the unused ports) and balance those two with the linkage screw between them. Because you can only access the adjustment screw with the throttle held wide open, you'll have to make this iterative adjustment stopping the engine to adjust, and restarting the engine to check vacuum.
3) Move the meter hoses to ports #3 and #4 and balance them with the linkage screw while engine is running.
4) Move the meter hoses to ports #1 and #2 and balance them with the linkage screw while engine is running.
5) Open all 4 air screws the same amount and remove the throttle lock. 3/4 turn each is a good starting point. If the idle speed seems a bit too low open them all an additional 1/4 turn each.
6) Once you are happy with the idle speed, sync each of the other three cylinders to the #3 as a reference one at a time, moving the vacuum hoses, adjusting the air screws of that cylinder. .
I have a TwinMax electronic vacuum differential meter that I bought when I owned a BMW oil-head, which I imagine is pretty similar to the Harmonizer. Here's how I would go about it:
1) Close down all 4 air screws fully to lightly seated. You will have to slightly hold the throttle open to get the engine to idle with the air bypass screws all the way in. Use a throttle lock or a ty-wrap around the throttle and brake lever to hold the throttle.
2) Hook the meter up to ports for #2 and #3 (caps on the unused ports) and balance those two with the linkage screw between them. Because you can only access the adjustment screw with the throttle held wide open, you'll have to make this iterative adjustment stopping the engine to adjust, and restarting the engine to check vacuum.
3) Move the meter hoses to ports #3 and #4 and balance them with the linkage screw while engine is running.
4) Move the meter hoses to ports #1 and #2 and balance them with the linkage screw while engine is running.
5) Open all 4 air screws the same amount and remove the throttle lock. 3/4 turn each is a good starting point. If the idle speed seems a bit too low open them all an additional 1/4 turn each.
6) Once you are happy with the idle speed, sync each of the other three cylinders to the #3 as a reference one at a time, moving the vacuum hoses, adjusting the air screws of that cylinder. .
Last edited by a moderator:
jammess
Well-known member
Thanks Fred, that's pretty much the way I planned to do it. Then I decided to build my own 4 port ATF filled manometer which I'll finish today.
Not much fun riding around here lately as the rain and cold wind just never stops this year.
Not much fun riding around here lately as the rain and cold wind just never stops this year.
There is only an adjustable throttle stop for idle adjust on the 1st Gens (thru 2005). After that, all 2nd Gens idle adjust is an added air bypass manifold. Since I never had you touch the idle adjust knob, you can just leave it wherever it is. Or, you could find the center of its range and set it there, then adjust all 4 air screws the same amount open or closed until you get a reasonably close idle speed to 1100 rpm.
The 4 stop screws that you see on the individual throttle bodies should never be adjusted.
The 4 stop screws that you see on the individual throttle bodies should never be adjusted.
Last edited by a moderator:
jammess
Well-known member
Finally got around to the unauthorized TB sync using my two port harmonizer. First I noted that the air bypass adjustments were the same (out 3/4 turns from seated) on C1,3 and C4 with C-2 out 1/2 turn. After seating all 4 bypass screws I proceeded with throttle plate adjustments using a Go Cruise to lock the throttle at 1500 RPM up from 750 RPM with bypass passages closed. The first adjustment for C-2,3 balance showed a +6 millibar imbalance which a small CW turn on the adjuster corrected. The other two adjusters needed no adjustment since maximum imbalance was only 1 to 2 millibars.
I then adjusted all bypass screws to 3/4 turn out from seated and checked sync at idle. Sync at idle was only 1 to 2 millibars off with C-1,2,4 referenced to C-3. C-2 was perfect at 3/4 turn from seated where before it was a touch under 1/2 turn. Don't see how tweaking the C-2,3 adjuster could account for that.
I then went for a 35 mile test ride and about all I can say is the bike was smooth, very smooth. Was there a detectable improvement? Maybe yes maybe no maybe if there was it was all between my ears? I just can't say but I'm glad I satisfied my curiosity and the Harmonizer worked fine. Oh, oddly enough I averaged 49.3 MPG on this ride and I had about a 25-30 MPH headwind part way. I also rolled up the throttle to pass a couple cars topping out at around 90 MPH in the process. This is the highest MPG I have experienced with this bike but it was only 35 miles but still..... I shifted into 4th and set the tach at 4K RPM and felt maybe a slight buzz but can't say for sure as road caused vibration was slightly present.
Anyway, that's my story and I'm sticking to it.
I then adjusted all bypass screws to 3/4 turn out from seated and checked sync at idle. Sync at idle was only 1 to 2 millibars off with C-1,2,4 referenced to C-3. C-2 was perfect at 3/4 turn from seated where before it was a touch under 1/2 turn. Don't see how tweaking the C-2,3 adjuster could account for that.
I then went for a 35 mile test ride and about all I can say is the bike was smooth, very smooth. Was there a detectable improvement? Maybe yes maybe no maybe if there was it was all between my ears? I just can't say but I'm glad I satisfied my curiosity and the Harmonizer worked fine. Oh, oddly enough I averaged 49.3 MPG on this ride and I had about a 25-30 MPH headwind part way. I also rolled up the throttle to pass a couple cars topping out at around 90 MPH in the process. This is the highest MPG I have experienced with this bike but it was only 35 miles but still..... I shifted into 4th and set the tach at 4K RPM and felt maybe a slight buzz but can't say for sure as road caused vibration was slightly present.
Anyway, that's my story and I'm sticking to it.
