Guage recommendation

Bottom line up front.

I need to purchase a gauge that would allow me to set number 1 cylinder to the correct vacuum. I have a couple multi-cylinder bikes and to a good job on synch'ng, but I don't have anything to set to a specific reading. Any recommendations on the best one to purchase.

Lessons learned:

1. Don't let anyone else work on your bike.

2. Especially if it's a dealer that doesn't have an FJR in inventory or in the parking lot.

Could an incorrectly adjusted #1 cylinder lead to any issues with the TPS. It's a Gen 1 but I bought it used several years ago, I've read the thread on that, but as I said I bought it used a couple states away and have no idea of it's status as far as the recall. It has just been replaced.

Recommendations appreciated. Feel free to chuckle at my expense, grrrrr

Morgan Carbtune. Love mine!

The Morgan Carbtune is a better tool than most these days.

The FJR uses the #3 cylinder as the reference cylinder.

If you live above sea level in altitude or if the day does not have a barometric pressure of 14.7 psi at 72°F you will never set the throttle bodies to the FSM specification. So just forget about the absolute reading and make all four equal.

You do want the idle speed to be 1.1k rpm and you want to keep it there as you adjust the TBs, the idle speed will want to change. Failure to keep the idle speed around 1.1k rpm as you adjust the TBs often causes the idle speed adjustment knob to bottom out or top out and not be able to get the idle speed where it should be later.

You should read Fred W's procedure for the RDCUA TBS which adjusts the throttle plates as well as the air bleed.

The FJR uses the #3 cylinder as the reference cylinder. On the Gen1 and 2, then #1 TB (or where the painter dot is) on the newer servo throttle bodies.

You can't set the cylinder for a particular vacuum level. It will be whatever it is when the engine is at idle speed and the 4 cylinders are balanced. If you close down an air screw to increase vacuum in that channel, you will reduce the idle speed and just end up adding air by increasing the idle adjuster. Same is true for 2nd Gens with their idle speed bypass mechanism.

The only thing that is important is that the 4 cylinders have balanced vacuum, and that the idle speed is between 1000-1100 rpm, ideally closer, (or exactly at) 1100. If you want the best possible smooth running engine, read through the procedure I came up with and ionbeam posted the link to.

On 3rd Gens the "reference" with the paint dot is the only one that is fully closed. They simply chose the cylinder with the lowest vacuum and then opened the other three a little to match. That way you have the least possible air going through the air screw circuits, and the most possible air going through the Idle Air Control solenoid operated valve.

Quote: "Could an incorrectly adjusted #1 cylinder lead to any issues with the TPS."

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An out of balance sync wouldn't affect the TPS.

Plus 1 on the Carbtune as well.


Just a side note, per your first post. Prior to me obtaining the Carbtune back in 05 or so,
I paid a Yamaha dealership for a sync when I had issues (with the main electrical connector
corrosion under the tank-common issue with the Gen 1).

They adjusted the BUTTERFLY SCREW (with the white paint on it)which is NOT TO BE TOUCHED

(under normal syncing procedures).

I could see the paint broke and the screw was adjusted about 1/4 turn.
Apparently, it was easier to get to that screw than the correct one.. Put that screw back
and re-sync'ed. Checked again at 4K and re-adjusted just slightly (helps with lower RPM vib's).

That was pay someone (a YAMAHA TECH), $125 to screw up a sync...Never again.

Thanks for all your info. I'll read later today. I clearly recall a factory spec for the reference cylinder and noticed quite a difference in throttle response, to the worse, with all cylinders being equalled out after the reference cylinder wax changed. I'll let you know how and when this ends up to my satisfaction.

I use P/N 38545K16, vacuum only. Along the lines of stated opinions, I have never been able to set vacuum level exactly to the FSM-specified "33.3 kPa (9.8 inHg) (250 mmHg)". But I feel better knowing that the value to which all other cylinders are adjusted to is at least close to the FSM rather than balancing all to some arbitrary number. It's just the way my brain works. YMMV.

rbentnail said:

I use P/N 38545K16, vacuum only. Along the lines of stated opinions, I have never been able to set vacuum level exactly to the FSM-specified "33.3 kPa (9.8 inHg) (250 mmHg)". But I feel better knowing that the value to which all other cylinders are adjusted to is at least close to the FSM rather than balancing all to some arbitrary number. It's just the way my brain works. YMMV.

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+ 1 ^^^^. I tried setting the initial vacuum # and it ain't gonna happen! And I am at sea level...

Simply sync them to each other, the closer the better. I re-check at 4K and adjust accordingly.

I keep reading that everyone has a morgan carbtune. I must be the only guy on this forum to have made one. Cheap and easy to make, just like me, lol.

Finally picked up a gauge. Found a website to compensate for temp and ASL. This remains a work in progress.

Quote: "Could an incorrectly adjusted #1 cylinder lead to any issues with the TPS."

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An out of balance sync wouldn't affect the TPS.

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Well, that's not entirely true But, essentially true. True for 2001 to 2012 FJRs: As you adjust the synch your idle speed will change so you twiddle the idle adjust screw which moves the idle stop, which moves the throttle plate rod that links all the throttle plates together. The TPS is connected to this rod and moving the rod will change the idle and WOT voltage going to the ECU, not much, but it will be changed. When you go to diAG and read the TPS, the range specification is:

Throttle fully closed 15 - 17

Throttle fully open 97 - 100

This is the ECU saying that at idle the throttle plates are 15% to 17% open to allow idle air flow and at WOT the throttle plates are 97% to 100% open. I have seen TPS reading as low as 11% and as high as 104% and it doesn't really matter. For the anal and compulsive that can't sleep at night over BIG issues like this the TPS is adjustable.

I must be the only guy on this forum to have made one

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Take a look at tech day pictures, you will see home made manometers are not uncommon.

Found a website to compensate for temp and ASL

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Don't get to carried away with this. Absolute readings aren't important, just make sure the readings are fairly close to equal. Do consider the 'The Really Definitely Completely UnAuthorized TBS' procedure.

As you adjust the synch your idle speed will change so you twiddle the idle adjust screw which moves the idle stop,

Click to expand...

Only true for 1st and 3rd Gens.

2nd Gen idle adjust is a little air bypass manifold gizmo, so the the throttle plates do not change their position, nor does the TPS, when you adjust the idle.

On 1st Gens the idle adjust is the 3rd cylinder throttle stop and the other 3 are ganged off that one.

On 3rd Gens the ECU will automatically open the servo operated throttle plates the amount it needs to maintain idle speed. So if you open up the air screws too much the ECU will attempt to close the throttle (more than it should) and will affect the TPS at idle.

I apologize for not returning sooner. Thank you all for your help. I just balanced them without worrying about an absolute index reading and things got a lot better. The idle still hunts some. I see there were some posts that I didn't read and I'll take them into consideration. Thanks again.