Throttle Body Sync - Jumping vacuum gauges?

[petaminox]

So... I messed up trying to get by throttle body synced by adjusting screw #1. Thus, I went to get a vacuum gauge hoping to fix it. However, when I try to get a reading, the needle on the gauge swings wildly. This is even with FOUR Dorman restrictors attached.

So it swings from ~5 in Hg to ~15 in Hg.

I read in another thread that pinching the hose or kinking it will steady the needle. However, doing so would prevent any meaningful reading to be taken, as the needle still jumps. If it does not jump, it is because the kink is holding the needle at a particular reading.

Thoughts?

 

[TownsendsFJR1300]

So... I messed up trying to get by throttle body synced by adjusting screw #1. Thus, I went to get a vacuum gauge hoping to fix it. However, when I try to get a reading, the needle on the gauge swings wildly. This is even with FOUR Dorman restrictors attached.

So it swings from ~5 in Hg to ~15 in Hg.

I read in another thread that pinching the hose or kinking it will steady the needle. However, doing so would prevent any meaningful reading to be taken, as the needle still jumps. If it does not jump, it is because the kink is holding the needle at a particular reading.

Thoughts?

With my Carbtune, (4 cylinder sync tool), the hoses are approx 3' long and the restrictor is approx 4" from the TB's when set up. I don't know what size your restrictors are but the Carbtune' are very, very small.

If your using ONE single vacuum gauge and trying to sync it moving the single gauge back and forth, your about wasting your time as adjusting one will change another. When adjusting, make sure your idle is about 1,300 RPM's.

If you don't have a bike specfic sync tool, IMHO, you need to purchase one or make one. ( www.carbtune.com )

My Carbtune paid for itself many times over doing customers bikes, there's no fluid to lose or suck into the engine and very, very easy to use. Should be under $100 (Yamaha gets more that $125 for a single sync ((and mis-adjusted mine on my old FJR-turned a butterfly screw, NOT the air screw))

I, at one point messed with my #1 screw (by accident) and ended up with a final setting of about 3/4 out. I've since read it should be out 1-1.5 turns out but it runs fine, so I haven't messed further with it.

I'd start with #1 at 3/4 to 1 full turn out WITH a four gauge sync tool and start syncing the rest from there. Yamaha gives you 10mm's variance, I was able to get mine within 2-3mm's. Also, recheck and adjust at 4K RPM's as it will help smooth out vibes. You'll find you can get it real close at 4K and at idle.

If its still bouncing around, how many miles on the bike, is it due for a valve check and do all the cylinders bounce or just one?

 

[FinalImpact]

To Scott's point, adding volume after the restricter will smooth out the needle. The meter only needs to see a signal not a large volume. So an orifice of 0.020" is likely too big.

At work we use syringes for mixing epoxy and they are thrown away often. They make great adjustable reservoirs for tasks like this. It adds volume and will stabilize a jumping needle...

 

[FinalImpact]

Something else that comes to mind; A vacuum leak under the TB!

I don't recall the size but its either 3 or 4 mm. I'd suggest you remove the air box and snug up the bolts holding the TB to the intake. I've found two of our FZ's to have these loose.

The bolt has a positive stop so once tight, it should stay. It doesn't need much torque so reach in and snug it down.

 

[DavesFZ]

Pm sent Scott.

 

[TownsendsFJR1300]

Pm sent Scott.

PM sent back, go for it!

 

[FinalImpact]

^^
^^

Looks like the "PM cycle" is complete! Pun intended! :spank:

 

[TownsendsFJR1300]

^^
^^

Looks like the "PM cycle" is complete! Pun intended! :spank:

PM sent.:BLAA:

 

[FinalImpact]

PM sent.:BLAA:

LIES!!!!! ALL LIIIIIIIEEEEZZZZZZZZZZZZZZZZ!!!! I see nothing!

 

[TownsendsFJR1300]

LIES!!!!! ALL LIIIIIIIEEEEZZZZZZZZZZZZZZZZ!!!! I see nothing!

You sound like Sgt Shultz on "Hogans Hero's"!

:shakehead:

 

[erar]

Use aquarium air pump valves and one vacuum manometer for each cylinder at the same time.