TB sync issue

[Gaz.sv650]

Hi all,
My k6 650 has been running a little bit rough recently, bit rich and bogs down low in the revs.
I've set the TPS and been trying to balance the TB's.
This is where the problems start, the rear TB is reading way high, maxing out the tool at idle and the front is reading what you would expect on idle.
They are definitely not that out of sync and I'm sure it's not the tool as it does it anyway the tool and hoses are set up on the suction ports.
What would cause it to read so high?
I have to turn the adjustment screw right out to get them reading similar but that is definitely not right as it runs like S***.
Any help would be massively appreciated, I'm able to service/maintain my bike but when it come to diagnosing something like this I'm stumped.
Cheers

[glang]

all I can come up with is that something is restricting the flow on the rear TB so that more vacuum is pulled at the test point. It would have to be something in the TB like the STV not opening properly or in airfilter/hose connection....

[Gaz.sv650]

I've set the STV and replaced the hoses for new as that was my first thought.
Would it be worth trying at sync tool the sit on top of the TB? That's my only other ideas to eliminate it being something within the port?

[Gaz.sv650]

Something like this? https://www.mecatechnic.com/en-GB/synchrometer-for-carburettor-throttle-body-balancing_VO09552.htm?utm_source=google_shopping&utm_medium=cpc&utm_campaign=acquisition-produit&utm_content=VO09552&gclid=Cj0KCQiA1sriBRD-ARIsABYdwwG84XG4_PS2iFUJ3ZfxmmiGSsYElPlZyAcM9auoMg z6Tm5iGcFOOBEaAhA3EALw_wcB

[Adam Ef]

Is it carbed or injection? Guessing injection as your avatar is a pointy. Are you using the tool that locks the injection?

[glang]

I think the K6 was before you need the injection lock as it still has the manually adjustable tick over....
Gaz that flow meter is a bit of an an unknown and anyway it wouldnt cure the problem. What did you do to the STV as I thought they should be left as set up in the factory....

[Gaz.sv650]

Is it carbed or injection? Guessing injection as your avatar is a pointy. Are you using the tool that locks the injection?


It's a 2006 with throttle bodies as mentioned above.
I have a Morgan carbtune this has worked perfectly fine before.
Not sure what an injection lock tool is? No mention of it on the sv650 service manual on throttle bodies sync process

[glang]

Just thought is the FI light showing along with any codes?

[Gaz.sv650]

I think the K6 was before you need the injection lock as it still has the manually adjustable tick over....
Gaz that flow meter is a bit of an an unknown and anyway it wouldnt cure the problem. What did you do to the STV as I thought they should be left as set up in the factory....

Just made sure the valves heights are the same.

[Gaz.sv650]

Just thought is the FI light showing along with any codes?

No nothing, nothing showing when in dealer mode either

[glang]

The later models had their tickover controlled by the FI so when doing adjustments with the engine running it will keep changing the tickover automatically and mask the real effects so this then has to be disabled during tuning.
As you havent got any codes it rather discounts any problem with the STV (I take it when you turn on the ignition they both go through their usual automatic full range movement check?) so that leaves an inspection inside the airbox and intakes...

[Gaz.sv650]

The later models had their tickover controlled by the FI so when doing adjustments with the engine running it will keep changing the tickover automatically and mask the real effects so this then has to be disabled during tuning.
As you havent got any codes it rather discounts any problem with the STV (I take it when you turn on the ignition they both go through their usual automatic full range movement check?) so that leaves an inspection inside the airbox and intakes...
Yes the STV go through the cycle. All of the balancing attempts have been done with the air box off But that is all okay

[Bibio]

being a k6 its a single plug head?

[Gaz.sv650]

being a k6 its a single plug head?

Yes single spark plug

[Bibio]

have you tried plugging the gauges into both vacuum spigots? e.g. take the back one off and put it on the front one and visa versa. to see if the read the same

are you sure your adjusting the correct screw?

have you checked that the link rods are not sticking?

[Adam Ef]

I thought with the injection models that any adjustment on the throttle bodies and the engine management tries to compensate, adjusting the auto idle. That throws everything out of whack as you adjust, so the idle needs to be locked? I've never done it as when I looked into checking mine I couldn't find anyone except Suzuki with the tool / gizmo for locking the idle. I worked out (was suggested) my problem was actually the TPS adjustment and once that was sorted I didn't look any further into it.

[glang]

yeh your right but only on the K7 onwards twin spark engines. The earlier injection engines have a manual tickover adjusting crosshead screw on the lefthand side of the engine which you just twiddle to get the revs you want. Its simpler but the downside is that you can stall the engine easier than the auto control type...

[Adam Ef]

Simpler and you save having to buy the tool... http://www.bikersdiscountstore.co.uk/workshop-servicing-equipment/healtech-electronics/healtech-electronics-kawasaki-suzuki-honda-obd-f-i-diagnostic-tools-pd-51.php

[Gaz.sv650]

have you tried plugging the gauges into both vacuum spigots? e.g. take the back one off and put it on the front one and visa versa. to see if the read the same

are you sure your adjusting the correct screw?

have you checked that the link rods are not sticking?

Yes swapped the hoses and gauges Evey possible way and it always shows the same result.
Yes definitely the correct screw.
I will check the link rods but I'm fairly sure they are fine.

The bike is not running as rough as the gauge would suggest, my only other thoughts is to try a different set of gauges but I'm confident that isn't the problem.

[glang]

yes Ive had to tweak my tickover occasionally as I like to keep it at 1300rpm

[glang]

Gaz is it possible that the high reading is the correct one and the other the problem? If this was the case then low vacuum could be due to air leaks, poor engine valve adjustment, worn engine etc

[Gaz.sv650]

Gaz is it possible that the high reading is the correct one and the other the problem? If this was the case then low vacuum could be due to air leaks, poor engine valve adjustment, worn engine etc


I'm not sure, the high reading is off the scale so that is never right at 1200rpm never used to be like that anyway.
The valves are due a check now on 30k they were well within spec at 20k.

Air leak would cause high revs?
The engine is using very little oil so hoping it's not worn.

[Bibio]

check the rear TB is in and on its inlet rubber properly and the clip is tightened up.

IIR there are two vacuum spigots on one of the TB's and i think its the rear or maybe not. make sure that the cap is not perished.

[Gaz.sv650]

check the rear TB is in and on its inlet rubber properly and the clip is tightened up.

IIR there are two vacuum spigots on one of the TB's and i think its the rear or maybe not. make sure that the cap is not perished.
Will try that a report back on the weekend.
Cheers for the help so far

[glang]

difficult to see what can give a high vacuum. I would have thought any air leak would reduce the vacuum and the only possible explanation is a restriction somewhere on the inlet side of the tapping point. For me an STV thats too closed would fit the bill perfectly....