Need help idle issue.

[Gary Thompson]

2005 Suzuki Hayabusa all stock except for a full voodoo exhaust no cats or baffle. The problem im having is it idles with a miss and boggs down under acceleration in any gear, randomly backfires through exhaust only at idle. I have replaced and checked the following items. Any help would be greatly appreciated. Thank you
Spark plugs
Fuel injectors
Stator and crank sensor
Rectifier
Cam sensor
Fuel pump and filter
Set the tps sensor
Check ohms on all 4 coils

 

[Hayabusa Wannabe]

Welcome @Gary Thompson.

Just double checking that there is no add-on fuel computer, in the tail or under the seat, yes?

Air box and filter clean?

 

[Gary Thompson]

Welcome @Gary Thompson.

Just double checking that there is no add-on fuel computer, in the tail or under the seat, yes?

Air box and filter clean?

That's correct no add ons all stock. New Air filter also. I'm being told to do the marble trick on the crank case tube on the air box and see if that helps.

 

[Bumblebee]

How's the compression?

How many miles are on it?

 

[Gary Thompson]

How's the compression?

How many miles are on it?

Compression is 140psi on all cylinders at running temp that worried me till suzuki told me that was fine. Miles are right at 24,000

 

[Bumblebee]

Compression is 140psi on all cylinders at running temp that worried me till suzuki told me that was fine. Miles are right at 24,000

At least that rules out low compression and high miles...

It's a head scratcher, it seems you have covered most everything...I don't think the "marble mod" will do anything to clear up the idle or hesitation.

It might be worthwhile to check all electrical plugs-if any of them are corroded in any way, it might create an issue....

...and check the valve clearances as you might have one or more out of spec.

 

[Kiwi Rider]

Have you checked the air temp sensor, coolant temp sensor, and intake air pressure (MAP) sensor?
Have you checked the plug s condition/color? Rich or lean?
Have you checked the cam timing is correct?
OEM cam chain tensioner or aftermarket manual adjust tensioner?
Charging system voltage output within spec?
Any fault codes in the ECU?
Have you checked the live data in the ECU for correct functions?
Battery terminals clean and secure?
Just a few things to check on . . .

 

[Berlin Germany]

Compression is 140psi on all cylinders at running temp that worried me till suzuki told me that was fine. Miles are right at 24,000

140 ? really? then the engine is scrap

so ! do the test again with full open throttle

the manual say standard is 171 - 228 psi when "cold" !!!!!! (page 2-31)

and if not done yet download the manual here and READ!

eg

my 2nd (kept as a reserve) gen1 engine from ´04 has 14.1-14.5 bar / 204-210 psi at a milage of 55000 km / 34100 mi
all measured cold = at 20-22°C / 68-77 °F

 

[Hayabusa Wannabe]

Compression is 140psi on all cylinders at running temp that worried me till suzuki told me that was fine. Miles are right at 24,000

Please check your equipment and process, and possibly the techs here can comment on such. I am thinking of a member that used extension tubes that were not included with the tool. That increased the volume which caused the compression to be underreported.

 

[Gary Thompson]

140 ? really? then the engine is scrap

so ! do the test again with full open throttle

the manual say standard is 171 - 228 psi when "cold" !!!!!! (page 2-31)

and if not done yet download the manual here and READ!

eg

my 2nd (kept as a reserve) gen1 engine from ´04 has 14.1-14.5 bar / 204-210 psi at a milage of 55000 km / 34100 mi
all measured cold = at 20-22°C / 68-77 °F

Yes sir I will check again I do have the manual and that's why I questioned the pressure. The suzuki mechanic at Oklahoma city is the one that said if all four cylinders are reading 140psi and not 20pis or more off from each other that is what they see all the time at there shop. Bike starts and revs like it is new just a miss and exhaust pop at idle that's driving me crazy.

 

[Kiwi Rider]

Yes sir I will check again I do have the manual and that's why I questioned the pressure. The suzuki mechanic at Oklahoma city is the one that said if all four cylinders are reading 140psi and not 20pis or more off from each other that is what they see all the time at there shop. Bike starts and revs like it is new just a miss and exhaust pop at idle that's driving me crazy.

As Berlin said, my Gen 1 with 148000kms has compression of between 200 and 215 on all 4 cylinders. Runs perfectly, I reckon it’s gonna be a possible coil (over plug) issue, check voltage up to coils and check spark plugs for irregular Color.. maybe one is a bit sooty?