R3 classic running like a twin. Backfiring and stumbling

[atomsplitter]

I know you said you get spark, but it occurs to me it may not be a strong enough spark. To test this, switch coils front to back and see if the back cylinder begins misfiring. If so it's your coil. It will also give you a chance to verify low voltage leads are tight.

 

[busy_rydin]

What numbers per cylinder you getting on the TuneECU throttle balance screen?

1. 720 hPa
2. 880 hPa
3. 720 hPa

 

[busy_rydin]

I know you said you get spark, but it occurs to me it may not be a strong enough spark. To test this, switch coils front to back and see if the back cylinder begins misfiring. If so it's your coil. It will also give you a chance to verify low voltage leads are tight.

Yes, I’ve swapped coil positions and it runs the same. Also crimped the leads so that they fit tighter to the coils. Still the first cylinder stays cold. I’ll try to upload a vid of how it sounds.

 

[busy_rydin]

Have you checked fuel pump pressure?
Might need a new fuel filter...

That would have been my next stop but usually the pressure would affect all 3 cylinders. Not just 1. I’m not seeing a constant starving of fuel. But I may just check anyway as I’ve tried almost everything else.

 

[busy_rydin]

I removed the power commander just to take one more element out of the equation. No change in behavior. Here is a video of a cold start this morning.
Cold Start Video

 

[R-III-R Turbo]

1. 720 hPa
2. 880 hPa
3. 720 hPa

Looks like you got a vacuum leak on #2, and that's why it running so bad.

880hPa is normally seen when at like 50% throttle, so when the ECU sees this is dumps in a lot of fuel, to try maintain correct AFR. Trouble is, the actual amount of air going in is still a trickle as the butterfly is closed and engine idling. So it runs super rich on that cylinder and bogs and stalls and won't fire on that cyl etc.

Recommend checking the vac lines again, they need to be good and tight, seated well at the ends, no cracks or perishing etc. And don't forget each throttle body has a 2nd vacuum nipple, these are blacnked with little rubber caps on most bikes but on California models have a tube going to the evaporated loss recovery canister.
The 3rd body has 3 nipples total but that cylinder isn't the problem here apparently.

I'm assuming the vac tubes are factory ones. If anyone ever replaces them they need to be the same length as the factory ones 255mm iirc.

720 on the other 2 isn't bad but they should probably be 6xx not 7xx level. They might come in when you fix the leak on 2s tube.

They 3 values need to be practically the same to be balanced but that can be checked after the leak is fixed.

 

[busy_rydin]

You got a vacuum leak on #2, that's why it running so bad.

All of my hoses are good. How would I go about finding a fantom leak? It would be great if it’s something simple like that but my gut says it’s reading that way because a cylinder is not firing. I’m no expert tho so I’m open to all suggestions.

 

[R-III-R Turbo]

All of my hoses are good. How would I go about finding a fantom leak? It would be great if it’s something simple like that but my gut says it’s reading that way because a cylinder is not firing. I’m no expert tho so I’m open to all suggestions.

Unless you busted a head gasket, piston ring or dropped a valve then the cylinder will still pull a vacuum whether it is firing or not.
Highest probability here there is a vacuum leak on the tube or the blank cap, also check the boot that connects throttle to cylinder head, seen them cracked before.

You might have to flex these rubbers about a bit to reveal a crack - they're often not visible while just sitting there...

 

[atomsplitter]

The number 2 TB is what number #1 and #3 cylinders are tuned to, so that's way off for starters. Check the TB boot to cylinder head isn't leaking.
You can test with some WD-40, spray the boots and if you get the cylinder to fire you have the culprit.

 

[busy_rydin]

The number 2 TB is what number #1 and #3 cylinders are tuned to, so that's way off for starters. Check the TB boot to cylinder head isn't leaking.
You can test with some WD-40, spray the boots and if you get the cylinder to fire you have the culprit.

What number depicts TB Boot in this diagram?