Exhaust Problems

[psychogirl]

I bought a new Vance and Hines 4:1 exhaust and got it fitted on my z650. My old 4:2 exhaust was blown and I thought with it drawing in air it was causing popping and banging. However, the same thing is happening with the new 4:1. It happens on low revs which has confused my mechanic. Does anyone have a suggestion as to what's going on?
I said I would post a message and see if you bunch of knowledgeable guys could help.
Thanks,
psy

[Padders]

Cheack the carb to head rubbers that can have hair line cracks that allow air to be sucked in under pressure.

[Taffus]

Cheack the carb to head rubbers that can have hair line cracks that allow air to be sucked in under pressure.

an old 2 stroke trick to check this is to spray wd40 on the rubbers when you are revving the engine, if you hear a change in tone then the rubbers are leaking air making the mixture lean....

[Mark Tiller]

Ditto on the inlet rubbers, do you have standard airbox/airfilter/jets? as it will need bigger jets for the new zorst
is the V&H fully sealed at the silencer/collector joint?

[Pigford]

Just spray the WD40 around the rubbers with the engine idling - there's more back pressuer & its easier to hear the revs pick up if there is a leak. You sometimes see a damp patch where they're leaking too

Spitting on overrun is not always air leaks in the exhaust

[psychogirl]

Thanks for your advice guys.
The wee z is still at my mechanics shop. I shall take your views and see what he can do.
I am so clueless (but learning - slowly).

There'll be 100's more questions to come from me as I'm just starting this project as the RS is near completion.

[psychogirl]

Having checked the carb to head rubbers... all is ok in that department.
Still throwing flames on very low revs. When it's ticking over and I blip the throttle I have flames.
Any other suggestions?
I don't want to set fire to anyone stupid enough to cross behind me!

What's really nice though is, it's been at the mechanics for over 2 weeks. He fitted the new zorst, got it running a bit sweeter, tried to solve the flame issue, made many calls and spent time on it then said all work was done free of charge. Sweet. It pays be a girl sometimes

[jimmock]

Having checked the carb to head rubbers... all is ok in that department.
Still throwing flames on very low revs. When it's ticking over and I blip the throttle I have flames.
Any other suggestions?
I don't want to set fire to anyone stupid enough to cross behind me!

What's really nice though is, it's been at the mechanics for over 2 weeks. He fitted the new zorst, got it running a bit sweeter, tried to solve the flame issue, made many calls and spent time on it then said all work was done free of charge. Sweet. It pays be a girl sometimes

If I was a girl, I'd be ABSOLUTELY LOADED today!!!!!

[jimmock]

On a serious note, is the ignition timing OK??

[ZedHead]

I would start by finding out which cylinder/s if not all are misfiring. A Gunson Colortune is useful for this as you can see the actual explosions. You can also check for any mixture issues while you are on. If the misfire is on one cylinder only, start by looking for the simple things ... swap plugs around or better still replace with new, check for lose plug caps etc.

Another thought ... were the exhaust gaskets changed when you replaced the exhaust? A leak hear could cause problems.

Failing this I would agree with Jimmock ignition timing, valve timing or low compression need to be checked.