Popping and banging on the over run.

[R1ffR4ff]

As Blapper says air-leaks around carb joints can cause over-run popping but also on CV carbs perforated or worn Air-cut-off valves are a common cause.

The ACVs are part of the CV carb system.They enrich the fuel when the throttle is closed on deceleration.Without them the fuel to air mixture is too lean and popping can result.

In this respect they are the same as the CV carbs in my Honda CX500s which I've done a lot of work on over the years.





HTH

Cool thanks for the info, I'll have a look.

[R1ffR4ff]

Originally Posted by motorhead13

Cool thanks for the info, I'll have a look.

I use Parts-fiche for my model/s as an additional reference to my manuals when looking for how things are put together,

https://www.cmsnl.com/suzuki-sv650-1...6.html#results

You can see the ACVs on the diagram.Always worth bookmarking the Parts-fiche for your model.

Also if the bike is getting on in years it's worth taking the tank off and checking to see if there are any water droplets in it(Good clean out).

Condensation over the years can well down at the bottom and gasoline itself has a moisture content.If any of this gets sucked into the carbs it can settle at the bottom of a float bowl and then gets flicked up into the fuel-to-air mixture causing all sorts of misfiring problems

[johnnyrod]

The leaks Blapper meant are at the exhaust, so drawing in air and burning unburnt fuel in the exhaust. With a closed throttle the vacuum in the carb venturi is high so it is often a bit rich on overrun so can pop a bit, not loud backfiring though, that would be more like air leaks.

If you have no info on what's been done to the bike then a dyno run for around £25 will tell you power output and about the fuelling. A new zorst means the carbs need fiddling with to compensate (by some unknown amount, depends on the set-up) but some of this may already have been done.

[Blapper]

I did.

[Teejayexc]

What's wrong with a bit of popping and banging on over run anyway?

My ol' D9 does it and I love it

[johnnyrod]

Mine pops and burbles too, I've got a full Akro system, K&N and dyno set-up. Actual backfiring isn't so good, but it's pretty easy to tell the difference. If it were then that would mean an exhaust leak which would also mean lean running on that cylinder, and most likely unbalanced carbs.