What would cause a random pop sound in mufflers, sorta like backfire... Idle or even at times on deceleration. 2002 vfr 800
if the engine is running too rich. Mine runs a little rich and engine braking coming out of third into second gear causes grumbles and pops. I have a 6th gen happens all the time.
It is mostly caused by the Pair valves burning off unburnt fuel in the exhaust. Get rid of the Pair valves and it stops.
Hi and welcome to the MadHouse:welcome: When you get time please visit the "Introductions" part of the forum and say Hi to the rest of the folks on here, and add a photo of your VFR or people will be raggin on you. You might want to update your forum profile to include the specs of your VFR version/year and an approximate location - city/state is fine - that way it will appear automatically with all your posts and if you need help you may find someone living nearby is willing to swing by and offer advice - especially if you have a well stocked beer fridge. :focus: :boom: As for the exhaust popping - it is usually down to poor fueling with excess fuel detonating inside the hot exhaust - not good for your ears, your exhaust or your wallet as you are wasting fuel. Before suggesting making substantive changes it might help to know how and when was this bike maintained. If its overdue a service then I would probably get that done first, and see if the problem goes, before taking an axe to parts of the fuel system. As in parts of the world your model year was a changeover between the 5th gen 800FI models to the Vtec 6th Gen models it would also help to know precisely which bike you have, as by now even on low mileage - there are other things like balancing the throttle bodies which might be overdue and also contributing to too much fuel ending up in the exhaust. Take care and let us know how you get on. SkiMad
I agree with skimad4x4, you must identify if something is not working correctly. A well-maintained bike with an old battery can have strange problems if the battery is at its end of life. Is the air filter clean? The starter valves must be tuned or at idle there could be rich and lean cylinders which could cause popping in addition to a lumpy idle and difficulty starting. You can use a laser thermometer on the different pipes coming out of the engine. If you find a pipe with a very different temperature from the others, you have identified a problem cylinder. A visual examination of the spark plugs can identify problems in each cylinder. The answer to the questions about how the bike was serviced can then help narrow down further tests such as the stator, rectifier, coils, continuity to the grounds, condition of the fuel injectors, or a vacuum leak in the intake or the exhaust. This isn't a comprehensive list, but includes many of the applicable air/fuel/spark issues.
Either clean / get rid of the PAIR valves - reeds and all. This is most likely the cause. If you gutted the exhaust or slapped on some aftermarket ones, then this would make the popping even worse.
You need a set of block plates if you want to remove it completely. Otherwise some assorted marbles will do the job. Just do a quick search on the forums here. There are plenty of threads about it.
