[Andy Hogarth]

Tm's doing my head in (gonna be a long thread so bear with me)

Starts first time and runs a treat... no problemo

shut it off

Second time it'll back fire for a while (sometimes loud and sometimes tiny), rubbish pressure then catch the revs and run fine.

If I take the right hand side (looking at the tm) spark plug off when back firing it'll stop popping but only run at low revs. replace it and it back fires again. then as if by magic run fine again.

Now today it ran fine for 20 mins then started backfiring!!

All of a sudden it will run a treat and have nae problems

seem to be going through spark plugs at a quick rate too, new plugs do stop it but short time but quickly the cycle starts again.

Any ideas?

I'm heading over to alltec to do the cct next week so if push comes to shove I can have them look over it.

[Shaun_Ashmore]

Tried taking the air filter out?

Shaun

[Andy Hogarth]

Tried without and replacing it Shaun

[Simon@arenaclean]

Plug lead faulty, helicoil could be worn (where the plug screws in) head may have a hairline crack which would expand when hot. know more about car engines really so any kind of coil or distribution system may also be breaking down

[Andy Hogarth]

Funnily enough Simon me old chum, you're not the first to mention this (however I was hoping nobody would lol)

So if this is the case, how easy is it to replace a coil on a b and s 16hp ??

[Simon Gerrard]

Andy,
Take it to a b&s  dealer, some things are best done by the pro's.

Simon

[derek west]

Andy,
Take it to a b&s  dealer, some things are best done by the pro's.

Simon

just don't get ripped off by the bar stewards,make sure you get any verbal quotes in writing.

[CarPete Cleaning]

When I had a similar problem on my Kohler engine, I had to replace the ignition coil (both eventually). 

[Andrew Briscoe]

Have you still got the spare engine Andy ?
Andrew

[Andy Hogarth]

I do Andy yep, took it with me to a mechanic today, he seems to have sorted the problem without needing it, just need a carb repair kit now but it's back running fine.

Any more problems and he's going to fully strip it down for me, rebuild it and keep it reg serviced for me. Sisters new boyfriend, keen to impress her so he didn't charge me......... gotta love it. 

[Neil Williams]

If you've got an ongoing problem which is carb related then change or fit an inline fuel filter, also make sure the air filter is changed regulary, because this sounds like contaminants either by air or fuel are getting into the carb, causing blockages which then undo the fine balance needed to get the correct fuel/air mixture..... hence the back firing.
Back firing happens when unburnt fuel gets into the exhaust and ignites in there, hence the 'pop' sound.