Spitting and back fireing URGENT

Sgt. Hobo · Two Stroke Sniffer Joined: 30 Sep 2006 Karma :

Ok so i finnaly have my bike running and now while goin to ride it, the bike spits sputters, bogs down, and backfires. ANYsuggestions on what the problem might be ? it revs up fine the first time in neutral then i let of the throttle, go full throttle again and the bike either back fires or bogs down, then it will rev after bogging down

PLEASE HELP ME

davidimurray · Nitrous Nuisance Joined: 04 Jul 2006 Karma :

What have you checked ?

Have you checked the carb float levels ? What about spark plugs - do you have a spark?

Cheers

Dave

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Any loose vacuum tubes?

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

Likely cause of backfiring is the sparkplug misfiring at higher revs. Could be defective plug / plug cap / ht lead / coil.

finpos.

KelvinZXR750 · Borekit Bruiser Joined: 15 Aug 2006 Karma :

What bike is it mate, it sounds like the same problem i am having the timing is out on my bike its causing it to splutter and bog down

Sgt. Hobo · Two Stroke Sniffer Joined: 30 Sep 2006 Karma :

It gets spark because it starts its a brand new spark plug, and the cap has a small piece missing but it was never a problem before

davidimurray · Nitrous Nuisance Joined: 04 Jul 2006 Karma :

I had the float levels go crazy on my bike a while back. It resulted in one cylinder slowly flooding. The bike would run very roughly for about 60 seconds then eventually completely die. Checking the float level should be quiet easy - just need a bit of tube and a screwdriver/allen key.

Cheers

Dave

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

You should really replace the cap - the sparking performance is different at high and low revs. Anything wrong with the cap - especially cracks - can lead to the spark getting lost.

If there is a crack on the cap, look for soot deposits along it.

Of course, that might not be what's actually wrong with it, but you need to start eliminating stuff.

finpos.

krebsy · World Chat Champion Joined: 01 Jun 2005 Karma :

Reminds me of one of my bike tests where the dodgy fuel the Shell garage sold us (all the bikes started popping) was flooding the cylinders of the GS500 I was doing the test on. 20 yards out of the test centre and the engine flooded, backfired so loudly it sounded like a gunshot and Killed the bike stone dead. No engine, electrics, nothing.....

Managed to get it running again but it was bogging down all through the test. Turned out that the tap had been left on Prime and combined with the dirty fuel had scuppered me that day... Sad

I'd recommend shoving a load of Redex through the carbs and checking the fuel flow. Too much fuel is getting in there by the sound of it...

K.
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Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

I reckon the woodruff key that locates the flywheel has sheared. This determines the ignition timing, and when they shear it allows the flywheel to rotate on the crank and puts the timing out. Sometimes it will start and sometimes not, it might run ok one minute then pop and bang the next as the timing moves all over the place.

Marci · Brolly Dolly Joined: 01 Sep 2005 Karma :

SO.... long n' short - it could be anything and everything. Give us more info. Otherwise your just gonna get folks throwing in there two-penneth on every similar problem they've had and what they did to fix without anyone finding out conclusively what the actual problem is.
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hmmmnz · Super Spammer Joined: 22 Aug 2006 Karma :

this happened to me yeterday, it turns out one of the cables going to the main fuse had broken and was just touching and not really making good contact. so check your wires as well Very Happy

i thought my bike was fooked :d
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V2 · Nearly there... Joined: 06 Feb 2006 Karma :

check the plugs/leads arent damp too in this new morning dewey weather!

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

You check the ignition timing? I think we worked out that it has points ignition. Too far advanced or WAY retarded ignition timing could cause the symptoms you describe.

Gap the points (if you don't know how far, I'd go for around 0.016", seems to work on most things).

Did you earth that condenser yet by bolting it back to the frame or is it still flapping about in the breeze?

Sgt. Hobo · Two Stroke Sniffer Joined: 30 Sep 2006 Karma :

SO once again the bike wont start.. do any of you have aim or yahoo maybe i can talk to you on there. the bike started last night and ran then today i tried to start it and it just turns over choke on and off doesnt make a difference i got it to start once today it ran for about 2 seconds then died i just changed the vaccum line and gas line last night ten ran it and it started but today it wont start any ideas?