BenB
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| posted on 31/3/07 at 03:25 PM |
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Engine backfiring out of carbs
What causes an engine to backfire through the carbs? Would mixture alone do this? I'm certain the timings right on the engine 'cos
everything is pretty much standard... I'm certain its running rich- would this allow backfiring through the carb??? I've done a
compression test in case it was a carboned inlet valve but the test came back absolutely fine....
I'm pretty sure its backfiring because a bit of my airbox keeps on blowing off. I've replaced it three times(!), each time making it
increasingly more securely attached to the rest of the airbox but low-and-behold after this weeks blat, took off the bonnet to find (yet again) I
didn't have a top to the airbox!!!! Not the best situation (running without a sealed airbox)....
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tegwin
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| posted on 31/3/07 at 03:30 PM |
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hmm...
I had a similar issue with carb backfire....even had some impressive flames...
It was caused by the simple fact that the camshaft was 180 degrees out...
You would also get similar symptoms if your HT leads were in the wrong place...
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BenB
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| posted on 31/3/07 at 03:35 PM |
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hmmmmmm....
seems to drive okay- but I might just recheck that the right coils are going to the right plugs....
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turbodisplay
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| posted on 31/3/07 at 03:40 PM |
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I had backfing.
Turned out the inlet cams were in the wrong posistion, things to be careful when buying a secondhand engine!
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Catpuss
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| posted on 31/3/07 at 03:42 PM |
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My firestorm does it every so often when I blip the throttle whilst stationary.
From my understanding, having the fuel too rich can cause this as well as cam problems.
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jacko
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| posted on 31/3/07 at 03:43 PM |
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Air leek on inlet manifold ?
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BenB
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| posted on 31/3/07 at 04:00 PM |
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quote:
Originally posted by jacko
Air leek on inlet manifold ?
Good point! I swapped the carbs at one point and not sure if I tighten up the clamps properly.... I'll check!!!!
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Jon Ison
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| posted on 31/3/07 at 04:03 PM |
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inlet valve sticking open, exhaust valve opening too soon, ignition curve sticking firing with a valve open, cam timing......
just a few.
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nitram38
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| posted on 31/3/07 at 10:21 PM |
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If it is carbs, then balance could be out.
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