V&H Big Shots, SS Filter. What damage to engine does backfiring do? Backfires when backing off throttle.

SOURCE: ktm 250 sxf 2008 backfires

go on google check the air mixture and altar the air screw on the carb to wot u find on the net easy job thers only 2 screws on the carb

SOURCE: 1996 Suzuki Savage 650 backfires on cutoff

I had the same prob with my 97, It was not the head gasket but the O-ring on top of the head. Replaced the O-ring and has been running good for a year now with no backfire. Hope this helps.

Roland W VanLue

• 486 Answers
• Posted on Nov 23, 2009

SOURCE: i have a 24 hp briggs & stratton els 725 motor

The engine ignition can be interupted by a safety switch (seat) out of place or adjustment, or a carburetor fuel solenoid that is loosing it's supply of voltage.
1) Check the wiring at the starter area, looking for a main engine wiring harness plug-in.
Check for connections that are burnt or loose.
2) If you can locate the 'kill' wire connection at the main harness, disconnect it, and retry the engine.
3) If the engine continues to fail to run properly: you might replace the plugs first, then I have listed a few things to check. They may not all aply, but this may help with an idea or two to try.

1) Determine that there is spark?
2) Have you used a type of spark tester?
3) What is the condition of the plug. Brown or dark brown is OK. Black or silver is NOT Ok.
*If you do not have a spark tester,
a) remove the plug, and with it connected to the wire,
b) find a portion of metal around the cylinder that you can ground it on, and then pull the rope.
c) If the plug is black, you may see spark, but you should replace the plug.

*** PLEASE NOTE ; if there is excess fuel in the cylinder or on spark plug,
it can catch fire, so be carefull to cover the hole with a heavy rag so that any fuel
cannot be exposed to spark plug durning test !!!!
Get back with me on how this issue works out.
thanks, rwvanlue

Fuel Related issues that take a certain amount of time to appear
Depending on make and model of mowers:
a) Fuel tank outlet plugged (some have a screen filter,
some are 90' angle and plug with rust and debris inside the corner of fitting)
b) Fuel lines collapse when they are routed thru fasteners and between frame and seat decks
c) Fuel cap vent clogged
d) Fuel filter clogged
e) any fitting that has an orifice that can trap debris or rust will eventually become clogged
f) fitting on the side of the carburetor
g) some systems have a filter inside the line at the opening of the carb inlet
h) fuel pump
i) vacuum hoses to fuel pump
j) debris under inlet needle/seat on carb
Fuel Starvation - Float Bowl Carburetor
1) remove air filter assembly
*be cautious of tearing the mounting gasket. If it does tear, you HAVE to replace it. It is part of the priming system
2) remove the float bowl fastener. This is the main jet
3) carefully remove the float bowl, the rubber o-ring/gasket will not be able to be used if it is removed, you WILL have to replace it
4) using a spray 'carb cleaner'
spray up thru the center of the carburetor
spray and clean the main jet with cleaner and 'tag' wire
(tag wire is very thin, and can be used to clean the hole in the center of the main jet)
5) clean any debris from inside the bowl or carb body
6) re-install bowl and center bolt, air filter assembly

*if you need gaskets, your Briggs dealer can supply. The kit is cheaper than individual gaskets, and all the parts needed to finish the above repair are in the kit.

I’m happy to assist further over the phone at https://www.6ya.com/expert/rolandw_c013176d62ee17ae

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• 12061 Answers
• Posted on Apr 08, 2010

SOURCE: mower engine backfires through air filter! will

A: Backfiring (and misfiring in general) can be caused by a large number of problems; unfortunately not only you do not even say what kind of Fulvia you have but your description of backfiring is superficial. You certainly have not attempted to exclude some obvious causes of backfiring. With these limitations I can only try to list a number of potential causes and how to solve them.

1. None of the things you have done (plugs, cables, alternator, filters etc)has anything to do with backfiring. I am not surprised that no improvement was obtained.
2. You must check that the valve timing is correct and that the timing chain has not jumped one tooth of the camshaft sprockets (details will depend on the car engine). Ensure also that the valve clearance is not badly out.
3. You must check that the ignition timing is neither too advanced nor too retarded and that the correct dwell angle is set with respect to the points opening gap (details depend on the engine).
4. It is unlikely that the problem is due to carburettor malfunction: however, check that the two carb floats are OK if everything else seems fine. I presume that by inspecting the spark plugs you concluded that the carb air/fuel mixture was basically correct.
5. A leak in the intake system can cause backfiring but you do not even say if your car has a brake servo (some Fulvias did not have one). It is very unlikely that the servo is causing your problem since you would notice that a strong effort is needed to stop the car and that the same amount of brake pedal pressure can be applied with the engine running or switched off. It is possible, that the vacuuum hose running from the cylinder head to the servo (or its one-way valve) is damaged: a crack in the vacuum hose occurs very often although I have not seen it to produce symptoms as bad as the ones you describe. Any vacuum hose (with suitably rigid wall) of the same diameter will be OK to replace yours: it does not have to be a Lancia product.
6. Your car may have a leak either in the carburettor rubber support or in the intake manifold gasket.
7. I do not know if the Polonez servo can fit your Fulvia. Reconditioned servos can be obtained from commercial suppliers but I suspect that the servo itself is not the cause of your problem.
8. Poor throttle response (when everything is tuned up correctly) can be due to failure of the centrifugal advance mechanism in the distributor (broken springs, stuck bob-weights etc) or to inefficient acceleration pumps (holed diaphragm) at the bottom of the carbs. However, neither of these problems should create backfiring.
9. Fulvias do not necessarily start instantly from cold because, if the car has not been used for some time, the carbs must be primed, a process which takes a bit of time as the fuel pump works while the engine is spinning. Some people have fitted an electric fuel pump to prime the carbs. Of course, using the choke will help starting from cold.

SOURCE: I have a 24 hp

What is your engine model number? It will be in the form of xxxxxx-xxxx-xx.
As far as I know the 725 ELS plug gap is 0.030"
Intake and exhaust valve clearance must be .004"-.006"
Incorrect valve clearance is the most likely culprit for backfiring. This can be caused by normal wear and tear.