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Most people have this problem after changing the exhaust system. In your case you have to unbolt the exhaust system just to change the oil filter during an oil change. There is an oil filter relocation kit available for around $400 that allows you to both use a spin on filter and not have to unbolt the exhaust system every time you change the oil. The cause of your problem is air leaking past the exhaust o-rings in the head. Buy new exhaust o-ring gaskets for the head and your problem should be solved. If there is a sealing pipe gasket going from the head pipe to the muffler you may have to replace that too. The cause of your problem was probably an oil change where the mechanic replaced the oil filter but did not bother to replace the exhaust o-ring gaskets. Happy riding.
Well - the front pipe has to be removed to change the oil filter on this bike, so it's very likely that when reinstalled the mechanic did not get it back in place correctly. Couple that with the likelyhood that he re-used the old exhaust gasket and this is your most likely cause for the backfire - a simple exhaust leak. Other typical causes for exhaust backfires are insufficient valve clearance, burnt valves or incorrectly adjusted carbs. In my experience the most common cause for exhaust backfire is a leak in the exhaust circuit which can draw in fresh air during decelleration.
Unbolt the exhaust from the cylinder head to access the oil filter. For around $400 you can buy a kit that moves the filter to a better location. You may need to replace your exhaust gaskets if you experience popping in the exhaust after the filter change.
Unbolt the exhaust from the cylinder head to access the oil filter. For
around $400 you can buy a kit that moves the filter to a better
location. You may need to replace your exhaust gaskets if you experience
popping in the exhaust after the filter change.
Rick, since 1994, Harley has used what we call a "head breather" system in that the crankcase breathers are located in the heads. This was done in an effort to reduce the amount of oil that gets into the air filter. In earlier case breather model engines, the oil would pour into the air filter if the bike had been sitting for a few months. Prior to that, the bike would "puke" what looked like a quart of oil on the ground below the bike when first started after a long period of sitting.
If you'll remove the air filter cover and element, you'll see that the large bolts that hold the breather onto the heads are hollow. Inside the rocker boxes, there are small rubber "umbrellas" that are opened and closed by crankcase pressure. These are designed to allow your engine to breathe without an excess of oil being blown out. Still even though this system is better, a little oil still gets into the air filter. You can either keep this cleaned out or you can replace the "head breather" systems with an aftermarket system that changes the location the system exhaust crankcase pressure from. Also, you can change the "umbrella" seal and put in new ones. It isn't that difficult to do on the front head. The rear head can be tricky since there isn't much room to get to the bolts to take the rocker box cover off. The umbrella seals are located in the center section of the rocker box cover.
Several things here. Do an oil change, 10w40 motor oil. Run premium gas and install a new NGK spark plug one heat range colder than stock. It sounds like you have an air leak causing a lean fuel mix. Check the carb mount bolts and the intake manifold bolts for tightness. Also set the valve clearances with a cold engine > .002 intake and .003 exhaust. Check for any cylinder head leaks. This would show up as oil on the cooling fins at the base of the cylinder head. Tighten the head bolts if needed.