Popping noise from engine
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Cruiser
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Popping noise from engine
The bike is a 1977 fxe with 15 k original miles on it. Since starting it up this season, I noticed a rather pronounced popping sound coming from the engine once it’s warmed up and is idling. It is not coming from the exhaust pipes and it is not consistently rhythmic with the idle . It literally sounds like popcorn popping and is fairly loud. I can’t seem to pinpoint where it’s coming from but it is pronounced. It didn’t do it last year but only after starting it up this season.
Over the winter I installed an Andrews J grind cam and readjusted the lifters according to spec. The bike idles fine and runs smoothly. This noise appears once the engine warms up. Any ideas as to what this could be. Could this be engine knock? Any help would be appreciated.
Over the winter I installed an Andrews J grind cam and readjusted the lifters according to spec. The bike idles fine and runs smoothly. This noise appears once the engine warms up. Any ideas as to what this could be. Could this be engine knock? Any help would be appreciated.
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From: la la land jerzey
so keeping it a secret - does it have oem stock hydraulic lifters and with what push rods is helpful info - or does it have solids < any cam can end up with what ever it seams
the correct method of adjusting valves is in correct correlation to the parts you have with the cam you have
info needed -- and what did you do exactly ends all the guessing
the correct method of adjusting valves is in correct correlation to the parts you have with the cam you have
info needed -- and what did you do exactly ends all the guessing
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Cruiser
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The lifters are stock hydraulics and the pushrods are OEM as well. I adjusted them dry with 24 flats. It would seem that if it were related o the lifters , the sound would be more rhythmic. This is a very erratic pop which comes and goes which seems to be unrelated to the timing.
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From: la la land jerzey
its possible one of the lifter rollers has worn out - holding the lifter tube can sometimes transmit the ( feeling sound pop click tap what ever ) into your fingers and this would be a mechanical sound rather then a plug that is gas fouled and the sound is in the exhaust
your hearing it what does it run like going around the block
your hearing it what does it run like going around the block
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Cruiser
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John--it seems to only be happening at idle. When I rev the engine I don't hear it and when riding it I don't hear it. It's like an erratic pop/ knock after it warms up and idles. The valve train sounds nice and quiet, the idle is smooth, and performance is perfectly normal. I've never heard anything like it--it's strange.
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From: Long Island, New York
Like John said, feel around while idling and try and isolated the location. Any thump you should be able to feel it with your fingers. Long screw driver, one end on the motor, the other to your ear might help as well to locate.
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From: la la land jerzey
ok pull the lifter blocks its not that much of a thing
what to look for - loose roller on one of the lifters and they are directional when re installing the flats face each other
cam end play can be checked using a feeler gauge .012 to .018 is kind of in the range
cam shaft walk in the gearing is it loose as in teeth play you can feel -
the idler for the generator pull the 2 bolts out and slide it out a bit no need to pull totally - once out - you can reach in and pull the gear back and forth from the gen hole is it loose on the shaft
pull the distributor top cover for the points now take the points out rap the points trigger with electrical tape good use a plyers looking for excessive turning movement between the dist gear and the cams driven gear in the case - look in and over into the lifter block that has been removed watch whats happening - nothing should really be moving
its going to be a process of elimination and you might just have it all worn out as most even in shops do not have the tooling or the real experience to fix ( machine - ream and hand fit ) so they don't touch any of it even when supposedly completely rebuilt
what to look for - loose roller on one of the lifters and they are directional when re installing the flats face each other
cam end play can be checked using a feeler gauge .012 to .018 is kind of in the range
cam shaft walk in the gearing is it loose as in teeth play you can feel -
the idler for the generator pull the 2 bolts out and slide it out a bit no need to pull totally - once out - you can reach in and pull the gear back and forth from the gen hole is it loose on the shaft
pull the distributor top cover for the points now take the points out rap the points trigger with electrical tape good use a plyers looking for excessive turning movement between the dist gear and the cams driven gear in the case - look in and over into the lifter block that has been removed watch whats happening - nothing should really be moving
its going to be a process of elimination and you might just have it all worn out as most even in shops do not have the tooling or the real experience to fix ( machine - ream and hand fit ) so they don't touch any of it even when supposedly completely rebuilt
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Cruiser
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Thanks for the input guys. Today I started her up and let her idle until hot and the noise began again. I think that it's coming from the kicker cover. Interestingly, at the same time, it was difficult to get the tranny into first gear and it actually popped out of gear a time or 2. I also noticed that there was suddenly more play in the clutch lever/ cable and , finally, about 1-2 ounces of gear oil suddenly puked out onto the floor from the vicinity of the mainshaft seal. So, it appears that something is amiss in the tranny/ clutch dep't. So that's the next level of investigation. I'm wondering if the throwout bearing may have come off of the clutch pushrod, casing these various symptoms. Any thoughts about this ?
Last edited by doc308; May 5, 2019 at 06:57 PM. Reason: need to include more info
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From: Cental, MI
Thanks for the input guys. Today I started her up and let her idle until hot and the noise began again. I think that it's coming from the kicker cover. Interestingly, at the same time, it was difficult to get the tranny into first gear and it actually popped out of gear a time or 2. I also noticed that there was suddenly more play in the clutch lever/ cable and , finally, about 1-2 ounces of gear oil suddenly puked out onto the floor from the vicinity of the mainshaft seal. So, it appears that something is amiss in the tranny/ clutch dep't. So that's the next level of investigation. I'm wondering if the throwout bearing may have come off of the clutch pushrod, casing these various symptoms. Any thoughts about this ?
Only thing that should/could effect Clutch adjustment, is Throw out, and/or Basket and Hub Interface Problems,,
Last edited by Racepres; Sep 20, 2019 at 12:36 PM.
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