engine noise question, piston slap?
10-04-2009, 08:11 PM
#1
Captain Chaos
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engine noise question, piston slap?
wondering if this is a normal thing for hawks with a lot of miles I have one I just bought with 35K on it, I put APE's on it, valves don't make any noise, but it makes a slight rattling/knocking noise that sounds like piston rock, its louder when cold, once it warms up it almost totally goes away, unless you really roll on the throttle under 3000rpm, once it gets to 4000rpm and above it's totally quiet...the local honda tech says they make a little noise but he hasnt listened to the bike yet, I am harley tech for a living but not super familiar with the hawks yet...thanks...
10-04-2009, 09:16 PM
#2
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As a tech you know that piston slap decreases or goes away after warmup. The only way to know for sure would be to do a tear down.
But without hearing it in person, its hard to tell otherwise. These bikes do make weird noises, especially at low rpms.
But without hearing it in person, its hard to tell otherwise. These bikes do make weird noises, especially at low rpms.
10-04-2009, 09:26 PM
#3
Captain Chaos
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well it is primarily at low RPMs don't worry we arn't alone, the harleys chug along at low rpm too, but for them its at a lower rpm since they are made to run slower. the sound going away is why im thinking its the pistons, if it is should i be concerned, do these have a habbit of cracking skirts, the screamin eagle harley pistons collapse over time and get a rattle, they have earned the nickname rocker pistons over for that reason. I just dont want it to blow up, if all its gonna do it make noise till it eventually wears out and looses power, then I'll just run the hell out of it till then and either rebuild or buy a low miles used mill so I dont have down time...
10-04-2009, 09:50 PM
#4
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The SuperHawk uses a slipper piston with hardly any skirt, and in my time on the forum I've never heard of a piston slap problem. The cam chain tensioners (CCTs) are a different matter though. Some forum members have had catistrophic engine failures when these give out, mostly on pre 02 models I believe. Do a search to check on CCT problems.
And I do know what piston slap sounds like. My wife bought an 86 Toyota 4x4 new, and after it had about 200,000 miles on it, I noticed piston slap in the morning. The 22R engine is famous for it. So I just told my wife to warm it up for several minutes before driving. We still have the truck at 370,000 miles, and the engine was rebuilt at 332,000 only because the timing chain started rattling.
So I'd say ride it and don't worry unless the noise gets louder, unless its the CCTs.
And I do know what piston slap sounds like. My wife bought an 86 Toyota 4x4 new, and after it had about 200,000 miles on it, I noticed piston slap in the morning. The 22R engine is famous for it. So I just told my wife to warm it up for several minutes before driving. We still have the truck at 370,000 miles, and the engine was rebuilt at 332,000 only because the timing chain started rattling.
So I'd say ride it and don't worry unless the noise gets louder, unless its the CCTs.
10-05-2009, 07:13 AM
#6
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yeah, I wouldn't ride for like a week after I bought it because I was waiting for the APE's, not worth the possible damage, one had been replaced with the red dot one, but still don't trust them, I put some pressure one the one and wiggled it a bit and it collapsed so I guess those were a good investment.
10-06-2009, 03:56 PM
#7
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Come on guys! This is an easy one!
It's the carb slides bumping on their stops and is completely normal. They reciprocate about a cm due to the large pulses of the twin. The reason it goes away above 3k rpm is because the slides get high enough so they don't hit the bottom.
It's the carb slides bumping on their stops and is completely normal. They reciprocate about a cm due to the large pulses of the twin. The reason it goes away above 3k rpm is because the slides get high enough so they don't hit the bottom.
10-06-2009, 04:58 PM
#8
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Ahh.. the ol clacking slides trick. Thanks Greg, I'm still getting used to the hawk, only had it about 3 mos now, she was kinda tired when I got er. Put APE's in immediatly as she had 33k on the clock at the time and it didn't seem as if the PO kept up with the maint needs, but have still been hearing that noise that went away as rpm's went up.
As I also own a custom V-twin I have a tendancy to lug the hawk a bit, have to work on that, keep it in the sweet spot.
As I also own a custom V-twin I have a tendancy to lug the hawk a bit, have to work on that, keep it in the sweet spot.
10-06-2009, 06:57 PM
#9
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Come on guys! This is an easy one!
It's the carb slides bumping on their stops and is completely normal. They reciprocate about a cm due to the large pulses of the twin. The reason it goes away above 3k rpm is because the slides get high enough so they don't hit the bottom.
It's the carb slides bumping on their stops and is completely normal. They reciprocate about a cm due to the large pulses of the twin. The reason it goes away above 3k rpm is because the slides get high enough so they don't hit the bottom.
10-08-2009, 12:41 PM
#10
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Come on guys! This is an easy one!
It's the carb slides bumping on their stops and is completely normal. They reciprocate about a cm due to the large pulses of the twin. The reason it goes away above 3k rpm is because the slides get high enough so they don't hit the bottom.
It's the carb slides bumping on their stops and is completely normal. They reciprocate about a cm due to the large pulses of the twin. The reason it goes away above 3k rpm is because the slides get high enough so they don't hit the bottom.
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