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EVO MOTOR 2500 RPM Rocker BOX Rattling Noise

T

THE BOGGER

Member
1997 Ultra Classic with EVO 80 CI, Just turned 30,000 miles

Seems that when the engine is hot there is a strange noise (rattle ) coming from the top of engine rocker box. Now I run synthetic Oil Royal Purple 20W-50W. When the oil is hot this seems to be the problem, Symptomatic of thinning oil viscosity, but once up to 3,000 rpm the noise is gone. It seems to start at 2500-2800 rpm.

Anyone having this problem or having heard of it please chime in. We would love to solve the riddle of the rattle.

Thank You

The Bogger
 
I would start by changing to a different oil. RP isn't a bad oil but it isn't on top of the list IMO anyway. Not much to loose here other than a few quarts of oil. Sure it's not pinging?
 
glider said:
I would start by changing to a different oil. RP isn't a bad oil but it isn't on top of the list IMO anyway. Not much to loose here other than a few quarts of oil. Sure it's not pinging?
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No, it is not a Pinging noise. That would be at a much lower RPM. I am going to change the oil this weekend trying the MOBIL 1 M/C oil.
Thank You, I am looking into the components of the top rocker boxes, maybe something is worn out and only shows the rattle at certain rpms.

BOGGER
 
Just for curiosity, did you check the oil during your last change, was there anythng unusual or odd in the crankcase oil drainings, more metal bits then usual caught by the oil plug magnet? May want to verify oil pressure, oil pump is working okay. Might have to look under the rocker covers. Was there any circumstances or maintenance done before this problem started to appear?
 
Does it have a stock cam? I've seen the adjustable pushrods loosen up and or sometimes not tightened at the right length to start with. It wouldn't surprise me if it was the oil and a hot day. They do make some valve train noise especially when they get hot. Sometimes the primary chain can get a little lose and make some noise at different RPM's, although usually it will slap when you roll the throttle back and forth in gear loading and unloading the drive train. Let us know what you find. Good Luck.
 
Mine make some noise as well. after replacing the primary chain, adding an auto adjuster, new Jims big axle tappets, new Riveira Taper lite pushrods, new Andrews EV23 cam with the improved bearing, tightening up everything under the sun and checking the rokcers and replacing the bushings, the noise is still there. My wrench says, "It's an EVO, it makes noise, ride it until it quits" At 150k miles, it still runs strong

Let me know what you find out.

Bubba
 
After a new cam change and rule of thumb is if it whines the drive pinion (on crank) is too big (BAD). If it clatters like tappet noise the pioion is too small (annoying). Adjust as needed. Refer to Andrews Cam site for more.
 
i have the same rattle on my evo. im thinking it might just be a heat shield though? havent really looked into it much. ive heard when they stop making strange noises, then worry.
 
Bubbaglide said:
Mine make some noise as well. after replacing the primary chain, adding an auto adjuster, new Jims big axle tappets, new Riveira Taper lite pushrods, new Andrews EV23 cam with the improved bearing, tightening up everything under the sun and checking the rokcers and replacing the bushings, the noise is still there. My wrench says, "It's an EVO, it makes noise, ride it until it quits" At 150k miles, it still runs strong

Let me know what you find out.

Bubba
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Exactly the same as mine except I also had Wisco pistons and S&S oil pump still had the noise.
 
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