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Anyone know what this rattling is (video)

C

Cprisco13

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So Ive noticed this rattling once the engine has been warmed up after about a 20 min ride. Here is a video of it. sounds like the exhaust or bottom of engine. Also makes the exhaust pop a little. Alost the header on my 3rd exuahst seems to be not all the way flush because of the exhaust pipe having a slight bend in it from my dad dropping it many years back. 72 cb750.

<iframe width="560" height="315" src="https://www.youtube.com/embed/Wa113qlwVGI" frameborder="0" allowfullscreen></iframe>

https://youtu.be/Wa113qlwVGI
 
Exhaust leak of some type and possibly even blown head gasket. Almost sounds like a one half of engine paired leak...................engine besides that not running well at all.
 
amc49 said:
Exhaust leak of some type and possibly even blown head gasket. Almost sounds like a one half of engine paired leak...................engine besides that not running well at all.
Click to expand...

Ya the engine sounds good at first but then after a while starts sounding like that. Also it sounds way worse in the video actually.
 
amc49 said:
Exhaust leak of some type and possibly even blown head gasket. Almost sounds like a one half of engine paired leak...................engine besides that not running well at all.
Click to expand...

Yeah, sounds like multiple air/fuel leaks that are igniting each other. Knowing "where" on the bike the sound is coming from would really narrow it down.
 
Ok here's a video of what I'm looking at. The one exhaust is a little off the header, I can't put it flush because the pipe is slightly bent. Anyone know a way to bend an exhaust pipe? Also the black stuff on the engine part does that mean that there is a blown gasket or something in the engine? Thanks
http://youtu.be/s820KFEH7q8
 
Try adjusting the valves.....put your hand over the exhaust pipe and rev it up.....find which one is doing it....
then adjust those valves....... see if that helps....
 
Just did a compression test and all four are pretty low. Like 70-90psi. I'm about to check the valves now. Basically trying to do everything before taking the motor apart, Which is one thing I don't know how to mess with . So I'll probably have to take it into a shop which sucks cause I can't really afford that.
 
did you hold the throttle wide open when you did the compression test? With 70 to 90 psi it shouldn't even run.
 
That exhaust is barely on, I am sure you are getting some exhaust noise but it would make the noise when it is cold too. Warm compression would be a bit higher but you should have AT LEAST 120psi to make it run decent. Check the valve clearance, I doubt they are all tight though. Its really hard to diagnose noises not being there with the bike, audio online is not that great because there are subtle differences in different engine noises.
 
dirtdigger said:
That exhaust is barely on, I am sure you are getting some exhaust noise but it would make the noise when it is cold too. Warm compression would be a bit higher but you should have AT LEAST 120psi to make it run decent. Check the valve clearance, I doubt they are all tight though. Its really hard to diagnose noises not being there with the bike, audio online is not that great because there are subtle differences in different engine noises.
Click to expand...

Ya it's hard to tell in the video. But it defining rely only makes the rattling sound after being warmed up a while. Sometimes it even takes bout 30 minutes or more. whats strange is that just today after I tested the compression I put everything back on and tightened the exhaust as best I can. I had to rig the back part where it connects to the passenger peg. I started it up and it actually sounded really good and idled good. Usually when I started up I have to mess with the idol a few times and it takes it a few minutes to run good. But not this time. I'm going to take a little ride once I get another bolt and figure out a better way to Hold the two pipes on the back together better. Then I'll see how it goes.
 
Ok, so I hooked up the exhaust back and it's flush on the headers. So I start it up and let it run and is sounding good except now it seems to be getting too much fuel!! It's coming out the overflow. i haven't had that problem since last year when I got the bike and redid the carbs. Geez Louise!
 
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