Rattle
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Howard Burns
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- Posts: 6
- Joined: Tue Jun 05, 2007 12:53 pm
Rattle
I have a used crf450r. It had two rattles when I put it under load with low throttle. I fixed one by adding actaine booster to the fuel. The sencond rattle sounds like the chain slapping the frame, but I believe it is internal. Any ideas on how to identify the source of this rattle woud be greatly appreciated.
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BuzZz
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- My Motorcycle: makes my 'nads tingle
- Location: Buttfluck Nowhere, Manitoba
Check the cam-chain tensioner and valve lash.
And it could very well be the drive chain slapping the frame. Long travel bikes have significantly more slack at the extreme ends of their travel and that coupled with lugging a 4 stroke in a low gear can make the engine power pulses wag that chain around pretty good. It is not un-common on dirtbikes. Does a good, long pull on the throttle make this noise go away once it starts?
And it could very well be the drive chain slapping the frame. Long travel bikes have significantly more slack at the extreme ends of their travel and that coupled with lugging a 4 stroke in a low gear can make the engine power pulses wag that chain around pretty good. It is not un-common on dirtbikes. Does a good, long pull on the throttle make this noise go away once it starts?
No Witnesses.... 
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Howard Burns
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- Joined: Tue Jun 05, 2007 12:53 pm
rattle
Yes,
actually it does not take much of a pull on the trottle to make it go away. However, I can duplicate the rattle when the bike is out of gear.
actually it does not take much of a pull on the trottle to make it go away. However, I can duplicate the rattle when the bike is out of gear.
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BuzZz
- Site Supporter - Platinum
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- Joined: Sat Mar 20, 2004 12:02 am
- Real Name: Never Used Here
- Sex: Male
- Years Riding: 47
- My Motorcycle: makes my 'nads tingle
- Location: Buttfluck Nowhere, Manitoba
It really sounds like normal drive chain noise from here.....
When re-creating the noise in neutral, try putting your hand or boot on the chain near the countershaft or the rear chain guide. It is probably harmonics buzzing the chain against something at a certain rpm.
Keep an eye on the chain slider at the swing arm pivot. Not only for unusual wear patterns, but they do wear in normal use, and once they are cut through, your expensive and soft aluminum swingarm is the next item to get eaten.
You might also try taking a little preload out of the rear spring and dropping the ride height slightly. Test ride it and see if it helps or hinders the handling for you, and decide what works best for you from there.
When re-creating the noise in neutral, try putting your hand or boot on the chain near the countershaft or the rear chain guide. It is probably harmonics buzzing the chain against something at a certain rpm.
Keep an eye on the chain slider at the swing arm pivot. Not only for unusual wear patterns, but they do wear in normal use, and once they are cut through, your expensive and soft aluminum swingarm is the next item to get eaten.
You might also try taking a little preload out of the rear spring and dropping the ride height slightly. Test ride it and see if it helps or hinders the handling for you, and decide what works best for you from there.
No Witnesses....
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Howard Burns
- Rookie
- Posts: 6
- Joined: Tue Jun 05, 2007 12:53 pm
rattle
You are right on target. Thank you for your patience in getting the message through my block head. Boy, did it sound like it was coming from within the engine. Thank you so very much for sharing your experience and knowledge.
