cbr 600rr sounds like a chain saw at 7000rpm and up

GeordieFitzsimo · 08-15-2009, 1:26 PM

hey.. i have an 2007 cbr 600rr with little over 20000km on it it is making an load chain saw noise when i hit 7000rpm and up it is not the timing chain or the tensioners. there is also the same bike down at the shop that is doing the same thing but he only has less then 4000 km on it. i am thinking that it might be internal does anyone know what this would be?

MACI4LIFE · 08-15-2009, 1:40 PM

spun bearing maybe?

GeordieFitzsimo · 08-15-2009, 2:11 PM

thats what i was thinking just seeing if anyone else has had this problem casue i have 2 of them doing it

Sideshow bob · 08-15-2009, 2:42 PM

Is it only under hard acceleration or all the time?

GeordieFitzsimo · 08-15-2009, 5:39 PM

Quote:

Originally Posted by Sideshow bob

Is it only under hard acceleration or all the time?

it is all the time no matter what gear and in neutral

MACI4LIFE · 08-15-2009, 6:49 PM

taken from a honda auto messageboard. he seems like he knows what he's talking about.

You can have a mild knock that's only discernable at certain rpms.

The best way to check is when the engine is cold quickly *blip* the throttle so the rpms go up to about 2500 and as they descend listen for an accentuated *rattle or knock*. If you suspect this, with the engine idling, go to your spark plug wires and pull them off out one at a time if the noise goes away after pulling a spark plug then you know which cylinder is guilty.

If none of this applies to you then you probably don't have a bad bearing.

But if you do have a bad bearing, there is a possability that you can just replace the bearing without having to regrind/replace the journal. But of course you have to check the tolerances on the journal. If the journal needs to be lathed or replaced, you have a rebuild on your hands. If the journal is fine, you can (in certain cases) get away with just replacing the bearings.

An interesting thing that happened to me was my h22 started getting this 'cold engine knock'. I determined that the no.1 cylinder was guilty and dropped the oil pan. As I was preparing to remove the cap from the no.1 rod, one of the bolts literally fell out... checked the tolerances and everything was fine. So I just locktited the bolt and reinstalled it with stock torque specs.

What happened was the company I get my engines from check the bearings prior to selling the engines and someone didn't torque that bolt sufficiently! http://hondaswap.com/images/smilies/blink.gif

Anyways, the point is don't always assume the worst, check everything out for yourself. It takes about 2 hours for the layman to drop an oil pan so if you're really worried get in there and check it out.

Other problems could be:

1) Exhaust rattle

2) maybe even your ignition timing is too advanced and you're getting detonation (since you said you hear it when you get hard on the throttle right?)