CB500 bogging down at high revs

multijoy · World Chat Champion Joined: 03 Oct 2008 Karma :

Title sums it all up, really!

Runs fine, generally, but when you get to 8500 rpm or thereabouts, it just bogs down and loses power till it drops back below.

First guess would be carbs (which, being inept with a spanner, I've not ventured near!), backed up by the problem being improved by dumping a load of redex into the tank. Anything else I could look at before I take things apart?

Cheers,
Rich
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Check your air filter.

Change the sparkplugs.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

multijoy · World Chat Champion Joined: 03 Oct 2008 Karma :

Air filter it was!
Somehow there was some oil in the airbox, which is probably a symptom of something else even more worrying. In a short term bodge, I reseated the air filter, made sure the seals were tight and it seems to be significantly improved.

So, the question is: should a CB500 air filter be oiled? And, if not, any thoughts what might be putting it in there?

Ta,
Rich
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

evoboy · World Chat Champion Joined: 20 Aug 2009 Karma :

Could of possibly overfilled the engine with oil and its overflowed through a breather into the airbox..

multijoy · World Chat Champion Joined: 03 Oct 2008 Karma :

That was my first thought, actually! I didn't know if it could be that simple...

Not that I'm a pessimist or anything Shocked

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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

the grim reaper · World Chat Champion Joined: 29 Jun 2005 Karma :

Keep an eye on the oil in the airbox, it could be that the crankcase breather seal has gone.

Cheers

Grim
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Adverts don't always work: Remember that advert, where the army are running across the desert and they have a wounded man on a stretcher. They get to a ravine, the bridge is down and a caption pops up that says, 'What are you thinking?'. I don't know about you but I was thinking, 'Christ, I'm glad I'm not in the f***ing army'.