Any MotorBikers here suggestion needed pls

  tein 13:20 11 Sep 2009

Hi everyone! my brother in law has just bought a CBR600 1993 model BUT its only done 8k miles! its a absolute minter BUT there is a problem? The bike when ridden stalls when coming to a stop it kinda runs out of petrol?

He has had it in a garage & about 3 other people have had a look at it & none of them could locate the problem.? Today he forwarded me some photos of the manual that show he is in fact a breather pipe missing from the sump.? would this be the problem.?

He doesnt think the other people that looked at it saw this.?

Here are the manual photos of its location:

click here


click here

  Seth Haniel 13:21 11 Sep 2009

needs something to break the vaccuum.

  crosstrainer 13:26 11 Sep 2009

The problem is the fuel. I have posted links in the past of some of the stuff I have re-built over the years.

It's a question of valve hardening. Tell him not to run such a nice example on unleaded fuel (The additives won't work either...honestly)

Depends on where you live, but if he wants to use this bike on a daily basis, valves, valve seats must be hardened professionally.

If you want technical details, email me via the yellow envelope.

It's a classic...And worth spending the money on.

  Quickbeam 13:31 11 Sep 2009

Breather pipes, assuming no blockage, only direct fumes to vent, or be re-consumed into the intake side.

You say it's a '93 with not many miles on it, and I'm guessing it'll have constant velocity carbs on. It could be that the rubber diaphragms have age hardened. If it had done more mileage they would have been more flexible verging on being perished. So I would check them out.

  crosstrainer 13:33 11 Sep 2009

click here


click here

Still have manuals and stuff.

  crosstrainer 13:41 11 Sep 2009

Floats may be an issue, but the fuel is the real problem...The pictures in the link I posted above are of the last re-build I did...I had my eye on a Suzuki 1000GS but the valve and engine issues made part of it a "Non DIY" job.

The Honda in the pictures was not valve hardened when I sold it, but the purchaser was informed, and has long since had the job done.

Last I heard, he was using the bike everyday...As it should be.

  Quickbeam 13:56 11 Sep 2009

Another simple possibility could be if some one has stripped the carbs and not put the float bowl with the drillings for the cold start onto the correct carb. The Japs have the cold start drawing fuel from only one float bowl, and then use a connecting tube that links the other carbs to give the richer starting mixture. If that float bowl is on the wrong carb, you get no enriched mixture as there is no hole to draw the fuel through.

  Quickbeam 13:58 11 Sep 2009

That problem self cures when you switch the cold start off when the correct running temperature has been reached.

  I am Spartacus 14:02 11 Sep 2009

If it's been stored for a while the petrol forms a kind of 'varnish' in the tank but more importantly in the carburettors. A full strip down and clean might be needed.

  I am Spartacus 14:07 11 Sep 2009

Other sort of obvious things are to check the filter in the tank isn't gunged up and also that the tank breather hole isn't blocked.

The rubber diaphragms in CV carbs used to give me loads of problems in the 70's.

  crosstrainer 14:22 11 Sep 2009

Are valid suggestions for a short term fix....If the valve job isn't done, then the engine will die....

I know I'm being hard on this one (no pun intended) but it's a fact.

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