CBR600 problem.

My 89"CBR600 (23,000kms) has developed a huge hesitation if I crack open
the throttle anywhere in the rev range. It feels like I've hit the brakes
for half a second, but then takes off OK. It seems OK if I slowly roll on
the throttle. I'm thinking it is starving for fuel, and is a carbie problem
of some kind. I do use Optimax. They are CV carbies ! Any suggestions as to
what the trouble could be would be greatly appreciated, thanks guys. Alan *

 

Try hotter plugs

 

Bogging down them coming good on WOT ? I'd suggest those are symptoms
of too rich not too lean. Try swapping off Optimax back to ULP (Optimax
does tend to run richer).

I'm no expert on carbs, others here have much more experience, however
I'd be looking to things like float levels and worn needles and guides,
the air/oil cooled suzukis of that era were prone to ovalling (wearing)
the tube the needle ran in, and then giving poor throttle response
because of it. My Bandit had that problem.

Also given the age look to rubber components that should be holding
vacuum, I'd replace everything rubber if it were me. You can get cracks
that leak vacuum but are nigh on impossible to spot.

JL
(how the hell can you only have 23,000 Km on an '89 vintage bike ? I've
got more than that on a 2stroke !)

 

The first thing I'd check for would be a blocked air filter. The second
thing would be a blocked air filter.

After that it gets more complicated


G-S

 

Replace your air filter first.

You'll then need to check your fuel lines if they haven't been done in the
last 5 years as fuels like Optimax are known to cause the rubber to perish
at an accellerated rate due to the various aromatics used.

justAL

 

Someone stole your motor and replaced it with a 253 HQ donk.

Nev..
'03 ZX12R

 

Hiya Alan.
I had the same prob with my 2000 600 Hornet (Same Motor), I had the
carbs cleaned & balanced, didn't fix it completely, All that could be worked
out is that I had a bad batch of fuel & it took 3 or 4 tanks to clear it
out, It started happening the tank after my first & only tank of Optimax I'd
run in the bike, So it's also possible that that was the cause.
I've heard that the cleaning agents in Optimax can be quite harsh, maybe
that has caused some gunk or such to jam the jets in some way. I went back
to Mobil 8000 & never had the problem happen again.

My 3 cents.

 

Perhaps it needs to be ridden more often?

 

You're gunna have to split the cases.

 

Thanks for that advise. I will change the air filter, and also buy some
different fuel next.