Help with running problem!

The 2001 Bandit 1200 has developed a rather strange problem. It feels like a
fuel problem (as if it is running out of fuel and stuttering at low revs)
but sounds like an electrical problem as the exhaust note as a fairly
consistent misfire noise.

This is the list of checks so far:

I have checked the air filter - all ok.
Good quality fuel used.
Choke operation ok (not sticking on)
All plugs (new) have a very sooty look to them which suggests rich running.
All cleaned up and replaced. Spark check seemed fine.

I first noticed the problem some weeks ago after refuelling - after 30 miles
or so when the level dropped the problem would go. This led me to believe it
was an air vent problem from the tank but I have also checked this.

Recently the problem has got worse and takes more miles to go (after filling
up). Today, on leaving from work, the bike wouldn't idle and was restarted
several times - it ran like a pig the couple of miles home so I kept the
revs up and this helped a bit. On geting home the ehhaust downpipe on no 4
cylinder was definately cooler than the other 3. I took it out for a spin
after the above checks and it is better but still a problem below 3000 revs.

I'm beginning to suspect coils? Any views?

Cheers,

Mark

 

My old GPz305 wouldn't run below around 3000rpm and wouldn't idle.
Apparently there were two windings in the coil(s) - one for low engine speed
and another for high. I don't know if this system is used these days but
your bike's symptoms reminded me of it and a new coil cured it.

Si

 

Mark wrote:

If it's running rich, could the float valve be stuck open?

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Is there an easy way to test this with the carbs in place?

Mark

 

Yes. Turn the tap to "prime" and check if petrol is pissing out
of the overflows.

 

Eiron wrote

I'm wondering if it is already but don't know that particular bikes
plumbing arrangements.


Talking of petrol and fuel and stuff I have got 150 miles so far out of
this tank on the bindit, that's not right is it? I should be getting
what 110? 120?

 

steve auvache says...

http://www.bio.utexas.edu/courses/stuart/specs.html

Says the 1996 Bandit 600 has a 5 US gallon tank and does 44mpg. So you
do the maths. 150 is ok, but I wouldn't expect to get 200 from a tankful
on a 50K mile engined 1998 bike.

 

Lozzo wrote

Loz if I got 200 from it I would be so fucking ashamed I would cry.

 

steve auvache says...

I used to regularly get 200 miles to a tank from my 2nd black ZZR1100,
on 100mph plus runs to Scotland. That was a really economical bike to
use on long distance trips.

 

Hmm, coming back from EOSM on the Zephyr I ran out on the M40 at about
130miles.

It's a tad thirstier than the old CB500, and obviously Mr Kawasaki had
improved his engines somewhat by the time they built the ZZR (is the ZZR
engine a completely different beast from the Zephyr apart from the obvious
water cooling).

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M'boy's bike 2003 Honda NSR125R
Spare Bike 1990 Suzuki TS50X
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Dan L says...

The ZZR engine is a completely different beast. It wasn't just a Z motor
with water cooling, it was a totally new development.

 

No fuel filter on the B12. I switched the tap to prime and the fuel pissed
out so I checked the needle in carb 2 as that was where the fuel came from.
Put it all together and went out for a ride and within 20 miles it was crap
again - this time fuel is pooring out of the carbs. I must have a bad couple
of racrs after some crap petrol?

Anyway Sunday now looks like a day of taking the carbs out completely and
checking them through. I "hate" the hassle of trying to get the throtle
cable reattached to the carbs - took me about an hour last time.

One thing that is still puzzling me - why would all 4 plugs be carboned up?
Would that indicate a problem with each carb? What are the chances of that?

Mark

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Mark

Not as good as the chances of your air filter being blocked.

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There is, but it is inside the tank.

If petrol is pouring out of the carbs, you must have a load of grit
(for example) jamming the float valves open.

You need a pair of bendy long-nosed pliers and the skills of a trained
proctologist.

Remote - unless it is as I suggested above or similar. If you have
checked the air filter and it can't be that, have you checked the
airbox inlet (the infamous 'snorkel') is clear?

Something that does affect B12s is the pipes that run across the top
of the airbox - well, they are supposed to run alongside it - getting
squashed under the tank. This can cause the problem you describe -
have the tank off and check.

 

It also ate a nylon cog deep in its innards which required me to take the
engine completely to bits, which I really enjoyed, actually.

These were just two of the problems I found in the few days after I bought
it for...um...not very much, thankfully.

Si