Paging FOAK: Bandit power issue (after service)

Hello all.

I've just ridden my B6 home after getting it serviced (not at THAT
garage, this time) but all is not cured.

It wasn't running as it should have been before the service (explained
later) and the Shoppe have replaced the plugs and one of the leads and
done everyone usual on a full service but I need some advice on what I
should point them towards tomorrow.

They described my problem as 'running a bit fluffy low down' and
suggested I replace the rear baffle in the exhaust. While I
understand their suggestion the bike has had that baffle removed since
just after I received it and it only started to go downhill power-wise
quite recently.

When chugging along up a hill it will appear to get behind on the
power (if that's the phrase to use) and will then give medium length
spurts of power and then they'll drop off a bit and come back. I
thought the problem might have been carb related and they say that
they've cleaned the carbs out. When going around a corner on a bend a
brief unexpected spurt of power is not ideal. Before this started the
power was delivered consistently.

Another symptom is theat when I go up a steeper hill the machine will
seem to lose a bit of power then the spurts of normal power are a bit
shorter and may occasionally be accompanied with a pop (Like a
mini-KSB) from the exhaust.

Should I point them in any general direction tomorrow?

 

Its fucked - 50p, final offer.

 

BGN wrote

<snip> what sounds so much like a fuelling problem it has to be.

Reproducible symptoms is all you can offer them that will be of use.

 

Thanks Steve & Ginge. I felt that it was/is a fuel problem too. I
will speak to them again tomorrow and will ask them if they're very
sure that the fuel filter(s) have been changed (will also ask them to
have a look in the tank to make sure there isn't any shit in there
either) and point them towards the nearest hill so they can ride it
up.

Ta. What do you think may be causing the mini-backfiring, out of
interest?

 

BGN wrote

A coil on the way out can do it, lean burn also does it.

 

Air leak in to the exhaust system, but that would tend to be on the
overrun not under load.

I suppose an air leak on the intake side could cause a lean mixture and
the symptoms you describe. Don't know much about new-fangled fours, but
all the other bikes I own have rubber intakes that the carbs push in to.
If one is a tad loose and a bit of air is leaking in that might create
these symptoms.

I have had it on a Morini, and I have to confess that an early shake
down ride on the Voxan included making adjustments in a lay-by to a
throttle body that was skewif as a result of a loose jubilee clip.

Unlikely on a four though as I assume all the carbs are clamped together
somehow so just one couldn't start to pop out.

That leaves fuel starvation. a blocked jet or as suggested incorrect
float level causing a lean mixture as the most likely cause.


--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

A sudden thought. If the baffle in the silencer was taken out back in
the balmy days of summer a bit of leaness thus caused might not be an
issue then. Given the colder weather it may now be sub-optimum enough
to give hesitancy.

It is amazing what difference a slight change in exhaust back pressure
can make sometimes make.

Doesn't really explain the 'surging' though.

 

<snip>

These indicate float height imo, although you can never be sure with
the black art of carburation.


--
Krusty
www.MuddyStuff.co.uk
Off-Road Classifieds

'02 MV Senna '03 Tiger 955i '96 Tiger '79 Fantic Hiro 250

 

This morning before my journey to work I bolted the baffle back in.

Journey to work = No power issues in 30mph town roads
Journey home = No power issues in town or at 130kmph up a hill in the
cun'ree.

Mind you, after my scream back from Rye last night which took about 30
or 40 minutes when I got back to my local towns it didn't have
problems at low revs.

I had filled up on the journey out with BP Ultimate (by mistake, at
£1.05 a litre) but doubt that any benefit at all will be had from it
in such a short time by such an engine unless it has uber cleaning
power on just a 70km run.

 

Good and hot then so able to tolerate a bit of leanness. Or, there was a
bit of shite somewhere that has been passed like a kidney stone. Reserve
judgement until it has done a few more journeys without recurrenc of the
problem.

Unlikely, although I have to admit the Tart seems livelier on it.

If you want to run with the baffle out in winter you could try
re-jetting. You can get in an awful mess with that though if you are not
skilled in the arts and don't want to pay for dyno time. Plus, being a
four it is 4 x the cost of a nice single - there Champ a definite plus
point for singles ;-)

Might only need the idle jets upping a size, or the slow running mixture
screws fiddling with (if the carbs have them). Is it worth the hassle
for a bit more noise and not a lot more go?
--

+-------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest Yamaha WR250Z |
| Gilera GFR Moto Morini 2C/375 |
+-------------------------------------------------------------+

 

Pete Fisher wrote

Typical half arsed fucking fixers of things and their fucking partial
solutions. Fucking useless you are.

....and then remove the baffle and see if the problem returns. If it does
then the cause is identified. If it doesn't then it is still there,
just lurking.