So, I fixed the holes in the zorst...

....and ever since it's been a bit sluggish.

The Viagra, that is.

There were various holes in the collector box so I gunged them with silicon,
covered them all with thick exhaust foil stuff, splurged more silicon all
over to hold them in place, then painted the whole thing with silver
Hammerite. Do not paint your exhaust with silver Hammerite; it is not
heat-proof. Despite reading all the words on the tin and not finding any
that said "Ok to paint bike exhausts with" I still went ahead. Impulsive,
me. Stinky, my exhaust, and smoky too. It's turned a nice shade of gold
though, which is nice.

Anyway, having fixed all the holes and fitting lovely new exhaust gaskets I
noticed a certain sluggishness. Normally it liked to rev its nuts off at the
merest whiff of petrol but after being lovingly repaired and fettled the
cunty thing's revs increased like a diesel van and overtaking became so
leisurely I could look into car windows to see how fast I was going.
Adjusting the mixture screws out (making it richer, hopefully; correct me if
I'm wrong) made it a little better but it still made the BORRRRRRRRRRRR
noise on full chuff and wasn't 'right'.

Today I removed the exhaust again, scraped off all the Hammerite and
silicon, thinking the box might be full of squidged-in silicon, restricting
the flow of the gases. Nope, not terribly. Bollocks. Dunno. I've fixed the
holes properly now but was tempted to leave them open to see if it improved
things! The exhaust ports are a bit black and sooty so I suppose it's
running rich. When the repairs have set I'll see if it's all back to normal.

Gotta love old bikes.

This has been a slightly pissed public service announcement.

 

Ahhhh, righto. When I fling it back on I'll weaken it to one turn out and go
from there.

Definitely not, I know for a fact that it is utterly unfettled, carb-wise.
I'll see what happens tomorrow before further investigation.

 

I'd have left the carbs well alone - bodging up a few holes in the exhaust
won't cause for something to go as flat as it sounds this has.

My first port of call would be to check to make sure that a big lump of rust
/ carbon or whatever hasn't come adrift when the pipes were removed, and
made its way up inside the exhaust, causing a blockage / restriction.

Seen this happen before, admittedly on an MBX50 which had a big chunk of
carbon do the above when dislodged by the fat fecker riding it laying it
down unexpectedly whilst traversing a roundabout.

I'd also reset the mixture screws to where they were originally, and whip
the plugs out and clean them, before going much further.

--
JackH

98 Honda VFR800FiW
05 Sachs Madass
03 VW Passat TDI Sport
89 Vauxhall Nova 1.3 Pearl

 

Hang on: are you adjusting the idle mixture screw on the carb or some
top-end or mid-range mixture screw that I've never heard of?

If the former then it'll have sod-all effect on overtaking.

What colour are the plugs *immediately* after a moderate-speed run?
Exhaust ports are often sooty on lower-performance engines.

Are you sure it's not just the illusion of sluggishness caused by a
quieter engine? Or are you inadvertently using a different gear for
the same reason?

 

There are holes and HOLES. Does seem a rather extreme reaction I agree.

Did sound as if he had a look see inside already.

Oh, yes a two stroke piss quick ? That's why you had to decoke silencers
in the bad old days before posilube.

Indeed.

I was only suggesting a tiny bit of idle mixture adjustment unless a
known re-jet had been done at any stage.

Can't rule out something entirely different, possibly ignition
connection or similar, having been disturbed during the refitting
process.
--
+----------------------------------------------------------------+
| Pete Fisher at Home: |
| Voxan Roadster Gilera Nordwest * 2 Yamaha WR250Z |
| Gilera GFR * 2 Moto Morini 2C/375 Morini 350 "Forgotten Error" |
+----------------------------------------------------------------+

 

The pilot screws.

It did strike me as odd that it ran very well until I patched up the holes
in the exhaust box and put new gaskets in. It feels as though the exhaust
gases can't get out quickly enough. If I accelerate slowly the revs pick up
well enough, but full chuff seems to bog it down. The air filter was clean a
few hundred miles ago but I'll check it for bunged-upness.

I'll have a squint in a bit.

No, it's definitely turned into a bit of a slug, though I take your point
about the quieter exhaust. It used to rev up to the limit very happily but
doesn't like to now.

<Sigh> Take the bugger to bits again!

 

Sounds like it. I'd be interested to hear what the problem was.

 

Well, I haven't taken it to bits yet because it's running fairly well now,
but I don't really know why. I think it was a combination of one exhaust
gasket not being completely central, or being squished out of central,
IYSWIM, and a fairly large lump of sooty silicon living inside the exhaust
collector box. I've set the pilots to what they should be now and it feels a
lot better, but not 'perfect'. ICBA to take the carbs apart now, not until
summer, as I'm lacking a nice warm garage, so it'll have to do as it is over
the winter. I fucking hate winter with a passion.