Petrol in exhaust pipe!!

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Petrol in exhaust pipe!!

Postby Stubaker58 » 19 Nov 2019 16:51

Hi,

I’m gradually getting to grips with my ‘79 Sport.
I’ve cleaned the carbs, fitted the slides in the correct way round (second time around) and set them up ready to run and then be balanced. Even before cleaning the bike was a good starter, this continues plus I’ve now got it to idle. So some progress ... BUT ... on starting a worrying puddle of fuel appears under the front of the right silencer where it meets the pipe i.e. from the front cylinder. I should say that both the enrichment tabs on the carbs were up at the time so I shut the front cylinder tab and it seemed better so I set off for a short run. After a short time I shut the other enrichment tab and the bike seemed to run pretty well (considering that the carbs have only been set statically). When I returned after around ten miles I could see no evidence of any leaking fuel.

So what would cause this issue? And how can I best sort it out?

One other unconnected issue is that whilst out riding there was a noise, a sort of metallic drumming, which I took to be loose tinware shaking about but it stopped when I pulled in the clutch ... how worried should I be to look at the clutch?!

Thanks
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Re: Petrol in exhaust pipe!!

Postby mbmm350s » 19 Nov 2019 17:19

Hi,

Did you smell it as fuel? It could be condensation. Some silencers have a small drain hole, near the join of the pipes and the silencers are angled downwards slightly towards this point.

If its fuel, then i would suspect the carburettor float valve is not sealing, but in this case it would run very rich on idle or even flood the engine.

Mark
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Re: Petrol in exhaust pipe!!

Postby Ming » 19 Nov 2019 19:03

I get condensation dripping from one of my pipe / silencer joints when ticking over when cold, disappears when hot. It is water, though. Maybe you just have enough unburnt fuel in it to be able to smell it?
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Re: Petrol in exhaust pipe!!

Postby themoudie » 19 Nov 2019 20:06

Aye,

I would suspect condensation, as Mark and Ming suggested, unless it smells like unburnt fuel or burns when a lit match is applied to the wee puddle! Dinnae take your eyebrows off! :shock:

As for the clutch noise :?: It takes no time to whip the clutch cover off and check things over and check for play/endfloat in the clutch or wear. I hope that you find it all in order.

Good health, Bill
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Re: Petrol in exhaust pipe!!

Postby rossguzzi » 19 Nov 2019 23:51

They are a dry clutch so there is a little rattle to them.
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Re: Petrol in exhaust pipe!!

Postby Stubaker58 » 20 Nov 2019 11:06

Thanks Guys,

I may have jumped to conclusions about the fuel, I naturally assume my incompetence and having serviced the carbs thought I’d probably mucked it up, never considered water! Doh! I’ll check next time out.

Grandchildren permitting I’ll get the cover off and have a look at the clutch too.

Thanks again
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Re: Petrol in exhaust pipe!!

Postby mbmm350s » 20 Nov 2019 11:54

Grandchildren permitting I’ll get the cover off and have a look at the clutch too.


get them to help! :D

my dad taught me all sorts of things about engines when I was small.
#MissMorini on Instagram, who is primary school teacher, takes her Morini into school for the instruction of i bambini.

The clutch outer drum in Italian is the campana della frizione, and the campana or bell amplifies the noise,
the noise may appear to be from the clutch, but often is caused somewhere else.
And the Morinist stays awake at night with the concern that the primary drive nut on the crankshaft is loose.

Was the engine rebuilt? Has it been stored for many years?

Mark
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Re: Petrol in exhaust pipe!!

Postby 3potjohn » 20 Nov 2019 19:58

Water will drip out if the bike is not properly warmed up by a good blast and it can get into the oil too. You can remove the outer clutch cover and run the bike, but the clutch will make some noise until the lever is pulled in. You will hear similar on a Ducati.. You can always check the hub nut is not loose. If the plates and outer basket have some wear that will contribute to the rattle but it’s probably nothing to worry about.
John
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Re: Petrol in exhaust pipe!!

Postby Stubaker58 » 02 Dec 2019 15:13

Thanks for all the advice. Took advantage of the sunshine today.

It’s oily water that’s dripping from the exhaust so all good there.

I investigated the noise a bit more and tracked it down to the rear of the petrol tank resonating against the frame, a bit more insulating foam and it’s gone away.

Shake down run of fifty miles, carburation not spot on but good enough until I have time to adjust further. Main concern is the age of the tyres which made everything a bit twitchy especially on uneven surfaces and along road markings.

Overall pretty pleased, engine sounds/feels strong, gearbox is a delight and even the electrics were co-operating!

Thanks again.
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Re: Petrol in exhaust pipe!!

Postby Stubaker58 » 02 Dec 2019 15:22

2EFC6990-4DEC-4D9B-AB90-913445D572B3.jpeg
2EFC6990-4DEC-4D9B-AB90-913445D572B3.jpeg (142 KiB) Viewed 230 times
e

Mines the red one.
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Re: Petrol in exhaust pipe!!

Postby 44dwarf » 02 Dec 2019 17:39

If I remember correctly for every 1 gallon of gas burned, 2.5 gallons of water is made. So yes normal as others have said.
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Re: Petrol in exhaust pipe!!

Postby mbmm350s » 03 Dec 2019 10:04

Hi,

Nice picture, thanks for sharing. So glad the noise was something easy to fix!

If the insulation under the tank is the correct thickness then the line of the seat trim and the line of the tank pin stripes is smooth and continuous just like yours is, which makes it more aesthetically pleasing.

Mark
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Re: Petrol in exhaust pipe!!

Postby George 350 » 03 Dec 2019 23:34

Hi Stu,

Your tank noise has been discussed a few times over the years - my own favourite 'fix' is to use something like these https://www.discovolantemoto.co.uk/tank-frame-rubber-ribbed-991-p.asp
I,'m pretty sure mine were originally for an LC250 Yamaha.

George.
George
350 sport 1978, 350 Strada 1978
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Re: Petrol in exhaust pipe!!

Postby Stubaker58 » 04 Dec 2019 09:17

Thanks George, ordered!
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Re: Petrol in exhaust pipe!!

Postby 3potjohn » 05 Dec 2019 07:09

My K1 tank tends to resonate when the fuel level is low. I tried some frame rubber mounts and also grey water pipe insulating foam, and bath tap washers under the rear bolt to frame mounting.Not entirely successful.
John
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