Strange behavior lately..

[Wildfire]

Since acquiring my 95 M600 and having a bit of a go at it:

Drained and cleaned tank
Cleaned and synched carbs
Changed the belts
Changed the oil

All has been running well. until last week. The bike was going fine and the weather was getting a bit colder so I thought I would fill up with Esso Super Unleaded for a bit more of an easy time as the temp dropped.

The next day I started having issues with idling. The bike's idle began dropping lower and then stalling. By Thursday it was running on 1 at low revs. I checked the plugs and found it running very rich. Plugs were black and fouled, so I gave them a clean.

I left it in the garage at work over the weekend, went to start today and the verticle cylinder wasn't firing. I swapped the plugs and they both fired. 2 miles down the road and I lost a cylinder. Made it to my parents to find the plugs totally fouled again.

Cleaned the plugs totally, bike fired first time and I made it home with no issues.

Any ideas as to what is happening? I've leaned off the idle mixture by half a turn, but am still concerned as to why after 3000 miles the bike has started playing up.

[utopia]

At this time of year, the first thing I'd do is dose the fuel with pro.fst.
The more expensive fuels don't seem to do much to prevent carb icing on my 750 (and neither do the electric carb heaters). Only pro.fst seems to work, and sometimes it needs a double dose.

[gary tompkins]

Yeah that ^^^^

http://www.opieoils.co.uk/p-809-silkolene-pro-fst-fuel-system-treatment-for-petrol-engines.aspx

Cold weather and mikuni carbs on 600's are not a good combination

[Wildfire]

Would carb freezing cause the rich running?

[Magic1971]

Did you dismantled the carbs to clean them

[Unit 18]

Would carb freezing cause the rich running?
Yes it does.
This explains what happens, http://www.caa.co.uk/docs/33/ga_srg_09webSSL14October.pdf

[gary tompkins]

I've had the throttle stick full open on the M20 due to carb icing on my 600

It can be a serious and dangerous issue during the winter season

[He11cat]

I was cursing the other day my bike wouldn't idle then ran like a sack of.......

Then the penny dropped "Its Pro fst TIME!!"
Wish their was an equivelent for humans

[Wildfire]

Right, got some ordered along with new plugs. Will retire the Monster in leiu of the Sports bike until the Pro FST turns up.

[Nickj]

I've had the 'don't want to shut off syndrome, can't make me' which is hairy when piling towards static traffic at 70 odd. It helps to have the cables really clean, I once found a blob of greasy crap had frozen onto the cables down by the carbs and was gumming up the works a bit
Practical experience says Shell V worked wonders on my old SS and the carbie moster. I go out in most any weather, if I can see road through the snow I'm good to go :banghead:
If I don't have any FST around then a 50:50 unleaded / V is good for most days .. cold and damp from say 10 down to -5C, any lower and just V does the biz. Yep the engine will be really happy at -8 but you need good gloves!!
Not sure what the differential on the cost would be, never bothered to sit down and work it out.

[utopia]

Practical experience says Shell V worked wonders on my old SS and the carbie moster. I go out in most any weather, if I can see road through the snow I'm good to go :banghead:
If I don't have any FST around then a 50:50 unleaded / V is good for most days .. cold and damp from say 10 down to -5C, any lower and just V does the biz.

I thought you'd say that, Nick.
I dunno why V doesn't seem to work for my bike, but when I did try it, it seemed to make no difference.
This was what led me to suspect that my electric carb heaters weren't working last year, but they checked out, as did the sensor.

Its perhaps worth emphasising what Nick says about temps....cold (+10 to -5) AND DAMP causes icing.....its the damp that does it, even if its not all that cold.

Agree with Gary....it can be bloody dangerous and is far from being a mildly annoying bit of character.
Even more annoying is the fact that my dominator, which has all of its 650cc sucking through a single carb, doesn't ever seem to suffer. It has an electric carb heater too, but maybe that one runs at a higher temp....I'll look into it.

I did do some quick calcs on the cost of double-dose pro.fst, and it makes your overall fuel costs considerably higher.

[gary tompkins]

There is a cure

It's called fuel injection

[utopia]

Yes, but that has its own issues re. extra complication and the potential for extremely expensive repair bills if a major component fails, as well as perhaps a more difficult diagnosis of any fault due to the complexity of the system.
For a long term ownership such as my monster will be, I'm happier, if a little frustrated, with my carbs.
And then there's my luddite tendency, of course.

Incidentally, I read somewhere that surgical spirit is an alternative to pro.fst. This may be a cheaper option, though I haven't tried it yet myself.
The dommie does most of the winter work anyway.

[Unit 18]

Couple of things, I was talking to a knowledgeable chap in the fuel industry and he said that petrol is now blended to make it suit fuel injection systems rather than carbs.
I think another problem with the carbed Ducatis is that the inlet manifold is so long that it helps insulate the carbs from engine heat, not that they would receive very much anyway.

[Wildfire]

Ok , Pro FST ordered, now ill so can't ride. Will try it next week. Hopefuly it will be better. Will report back.

[Wildfire]

Right! Pro FST has cured the running issues. It smells like some sort of IPA, used to use something similar to clean fibre optics. Seems that if you put 100ml into the tank with only 2 litres of fuel in the bike it causes flames, and lots of banging before completely clearing out the engine.

[gary tompkins]

About Silkolene PRO FST Fuel System Treatment For Petrol Engines

PRO FST protects against cold start wear and fuel system corrosion and helps to remove deposits from injectors, intake systems and carburettors ensuring optimum performance. It is very effective against carburettor icing in low temperature environments, and combats starting problems, stalling and rough running at low engine revs.



PRO FST may be used in leaded and unleaded fuel, for 2 and 4-stroke engines. It reduces the incidence of pre-ignition and also enhances the fuel’s octane rating to a small extent.

Dosage recommended mix ratio:- 1 to 2% of PRO FST in fuel. (100 parts fuel:1 part oil to 50 parts fuel:1 part oil).

[Wildfire]

Yes, I know. I topped up the tank with FST before filling up the bike. Still have a bit of a wayward idle, but that's it. Managed the commute this morning, covered in frost no issues.

[PETE.AKO]

I have a 2000 carb 750M had it 5 years now always ride through the winter !! the bike has K&N filter dyno jetkit fitted cut air box & Remus cans all the wrong things to things to make the motor run even colder !! the cold also makes the front cylinder run rich this also fouls up the front plug i always carry a spare plug !! i also use FST and Morey's petrol additive .Also heated grips hand protectors heated wast coat and two small spot lights so i can see in the dark !!the bike still runs like a bag of sh** till the temp comes up to +5 then all is forgiven!! And i just love it even after all these years !! very addictive and every one that has ago on the bike Says the same !!

[Wildfire]

Rode home last night, bike was a bit slow in the idle but other than that fine! I on the other had had ice forming all over me! But thanks to a base layer, micro fleece and my Hein Gericke GoreTex I was toasty. And my Keis heated inner gloves.

[utopia]

Glad you're sorted now.
For future reference, sustained periods of steady throttle opening, ie on open stretches and motorways, seem to be worst for causing carb icing.
Tickover is then erratic or impossible when you come to stop at a junction etc, until the heat rising from the motor has had chance to thaw things out a bit.
And as I said before, its the dampness rather than the cold which seems to be the major factor....dry cold days are not such a problem.

[urbanfireblade]

I can confirm super unleaded does nothing to help stop carb icing. I haven't tried Shell V-power, i'll fill up tomorrow and see/report back.
I'm firmly with Utopia on the carb vs injection, as crude as carbs are, when they go wrong its generally easy to identify the cause, and if all else fails, easy to swap out for another pair just like i did.
On a side note, its great to see peoples reaction when they watch you ride past them on a Ducati Monster when its minus 3! I've had some right looks to date. One of the reasons i love riding my Monster in the depths of winter! :)