M900 Cutting out

[CarloL]

Hi

1997 M900

Cold Monster keeps cutting out even with the choke on , got it to idle after it warmed up and with some persistent throttle to stop it dying , but if you give her too much throttle she cuts , feed throttle and slip clutch it cuts , on a hill she instantly cuts if you try to put load on the engine , new plugs ,oil and oil filter , fuel filter about 100km ago

any Idea's ? Fuel related ?

I did notice rust sediment in the old Fuel Filter

Any advise on how to approach this , test procedures?

Fuel system cleaner , redex type products?

Carb needs cleaning ?

thanks

blob:https://web.whatsapp.com/1d45d986-628b-4f8a-9d7c-c32c09771cf9

[utopia]

The rust sediment sounds a little ominous but ...

At this time of year, are you sure its not carb Icing ?
A dose of ProFST in the fuel should sort that.

Back to the rust, it might be worth draining the floatbowls and seeing what comes out.
You may even have water in there, in addition to further rust sediment.

I might also be inclined to drain (or at least siphon and flush) the tank.
Again, you might even find water in there, perhaps from condensation during storage.

Anything to avoid having to strip the carbs out completely really.

Further along ..... fuel pump could perhaps be an issue.
I'm told that they don't like standing idle for long periods as the diaphragm can dry out and perish.

For my money, first job drain floatbowls, maybe also flush tank, and also try some ProFST.

[Dukedesmo]

As above icing is a possibility but I had similar symptoms on my Moto Guzzi last year, it would start and run fine but would cough and splutter at high RPM under load.

I took the float bowls off and they had small bits of tank rust/sediment/water in them, not a lot and not enough to block anything fully but enough to kill the main jet when sufficient pressure was pulling them up the spout.

Fortunately cleaning out the float bowls on a Guzzi is only a 5 minute job, given their outboard location - takes a bit longer on a Monster but then a Monster does have a proper filter so a less frequent operation.

[Darkness]

How old is the fuel?
That sounds a bit like "gone off" petrol with ethanol in it.
Try syphoning the old stuff out and replacing with some nice new Esso Super Unleaded.

Edit: Can you still get ethanol free petrol in Dublin?

[CarloL]

How old is the fuel?
That sounds a bit like "gone off" petrol with ethanol in it.
Try syphoning the old stuff out and replacing with some nice new Esso Super Unleaded.

Edit: Can you still get ethanol free petrol in Dublin?

Thanks

Bike is used 5-6 days a week , I only filled up the fuel about 2 days ago, she was running great after I serviced her

Maybe the low tank of fuel caused the fuel pump etc to clog up

you can only get 95 crap here , all petrol is obligated to have 7% ethanol

[CarloL]

As above icing is a possibility but I had similar symptoms on my Moto Guzzi last year, it would start and run fine but would cough and splutter at high RPM under load.

I took the float bowls off and they had small bits of tank rust/sediment/water in them, not a lot and not enough to block anything fully but enough to kill the main jet when sufficient pressure was pulling them up the spout.

Fortunately cleaning out the float bowls on a Guzzi is only a 5 minute job, given their outboard location - takes a bit longer on a Monster but then a Monster does have a proper filter so a less frequent operation.

The rust sediment sounds a little ominous but ...

At this time of year, are you sure its not carb Icing ?
A dose of ProFST in the fuel should sort that.

Back to the rust, it might be worth draining the floatbowls and seeing what comes out.
You may even have water in there, in addition to further rust sediment.

I might also be inclined to drain (or at least siphon and flush) the tank.
Again, you might even find water in there, perhaps from condensation during storage.

Anything to avoid having to strip the carbs out completely really.

Further along ..... fuel pump could perhaps be an issue.
I'm told that they don't like standing idle for long periods as the diaphragm can dry out and perish.

For my money, first job drain floatbowls, maybe also flush tank, and also try some ProFST.

Thanks!

Will do , I want to POR treat the tank this summer

She was on low fuel light so I reckon the fuel pump picked up all the crap

Wahts the best way to clean out?

[slob]

... I only filled up the fuel about 2 days ago...
When did the problem start? ...Duff batch of fuel?

When was the air filter last cleaned/replaced?

What do the spark plugs look like?

Igniter box(es) or coil(s) failing?

[CarloL]

When did the problem start? ...Duff batch of fuel?

When was the air filter last cleaned/replaced?

What do the spark plugs look like?

Igniter box(es) or coil(s) failing?


The only thing that changed is new fuel

Will take the plugs out and check

Air filter is as new, 5 month old K&N

[slob]

Drain the tank and floatbowls, stick a gallon of fresh in. If that fixes it get rid off the duff stuff a pint/per tankful in a car (if you have one)

[CarloL]

Thanks lads

I had a look online and youtube , how do you drain the floatbowls, I comprehend via the screw but where is it on the bike , under the airbox

What exactly is a floatbowl, used for?

[Darren69]

A floatbowl is used to regulate the fuel flow into the carburetpr and also to maintain fuel height/pressure in the main jet and venturi which will affect the air/fuel mixture.

[CarloL]

Thanks Darren , every day is a school day

all I can see is the ball cock in the Toilet tank :P

[CarloL]

With a K&N Filter and Termi's , do you guys get the bikes fettled ? Carbs re-tweaked?

[Darren69]

Thanks Darren , every day is a school day

all I can see is the ball cock in the Toilet tank :P

Yes similar principle, it stops and starts the fuel from flowing and more importantly maintains a constant head of fuel available for the main jet, if the pressure/level varies too much then too much or too little fuel will be sucked in.

The engine will still run with air box and exhaust mods but may well be weak or not ideally setup which may cause heat damage. or running issues, flat spots etc. So tuning is advisable and a dynojet kit with modified jets and needle will ensure more accurate fuel control and better performance all round.

[CarloL]

Thanks Darren

One of the lads said this is a great site for the Monster , how to do mechanics

http://www.ducatisuite.com/basicmaintenance.html

[CarloL]

Was trying to figure out issue with the monster today , fuel pump works , bleed the float bowls, full of petrol (no water) , spark plug gap needed attention , set to .65 as per manual , still choking out with throttle, fie out the exhaust, pops N bangs from over fueling

I could not find the little gauze filter in the fuel line where it joins the T-piece between the carbs.

https://www.youtube.com/watch?v=g8_5VA_Y_kM

This was on top of the cylinder head , what ever it is , dropped down when I put it on its side stand

https://i.imgur.com/VPRel4Jl.jpg

https://i.imgur.com/L4D2Zh8l.jpg

https://i.imgur.com/uDdKrGCl.jpg

https://i.imgur.com/J7fieKSl.jpg

https://i.imgur.com/Syo7d4Pl.jpg

[slob]

Your mystery item looks like one of the rubber buttons that live between the cylinder fins to stop them ‘ringing’ at resonant frequency. they start out light grey and soft but end up hard and almost black.

[CarloL]

Your mystery item looks like one of the rubber buttons that live between the cylinder fins to stop them ‘ringing’ at resonant frequency. they start out light grey and soft but end up hard and almost black.

Thanks! One of the lads said the same

[Dukedesmo]

Your mystery item looks like one of the rubber buttons that live between the cylinder fins to stop them ‘ringing’ at resonant frequency. they start out light grey and soft but end up hard and almost black.

Indeed it does.

When I repainted the cylinders on mine - I took all of these out, don't know what difference they make to the noise? but best gone IMO.

[Darren69]

That's almost certainly what it is. I had them on both my 750 and 900SS, they don't do much if anything at all really, except drop out especially if you have open pipes. Its probably some long forgotten EU regulation?