1998 M900 Problems

The bike is quite a pain in the ass because it did broke down the road 3 times in a row ..it does something strange and i'm in the progres of finding out (without any luck ) . Wheen its on full working temp and during the city drive it starts to stals and dies ...it doesent starts or it just spins the starter.. when it starts the revs are so slow (and a huge smell of gas on the exhaust )because the oil pressure lights flickers. When you try to accelerate it instant dies. If you chouse to start it on choke it will start will rev high but again will die if u accelerate it. If you let the bike cool it self down it will work like a dream...when i drive it in the mornings from home to work 25 km it gows superb and with no problems at all..did changed oil + oil filter , air filter , spark plugs fuel filter and did mount an additional one from pump to cabrs (tank is rusted inside )....dono what can couse this madnes i love the bike it drives superb when its not doing any problems..engine is healthy and puls nornal..my gues is that the coils ore the ignition controlers are overheating and causes this madness , i dont blame the carbs because if they where a problem they shuld give this problem anytime, again lets say vacum but i shuld had this problem permanent ...its the only thing that can cause this problem...coils and coils contorlers
What do you guys think ? Thanks
PS dono where to post on engines or electric...dono where my problem goes in.

[350TSS]

Welcome, I think your analysis is correct - poor running only when hot is probably electronic related, coils, exciter boxes (next to the coils) or ignition pick ups (located in the alternator case).
The only other possible cause I can think may affect running when hot would be too tight valve clearances. Checking this should not cost anything (unless you find them out of tolerance and need to buy replacement shims) but is a bit fiddly and time consuming. There a plenty of videos on youtube on how to do it. If the clearances are in tolerance then that can be eliminated as a possible cause.
If you have other Monsters then it would be worth swapping compatible components on the 900 with known working ones on one of the other ones that will narrow down which bits really do have to be bought as replacements.
If you do need new coils Exactfit UK do higher output ones (same as California cycleworks) for a reasonable price compared to Ducati originals

[Flip]

I had a similar issue on my carby 900- exactly the same symptoms you describe- only on very hot days (we get a few in the UK) and usually when in heavy traffic which is not my normal riding environment.

It turned out to be a fuel vapour lock caused by the deterioration of both the vacuum fuel tap and the vacuum fuel pump diaphragm. The fuel pump is re-buildable but the tap isn’t so needs to be bought as a replacement Ducati part.

While I was doing that I also replaced all the vacuum and fuel supply hoses so at the very least it would be worth checking for any cracks or splits in those as the vacuum pipes would also not help the pumps supplying enough fuel to the carbs.

Originally Posted by Flip

I had a similar issue on my carby 900- exactly the same symptoms you describe- only on very hot days (we get a few in the UK) and usually when in heavy traffic which is not my normal riding environment.

It turned out to be a fuel vapour lock caused by the deterioration of both the vacuum fuel tap and the vacuum fuel pump diaphragm. The fuel pump is re-buildable but the tap isn’t so needs to be bought as a replacement Ducati part.

While I was doing that I also replaced all the vacuum and fuel supply hoses so at the very least it would be worth checking for any cracks or splits in those as the vacuum pipes would also not help the pumps supplying enough fuel to the carbs.

Thanks for the info i will check the tap and the pump , as i see here the pump looks like it was rebuild i see new gasekets inside it..just a remark dono if it has to do with my problem but every time this happends my fuel tank is at the half of petrol inside...if i top it up its working sometimes but this time i did filled it up and did like 2kms and died again without any chance to start it...

Originally Posted by 350TSS

Welcome, I think your analysis is correct - poor running only when hot is probably electronic related, coils, exciter boxes (next to the coils) or ignition pick ups (located in the alternator case).
The only other possible cause I can think may affect running when hot would be too tight valve clearances. Checking this should not cost anything (unless you find them out of tolerance and need to buy replacement shims) but is a bit fiddly and time consuming. There a plenty of videos on youtube on how to do it. If the clearances are in tolerance then that can be eliminated as a possible cause.
If you have other Monsters then it would be worth swapping compatible components on the 900 with known working ones on one of the other ones that will narrow down which bits really do have to be bought as replacements.
If you do need new coils Exactfit UK do higher output ones (same as California cycleworks) for a reasonable price compared to Ducati originals

Got my self a multimeter and i'l mesure the coils problem is that on cold i might get good readings...need to heat them up so i see if the stil got the rezistance.

[slob]

Like 350TSS says, try the coils from your 600

[Darkness]

Originally Posted by Alexandru

Thanks for the info i will check the tap and the pump , as i see here the pump looks like it was rebuild i see new gasekets inside it..just a remark dono if it has to do with my problem but every time this happends my fuel tank is at the half of petrol inside...if i top it up its working sometimes but this time i did filled it up and did like 2kms and died again without any chance to start it...

If the problem reduces when the tank is full, that suggests it is connected to fuel flow and pressure. Have a good look at the condition of pipes and hoses like Flip suggests, and try swapping components with the 600 to see if the problem swaps bikes.

Good hunting!

[Darren69]

Maybe having the extra fuel filter in there is a problem? I've had problems with fuel flow through these before, so maybe try without it.

Originally Posted by Darren69

Maybe having the extra fuel filter in there is a problem? I've had problems with fuel flow through these before, so maybe try without it.

Had the problem without the extra fuel filter so i dont think from there is the problem because when its cold the bike runs normaly so that filter there is oky.

[Darkness]

When the engine dies, have you tried opening the fuel filler to make sure it isn’t making a vacuum in the tank? Blocked vent pipe allows normal running initially, then progressively leaner at larger throttle openings, till it won’t run at all.

[Darren69]

I was just gonna suggest that actually, it's got to be something like that causing fuel starvation. What would cause the smell of gas though? if ignition coils can break down with heat but would it be likely that both do the same thing? I mean I had a coil stick on my S4 do it and it would just drop onto one cylinder when it got hot but other than the loss in power it was still able to run ok on one cylinder. Ignition pickups faulty would affect both I suppose?

Originally Posted by Darkness

When the engine dies, have you tried opening the fuel filler to make sure it isn’t making a vacuum in the tank? Blocked vent pipe allows normal running initially, then progressively leaner at larger throttle openings, till it won’t run at all.

to be honest i didint do that thing i'm to tired to push the bike to home every time it breaks down the road and always far away from home , i will do tests in the weekends if its sunny now we got some rain...unfortunately iv discovered that my frame is bent as well so this news kinda droped my moral on the bike...i allways wanted a dry clutch monster and when i found it ( here in romania they are so rare that when i searched for this model there where only 2 models this prick that i got and a 97 model thats it)...but i was blinded by the strong wish and happynes that it ended up to be a mess bike...

Originally Posted by Darkness

When the engine dies, have you tried opening the fuel filler to make sure it isn’t making a vacuum in the tank? Blocked vent pipe allows normal running initially, then progressively leaner at larger throttle openings, till it won’t run at all.

On the 600 i had a different problem when it was warmed up it was running way to rich on gas when you tried to leave the stop it wuld stal , when you where on crusing it was shaking bad and i ended up breaking the carbs changed the gaskets , cleaned them spotless and discovered that the cabrs membrans where distroied and that was the reason for my problems asambled them back bought a balance cabr clocks tools and its runing perfect ...ohh and i forgot i changed the metal tank to a carbed plastic one ...to much rust inside.
The m900 fuel tank is distroyed inside its full of rust and weleded at the lower mounting point where all of them rust or starts to leak cuz of vibrations..

Originally Posted by Flip

I had a similar issue on my carby 900- exactly the same symptoms you describe- only on very hot days (we get a few in the UK) and usually when in heavy traffic which is not my normal riding environment.

It turned out to be a fuel vapour lock caused by the deterioration of both the vacuum fuel tap and the vacuum fuel pump diaphragm. The fuel pump is re-buildable but the tap isn’t so needs to be bought as a replacement Ducati part.

While I was doing that I also replaced all the vacuum and fuel supply hoses so at the very least it would be worth checking for any cracks or splits in those as the vacuum pipes would also not help the pumps supplying enough fuel to the carbs.

I have read ur topic/post it might have sens. Because the simptom is happening when i leae from work on 27 ° and imagine that the bike temp get high plus the trafic it gows realy high my legs dont like it...in the mornings it does reach the operating temp (its still a 25 kms drive ) but due to low temps and the fact that the trafic is lighter it doesent do the problem.

Originally Posted by Darkness

When the engine dies, have you tried opening the fuel filler to make sure it isn’t making a vacuum in the tank? Blocked vent pipe allows normal running initially, then progressively leaner at larger throttle openings, till it won’t run at all.

See the front fender how close is to the engine cover...mesured from the center front shaft to the rear of the center shaft and i got 1380mm manual sayes 1430 mms so 50mms difference...front wheel is not origininal except that all parts are factory m900 from 98...