Dear friends, Hello, i recently got my first ducati (monster 600, 2000'). I will write a quick question at first, and then if you want to read my full problem please read the rest. So, on the carburator there are two caps for the Adjusting screws. The previous owner of the bike lost them. I am starting thinking that water could get into the carburator if the caps are missing. What is your opinion? **********MY FULL PROBLEM/STORY EXPLAINED************ As i said i recently bought my first ducati. It went straight to the service cause there was water in the tank for a while. My mechanical removed all the water and made a fresh clean of the carburator. After the service it was running quite good, except of a day that the road was wet. The engine stopped (like it run out of fuel). i called my mechanical and hopefully he was quite nearby and came to find me. At first we thought it was a electrical problem but then found out that spark plugs were good and running. So he thought it was the fuel supply(or something that involves the wet road). Finaly he made a quick check on the Fuel cock ( working ) and the pump ( working ). After that, and a blow at the pipe after the fuel cock, the engine could run again (weird). So after 4 mins of running i took the risk to go home ( about 8 min ride) and then decide to go another day to the service for a full check. To the way home it did it again hopefully a few meters before arriving home (wet road again). The next few days it run fine ( i just made a ride to check if the problem was temporarily fixed ). Nothing weird happened ( it was a sunny day ). Today, i took the risk again to ride in a rainy weather for a little night ride, and after 5 mins it happened again... hopefully (again) i was nearby a friend and asked for a screwdriver, so i took out the pipe (outlet) of the fuel cock and blow inside. I also unscrewed the bottom screw of the carburator to empty the cup of gas(just in case there was water inside), only the first one, i couldnt reach the second. The motor started once again. It was enough to go home. Also a final question. I dont know what my mechanical will say, but you think its necessary to take out the carburator and clean it once again if water was present inside it? THANKS A LOT if you read it all! (and if not thanks again anyways).
The caps on the adjusters are to prevent corrosion, not water ingress into the fuel. If you are getting water in the fuel in heavy rain, I would check the water drain from the fuel filler aperture isn't blocked or pinched (squashed). Water in fuel is usually caused by contamination at the fuel station or condensation in your tank. Your carburettors have drain screws on the float bowls, you shouldn't need to dismantle them.
But its not happening on heavy rain. It happens even with wet road. So i guess its maybe from the drops that beeing splashed by the front wheel.
My Moto Guzzi Le Mans used to play up the same way - heavy rain, no problem; but fog or wet roads it would be an absolute sod. I changed points, plugs, leads etc, etc; cleaned the carbs; checked all connections; had the coils tested. Made sure coils and battery couldn't get wet. I was so fed up with it happening, I took the coils to a real auto electrics expert - after explaining the problem; he got a cardboard box and filled it with damp newspaper. Connected each coil in turn and sent a charge into them - brilliant blue light appeared up the outside of the coil body, tracking and shorting the damn things out. Changed the Magnetti Marelli coils for Bosch - problems gone.
Thank you for your reply Arquebus, You gave me another reason for testing. But i cannot explane the solution of taking out the outlet of the fuel cock, blowing in the pipe and boom, it started fine again. Some more thoughts , maybe there is a fuel cock or pump problem ( both seems to be working ) or can it be air trapped somewhere between fuel tank and carb?
I would of thought it more likely to be electrical than fuel.Although it could be a combination of things.It maybe worth letting your mechanic have a look for a few hours and check it out.
could be several things of course, does it stop altogether or drop onto one cylinder to start with? As suggested above, it's fairly normal for a two valve to short out front plug lead to head in constant downpour of rain and even more likely on a Monster or Elefant. I can remember stopping many times to experiment with plastic bags etc in desperation but finally found that pulling spark plug cap up as far as possible without it falling off was the best solution to get plug body as far away from head casting as possible. If this is the culprit then probably one of the many available ignition damp start sprays might help but not the sort of thing I carry on a journey.
Yes , it did. It started with the front cylinder first. I also tried to unplug the spark plug and leave it a little bit before getting out but nothing. Oh! I see now! If one cylinder is out due electric problem, ether the fuel cock or the fuel pump is not working! ( Cause they are not electric). Thats why it stopps the fuel supply!
Pretty sure Chris is asking this because fuel is likely to affect both cylinders equally, so if one cylinder dropped out first, the problem is almost certainly electrical and if the problem happened on a wet road but without heavy rain, it’s likely to be the front plug, plug-cap or plug-lead causing the problem because it is extremely vulnerable to spray from the road. The fuel pump is indeed electrical but will affect both cylinders equally. My suspicion is that your fiddling with the fuel supply is irrelevant except that it allowed time for heat soak to dry out the plug, cap and lead enough to allow the engine to start again.
If the bike is a 600 then it will be a Mikuni vacuum pump Jeremy, ( I.e. – not electric) but you’re thinking is correct about the plug having time to recover. You have got me thinking laterally Alkinoos, did it typically carry on running on one cylinder for a while when you stop riding and then eventually cut out totally? I will go and check but I think front cylinder is designated for vacuum takeoff for pump and I’m sure it’s true to say the vacuum would not be as strong on a non-firing cylinder. A real long shot this one, and possibly not correct or relevant.
Indeed, it goes for about half minute with one cylinder and then its completely gone. All these you are saying sounds really rational and started thinking that i have to search more on this side, except of the fact that when i blow into the fuel cock outlet the motor goes on again. This is the only irrational thing here. PS. Guys thank you all for your answers, they really helping me out!
As old rider said, if the drain hole in the aperture under the fuel cap becomes blocked (and without regular checking this is very common) then rainwater eventually breached the fuel cap seal and ends up in the tank. This is also common and not the end of the world in small quantities but this often then works it’s way down into the Mikuni fuel pump. Again, the pump will tolerate a certain amount of this, but this also leads to corrosion when it’s standing so this, together with the water can make the operation intermittent before it finally packs up. I would recommend you strip and clean. It’s a really easy job and if you go carefully you can reuse everything. Make sure you don’t reverse the plastic one-way valves and if the main transparent diaphragm has a pant in it, then flip it over the other way. Ditto for the fuel cock to some degree, might be worth investigating depending what you find inside the pump.
Re-: – blowing into fuel cock outlet tube, it could simply be that you need to prime the fuel pump again, it varies from bike to bike but this could often happen if allowed to run dry and that’s exactly what happened as the engine carried on running without the pump pumping. Next time it drops onto rear cylinder only, turn the engine off to stop this (almost certainly) happening.
thank you all for your help! i think that now its up to my mechanical. ( i tried cleaning the pump after the first time it happened ). I have to say that on the pump outlet, fuel is coming out but i cannot say if this is pumped fuel or just the tank flow ( with the cock working ). i dont really know how much flow does it have to be to say that the pump is working correctly. Also i checked that the front cylinder is for the fuel cock and the rear for the pump.
Has bike been running normally until the rain downpour problem? If so, then from what you added it does sounds as though the pump is just running dry when it runs on rear cylinder so needs re-priming each time.
As far as the previews owner told me it was running without any problem (he is a trusted person). The bike was sitting for 2-3 years. My mechanical told me that he found a lot of water in the tank. He cleaned the carburators and tank ( he didnt told me if he cleaned the pump). After the service it started also working normal for some days. i also been to a mountain ride with about 90% hydro without problems at the days after the service.
