Y2K M600 keeps misfiring
- Thread starter gallardo
- Start date
Starting up a carbed monster after a long layoff is always difficult.
There is no gravity feed of fuel from the tank. It relies on a vacuum operated fuel pump.
While its not being used, the petrol evaporates from the float bowls leaving them empty and the fuel pump then has to refill them before the motor will start.
This can mean cranking the engine on the starter for a long while. A very long while.
After a winter layoff on my y2k M750, I always fully charge the battery before I even try to start it but it usually requires so much cranking on the starter motor that the battery is drained very low and nearly always needs recharging before the carbs are refilled enough for the engine to start.
When it does start, it usually just runs on one cylinder at first, probably because that carb has a full float bowl but the other hasn't quite refilled.
The second cylinder kicks in eventually and then it runs fine.
After that first start up, it then starts immediately the button is pressed and runs cleanly.
This may be your problem.
After 25yrs I have recently wondered whether I should overhaul the fuel pump but the bike runs fine after the initial start up so I've left the pump alone for now.
There is no gravity feed of fuel from the tank. It relies on a vacuum operated fuel pump.
While its not being used, the petrol evaporates from the float bowls leaving them empty and the fuel pump then has to refill them before the motor will start.
This can mean cranking the engine on the starter for a long while. A very long while.
After a winter layoff on my y2k M750, I always fully charge the battery before I even try to start it but it usually requires so much cranking on the starter motor that the battery is drained very low and nearly always needs recharging before the carbs are refilled enough for the engine to start.
When it does start, it usually just runs on one cylinder at first, probably because that carb has a full float bowl but the other hasn't quite refilled.
The second cylinder kicks in eventually and then it runs fine.
After that first start up, it then starts immediately the button is pressed and runs cleanly.
This may be your problem.
After 25yrs I have recently wondered whether I should overhaul the fuel pump but the bike runs fine after the initial start up so I've left the pump alone for now.
Mine's always tricky to start after a winter layoff.
I did it the other day, a fully charged, high capacity battery and I still needed a booster pack as it ran it down.
Mine is worse than normal though as the Keihin carbs don't have any choke/cold enrichment so you rely on 'flooding' the cylinders by means of the accelerator pumps and it's easy to overdo it.
That said, I've just finished servicing and replacing the clutch so will be getting out on it either later today or tomorrow- Happy days.
I did it the other day, a fully charged, high capacity battery and I still needed a booster pack as it ran it down.
Mine is worse than normal though as the Keihin carbs don't have any choke/cold enrichment so you rely on 'flooding' the cylinders by means of the accelerator pumps and it's easy to overdo it.
That said, I've just finished servicing and replacing the clutch so will be getting out on it either later today or tomorrow- Happy days.
Thanks guys that's helpful. Same I carry the booster and have a battery charger. Battery was fully charged and plugged in at start. Starts (one cilinder) ride around but will go off. Do you guys use the choke to start it? I had to leave it as too much noise and I stunk of petrol. Not sure what's next
I don't use the choke very much when starting up after a layoff.
There's little point in using it while the float bowls are refilling and it only risks flooding the engine on the first cylinder to refill its floatbowl.
After I've cranked it over lots, I occasionally try a little choke but not for very long if it doesn't fire.
There's little point in using it while the float bowls are refilling and it only risks flooding the engine on the first cylinder to refill its floatbowl.
After I've cranked it over lots, I occasionally try a little choke but not for very long if it doesn't fire.
What fuel do you use ?
Fuel containing ethanol is not ideal for a carbed motor, particularly if you leave the bike unused for a long period as the ethanol worsens the tendency for the fuel to gum up the carb's internals. It can also attack certain types of rubber o-rings etc.
I only use Esso E5 fuel which is reputed to be ethanol free (in most parts of the country, though not all).
Also, after a layoff I always drain off all the old fuel (which will have deteriorated over time) and refill the tank with fresh fuel before trying to start the engine.
As a last resort you could try stripping and cleaning the carbs but I would first try and get it running on fresh, ethanol free fuel and see if that clears any light gum residue.
Fuel containing ethanol is not ideal for a carbed motor, particularly if you leave the bike unused for a long period as the ethanol worsens the tendency for the fuel to gum up the carb's internals. It can also attack certain types of rubber o-rings etc.
I only use Esso E5 fuel which is reputed to be ethanol free (in most parts of the country, though not all).
Also, after a layoff I always drain off all the old fuel (which will have deteriorated over time) and refill the tank with fresh fuel before trying to start the engine.
As a last resort you could try stripping and cleaning the carbs but I would first try and get it running on fresh, ethanol free fuel and see if that clears any light gum residue.
yes that's where I go wrong. My engine is def flooded now. I use normal Unleaded. Even premium uses 5% ethanol correct?
Stripping the carbs sounds needed, but I wish I knew how to do it without having to spend an arm and a leg. Is Ultrasonic carb cleaning worth it? Do you know anyone who does it?
Stripping the carbs sounds needed, but I wish I knew how to do it without having to spend an arm and a leg. Is Ultrasonic carb cleaning worth it? Do you know anyone who does it?
E5 premium fuel contains UP TO 5% ethanol.
But in the case of Esso E5, it doesn't actually contain any ethanol at all (except in certain parts of the country .. Scotland and the far south-west of England if memory serves.
There is a thread on the subject from a few years back, started by our member "Luddite" who used to do sample tests on Esso E5, but I haven't heard from him for a year or so.
I only use Esso E5 in both my (carbed) bikes.
I even use it in the car, just to keep the demand/supply up as much as I can.
I would start with draining the tank and refilling with a little Esso E5.
If it starts and runs ok...ish, then I would run that tank's worth nearly dry and then refill with more E5 and run that through in the hope than any gumminess is flushed through.
My carbs are as old as yours and have never been cleaned (but then I have used Esso E5 for most of that time ... 35k miles or so).
If you resort to a dealer to clean the carbs, my recommendations in London would be either Max at Vanoni moto, or Ray Petty Meccanica.
But in the case of Esso E5, it doesn't actually contain any ethanol at all (except in certain parts of the country .. Scotland and the far south-west of England if memory serves.
There is a thread on the subject from a few years back, started by our member "Luddite" who used to do sample tests on Esso E5, but I haven't heard from him for a year or so.
I only use Esso E5 in both my (carbed) bikes.
I even use it in the car, just to keep the demand/supply up as much as I can.
I would start with draining the tank and refilling with a little Esso E5.
If it starts and runs ok...ish, then I would run that tank's worth nearly dry and then refill with more E5 and run that through in the hope than any gumminess is flushed through.
My carbs are as old as yours and have never been cleaned (but then I have used Esso E5 for most of that time ... 35k miles or so).
If you resort to a dealer to clean the carbs, my recommendations in London would be either Max at Vanoni moto, or Ray Petty Meccanica.
Mark64
UKMOC Member
I've had success with pouring petrol straight into the cylinder to make it run on really stubborn bikes
Which is basically what Keihin FCRs do...
I wouldn't know how to do that! I know the basics. I've hung on her for a long time but might be time to more newer/injection..Which is basically what Keihin FCRs do...
Mark64
UKMOC Member
FCR's = kerching ;-)
Going by symptoms, if it was my bike i would try changing the exciter units just to rule them out as one of these (usually only one) misbehaving fits your symptoms exactly.
P.S. I've only owned over 20 Monster/SS of this type, and repaired/maintained absolutely everything that's ever gone wrong with them for over 15 years, so probably only a lucky guess.
P.P.S. Respect gallardo - i see you've been on here for 4 years longer than me.
P.S. I've only owned over 20 Monster/SS of this type, and repaired/maintained absolutely everything that's ever gone wrong with them for over 15 years, so probably only a lucky guess.
P.P.S. Respect gallardo
- i see you've been on here for 4 years longer than me.
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thanks! Any advice is highly appreciatedGoing by symptoms, if it was my bike i would try changing the exciter units just to rule them out as one of these (usually only one) misbehaving fits your symptoms exactly.
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P.S. I've only owned over 20 Monster/SS of this type, and repaired/maintained absolutely everything that's ever gone wrong with them for over 15 years, so probably only a lucky guess.
P.P.S. Respect gallardo
do you have access to a pair you could borrow? I see you are London way, i know i have spares but not sure where they are these days.
I can have a look on ebay. What should I be searching for?
there's always a risk with s/hand, but the units are pretty reliable overall.
Ducati Monster M900 ECU CDI Ignitor box BB1105 from running bike T6 17071 | eBay UK
11 LexMoto?. Classic Scooter Lambretta Vespa?. I bought a job lot just have chance to read them again as with all our magazine they are used and read. We try to show the condition in the photos but can’t cover every page.
www.ebay.co.uk
2 in Dagenham for £75 - you could even pick them up?
the link to these is below - I have no idea why the link says "Pardon our interruption"
the link to these is below - I have no idea why the link says "Pardon our interruption"