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Flip · 12-01-2020, 10:15 AM

A reminder of the thread you are probably referring to in which you say you have seldom needed to do anything to carb'd bikes when laying them up and as stated back then- carburetted Monsters are a rather unique animal with their vacuum taps and pumps.

http://www.ukmonster.co.uk/monster/s...draining+carbs

So lets try and help- what was the fuel additive you put in?
I wouldn't have thought it would cause the problem but it is possible it dislodged some muck which prevented the float valve from shutting off.

If you removed the fuel tank there shouldn't have been any fuel draining from it as there is a tap but it is operated by vacuum not a manual shut off- this vacuum tap flows fuel to the vacuum fuel pump when the motor is turning so it can't keep filling the carbs- especially as they are higher than the pump and gravity prevents it.

Vacuum Fuel Tap:

Vacuum Fuel Pump:

Obviously in order for them both to work properly they require the associated hoses and the internal diaphragms to be in good order.

While the tank is off it would be a good idea to change the fuel filter as well as lots of owners don't bother.

You could also change the (very prone to cracking) plastic sender unit nut to a more robust Aluminium replacement:

But I know, owning an older motorcycle can be a never ending list of jobs and near constant tinkering to keep them running sweet

Anyway, I digress, as mentioned in the above thread, in my opinion you are far better off removing the carbs to work on them on a nice clean bench taking care not to mix parts between the two so I would say don't even bother to try and remove the float bowls in situ (others may disagree here but just the way I would do it).

My thoughts on the clunk you heard are that if your battery was getting down while you had the starter pressed and the motor 'blew back' (hence the 'Pop!') then it was probably caused by the Sprag catching it- whether or not it has done damage partly depends on the condition it was in before- repeated turning the motor over until the battery dies while attempting to start it is a sure fire way to kill the Sprag clutch.

12-01-2020, 10:15 AM	#3
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	A reminder of the thread you are probably referring to in which you say you have seldom needed to do anything to carb'd bikes when laying them up and as stated back then- carburetted Monsters are a rather unique animal with their vacuum taps and pumps. http://www.ukmonster.co.uk/monster/s...draining+carbs So lets try and help- what was the fuel additive you put in? I wouldn't have thought it would cause the problem but it is possible it dislodged some muck which prevented the float valve from shutting off. If you removed the fuel tank there shouldn't have been any fuel draining from it as there is a tap but it is operated by vacuum not a manual shut off- this vacuum tap flows fuel to the vacuum fuel pump when the motor is turning so it can't keep filling the carbs- especially as they are higher than the pump and gravity prevents it. Vacuum Fuel Tap: Vacuum Fuel Pump: Obviously in order for them both to work properly they require the associated hoses and the internal diaphragms to be in good order. While the tank is off it would be a good idea to change the fuel filter as well as lots of owners don't bother. You could also change the (very prone to cracking) plastic sender unit nut to a more robust Aluminium replacement: But I know, owning an older motorcycle can be a never ending list of jobs and near constant tinkering to keep them running sweet Anyway, I digress, as mentioned in the above thread, in my opinion you are far better off removing the carbs to work on them on a nice clean bench taking care not to mix parts between the two so I would say don't even bother to try and remove the float bowls in situ (others may disagree here but just the way I would do it). My thoughts on the clunk you heard are that if your battery was getting down while you had the starter pressed and the motor 'blew back' (hence the 'Pop!') then it was probably caused by the Sprag catching it- whether or not it has done damage partly depends on the condition it was in before- repeated turning the motor over until the battery dies while attempting to start it is a sure fire way to kill the Sprag clutch. __________________ You're perfect, yes, it's true- But without me you're only you!