UK Monster Owners Club Forum » .: Technical :. » Fuels & Oils » Draining Carbs

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Old 04-01-2020, 04:42 PM   #1
gwyndaff
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Unhappy Draining Carbs

I’ve got a 1998 M600 that I can’t get to start. I haven’t been able to start it since September. The fuel in the tank/carbs is over 12 months old so I’ve been trying to drain the carbs. The right hand side is easy but I can’t see how to get access to the left hand side. I can see the drain screw but I can’t see how to loosen it. Anyone done this task?
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Old 05-01-2020, 11:50 AM   #2
350TSS
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I think you will need to take the carbs off and strip them down to clean out all the resinous stuff left in them from evaporated petrol. The jets will have to come out and all the drillings in the carburettors blown through with an airline. Better still would be an immersion in an ultrasonic cleaner.
I suspect if you do not do this you will be chasing a poor starting /poor running bike for the rest of the year. Just draining the carbs will leave the gum in the carbs and putting new petrol might dissolve some of it but there will be jet blocking globules that will drift in and out of play unless they are completely removed.
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Old 05-01-2020, 09:06 PM   #3
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Thanks for the response 350TSS. I’ll have to get the old Haynes book out. I’m a mechanical luddite but I’ve got basic tools and I don’t mind giving it a go. Any pitfalls I should be mindful of? Wish me luck ��
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Old 06-01-2020, 02:00 PM   #4
350TSS
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I would get them off and give everything a large dose of plusgas particularly the slow running jets located (maybe ) under some rubber bungs (bungs usually go AWOL) just in front of the float drain plugs.
The cross head screws on the carburettors are soft and Japanese standard cross head (forget the correct reference letters - JP1?) whatever a PZ1 or PZ2 or a Phillips cross head will almost certainly chew it up before it undoes and then you have a problem.
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Old 06-01-2020, 02:58 PM   #5
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Quote:
Originally Posted by 350TSS View Post
The cross head screws on the carburettors are soft and Japanese standard cross head (forget the correct reference letters - JP1?)
JIS? (Japanese industrial standard).

JIS screwheads are usually marked with a dimple/punch mark or an 'x'.

It's definitely worth having a couple of JIS screwdrivers in your toolbox. If you're used to struggling with Phillips/Pozi drivers on JIS screws, the first time you use the JIS driver is a revelation!
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Old 06-01-2020, 07:48 PM   #6
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Cheers Luddite - good username by the way
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Old 06-01-2020, 08:49 PM   #7
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Vessel Megadora make some very good Japanese Industrial Standard screwdrivers.

https://www.ebay.co.uk/itm/Vessel-Me...oAAOSw2Xdd4o~l

They are similar to philips drivers, but with a smaller radius at the centre of the cross.

https://www.instructables.com/id/Whe...ot-a-Phillips/
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Old 06-01-2020, 09:10 PM   #8
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Everyone is right, modern fuel goes off very quickly (more so in small quantities) and the carbs dry out reasonably quickly when left for any length of time and the fuel leaves a horrible yucky glaze behind which blocks jets and airways.

These should help you get the float bowls off but I would give the screws a good squirt of release spray and allow to penetrate before attempting to remove them as they are indeed made a cheese like material- possibly Dolce Latte?

https://www.ebay.co.uk/itm/US-PRO-To...wAAOSwqWZdMEfy

If they hint at getting rounded off I would stop and try and get a pair of pliers on them if you can to start them off.

Also if you're not familiar with CV carbs take care when handling the diaphragm when you remove the slide as they can be easily damaged.

And finally, have a nice clean work area with some little pots (rattle can lids are ideal I find) for putting the bits in as You dismantle, clean then reassemble one carb at a time.

Enjoy
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Old 07-01-2020, 02:12 PM   #9
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I'm going to throw in a curved ball here.
I've been following this thread and wondered why all of a sudden the advice is to remove and strip the carbs?
Yes the op did ask how to drain the carbs because he wanted to get rid of the old petrol.. Fair enough, fresh petrol throughout will be a big help... But.
The usual advice with a 600 that won't start after a lay-up, is to prime the carbs with petrol, as the vacuum pump and tap take their time to fill the carbs and it needs a LOT of cranking. Folk usually report that the battery goes flat before it will start, due to all the cranking. This leads to unnecessary fiddling with electrics sometimes, although it can reveal a sad battery too.

Just saying.. It might be worth getting rid of as much old fuel as possible and then trying again with the carbs full of nice clean stuff.. either expect a lot of cranking to get it through or devise some means of filling the carbs before the cranking starts.

I think stripping the carbs at this stage is just going to open a whole new box of frogs that could lead to more problems.. Your call..

If it does start with full float bowls the next step would be the Italian tune up..
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Old 07-01-2020, 03:26 PM   #10
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I've got to say ... Mr Gazza's advice sounds good to me.
I'd be inclined to give the battery a damn good charge and then be persistent with the starter button. ...very persistent.
If it still doesn't start before the battery goes flat, I'd be inclined to recharge and repeat before stripping the carbs.
I would probably also check that fuel was reaching the carbs before stripping them. There is every possibility that the diaphragms in either the fuel tap (if a vacuum tap is fitted) or the fuel pump itself have deteriorated though standing dry for a while.
Removing the carbs is quite a lengthy process, never mind stripping them.

Removing the plugs to see if they're wet (indicating that fuel is reaching them) would also be worth doing.
While they're out it might be worth cranking the engine a few times as it would spin up faster with the plugs removed, thereby pumping fuel to the carbs faster too.

Club member Dookbob used to prime his floatbowls using a syringe if his 600 had been standing for a while.
Eventually I think he even fitted a manual priming pump.
Personally I've never had a problem as long as I've been persistent with the starter button after a period of non-use.
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Old 13-02-2020, 12:42 PM   #11
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Club member Dookbob used to prime his floatbowls using a syringe if his 600 had been standing for a while.
Interesting to read that! I did exactly the same on my Suzuki VX800, which also had a vacuum stopcock and vacuum pump. I tee'd in a spur in the pipework below the pump and used to fill the carbs with 50ml of fuel from a big glass syringe. It saved a lot of punishment for the battery and starter-sprag, though one VX-er suggested that the engine oil wouldn't have gone around so well prior to firing.

That bike (the VX) was charming but had to make way for the S4R: chalk and cheese, I reckon!

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Old 13-02-2020, 03:57 PM   #12
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Interesting to read that! I did exactly the same on my Suzuki VX800, which also had a vacuum stopcock and vacuum pump. I tee'd in a spur in the pipework below the pump and used to fill the carbs with 50ml of fuel from a big glass syringe. It saved a lot of punishment for the battery and starter-sprag, though one VX-er suggested that the engine oil wouldn't have gone around so well prior to firing.

That bike (the VX) was charming but had to make way for the S4R: chalk and cheese, I reckon!

Nick
For my recent refill, i took out the plugs and spun it for a while till petrol smell appeared in the cylinders. Took a fair wee bit of time to prime it. The battery would never have lasted with the compression on it.
I thought about your idea of the tee spur-ed into the line past the pump but ended up not doing it.
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Old 13-02-2020, 07:53 PM   #13
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Originally Posted by The Clockie View Post
Interesting to read that! I did exactly the same on my Suzuki VX800, which also had a vacuum stopcock and vacuum pump. I tee'd in a spur in the pipework below the pump and used to fill the carbs with 50ml of fuel from a big glass syringe. It saved a lot of punishment for the battery and starter-sprag, though one VX-er suggested that the engine oil wouldn't have gone around so well prior to firing.

That bike (the VX) was charming but had to make way for the S4R: chalk and cheese, I reckon!

Nick
I had to Google Suzuki VX800 because i never heard of one or seen one before . But yea, its a cruiser engine in a kind of 600 Bandit frame. A bit meh imho. Was it an official model or a grey import? Closest jap bike to an S4 woud probably be a TL1000 but without the suicidal handling issues!
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Old 17-02-2020, 08:55 AM   #14
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I had to Google Suzuki VX800 because i never heard of one or seen one before . But yea, its a cruiser engine in a kind of 600 Bandit frame. A bit meh imho. Was it an official model or a grey import? Closest jap bike to an S4 woud probably be a TL1000 but without the suicidal handling issues!
The VX was certainly an official import into Europe and the US, though the US got a different crank angle to give extra vibration to suit their tastes!

I've just been reading a 1990 Bike magazine test, which is one of the few aspects of the bike I have left after it had to make room for the S4R (No way did I mean that the VX was Japan's version of the Monster: LOL) and one of the testers really caught the vibe of a release from trying to ride ballistically on sports-bikes and finding the pleasure of relatively-sedate and comfortable travel on two wheels. As I said, a real charmer of a bike with nothing to prove. If I had more space, it'd still be here.

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Old 07-01-2020, 06:08 PM   #15
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I tend to agree with Mr Gazza and Utopia. I've been riding carby bikes for many years and have never had to strip carbs to start a bike that was laid up. Fresh petrol and a well charged battery, making sure the battery connections are tight as there's a fair current flowing which will heat up and melt any poorly connected joints if you have to keep it spinning for a bit.

What i have done many years on first start up is set a hot air paint stripper a few feet from the bike pointing at the engine for an hour or so before starting. They always start first jab of the button, just as if they've been ridden within the past hour or so. A hair drier might do he job too, it's just about raising the temp of the motor a bit.
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