Carb set up help.

[Billinjah]

Hi guys struggling to get my new m600 running right seems to foul plugs almost straight away. If I put new plugs in it starts and runs lovely start to ride and is misfires through the rev range stop and chop plugs they are black. I'm thinking fuelling is to blame?

[don_matese]

Its probably way too rich, if its mikuni carbs on it you want to lean it out a little following the instructions on ducati suite http://www.ducatisuite.com/carbsynch.html

[Blah blah]

Sounds like fueling, standard cans or loud ones?

Also, when I sold my old 750 the chap couldn't get it to tick over - but he hadn't fully closed the choke all the way (it was only a little bit) and that filled it full of fuel

[Billinjah]

It's all standard but wonder if its been jetted to loud cans. Ill try that link and set them up.

[Billinjah]

Can't see anything about leaning off the carbs on there I've read about the needle jets becoming oval and increasing fuelling?

[don_matese]

Theres an image near the bottom that shows where the mixture screws are. If i remember right its tighten to lean the mixture.

[don_matese]

You may also not be getting a good spark. Check the coils, leads and caps for the correct resistances.

[utopia]

If you suspect rich fuelling, I'd start with the basics before moving on to the jetting.
ie...is the air filter clean ? (how does it run without the filter ?)
...are the float levels correct, and are the float valves sealing properly ?
...is the complete choke mechanism (not just the lever) operating correctly ?
...are you using old fuel ?

The other thing is....when were you riding it, ...and was it fairly cold and damp at the time ?
It could perhaps be carb icing causing your misfiring problems. It doesn't have to be all that cold for this to happen.

I'd eliminate all the above before hauling the carbs apart or adjusting anything.

I notice that this is a 2000 model. Same as my 750.
What mileage has it done ? I wouldn't expect jet or needle wear on mine just yet.
Mine runs loud "race only" termis with no fuelling changes and doesn't particularly seem to need rejetting.

[Dookbob]

Theres an image near the bottom that shows where the mixture screws are. If i remember right its uncrew to lean out.

I am under the impression that the idle screws need to be UNSCREWED to RICHEN the mixture, so one of us has got it right, can anyone answer this for us please.

[don_matese]

Dookbob, you are right :) I'll update my post...

[gary tompkins]

You may also not be getting a good spark. Check the coils, leads and caps for the correct resistances.

Deffo a good move to check the HT side of things out

HT Coils, pickups and igniters are all prone to failure on early monsters, and if you don't get a good spark it will foul the plugs really fast. Turn over the engine with the plugs out to see what spark is like, and if its a bit feeble or non existent trouble shoot from there. All this needs to be done with battery fully charged and good output from alternator as well

[Billinjah]

Seem to be getting a good spark. What do the igniters do exactly? Ill replace the ht leads as they look a bit old.
Good advice there utopia. Ill run it without air filter it looked a bit grubby so I've ordered a replacement. The choke mech moves in and out unsure what's happening inside the carb when it does this. It does feel like a bike with the choke left on to ride.

[Billinjah]

It's on 16k. Ill check the resistances of the coils and compare to the Haynes manual.

[Billinjah]

Coil resistance all looks ok. Is there a way to check the igniter boxes? I'm fairly sure it's spark as It was running on one so I stopped and pulled the plugs one was hot and dry the other was wet assume it was getting fuel but not igniting it? The pickups register the correct ohm reading as well. It idles fine and revs fine when stationary but underload misfires badly then goes onto one cylinder eventually cutting out and refusing to start.

[Sirc]

hate to add to your list of checks but symptoms you have just described do fit in with the way the pick-ups tend to fail - i.e. fine when cold but start to play up/work erratically as engine warms up ending with total breakdown. there is a test for the igniter boxes but failing this you could swap them over and see if the 'breakdown' moves to other cylinder.

[Billinjah]

Just had it running on one seems to be vertical cylinder put another plug in the cap it was sparking strongly. Pulled the plug out of head and it was dry. So thinking fuel again.

[Sirc]

has your bike stood unused for a while prior to your current use? Might be worth draining both float bowls for a start as you can do it in situ (M8 full-hex socket on long 1/4" drive and don't overtighten when finished). It's worth catching the contents just to try and confirm the presence of water. If you do feel it's fuel then you could strip and clean check the diaphragm pump as this can also misbehave and part perform (and also be full of rusty fuel and water). While you're at it, it's worth checking that vacuum pipe is sound as they can split close to the ends.

[Billinjah]

Yes it has stood. I've stripped and. cleaned the carbs with carb cleaner. emptied the tank and have fresh fuel. out there seems to be fuel in the bowls. Ill check the vacum pump good call.

[Sirc]

I suppose we better not rule out the 'blocked tank breather' syndrome either as it seems to happen more on Monster tanks than SS ones for some reason - when you feel bike is starting to cough and struggle then (carefully and stationary preferably!) open the filler cap to confirm it's not starvation as a result of above.

[gary tompkins]

Have you replaced the fuel filter as well?

This should be done regularly especially on a bike that's been laid up for a while

[Billinjah]

Ok I'll try the tank cap one. Fuel filter is new also.

[Billinjah]

Tried the tank cap no luck. Ill strip the pump and carbs again at the weekend. Still unsure as to whether its fuel or spark.

[Sirc]

if you are finding that it will go through the same routine every time almost to a stopwatch then you could definitely rule out fuel by using Bradex 'Easy Start' - but do be careful if you haven't used it before. With your Bradex aerosol close at hand, you could run-up the engine or ride it briefly if necessary to get to the point where it starts to play up then turn off. Pop the seat and tank and either spray into one or both of the air filter snorkels or whip the filter top and filter off and spray directly into the carb mouths for no longer than 2 seconds and then try to start immediately afterwards (keeping your head away from above the filter!). If the engine spurts into life for a few seconds and then dies then repeat above just to confirm that motor will run with the aid of Bradex. Whatever you do - DO NOT repeat the spraying part if the engine doesn't run briefly as a result. You can wait a minute or two if you want to try again (if no success) giving the Bradex a chance to evaporate.

[utopia]

To answer your earlier question, the so called "igniter boxes" would be more correctly called ignition control boxes, as they don't actually do any igniting themselves, but merely control the generation of the spark.
They are electronic devices which receive pulses from the flywheel mounted ignition pick-ups and convert them into timed pulses to the coils, taking into account the amount of spark advance or retard required as dictated by engine speed.
In simple terms the pick-ups are the equivalent of the points in an old fashioned ignition system, and the "igniters" are more like the equivalent of the mechanical advance/retard unit.
They used to be called Capacitor Discharge Ignition units (CDI units), but I'm guessing that modern versions no longer contain capacitors but use more advanced electronic components. I'm no electrician myself, so that's as much as I can say, but hopefully its not too far off the mark.

I believe they can be tested by a dealer using the Mathesis tester, but are beyond the scope of diy testing.
And incidentally, although a coil may pass the resistance tests, this only indicates that its probably ok. I think the Mathesis tester can also be used as a more reliable test of the coils.
I have heard of coils which check out on the tests but fail under operating conditions.

[stef]

I believe they can be tested by a dealer using the Mathesis tester, but are beyond the scope of diy testing.
And incidentally, although a coil may pass the resistance tests, this only indicates that its probably ok. I think the Mathesis tester can also be used as a more reliable test of the coils.
I have heard of coils which check out on the tests but fail under operating conditions.

..well.. if you have access to an oscilloscope, the whole ignition system is easily checked. you can see the control signals from the CDI and check the timing.
see here
http://www.ukmonster.co.uk/monster/showpost.php?p=430230&postcount=61

[Billinjah]

That's a good idea on the easy start. When It was running one I checked the spark and it was good on the cylinder that wasn't firing and the plug was dry. As its under load I'm going to check the diaphragms for mini splits etc.

[Billinjah]

Back on this now haven't had much free time. There was an o ring missing off the air passage for the diafragms so replaced that it is a hundred times better but it still stumbles at higher revs if you throttle off it will accelerate again. I've tried balancing the carbs.

[JuZ]

My carbs have been stripped and meticulously cleaned, then balanced with an oscilloscope and CO set at idle to the recommended level. I still get black plugs after a ride, that said it runs fine so I'm not too bothered..

[Billinjah]

I used a pair of vacuum gauges got them as close as possible. Wonder if my needles and jets are worn.

[urbanfireblade]

Lol, i been here before with my Monster 600 as a few might remember! Mine i'm guessing ran exhausts and filter and so the carb internals were Dynojet stage 1 or 2, but when sold to me they just fitted the standard exhaust hence chucking fuel in and it not being burnt. Check your main needles have engraving on, 5CJ1 to be precise. My advise to save all the heartache i went thru, just buy another set of carbs for 60 quid and bolt them on, 600, 750 or 900, doesn't matter what engine size they came from, it'll run fine(i fitted 900 ones to mine without doing anything) and will most likely solve all your fuelling problems. Much cheaper than what i did and buy pretty much all the internals and then another set of carbs!

[Billinjah]

Good advice right there think ill just do that!!

[Billinjah]

Found a clean set of carbs so ill report back once they arrive. I thought I'd solved it as the fuel tap had broken down inside and the vac line was sucking fuel in. Alas no difference.

[utopia]

Hmmm.....
You have to wonder how long that fault has been present, and whether a previous owner has twiddled with the carbs in an attempt to fix/mask it.
Maybe there's something to be gained from reversing that earlier twiddling ....somehow. ...?
I'm not familiar with that particular fault, but would I be right in thinking that this vacuum line connects to just one of the inlet tubes ? If so, it may have been responsible for the cylinders running unevenly, as only one would have been getting the extra squirt of fuel, while the other may have been starved of fuel.

[Dookbob]

I,m with Utopia on this one, you need to re- sync the carbs and mixture screws now that you have fixed the fuel tap fault.