M600 cutting out

[Rockhopper]

Hi. We are having a problem with our 1997 m600. The thing just doesnt want to tick over correctly, we get it started and warmed up and it idles beautifully. Take it for a run and its okay for a few miles. Then the problem starts. If you pull the clutch in it just dies, drop the clutch again and it bump starts fine or you can start it on the button with no problem but pull the clutch in again and it stops. When its running its great with loads of power and its nice and smooth but there is awlays the worry in the back of your mind that its going to die at every junction. I dont think its the wiring around the headstock, the bike just ticks over very slowly and then stops but will immediatly restart so its not a fuel starvation problem.

Thinking about it last night while lying in bed it appears the problem starts when the motor cools down slightly like after a long high speed run.

Neil at Cornerspeed has set the bike up three times (CO, mixture, plugs etc) and it all checks out perfectly on the bench. Its just after a fast run of a few miles that the problems starts. Its not carb icing, this happens in all weathers, the fuel is fresh and its got loads of Pro FST in there.

My partner who owns the bike is a new rider and she is really struggling with it so anyone who has got any ideas would be doing us a huge favour.

I feel like i just want to get rid of it but i couldnt sell it to someone like it is at the moment.

[Elmo]

When you say it warms up beautifully are you useing the choke at that time? I was just woundering weather it mite be something simple as the idol screw may have worked lose.

[opwierde]

I solved a similar problem by replacing the fuel filter on my '96 M600. You would think that a dirty filter would affect high speed driving more but my main problem was stalling when I pulled the clutch.
First post btw!

[bod]

I presume you bike is carb model.Could be the idle jet in carb getting blocked,with dirt or something(is the tank clean inside no rust/dirt).

[gary tompkins]

Check to see if there is any water sloshing around in the bottom of the tank, it could be finding it's way into the pump/carb floatbowls causing intemittant fuel starvation. Also make sure that tank and carb breathers are not blocked and causing a vacuum.

[nik_the_brief]

I presume you bike is carb model.Could be the idle jet in carb getting blocked,with dirt or something(is the tank clean inside no rust/dirt).

Mine doesn't bloody idle at all!! I have to blip the throttle whenever I stop at junctions, traffic lights etc. maikng me sound like a boy racer :mad:

I have tried adjusting the idle screw and no amount of turning it seems to make any difference whatsoever!

Would I be right in thinking that it's definitely the idle jet in this case?(particularly since I ran out of fuel not so long ago and had to refill the tank and then bleed the fuel system!).

If so what's the best solution? - I presume I'll have to bite the bullet and take the bloody things off again! :confused:

[Rockhopper]

I dont think its a carb problem as such becasue we rebuilt them to cure a butchered air bypass screw! Took Neil a full day with the dremel to get it out. Also inclined to think its not fuel starvation becuse when it stops it will immediatly restart either on the button or by bumping it. I will change the filter though just to eliminate it.

Yes we start it on the choke and then it'll sit quite happily till its hot enough to run without it. Infact the hotter the motor gets the better it runs. After a five mile run at 80mph i think the engine cools down which is when the problem starts.
#
I'm begining to think its a valve clearance problem.

[M0nstermann]

I have a 99 Dark which had a similar problem. I did two things, firstly used the Petrol pep pills from M and P, then switched to using premium grade fuel and although the engine rpm does drop at idle after a long run, it doesn't stall like it used to. I'd done everything, had the jets checked, drained the tank, bled the system and checked the idle screws. The last two things seemed to have done the trick (fingers crossed)!

[Rockhopper]

Well i spent sunday afternoon checking the valve clearances. It appears that both the exhaust valves are really tight. We think that as the motor warms us the clearance opens up a little then as it cools down the clearance tightens up which is keeping the valve slightly off its seat hence a lack of comression and it stops. Its going in on sunday to have them re shimmed so i'll let you know what happens.

[A Yerbury]

if you adjust the idle jet you will hear the note change with even small adjustments nik, if you are rotating the correct thing and it stays the same then something is amiss in the state of denmark.

[DesmoDog]

How easy is it to remove the carbs? I have asimilar problem but once it stalls it stays dead. Someone else suggested carb jet problems for mine and I'm thinking about removal and cleaning.

[nik_the_brief]

That's what I thought Yerbs. I've adjusted the idle speed before and only minute increments changed it quite dramatically. This time round no amount of turning the screw appears to make any difference! It does make a sort of 'spring boinging' sound (sorry can't explain it better than that ) when turned too - wondering if it's not simply revolving on the same spot and not adjsuting anything at all! :confused:

I'm wondering if the idle jet isn't completely blocked hence my bikes refusal to idle altogether unless the throttle is held slightly open. Going to try the cheats method first, an aerosol can of carb cleaner followed by a substantial amount of Redex straight into the carbs. If that doesn't work it looks like I'll have to take 'em off and strip them down for a bloody good clean. :mad:

[Bobble]

Hi all

I don't know if this helps but my other halfs M750 cuts out when you close the throttle i.e. slowing down for juntions etc. I was talking to a well respected Ducati mechanic and ex racer last week, he reckons it is carb balancing. Other than cutting out it runs really well, starts easy, pulls great. Going to take the bike to him in the next couple of weeks. Can't say for sure that it is THE cure as we havent done it yet but it could be worth a try......

[nik_the_brief]

How easy is it to remove the carbs? I have asimilar problem but once it stalls it stays dead. Someone else suggested carb jet problems for mine and I'm thinking about removal and cleaning.

Easy(ish) but time consuming coz ya have to remove the tank, air filter box (which involves having to remove the ignition elastic-trickery stuff too). Then you'll need to detach the throttle and choke cables before undoing the jubilee clips to lift them off.

If you do remove them to clean them - don't, whatever else you do, separate them as you don't need to. You'll also need to make sure you've a new set of O rings before you take the carbs apart as you can't re-use the old 'uns.

[Bobble]

Follow up to my last message.....ment to say carb syncranisation not balancing..soz

[DesmoDog]

Cheers Nik. Carb balance and sync is the same thing innit?

[nik_the_brief]

Cheers Nik. Carb balance and sync is the same thing innit?

As far as I know two phrases for the same thing yep.

No bother Desmodog - hope it's of help. It might be worth trying the cheats route first as some of these aerosol cleaners are pretty good at cleaning off varnish deposits etc. and it may save you a heap of trouble and skinned knuckles! Having said that I'm pessimistic about it myself and am almost positive that I'm going to have to remove the buggers and strip 'em down for cleaning! Serves me right for allowing the tank to run dry though!

[Bobble]

More than likely.. but just in case it is'nt I cant be held responsible for suggesting the wrong thing! :lol:

[monstro78]

My m750 suffers from the same problem, but only when the air is cold (around 4C and below) and damp. Its the old carb icing problem which can be a nightmare if you commute in heavy traffic as I do. Thankfully its cured by precise carb balancing, a raised tickover and a good dose of Silkothene Pro FST. May be worth a try before hours of labour with the carbs?

[Plum]

Probably sound stupid, but what about an electrical fault? I know that with one problem i had, it turned out to be electrical. Maybe i am being a plank, i dunno?

[Rockhopper]

Well Neil at www.cornerspeed.co.uk did the valve clearances today. First indication that something wasnt right was his ability to turn the motor over by hand with the plugs in! No compression! The rear exhaust valve was .5mm out and the front one was .25 hence they were never actually closing properly unless the motor was really hot. Now those measurements are huge and there is no way the bike could need that kind of adjustment after only 5000 miles so it looks like some well intentioned "mechanic" has had a go at shimming it up and got it very wrong!

The bike now starts without any choke and idles nicely from cold also with no choke.

We are well pleased!

[nik_the_brief]

Well Neil at www.cornerspeed.co.uk did the valve clearances today. First indication that something wasnt right was his ability to turn the motor over by hand with the plugs in! No compression! The rear exhaust valve was .5mm out and the front one was .25 hence they were never actually closing properly unless the motor was really hot. Now those measurements are huge and there is no way the bike could need that kind of adjustment after only 5000 miles so it looks like some well intentioned "mechanic" has had a go at shimming it up and got it very wrong!

The bike now starts without any choke and idles nicely from cold also with no choke.

We are well pleased!

Snap!! :D