M600 poor idle and low speed - Shim kit group buy or loaner?

[sram]

Hi all

I'm just starting to use the bike more again now that the weather is (possibly) getting better. I was riding over the winter, but only every couple of weeks. I'm now back to the same point I was at the end of last summer, where the bike seems to perform fine when accelerating and under full throttle, but low speed tractability and tootling along just off idle is very lumpy, with a bit of surging.

I checked the clearances last year and shaved a tiny bit from the opener shims to get them perfect. Some closers were in spec and some were a tad out, but not by much. As part of general maintenance I'd like to get all valves perfect, as that seems to be the number one place to start when troubleshooting running issues.
I've already had the carbs off twice, completely stripped them including every single jet and rebuilt them with Tourmax rebuild kits. I didn't separate them, but I've just ordered a twin vacuum gauge to check the sync, although I read that the valves must be set and shimmed before balancing the carbs will make any difference.
The horizontal plug looks golden and great, but the vertical plug is quite fouled. I've tried leaning out the idle screw but I can't seem to get it to maintain idle if I lean it out anymore than it currently is. The bike has fewer than 7000 miles on it and so am I right in saying that nothing in the carb (jet needles & needle jets?) would have worn out and even if the needle or jet were worn it wouldn't manifest itself with a poor idle and just-on-throttle performance, as this relies mostly on the idle screw & jet (please correct me if I'm wrong here!).

Anyhow, with that out of the way I am going to order a EMS shim kit from the US, but at £200 + shipping it's quite painful. I wondered if anyone else had ordered one and had used it and now had a load of spare shims sitting around doing very little? It's unlikely both of us would need the same shims and I know EMS allow you to send in your old shims in exchange for the sizes you need and so is there any option for doing a uk monster shim swap or group buy?

Alternatively, if perhaps one or two other people were eyeing up the kit and wanted to come in with me, we could each put in half or a third of the cash and just send the box round to each other when we're doing valve adjustments.

Just a thought! Trying to watch money at the moment. I was going to pay to have the valves done, but by the time I pay the labour and parts I may as well have bought the shim kit myself.

Cheers

[Darren69]

It sounds like your shims are pretty much in spec and I doubt if that would be the problem you describe, if just a bit out it should still run ok. I agree that you are right in saying that they run better when its just spot on, just after a service you usually can tell the difference. However your logic appears to be correct and the problem does appear to be idle jet/circuit/mixture. So did you balance the carbs? I'm wondering if its that because I can't think of anything else atm?

[Darren69]

Is the choke shutting off on both carbs? I seem to remember that the cable mechanism is linked to both carbs.

[Flip]

As you say, valve adjustment needs to be within tolerances for it to run and perform well and if you are confident they are then I agree with Darren- you should be looking at carb balance and set up- Especially as you have had them apart, they will certainly need balancing.

As for the plug colour- you are probably only getting half a story and you need to understand how the various carb circuits work and how it is 'throttle opening' not engine revs that govern them.

This little graphic might help:

[Darren69]

Flip, is there a mechanical link for the choke circuit on the carbs? I seem to recall there was a rod that pulled and pushed both on and off? The choke circuit was a big problem for Lav triples with those old Dello Ortos as I know and it was all mechanical because the little rubber tipped brass plungers that closed the choke were not all going back down enough equally so the choke circuit might be slightly on for one carb.

[Flip]

Yes good point Darren- there is much the same kind of linkage as that for the choke on the carby Monsters.

You'll probably have to lift the tank and remove the air box to be able to see if it's not returning properly though but a little silicone grease while you're there will help keep it smooth.

[Darren69]

My guess is one is not fully closing but those Mikunis can mask a whole host of problems. I bought my 900SS from a dealer and it always started ok, had open pipes, airbox and a dynojet kit. it would start ok most times but sometimes it would not Carbs were balanced etc, etc.

It was only when they did some digging that the jets were checked and one needle was on clip 2 and the other one on clip 3.

[sram]

Thanks for all the info so far!

Flip, that graphic is a good one, cheers.

The choke does seem to return fully on both carbs. I paid close attention to the mechanism and cable routing when removing and reinstalling the carbs to make sure that it wasn't sticking. If the mechanism is visibly returning, is there a chance that it could still be getting 'stuck on' inside the carb internals?

I have not yet balanced the carbs, but ordered two vacuum gauges this evening. I hope to have them early next week and I will hook them up to at least get some kind of baseline. If it shows as being completely out then I'll have a tweak here and there and if no improvement is made I will then bite the bullet and order the shim kit. At least I'll then have it for as long as I have the bike - I think it's a wise investment seeing as my valves probably have a while to go before they settle down? :-/

Has anyone ever used an exhaust gas analyser via the blanking bolts/plugs in each exhaust 'downpipe'? I've seen Gunson ones for about £120 and sometimes they appear on ebay for about £80. Worth it?
I've got a colourtune, but I can't seem to get good visibility.

I should probably recheck coil resistance, plug leads, etc. Plugs are factory spec and I've been through a couple of sets. Is it worth swapping the coils over (possible?) in order to see if the fouled plug problem moves cylinder?

What's the best way of checking the strength of the spark to make sure that the cylinder is receiving the spark it needs? Both exhaust pipes & silencers are about the same temperature (measured by hand), so I know they're both actually combusting!

Sorry for all the questions...

[Dennis menace]

For the cost of the shim kit you could get two new carbs. I found that despite my best efforts I could not get my old carbs to idle properly on my M600 and in desperation I bought new carbs from Italy on EBay for less than £200. Best investment I ever made. Smooth choke operation, easy adjustments and even the drain plugs worked! The carbs attract a lot of road crud positioned where they are. Make sure the carbs are jetted for your bike as replacements are expensive, about £60 for jets needles etc. You can get replacements from Allen's Performance Parts, Grantham and elsewhere I suspect.

[Mr Gazza]

I would prefer to buy MBP collets, which are claimed to extend the valve servicing to 20,000 miles (not the checking!).
I would then tackle any adjustments at the beginning of winter, so I could afford to wait for just the required shims to arrive in the post.

That would be a cheaper option than the shim kit by a long way, and go towards new carbs or sumfink shiny..

[sram]

Well, I sprung for the shim kit while I was on holiday in New York. This weekend I started the job I'd been putting off for so long. Two things that I remembered I hate about Ducati valve jobs:

1) Holding down the arm (not sure what its correct name is) in order to remove tension from the closing shim to measure - just how the hell do others do it? Surely there's a correct way rather than wedging a screwdriver in there which slips off at every opportunity?
2) General access - there is just no damned room to get to anything. I think next time I'm just going to stump up and have a pro do it. I've spent all day out there today and have not got very far at all.

So I went out there, all excited with my shiny shim kit. I measured and then started to remove shims. I turned to my new little box to pull out a 6 or close to 6mm closing shim - not a single ****er in there! 6.2 is the smallest and that is way too large and causes binding >:-o
All my closing shims appear to be within 0.05mm of each other - is this normal or were the Ducati engineers having a high tolerance engineering day when mine was built? I think this is the first valve adjustment it's had (6k miles), so I don't think it's coincidence as a result of them being changed by a previous owner/service. Might be wrong of course.

I tried lapping down one of existing shims so that I could use it on another valve, but it took forever even with 80 and 100 grit wet or dry. Haven't got much feeling in the ends of my fingers!

Just when I had resigned myself to having to order yet more shims and as the light was fading, I started to pack up and thought I'd better put as much back together as possible. I got a couple of collets on one valve and then moved onto the vertical cylinder. I almost had it on and then PING, the screwdriver slipped, the shim popped off and the collet made a break for freedom and will never be seen again. ****.

So I'm now trying to get some ordered in time for next weekend. This is exactly what I was trying to avoid by ordering the shim kit and trying my best to be prepared!

To top it off, I'm out of beer.

Not a good weekend.

[Nickj]

Originally Posted by sram

To top it off, I'm out of beer.

I feel your pain

Originally Posted by sram

I tried lapping down one of existing shims so that I could use it on another valve, but it took forever even with 80 and 100 grit wet or dry. Haven't got much feeling in the ends of my finger.

That is much too coarse - I recommend 400 grade max with a light oil and a figure of 8 motion as in pic. Also regularly turn the shim 90° under your finger to even the wear. I use a piece of glass to keep it all flat.

If you go back and forward you wear a wedge shape or circular motion will not leave it flat.

This is why I don't recommend using anyone who offers an 'exchange' service - you don't know if the 2nd-hand ones are ok. I once ordered some shims from a main dealer and was sent 2nd-hand ones so next time I ordered I insisted on new ones in a Ducati packet.

I guess if someone takes their bike in for a service they most likely get 2nd-hand ones fitted?

[jonzi]

Originally Posted by sram

... the collet made a break for freedom ...

I believe our mighty lead, Slob, calls these 'ping ****its'

They go ping and you say **** it.

(Nothing else to add here)

[utopia]

In my opinion, the whole practice of re-sizing the shims is highly dubious.
As Blunt says, its almost impossible to keep the contact face square.
Ok, if you're very skilled in both engineering machining and hand-finishing of components then you might have a chance of doing it successfully, but there aren't many folk like that left in England these days.
Mostly, I hear the practice referred to by those who have picked up a little bit of "workshop lore" from the grapevine, which sounds "trick". Their ignorance is often betrayed by their suggestion of "sandpaper" to do the job.
These shims are hardened (presumably) and accurately ground to precise dimensions. Their tiny size makes accurate refinishing almost impossible and the hardness makes it hard work .. which further compromises the accuracy of the result due to the time and effort required to remove even a tiny amount of material.

And yes, secondhand shims are therefore always a dubious prospect.

ps.
Its also worth mentioning that the std wire collets bed in during their initial period.
With a hand lens it is possible to see tiny bedding marks on a used collet.
If you replace old collets with new, or replace the old ones upside down (compared to their original orientation) the valve clearance will be different.
In my experience, this can account for as much as one whole shim size step.
Of course though, this is only temporary, until the new/re-positioned collets can bed in.
I always replace my shims the same way that they were originally fitted.
The alternative is the MBP collets, which avoid the problem (but I haven't bothered).