Them sacred screws ????

Nope, I’ve not touched them...

But given how mechanical the setup is, including the cross-manifold linkage, do these settings not ‘drift’ with time? And regardless of that, if the motor has a major service (eg heads off) are you supposed to assume those settings will hold good upon reassembly. (Assuming you don’t need to undo them?)

So, I guess the big question is, if disturbed is it beyond the home workshop to fix, and if not what equipment would a dealership be using to put it all right?

intrigued...

Lobo,

Pulling the engine down is not a big task - I did mine earlier this year when COVID struck. Did a top end re-build because the old girl was playing up a bit.

Always loosen off you adjustments for valve clearances on re-assembly - presumably you might be replacing head gaskets? - even if you aren't, the correct way is to re-assemble, then do your clearances from scratch again.

Throttle bodies, even if removed should go straight back on as a set - they will only need cleaning - sacred screw you won't be touching anyway.

Probably the only real special tool needed is ye olde torque wrench, assuming you have spanners and sockets of the metric variety, screwdrivers and the like - most garage contents should have enough. The key is to take your time and ask on this forum if you are not sure - instead of diving in and making things worse.

Remember, if you don't feel benevolent towards the task, don't do it!

Your original question about drift is not normally - maybe a smidgen but not really - apart from the balance screw, which is dependent on the condition of other things in the heads, including wear and tear.

The only thing I had to outsource was the reseating of the valves in their seats at the local engine works.

The throttlebodies are very rigidly mounted for a reason. They are also very sensitive to being disturbed.

If the bike is kept properly tuned they will, provided air filtration is good, last a very long time. First thing to get wobbly will be the spindle bushings and these are critical as they effect the TPS interpretation.

As to what can be done to 'Correct' them if they've been fiddled with? The answer is not a lot. Michael has got pretty good at un-fucking them but it really depends on what has been done to them. If the throttle stop screw has been fiddled with but the TPS hasn't been recalibrated then correcting the problem, (As long as the linkage rod hasn't been screwed with.) is simple enough to fix. Once the TPS is calibrated wrongly in relation to throttle angle or the linkage rod has been moved you enter a world of pain!

We'll always give it a crack if we get a bike in with messed up TB's but we always point out to people that it will be as much luck as judgement and it's possible to spend literally hours chasing minor improvements.

The only way to truly fix the problem is with new, unmolested, TB's and yes, I do get a bit sick of people looking at me sideways and obviously thinking I'm trying to pull a fast one because somebody else has fucked up their motorbike. Yes, throttle bodies are expensive! Sorry but that isn't my fault either.

There is always a choice. You can put up with poor idle and weird fuel consumption or bite the bullet and buy new TB's. That's the long and the short of it. Believe me, we've been trying to find this 'Holy Grail' of a fix for fourteen years. I think if it was easy we might just of got there by now........

Just a thought but would it possible to recalibrate by setting the TB’s up off the bike? Using a high quality vacuum to create the pull and a carb balancer or manometer to measure flow?

One uk Italian bike specialist??? informed me that there was no point trying to balance the TB’s on a bike with more than 3000 miles as there would be too much play in shafts.

Another element of confusion- on my bike every nut bolt and fixing was dabbed with a yellow dot from the factory. The yellow paint on the sacred screws looks very similar to the other fixings on the bike. Was going to paint it with epoxy but then it just looks like it’s been fu*ked with.

Oz 1200 - my GRiSO looks and runs like new (<7000 kms), I am simply intrigued by these screws. Regardless, thanks for the reply.

Cheers Pete, I’m shocked to learn all this; had no idea as it all looks rather mechanical and kinda familiar  engineering (from the outside!). Given how motorcyclists, at heart, are born tinkerers I’m guessing there are 100s of modern Guzzis about the planet with buggered TBs. What a bloody pain...

Would you know how the manufacturer initially ‘tunes’ the TBs, and if so why is this not do-able in the field?

I’m with eeyore on the Yellow paint comment - given how monumentally important it is these settings are not to be altered it seems (to me) out-of-order that MG does not make these screws more tamper proof.

Thank god I read about it first; I consider myself pretty competent at vehicle maintenance and hitherto, have not come across such innocent looking adjustment grenades.

(A while back I repainted the sacred screw dayglow red - yea eeyore it looks a bit odd, but given the alternative it something I can live with!

Lobo wrote:

Oz 1200 - my GRiSO looks and runs like new (<7000 kms), I am simply intrigued by these screws. Regardless, thanks for the reply.

Cheers Pete, I’m shocked to learn all this; had no idea as it all looks rather mechanical and kinda familiar  engineering (from the outside!). Given how motorcyclists, at heart, are born tinkerers I’m guessing there are 100s of modern Guzzis about the planet with buggered TBs. What a bloody pain...

Yes, it's a pain. A real pain that people fuck about with stuff without understanding it. The system works, and in fact works very well. The W5AM system is one of the very easiest to tune of any motorbike ever. It's ridiculously simple. But still people fuck it up! It's for that reason primarily I believe that Guzzi has gone to a single throttle body. It's buried in the bowels of the bike meaning it's very hard for 'Harry Hometune' or Shaved Apes to get to.

Quote :

Would you know how the manufacturer initially ‘tunes’ the TBs, and if so why is this not do-able in the field?

Yes they are set up on a flow bench using carefully calibrated vacuum. Not something it's easy to replicate in your average workshop.

Quote :

Thank god I read about it first; I consider myself pretty competent at vehicle maintenance and hitherto, have not come across such innocent looking maintenance grenades.

You consider yourself to be but I'm sorry, in this case you obviously are not. Before you start randomly waving tools about because you *think* you know what you are doing I suggest you read up and study so you do understand how the set up works. I'm sorry if that sounds harsh but it's a simple and unassailable fact.

I, and many others, will be more than happy to explain and help but don't blame the technology, it is beautiful in its simplicity. And if you say something like 'I never had this problem with carburettors' I'm afraid you are beyond help.

eeyore wrote:

One uk Italian bike specialist??? informed me that there was no point trying to balance the TB’s on a bike with more than 3000 miles as there would be too much play in shafts.

This 'Specialist' is a raging fucktard.

[/quote]

This 'Specialist' is a raging fucktard.[/quote]

Yep total.
I asked this specialist loaded questions over the TB’s and resetting the ECU to determine suitability – this was just to keep the service book up-to-date with dealer’s stamps but they didn’t impress with any of the answers so nothing was booked.
We struggle in the UK for good service agents.
My nearest MG agent took on the brand around 2 years ago. Shortly after I called in to get a feel for their capability. They justified their ability as they were a Suzuki main agent and had been for over 30 years.
My other experience with one of the UK’s most praised MG service centre (now closed) was not great. They charged a bloody fortune for the second service. I completed the third myself and found that the oil filter had been marked in yellow marker with the date and mileage of the first service. It may be that the bike didn’t need one owing to ridiculously low mileages – but it was charged out on the invoice!

It's the auto reset point set in stone. I've had to fix a couple that I had nothing to do with but it's a BITCH to get that exact point back.
It has to be real clean so you can find the point it doesn't move TPS, no pressure on it but touching. Reset auto to 4.6, turn stop screw back in till it says 9.2 and auto reset to 4.6.
This should get you within a couple tenths of degree of where it was stock.
I know a few that have got rid of the stepper, in that increase once you need a lot of balance. Then you wait for a warm bike to go
The stepper fucks up the whole process w/balance screw in a grey area cuz ECU picks up the physical placement of TPS, auto reset doesn't fix it
Nice for an ideal perfect engine but some aren't and need more adjustment. It's like they forgot it's an engine and not perfect shit.
What the fuck would you expect from scooter people

Couldn't have been too hard to dab a drop of solder onto the throttle stop & linkage screw threads at the factory, as opposed to a bit of yellow paint, surely?

[You must be registered and logged in to see this image.]
On closer inspection I note the Throttle Stop locknut has been neatly spot-welded in place - kudos to ‘Guzzi, and bound to make you stop and think.

Have a great Xmas,
Lobo.