docc

The earliest Griso were 2-valve-per-cylinder? It was the early change to 4-valve-per-cyliner that need to be "rollerized." What would that cost like $800-1000US?

Yes, to the back/right/top of the gearbox behind the seat latch:

For sure, remove the caliper and turn the bleeder to the top for bleeding. That alone may solve it. Also, pull back the rubber boot under the master cylinder, inspect, clean, and grease. But only use silicon based lubricants around brake parts. Petroleum based lubricants will damage the seals. It is possible the WD-40 destroyed (swelled) your seals . . .

Both my failed TPS exhibited jumping (up and down) in the resistance (2000 Ohm range) with my Triplett DVOM. It was not apparent on the millivolt scale. This is testing the resistance through the TPS (potentiometer) slowly opening and closing it while reading the resistance. Normally, the TPS reads over one Ohm and scales through the tenths and hundredths, as I recall. My bad TPS would jump up and down at several points and even went "open" at a certain angle of opening. The Sport was getting hard to ride.

Looks like the CaCycleWorks PF3C is a good source, at least in The States. Probably half the price of a Moto Guzzi Part. And it seems the Harley-D part is No Longer Applicable (?) I'd like to say I can feel the difference between the PF3C and the PF4C, but that would be like trying out a new tire and declaring it "so much better" than the old tires. For me, that is likely only because the old tires were clapped out and any new tires would be a fabulous improvement. So, the stability of transitioning from closed throttle, as in coming out of a corner or maneuvering at parking, is resolved. The >hoogedie< jerking and jumping at slight throttle openings is also gone. My 49,000 mile TPS had just aged out, that's all. From my notes, it seems these potentiometer-based TPS might expire at 50-60,000 miles (80-100.000 km). I'll be checking mine at every tune-up now. So easy once the DVOM is hooked up, especially with a breakout harness. Again, I have never been able to see the glitches with millivolts, but Ohms give it away.

Looks like we've mixed a couple topics: "Cheaper source for TPS" and "Alternatives for the potentiometer based TPS." I have no way to separate these posts anymore, so let's all be aware there is more than one discussion going on in this thread. It's kinda like being at a party where the conversations and music sorta blend . . .

That's a good question. Mine lasted about 100,000 miles. Unless it has gotten wet from one of the eight oil leak opportunities in there . . .

I thought I would get busted for warning you about "partying out" the Greenie . . . Looks like *partying out* the 850 is okay with everyone here . . .

Only if you start partying out your Greenie to fund it . . .

PF3C arrived today, now installed. Well, it is a beautiful thing to watch the Ohms rise and fall perfectly smoothly on a fresh TPS. Hoping for a brief test ride tomorrow, but the coming weekend will tell the tale. I'll be adding the resistance test to the Decent Tune-up. After all, once the DVOM is hooked up to baseline the TPS to 157 mV, it is really simple to switch over to Ohms and look at how smooth the potentiometer (TPS) is functioning. I have never been able to catch a bad TPS watching the change in millivolts, but in the 2000 Ohm range the resistance variation (jumping around) opening and closing the TPS is obvious. Pretty sure Meinolf has said that a bad TPS can be seen in guzzidiag watching degrees of opening while opening and closing the throttle.

Dude, you should reverse the order on those functions . . .

Well, he did show up at a South'n Spine Raid, so that does not diminish anyone's barbarian status . . .

I was able to source all the parts from a MotoGuzzi dealer. Be sure to inspect the retaining washer on the gearbox input hub and take care of all the leak sources while you’re in there. Maybe something good in this thread: Sticking clutch

So, as the stumble has persisted at low throttle openings (where we spend most of our throttle time), I recalled this from a previous TPS failure. New TPS on the way. A bad TPS might explain why it was more sensitive (faulty) than expected at those low openings. Cheaper Source for TPS

That little screwdriver ought be framed with gallery lighting. . .

Custom earplugs are a delight. I had an audiologist make mine for about $100US at a place that handles hearing aids.

Even when you click on the last reply time/date below the last poster's username ll the way at the right?

This is using a mobile device? On my Mac I can click on the latest post Time/Date to open the last post, but on the iPhone I can only select the last page and scroll down from there. ( Android may interface differently?)

You're speaking of the center chrome cap in the top of the headset shown just left of the Agostini key fob? Gently slip something thin under its edge and pry it up being careful not to scratch the surfaces. There is a hex drive under that, as I recall.

My Sport has gotten all spitty and jumpy just off closed throttle where I "cruise," pull away from stops, and out of corners. Very annoying and I remember it doing this when the original TPS played out at 62,000 miles/ 100.000 km. Using the Caspers Breakout Harness and Triplett DVOM set to Ohms, the resistance jumps all around at those low throttle openings. Time for a replacement! I've been running a H-D PF4C over ten years (49,000 miles/79.000 km), but those now seems to be non-adjustable so I ordered the CA-CycleWorks PF3C they spec for Ducati. Almost $100US shipped. We shall see if the "Nasty Hiccup" resolves . . . and how the correct PF3C curve "feels" after all this time with the PF4C.

I don't know what those washers are actually called. They don't really "crush", but have an internal rubber ring that makes the seal. Also, check to see that the hose(s) have not been riding against the frame and have worn through. I added zip-ties to protect mine when I saw that happening:

A quiz!

Motowfo sez: check with John Zibell (Jlzibell>at<gmail.com) in Huntsville, Alabama. The man has a longtime, established, and positive Moto Guzzi reputation.

The relay in that circuit is #2, second from the front . Also, since that bulb lights by grounding, check / clean / secure your main ground from the battery to the back of the gearbox on the right. If your electrical system is finding alternate ground paths, bad things can happen!

Is the 30A fuse, or its contacts heat melted or damaged?