Nevada issues

[ratguzzi]

Ok, I bought a Nevada last weekend to ride when I am working in Poland. After about 200 km, I was hearing a bit of noise in the clutch and it would go away when I pulled the clutch in slightly. It would get worse as I rode and eventually had to adjust the clutch cable to the end. I assumed the thrust bearing was bad and it was wearing down the clutch rod. Saturday I drove 800 km round trip to Stien Dinse and bought the parts I needed. I tried the easy thing and just replaced the rod and bearing (which was bad)  but the noise was the same. I pulled the transmission and I could see the casing was being whacked by the clutch assembly because 2 of the 6 bolts were loose. Ok, so install a new clutch plate, the cup for the clutch rod, etc and now the clutch is perfect.
Ok, so having fun and enjoying it. Later, I stop at a friend's house and when I went to leave, the bike spins over but won't fire. Like if the plug wires were off. After trying a few minutes, there is one "bang" in the exhaust pipes and the bike is running perfectly. Rode it back to the hotel no problem.
This morning, it cranks over but not firing like last night.
I had no time this morning but I will check later. Confirm if there is spark. I will assume none. Then check the sensor in the transmission housing because I removed it earlier, then measure the voltage to the coils when cranking and when not.
I am not sure on Nevadas but the dash lamps (oil, charging, neutral) go black when cranking and then come on when I stop cranking. Maybe the battery cables. Or that's how a Nevada is.
JB

[Kiwi_Roy]

Which one of Carl's drawings is most like yours John?

http://www.thisoldtractor.com/guzzi007/schematics/1994_Nevada_350-750.gif

http://www.thisoldtractor.com/guzzi007/schematics/2002_Nevada_series_1.gif  I'm assuming it's this one.

Either one seems to rely on the side stand for power to the coils, my guess would be an intermittent coil supply.
No I don't think the lights should go out, oil pressure maybe.
The second one shows an electric petcock but that may be a NA thing.
Can you hang a small lamp on the power to the ignition coils, perhaps wrap a wire around the relay 87 pin with the other wire to chassis.

[ratguzzi]

Which one of these is most like yours John?

http://www.thisoldtractor.com/guzzi007/schematics/1994_Nevada_350-750.gif

http://www.thisoldtractor.com/guzzi007/schematics/2002_Nevada_series_1.gif

Either one seems to rely on the side stand for power to the coils

I found that schematic a few minutes earlier and I agree. I thought it affected the cranking too but per the schematic, it doesn't.
JB

[Kiwi_Roy]

It could be as simple as a dirty ignition switch, try exercising it several times.

Is it the second schematic?
 
Bear in mind the wiring over there may be somewhat different.

Does the headlight come on and turn off while cranking like over here with a 5 pin start relay? (trying to establish if the starter solenoid goes through the switch) If it doesn't
the start relay could be fed direct from the battery and not rely on a good switch.

In the essence of time you may just want to hot wire the coils through a separate switch.
http://www.thisoldtractor.com/guzzi007/schematics/2002_Nevada_series_1.gif
A wire stuffed in 30 - 87 of the relay (39) would do it

[Old Jock]

Hi John

Need to know which series of Nevada it is to get a better idea

I'd check the phase sensor for sure, then I'd check you are getting a good positive supply to the coils, especially if it's an older model, getting power via the side stand switch is a bit scary, to me.

Once that's done you can work back or forward into the wiring.

I'm also wondering if it's a later series about that petcock possibly being sticky

As usual Roy is supplying excellent advice

John

[ratguzzi]

I eliminated the side stand switch and it didn't help. Then I moved the relays around and it fired right up. One relay in the first position and I get no lights. I moved it to the third position and it fires up and runs. But also everything seems to work. Horn, brake light, starter. I am hoping the relay is similar to something automotive.
JB

[Old Jock]

Hi John

Do they look like this



or this



If so they should be readily available I reckon, 4 or 5 pin ISO micro relay, I reckon, my Sporti uses the 5 pin type, 20A rating on the N/O contact and 10A on the N/C

Any decent auto shop should have them

John

[Kiwi_Roy]

As John says it's a standard automotive relay, I know I have seen them in earlier model Jeeps
A 4 pin is all you require for two slots but most owners use all 5 pins. they will work in any position. the start relay is the only 5 pin that's required (for the headlight interlock)

Sounds like you are ok then.

A couple of times I have seen one of the contacts push out the back of the socket and make an intermittent contact, make sure they are clipped in.

[ratguzzi]

They all had the same part number and all were 4 pin. I see that they are used on some Fiats as well so I should be able to get new ones easily.
The equipment I work on here in Poland are full of 12-24vdc relays and in an emergency, I can make a temporary jumper wire set and use them.
Now I am hoping it wasn't a coincidence that it started!
JB

[Kiwi_Roy]

The relays are a well known problem on VIIs
All 4 pins, I guess the headlight's not interlocked with starter then, not quite like Carl's drawing
4 or 5 pins relays will both work.

[ratguzzi]

The relays are a well known problem on VIIs
All 4 pins, I guess the headlight's not interlocked with starter then, not quite like Carl's drawing
4 or 5 pins relays will both work.

Right, Euro models still have a manual headlight switch to turn on or off.
JB

[ratguzzi]

Well, it was coincidence. This morning, same issue. This time I pull a plug and no spark. Put in new relays and no spark. While I am cranking, I work the red run/off button on the right side and then I instantly see spark. So I will pull the switch today and clean the contacts.
JB

[Kiwi_Roy]

That's good you found it, just about 100 milliamps flowing there assuming it has a relay.
I don't think a Nth American Nevada would crank over if the kill switch was open, not according to Carl's drawing anyway but I know other Guzzis will, different wiring over there.

That bike will be sorted out by the time you leave, the next owner will appreciate it.

BTW did you find the relays at Fiat?

[ratguzzi]

Another coincidence, driving me crazy. This morning yet another repeat of no spark, I screw around with connections (which has no relevance) and all of a sudden it has spark and runs fine the rest of the day. After closer examination of the schematics, if the fuel valve is on, the ECU has all it needs. Whenever I turn the key on/off or remove the relay, I hear the fuel petcock click. So all other switches are ok. This is coming down to making sure the 12vdc is truly at the ECU. Most likely is but I will check next time it happens. If true, I am down to only a faulty ECU which rarely works then doesn't, usually a total failure or finally the phase sensor which I plan to remove today, make sure it's clean. Doesn't look adjustable.
It seems totally fine if the bike hasn't sat overnight. Never a hiccup or anything once it's running.
JB

[pete roper]

John, what Nevada? Is it a later fuel injection model or a Carb with the Motoplat ignition?

Pete

[ratguzzi]

John, what Nevada? Is it a later fuel injection model or a Carb with the Motoplat ignition?

Pete

Peter,
It's carburetor and no year on the vin plate. Paperwork says 2002 but my friend here says they get this wrong in Poland quite often. On the Stein Dinse website, I am confident it's the 98-02  version and the ECU looks identical to what they show.
ECU
NML Elektr. Zünd. Digiplex 750 Nevada `98-02
Has the same vacuum lines, pulse sensor, etc. Flywheel has 4 pick up tabs, 3 are single and one is a double tab. They look 90 degrees apart.
JB

[Kiwi_Roy]

The pickups are magnetic, perhaps the flywheel one has picked up some swarf from the gear

[pete roper]

Well that robably explains it. The 'Dodgyplex' system isn't an ECU, it's simply an electronic ignition. It is also as weird as buggery!

The vacuum lines aren't an advance system they are actually a sort of vacuum retard. It uses manifold depression to retard the spark at low rpm/high throttle opening to allow for the super-lean set up of the carbs. It was this sort of half arsed bullshit that eventually went to the bin, (Thank heavens!) when fuel injection was adopted.

That isn't the only weird thing though. When the engine is off and no trigger pulses are generated by the pick-up, (And I can't remember if there are one or two. On the 1100 Sport there were two.) it sets the ignition advance to a baseline figure. As soon as the engine fires and the crank starts spinning the ignition defaults to a much higher advance figure.

The problem is if the engine fires and then stalls because if it does this the ignition module doesn't return to the baseline, low, ignition advance. It then means you can crank away like a bastard and it won't start but eventually the unburnt charge in the exhaust get ignited by a misfire and you get the 'Big Bang'!

The trick is to a.) have it tuned *Exactly* right. And b.) when you start it, pull on the choke, don't touch the throttle, fire it up and don't touch anything until it begins to hunt and miss and then ease off the choke slowly until it will idle on its own.

YES! It's a huge. King sized pain in the arse and if it stalls during this absurd pantomime you need to turn the ignition off for several seconds and try again! And people wonder why I've become such a fan of FI!

Pete

[ratguzzi]

The pickups are magnetic, perhaps the flywheel one has picked up some swarf from the gear

That will be today's check because I did remove the sensor when I pulled the transmission. It looked symmetrical so I don't think it matters which way it is put in.
JB

[Chuck in Indiana]

I've never had a problem with Digiplex, but Pete is right about having to shut it off and start over if it fires but doesn't start. You'll have to excuse him, he thinks anything with carburetors makes his hands smell bad. <shrug>
Power to the Digiplex is on the middle wire of the plug. Power there, and it will run. I'd pull the plug on the Digiplex and deoxit it, along with the pickup and relay that powers the Digiplex. Sounds to me like corrosion somewhere.

[guzzisteve]

I think there is a ground wire that keeps it at 2* instead of going back & forth with the timing. You are to hook it up if using regular fuel. I have not experienced a bad one but the unit in my SP3 crapped out on the next owner.

[Chuck in Indiana]

I'm pretty sure that grounding that wire pair only retards the timing 2 degrees. The weird startup procedure is the same.

[ratguzzi]

Chuck, I hear you but if a bad connection I would expect these rough roads made of dirt and rocks would cause at least one miss fire. But same argument for the pulse sensor. I still lean towards the sensor because I had no starting issues until after the clutch job. Also, when it won't start, there is no spark. So that sort of eliminates the procedure situation, correct?

[Chuck in Indiana]

I'd check the middle pole on the Digiplex for 12v. If it doesn't have it, look at relay 39, fuse F2, and the kill switch. If it does have power, check the phase sensor.
It's a simple system..the Digiplex is a glorified set of points.
edit:
Fuse F4 powers the ignition switch. It and the switch itself could be not making connection, too. Other than that, I got nothin.