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V7 Classic, unreliable idle.

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Vegas Pete View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vegas Pete Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov 2017 at 05:45
Greetings, all- new member here.

I have a V7 Classic I bought new in 2010 that's had a problem with idle and low speed since new.  When I first got it, it had a terrible problem of simply dying suddenly with the throttle closed.  An example would be while making a turn at an intersection- enter the turn in 3rd. gear at about 2500 RPM, pull the clutch and shift to second, and when the clutch was released the rear wheel would try to pass the front wheel because the engine was dead-stopped.  Yes, it got my attention the first dozen or so times it happened.

I thought that the engine was just tight, and that it would improve as the engine broke in.  It didn't- it just got worse.  At the end of the first week I put it on the trailer and gave it the "Ride of Shame", back to the dealer- 350 miles away.  Since I was so far from the dealer, I had done the 500 mile service myself, and voided the warranty.  They kept the bike for a week, and called me to come get it.  The problem, they explained, was that "I'd set the valves too loose", and charged me $300 to set them properly.  It ran better, but I did notice upon getting it home that the TPS had been changed- and didn't appear on the invoice.  So... void the warranty, charge $300 to adjust four valves, and send the failed TPS back to Moto Guzzi for credit, shop makes a quick $300 and gets a free TPS in the process.  Nothing I could do about that except vow to never darken their door again- a promise I've since kept.

So, seven years and 17,000 miles later, the engine has ran itself in nicely.  It doesn't die during downshifting any more- at least not very often- but it still has idling issues.  Sometimes it will go all day without a hicuup, sometimes it will run perfectly for a week- but the unstable idle issue always returns.

Let's say that the idle is set to 1300 RPM.  The idle RPM will start surging to as much as 1800 RPM, and down to as low as 800 RPM.  It will do this for 3 or 4 seconds, then smooth out and idle fine again at 1300.  It might do this once or twice, or it might do this every time you come to a stoplight.  Heat or cold doesn't seem to be an issue- I live in the desert and it will do this just as redilly at 20F. as at 100F.  Humidity?  It's done it in the rain, and at 2% relative humidity.  Doesn't make any difference.

However, here is one thing I have noticed.  One of my other bikes is a Ural hack, that has been fitted with a manual control for the ignition timing.  After years of riding with non-automatic spark advance the relationship between idle speed and ignition timing becomes very obvious.  Retarded and advanced timing have completely different exhaust and intake sounds as well.  It sounds to me as though the unstable idle is being caused by inconstant timing.  And, it gets worse.  One of the things it does at idle is a sort of stumble- both cylinders are firing, but one will be down on power.  Every other power stroke will be weak, causing the RPM to drop and the engine to shake from side to side.  It will do this for three to five strokes and then everything will be instantly back to normal.

The one common denominator here is that it only does this with the throttle completely closed.  The instant the throttle is cracked off idle, it instantly stops doing all this.

So, I'm convinced that the problem is erratic ignition timing, and it must be coming from the ECU.  The question is, what can I do about it?  Is there some input to the ECU that could be doing this?  Is there some sort of reflash that can be done to the ECU?  Or, is this something that originated in Moto Guzzi's marketing department?  As we all know, nothing screams "Exotic!" like the erratic idle of something over carbureted and over cammed.    

Anyway, I really like the bike in general- it reminds me a lot of the Yamaha TX500 I had in the early 1970s.  If anyone wants to take a shot at it, I'm all ears.

Sorry for taking up so much of your time....

Vegas Pete.    
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Cylvabirch View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cylvabirch Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov 2017 at 07:05
Hi Pete, pleased you have joined us.
Mine seems sorted now and in looking back there are a number of things I have done.
Firstly the valves were reset to .008 inch on both inlet and exhaust to ensue they fully close. Baldrick balanced the throttles using his very accurate gauges. This is easy to do on the older V7s with twin throttles, the linkage has an adjuster on the left hand side near the throttle body that operates on the right hand side throttle. Using accurate gauges or a differential gauge you can set them up dead on. There is good guidance in the V7 Workshop Manual.
You need to get the engine warm, screw in both by-pass screws, hold the revs at 1800 on the twist grip and balance the throttles using the adjuster.
Then let the engine go back to idle by releasing the twist grip and open either by-pass screw to get the idle speed near 1200. Then open the by-pass screw on the other side until the revs rise a bit and then close each of them down a bit at a time to get back to 1150 rpm.
It all sounds more difficult than it really is!
I also fitted a Finebau Forge Aerolite Plus and have optimised the setting by having dip switches 1-5 on and 6,7 and 8 off.
There have been occasional reports of crankshaft position sensors failing, and this could give the symptoms you identify if the failure is intermittent.
I hope that you get it sorted!
David
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Post Options Post Options   Thanks (0) Thanks(0)   Quote theone&onlymin Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov 2017 at 17:55
Have a look on Guzzitech as well.

Cherry
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vegas Pete Quote  Post ReplyReply Direct Link To This Post Posted: 21 Nov 2017 at 22:50
Greetings, and thanks for the info and interest.

I'm pretty well convinced that the problem isn't mechanical in nature- say a loose sensor or electrical connection.  It feels to me more like it's something actually programed into the ECU.  When it's happening, it goes from "running perfectly" to "not right" in less than one crank revolution.  The recovery is just as abrupt- like throwing a switch.  Slightly increasing the idle RPM will stop it from happening, but it shouldn't have to idle at 1500-1600 RPM.

After a while, you begin to recognize it has several distinct failure modes, which it shifts between as it feels appropriate;  there's the "no advance on one cylinder until the RPM drops almost to stalling speed" mode, the "miss one or two firing strokes in a row and recover" mode, and the "advance the timing until it's idling at 1800 RPM" mode.  The "no advance in one cylinder" trick is it's favorite- it will do this several times a minute sometimes, and then clear up with no explanation.  The other two usually won't repeat without a visit from the "no advance gremlin".

The only thing I've ever experienced that's even close to this was a Yamaha XT550 back in the mid 1980's.  Here you had a four stroke single that would behave exactly like a Honda 350 twin with one bad spark plug.  It would "feel like it was running on one cylinder", barely make 30 miles an hour wide open, and then suddenly it would take off and run like nothing had ever happened.  After living with this far too long, I finally came to the conclusion that the ignition module had a rev limiter built into it that controlled RPM by killing every other spark, and thought that 2500 RPM was a good point to start limiting.  I finally fixed the problem by selling it to a friend for $150 (it was in excellent shape other than the ignition issue, and had 8,000 miles on it at the time.  He still rides it- when it does it's "run on one" trick, he takes the seat off and hits the ignition module with a rock until it stops doing it.  He's much more forgiving of this sort of thing than I am. 

Here's another head-scratcher that's probably closely related.  A couple of times a year I visit a shop in North Vegas, and for the return trip I take the freeway.  So, leave the shop, get on the freeway and cruise at 80 MPH for thirty miles (around here, any slower and you'd be run over).  After 30 miles, exit the freeway and slow to about fifty MPH while passing through the local airport, eventually coming to an intersection with a traffic light.  The light's red, so you coast down to about 2000 RPM in fifth, pull in the clutch and shift down through the gears to neutral as you roll up to the line... and by the time you get to neutral the engine is dead stopped, which doesn't do much for your opinion of your bike's reliability.  

I can't say it's because of a cold engine, after twenty plus minutes at cruise speed.  It's done it in 50 degree weather and in ninety degree weather.  Doesn't seem to matter.  It's done it several times, always at the same intersection, traveling in the same direction, and after the same ride profile.  It's never done it anywhere else.  One good point- it always restarts instantly and runs afterward like there was never any problem.  

Is it possible my bike's possessed by the ghost of Benito Mussolini?

Vegas Pete.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iansoady Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov 2017 at 11:00
This may be completely wrong, but does the V7 have fuel injection? If so, there will be an idle air control valve (stepper motor). This will be what controls idle speed, not the throttle cables.

A few years ago I had a Triumph Tiger and they were notorious for sticking IACVs giving very much the symptoms you report.

If it's not EFI then ignore all the above.......
Ian
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vegas Pete Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov 2017 at 18:44
Greetings, Ian, thanks for the reply.

My V7C is fuel injected, but it doesn't use a stepper motor.  I vaguely remember looking into this when I first started trying to solve the riddle about five years ago.  I believe the bigger Guzzis use a stepper motor, of which there was much internet discussion about at the time, but mine uses a manual fast idle control mounted on the left handlebar- disguised as a choke, but actually nothing more than an idle stop.  Also, the parts catalog for my model doesn't show a stepper motor or IACV.

Sooner or later, I'll catch it off guard and be able to confirm this condition originates within the ECU, and is not the result of some peripheral input.  Until then, I've mainly learned to live with it.

If it is the ECU, I'll bet it's expensive!

Vegas Pete.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Cylvabirch Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 07:51
Pete,
You could give a Finebau Forge unit a try.
David.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 08:38
On the V7C, some have just disconnected the O2 sensor, forcing the ECU to go to it's base map rather than be controlled by the sensor and so running a weak mixture.
 
Others have added a schottky diode in series with the signal output from said sensor to fool the ECU into running slightly richer. This is essentially what the Finebau unit does, though it's a bit more sophisticated.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 08:42
Wot Brian said...I fitted a FatDuc to mine and it's been fine ever since.
V7 Classic Black and gold is the best colour
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 09:08
The difference between the FatDuc and the schottky diode is a lot of money. The schottky diode costs a few pence/cents.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote BobV7 Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 10:32
There you go Brian, that's the difference between you and me......you know about all that electronic and electrical stuff and I know how to change a light bulb. And that why I buy kit ready made.
V7 Classic Black and gold is the best colour
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Post Options Post Options   Thanks (0) Thanks(0)   Quote V7Chris Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 14:59
You and me both Bob. Lucky there are one or two knowledgeable chaps like Brian to keep us well informed on the forum. The main reason I initially joined. God knows what we all did before t'internet, found out the hard way I guess.
(Anagram of Brian is brain notice, whereas anagram of Bob is errr Bob? And Chris is err... well never mind that point)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dukedesmo Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 16:48
Sounds to me like the usual emissions gubbins causing problems?

Try to conform to low emissions, 1% (or less) CO content and they don't run so well. 

I don't have any knowledge of Guzzi injection systems but my fuel-injected Ducati 916 runs lovely and smooth with the CO around 4-5%, lean it out to 2% or less and it backfires out of the throttle bodies on idle...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Brian UK Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 21:33
I'm sure that's it.
 
The diode solution was put by a guy calling himself Sign216 on another forum. I tried it on the Norge but it brought up the service light from time to time. He swore it didn't on the V7.
Brian.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vegas Pete Quote  Post ReplyReply Direct Link To This Post Posted: 25 Nov 2017 at 21:38
I will definitely be giving the O2/lambda sensor removal a shot. What do I have to lose?

I have to admit, my MG, despite the painfully lean idle, doesn’t seem to belch, cough, or backfire. It just has this annoying instability. When it wants to idle, it does so flawlessly.

I guess I’m just more comfortable around carburetors and vacuum tubes.

Vegas Pete.
2010 V7 Classic, 2005 Ural Gearup, 1980 Yamaha DT175, 1973 Rokon RT-140, 1969 Rokon MkIII
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