Idle too low when clutch pulled in Breva 1100

[frans belgium]

My oldest son rides a 2V Breva 1100.  It has been regularly maintained by the dealer and has 40000 km on the clock.  It ran pretty well except

1. startus interruptus
2. idle too low when cold.  Engine dying if not careful
3. dropping idle when clutch pulled in.

Yesterday, I took the bike to a friend who owns and maintains Guzzis since 35 years and lives around the corner. Bit harsh to say, but I'm pretty sure he knows more about Guzzi's than 90% of the official dealers.

He synched the bodies, were actually not too far out of tune.  Now they are dead perfect at 4000 rpm, and near perfect at idle
tps was reset to 4.6, was at 5.0
idle to 1200
And he took care of the startus interruptus.

Result:
Start in a blimp, runs perfect with cold engine at idle without holding the throttle.
pulls like a freight train

But: idle still dropping to almost dying point when shutting down the throttle and pulling the clutch.  Risk of stalling.

Releasing the clutch a few seconds later idle rises to 1200 rpm again.

Further information:
Mistral exhaust and no lambda.  The latter was fysically removed.  Yesterday my friend discovered that the software still showed the presence of a Lambda (with 0 voltage) and adapted the software. But this is probably not important.
The dash seems to have a problem: needle of speedo starts at 10 km, needle of rpm at 1000.  Connector was pulled out, no visible dirt or contact corrosion,  and put back in for reset.  No change.

For the rest, we assume the bascis are ok since it has always been maintained by presumably the best dealer around.

Pardon my dodgy English, I did the best I could to explain.

Any bright ideas on what causes the erratic idle?

[pauldaytona]

But is it clutch drag, or the switch in the handle that makes it do it?

[frans belgium]

But is it clutch drag, or the switch in the handle that makes it do it?

There is no clutch drag, so Philip (you know him) already suggested to remove the pin a the clutch handle and take it up from there.
 

[pete roper]

Have either of the throttle stop screws been messed with?

Pete

[frans belgium]

Have either of the throttle stop screws been messed with?

Pete

Not to my knowledge, can be checked. Thanks.

[ohiorider]

Just an observation on my part.  And I have to take into consideration that the ECU mapping on my 1200 Sport may not be the same as your Breva 1100.  Anyway, here's my story.

Late last summer, I killed  (stalled) my engine leaving a stop.  Bike is in 1st gear.  So, I leave it in gear, pull in the clutch, hit the starter button, and nothing.

Problem .... excessive wear of the clutch handle components (pivot pin, etc) caused the clutch microswitch not to engage when the clutch handle was pulled in.  I made a 'temporary' repair by trimming down a vacuum plug and slipping it over the tip of the pin (or on the little handle tang that makes contact with the switch, don't remember now.)  This allowed the clutch interlock to function again.

Prior to fixing the switch, I was also experiencing a higher than normal idle (1300-1400rpm) when creeping thru stop and go traffic.  This occurred when I left the bike in 1st gear and pulled in the clutch handle.  Once I cured the clutch interlock switch problem, the higher idle issue went away.

My assessment is ....... when the mapping in my ECU 'sees' that I'm in gear and am releasing the clutch handle, it is trying to 'help' me by slightly increasing idle speed as I let out the clutch.

If we're discussing the same interlock switch, and you remove it, you may not be able to start your bike in gear when you pull the clutch in (assuming both bikes use the same interlock logic.)

YMMV

[frans belgium]

If we're discussing the same interlock switch, and you remove it, you may not be able to start your bike in gear when you pull the clutch in (assuming both bikes use the same interlock logic.)

YMMV

We realise that, but otoh it would probably prove that the switch is the culprit.  And take it up from there.  Thanks for the reply!

[Chuck in Indiana]

This may have *absolutely* nothing to do with it, but on small blocks it can mean a worn thrust bearing. When it slows down, does it "feel" electrical or mechanical?

[frans belgium]

This may have *absolutely* nothing to do with it, but on small blocks it can mean a worn thrust bearing. When it slows down, does it "feel" electrical or mechanical?

Definitely electrical.  Tomorrow we'll run some more tests.  I'll keep you guys posted if you're interested.

[JoeW]

I've experienced this on older Guzzi big blocks and the most common cause was tight valves. I know the bike has been serviced regularly but, It's an easy thing to check. I assume you're just pulling in the clutch, not putting the bike into gear.

[pete roper]

Start from the beginning.

Do the valves.

Close both air bleeds.

Warm engine up and balance at 4,000.

Kill engine, re-set TPS.

Restart engine and whichever side has higher manifold vacuum open bleed until both sides are equal.

Reinstall narrow band lambda probe.

Turn lambda on.

Re-set trims.

Check OBD for errors.

Clear any and see if the recurr.

Check paint on throttle stop screws on both TB's. If they have been tampered with the stepper may not be able to adjust air enough to maintain target idle. Remember there is no MAF sensor so the only way the ECU knows how much air is being flowed is dependent on the signals from the TPS and AT sensors being accurate. If the stop screw/s have been messed with the amount of air flowed will not be accurately reflected by the TPS setting so the mixture, especially at small throttle openings, may be grossly rich or lean and the stepper may not be able to compensate.

Pete

[frans belgium]

Start from the beginning.

Do the valves.
didn't do that yet (was recently done and the engine seems to run fine)

Close both air bleeds.
check
Warm engine up and balance at 4,000.
check
Kill engine, re-set TPS.
check
Restart engine and whichever side has higher manifold vacuum open bleed until both sides are equal.
check
Reinstall narrow band lambda probe.
check
Turn lambda on.
check
Re-set trims.
check
Check OBD for errors.
check
Clear any and see if the recurr.
none recurred
Check paint on throttle stop screws on both TB's. If they have been tampered with the stepper may not be able to adjust air enough to maintain target idle. Remember there is no MAF sensor so the only way the ECU knows how much air is being flowed is dependent on the signals from the TPS and AT sensors being accurate. If the stop screw/s have been messed with the amount of air flowed will not be accurately reflected by the TPS setting so the mixture, especially at small throttle openings, may be grossly rich or lean and the stepper may not be able to compensate.
they were not messed with

Pete

Switch at the clutch handle is kaputt
Contact of the neutral sensor had to be cleaned, from time to time bike did not start, thinking it was still in gear

That's about it, rpm's still dropping when clutch pulled in.  "Solved" by setting tps at 5, so engine keeps running.

Thanks in advance for any useful suggestions.

Frans