Breva 750 Success

[Hugh Straub]

As the repeated recipient of useful advice regarding my 2006 Breva 750, I offer this update.
Since I acquired the bike last Fall, I’ve been struggling with bucking and surging issues which seem relatively common with this model.  As there is no Guzzi dealer anywhere around New Orleans, I have had to rely on Guzzi’s cryptic manuals and good advice from folks here to try to sort out this issue.  Over the months, I have removed emissions gear, rerouted sensor wires away from the coils, tested the coils, replaced plug wires and caps, fuel lines,  as well as all the usual maintenance work like replacing air filter, oil changes, repeated throttle body balancing and tune ups all to no avail.  So, then I paid to have the ECU reprogrammed.  When that didn’t help, I downloaded the Guzzidiag program and bought the hook up wires. Very helpful people shared numerous maps, which I tried, finally culminating in a too expensive three hours on a Dyno at the local Ducati/Triumph shop.  Fascinating experience, but the bike still bucked and surged. (FWIW, my poor running Breva made 40 HP at the rear wheel)
From time to time, I watched Ebay, looking for an ECU, but they were very expensive, particularly to put on a used bike when the ECU might not be the fault.  Finally, a relatively cheap ECU came up, reportedly from a wrecked, late model Nevada 750, which is essentially a Breva in a slightly different format.  The part numbers for the Nevada and Breva ECUs are the same.  I figured either Nevada ECU works or I turn the bike into a planter. 
Happily, it turns out the fault was in the first ECU.  The Nevada replacement ECU without any adjustment or remapping, has the bike performing as it should.  And for the first time since buying this bike, the plug reads are really good.  By the way, all sensors including the O2 sensor are in place, connected and presumably working as intended.
As Summer deepens and gets too hot to ride much in New Orleans, I’ll down load the Nevada ECU map to the unit which came with the bike to see if that ECU’s fault is uncorrectable.
Regarding tank swelling, during my endless efforts at trying to get the bike to work properly, I had the tank off many times.  I found the tank’s length had increased to the point it was difficult to insert the securing bolt at the tank’s after end.  So, during the most recent six week down time, I removed the fuel pump and fill cap assemblies and placed the empty, open tank in my uninsulated attic.  Six weeks in that hot attic dried out the nylon, returning the tank to its original dimension. Now it easily fits and I will try in the future to buy only non-ethanol gasoline.
So, I am delighted to have returned this bike to the land of the living…I suspect it never ran well, which is why the former owner sold it to me – without a word of warning.
Kind regards

[Moto]

Regarding tank swelling, during my endless efforts at trying to get the bike to work properly, I had the tank off many times.  I found the tank�s length had increased to the point it was difficult to insert the securing bolt at the tank�s after end.  So, during the most recent six week down time, I removed the fuel pump and fill cap assemblies and placed the empty, open tank in my uninsulated attic.  Six weeks in that hot attic dried out the nylon, returning the tank to its original dimension. Now it easily fits and I will try in the future to buy only non-ethanol gasoline.

Thanks for the report. You certainly have worked enough to deserve a long stretch of good riding on your Breva.

Also your account of drying out your gas tank so it shrank back to its original size is surprising and edifying, at least to me. (I presume the alcohol was driven out of the plastic, which makes sense.) Had you heard or read about this before? Good luck on using ethanol-free gas to control the problem. I hope you report back after a season or so's more riding to tell us how you tank does on that new regime. This could be important for others.

Bravo!

Moto

[RinkRat II]

  Way To Go Hugh! Persistence and sheer determination has great rewards,  not to mention the satisfaction of figuring it out and making it work.

    Besides, I always like a story with a happy ending


    Paul B
 

[Tom H]

Congrats!!

Tom

[chuck peterson]

  good on ya for the persistence...moto guzzi, making electricians out of riders since 1929

[Jurgen]

Good report, Hugh.  I also have a Breva 750, fortunately without running problems such as yours.  But, I did have the fuel tank elongation problem that I solved by elongating the rear mounting hole. No more removing hassles.

Jurgen

[Hugh Straub]

Thanks for the report. You certainly have worked enough to deserve a long stretch of good riding on your Breva.

Also your account of drying out your gas tank so it shrank back to its original size is surprising and edifying, at least to me. (I presume the alcohol was driven out of the plastic, which makes sense.) Had you heard or read about this before? Good luck on using ethanol-free gas to control the problem. I hope you report back after a season or so's more riding to tell us how you tank does on that new regime. This could be important for others.

Bravo!



Actually, the ethanol attracts water which in turn is absorbed by the nylon tank, causing the tank to swell. Left unchecked, the tank can swell and break on its mountings.  MG was not the only marque seduced into using nylon tanks to create swervy lines.  Reportedly no problem with pure gasoline, which is becoming increasingly difficult to find.

[Muzz]

Good report thanks Hugh. Pleased you got your Breva sorted. The motor on mine has always mean great from day1, and is a constant source of enjoyment.

We don't have ethanol in our petrol thank goodness to give our plastic tanks grief.

[M0T0Geezer]

My 2004 Breva 750 just rolled across the 50,000 mile marker today.
Your initial probs will be well worth the aggravations after you ride it another 5,000 miles.
'Geezer

[Moto Fugazzi]

Glad you got it sorted out! Sucks that you paid to have the ECU reflashed, and they didn't test it to see if it was corrupt. Maybe they can offer you a partial refund, or at least reflash the new one for free,
On a side note, I had the ECU on my V11S reflashed by a guy, and somehow the CO trim got set to -73. I had all kinds of bucking with that. You may want to reconnect your old ECU and check that setting. That may be your huckleberry.
Ken

[sign216]

Glad to hear that the bike's problem was found.  Cheers to you for keeping at it.

I also lament the lack of pure gasoline.  In New England everything is 10 - 15% ethanol.

[Moto]

Actually, the ethanol attracts water which in turn is absorbed by the nylon tank, causing the tank to swell. Left unchecked, the tank can swell and break on its mountings.  MG was not the only marque seduced into using nylon tanks to create swervy lines.  Reportedly no problem with pure gasoline, which is becoming increasingly difficult to find.

That makes even more sense, since the H2O molecule is so small. But where is a source for this information that I could consult?

Thankfully, here in southern Wisconsin pure premium gasoline, w/o alcohol, is pretty easy to find.

Moto

[Bonafide Bob]

Good to hear that you have it running as it should.

Bob