Cold starts on Breva 750

[GonzoB]

I'm new to my '07 Breva 750. When I start from cold I notice:

• Occasionally when I blip the throttle it will stall when returning to idle
• Unless I give a lot of throttle it may stall on takeoff
• As soon as it's warm all is good

Is this likely to be a problem with the fuel mapping? Where do I start looking?

Gonzo

[SmithSwede]

I’m really not trying to be a smart*ss.  And I’m sure there are ways to finesse the fuel mapping to alleviate your problem. 

But for 40 years I’ve been in the habit of starting my bike first.   Futz with choke or do whatever it takes to get it to idle steadily.   Then while it’s idling, I finish my hot coffee, get my gear on, stash my stuff, etc.   After 3 to 4 minutes of idling, I’ll ride the bike very gently for the first mile, then gently for the next 3 to 5 miles.   

I guess I just don’t understand why everyone today thinks there is a problem just because a freshly started engine is grumpy at first in cold weather. 

I do the same with my 2013 V7 Stone.  It doesn’t like to be ridden immediately after a first start in cold weather.    Does fine if I do the above. 

[GonzoB]

Err. OK.

I guess my first question really should have been: "Is this normal?". If so, that's fine.

I've been riding fuel injected bikes since '06 and none have exhibited these issues.

Gonzo

[SmithSwede]

Sorry man.  Not trying to be difficult.  Just my Abbie Normal thoughts.   

Yes, I’d say it’s normal on a stock Guzzi small block. Mine is cranky at first, and will start up dead cold but then race up to 2,500 or 2,800 rpm for a while.   Then it will sorta idle, but with missing and lurches.   It has died at times while warming up. 

I think the coldest I have started it was 7 degrees F.  Plenty of times in the low 20s F. 

Like I said, if you just ignore this early morning/cold start drama and let it warm up for 3 to 5 minutes, all is well.  I have frankly never tried to ride off on a stone cold engine like this. 

I bet Beetle’s revised fueling map helps with this condition.   

On a related note, when it’s really cold, it can be a bitch to shift out of first to second.  Again, gently riding a few miles makes a huge difference.  I’m running 75W-90 synthetic gear oil and it still gets stiff when frosty cold. 

[SIR REAL ED]

I'm new to my '07 Breva 750. When I start from cold I notice:

• Occasionally when I blip the throttle it will stall when returning to idle
• Unless I give a lot of throttle it may stall on takeoff
• As soon as it's warm all is good

Is this likely to be a problem with the fuel mapping? Where do I start looking?

Gonzo

My 07 Nevada 750 is the same.  IIRC, Beetle's response to one of my inquiries was (paraphrased) "the twin throttle body V7's run so well stock that little benefit is obtained by re-mapping." 

Apologies in advance to Bettle if I interpreted this wrong.

I remember thinking "a choke lever.... on a fuel injected vehicle.... that's a new one to me."

[malik]

My V7C has the same motor, and I know I used to use the fast idle (aka choke) lever regularly, until I replaced the battery with a lithium ion (SSB) and didn't need to use it. However, since I did the last throttle body balance & idle adjustment, the bike now requires a warming up period, likely only because the fast idle lever is not working well. I'm going to be tearing the bike down again soon for another clutch, so I've put off fixing the fast idle until then. It should be a relatively simple job, to adjust the cable and the lever action, so it operates smoothly once more. I'm running Beetle's map for the 15RC, and have removed the lambda sensor. Balancing the throttle body did improve the running, but it's probable that a nudge on the idle adjustment might help the cold starts. I tried setting the idle as low as I could reasonably get it.

Mal.

[timonbik]

My 2008 BB is exactly the same. Needs constant care with the throttle for 2 or 3 minutes and then ridden gently or she will buck like a bronco but once warm can be flogged to your hearts content.  I fear playing with the mapping because it does rum so well once warmed up.   
Cheers, Tim

[Kev m]

Ok, so a few thoughts.

Normal? Sorta. For some reason a lot of smallblocks seem to be very cold blooded. I'm not sure why the 2TB model would be as bad as the later 1TB models since the latter have a different idle strategy.

The 2TB models don't have a "Choke" per se. Cold start enrichment occurs via temp sensor and ECU mapping like any EFI. The lever is a mechanical fast idle control. Where MOST EFI systems use some sort of ide air control stepper valve or direct idle control to manage cold idle speed, a number of older Guzzis used a fast idle lever. It mechanically holds the throttle plates from closing fully to help cold starting and running during warm up.

Edit-if I wasn't clear. A cold motor stalls easily at lower idle speeds. Carb motors idled faster because of throttle plate position vs extra fuel from the choke circuit.

EFI motors have their throttle plates set to minimum positions for hot idle. Extra fuel is calculated by the ECM. But additional AIR is needed for higher idle to prevent stalling. Automatically controlled idle is done through throttle plate bypass. A fast idle lever simply holds the throttle plates open a bit to accomplish the same thing.

End edit

Anyway, there is no good reason a modern EFI motor should need to warm up for minutes. My big block Jackal would pull away instantly after start, as would my Breva 1100, our Ducati, and every EFI Harley I've ever owned or ridden... Oh and every EFI BMW etc etc etc.

But for some reason the smallblocks are more stubborn. Though I think you have way more control on a 2TB because if mechanical adjustment.

So tune it up, check TB balance, adjustment, and TPS setting, but you're probably fine or damn close and worse case scenario yeah, warm it up for a minute.

[GonzoB]

OK, so it's pretty normal. I'm happy to warm it up a bit.

Thanks all.

on to the next project....

Gonzo