Cold Weather = No Bucking - K-Bikes.com - Excellence in Motion
 
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post #1 of 5 (permalink) Old Oct 25th, 2006, 1:09 pm Thread Starter
 
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Cold Weather = No Bucking

So there I was...knee dragging doing 145 on a 45 mph posted curve with hard parts showering the 911 behind me with sparks.

Oh wait wrong story. Guess I better tell the no BS one...

Anyway, I went riding today to do some errands. I know that the weather forecast for NE Wisconsin is on the top of everyone's must know list. However, in case you missed it, it has been a little cooler lately. Mostly in the mid to upper 30's.

The point to all of this drivel is that in about 100 miles I never once noticed any bucking or fueling problems. I do not have 7.x installed yet and I have had recurrent problems with low speed/RPM bucking. Not today though! There were several places where it should have happened, but didn't. I even tried my best to make it happen and it didn't. The only thing different today was the ambient air temp. Could that have made that much of a difference in the mapping?

The mystery grows deeper....

Brian
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post #2 of 5 (permalink) Old Oct 25th, 2006, 2:04 pm
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Hmmmm,
Is their a sensor in the air intake?? Or maybe the cool air is cooling the fuel/air mix.
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post #3 of 5 (permalink) Old Oct 25th, 2006, 3:22 pm
 
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Frosty..... I mean Brian,

Interesting info. I don't have the "bucking" issue, but it's not perfect in the low gear, low rpm range. I have not had the 7.0.1 update based on some of the results that have been
posted. I experience very smooth operation when first pulling off and the engine is cold.
Not being qualified in fuel injection I do believe the fuel mixture is enriched during start-up
and maybe colder ambient temps. I hope other members mention your findings to their dealers. So far it seems nobody has come up with a reason/solution.

Phil
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post #4 of 5 (permalink) Old Oct 25th, 2006, 4:33 pm
 
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Quote:
Originally Posted by bnblazer
So there I was...knee dragging doing 145 on a 45 mph posted curve with hard parts showering the 911 behind me with sparks.

Oh wait wrong story. Guess I better tell the no BS one...

Anyway, I went riding today to do some errands. I know that the weather forecast for NE Wisconsin is on the top of everyone's must know list. However, in case you missed it, it has been a little cooler lately. Mostly in the mid to upper 30's.

The point to all of this drivel is that in about 100 miles I never once noticed any bucking or fueling problems. I do not have 7.x installed yet and I have had recurrent problems with low speed/RPM bucking. Not today though! There were several places where it should have happened, but didn't. I even tried my best to make it happen and it didn't. The only thing different today was the ambient air temp. Could that have made that much of a difference in the mapping?

The mystery grows deeper....

Brian
Nice try, but no cigar!

Sorry to tell you that's not it... I been riding in all kind of weather... In California anyway...

2 weeks ago, I rode up to big bear... Temp was about 50F... then up to 90F plus on the way home... 200 miles... Everything works perfect.

Last weekend, I rode up to Idyllwild... Temp was again 50F... My GT started doing the "RPM stay up for 1/2 second before coming down slowly" all day... When I turn off the engine to rest, the next time I start up, it will be okay for a few minutes and start doing the funny thing again...

For me, it does seem to do it more in hot weather... It has also do it in colder day also...
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post #5 of 5 (permalink) Old Oct 28th, 2006, 11:16 am
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Brian,

You're probably right. Any injected motor gets a richer fuel mix when cold. The electronic fuel management system measures the inlet air temp, motor temp, O2 in the exhaust, and usually a few other things like engine knock. The fuel mixture gets adjusted to keep the motor running smoothly at low temps. The amount of enrichment is dictated by the "map" in the software.


The bucking/sharp throttle response folks are getting with the early software is an overly lean (yah, yah grammar) profile trying to keep low rpm exhaust emmisions legal. Most motors don't struggle so much, but with a compression ration of 13:1 our bikes are special.

In cold weather most motors eventually warm up and fuel metering goes to a nice lean mix. The 6 liter V8 in my pickup is hidden behind a radiator, hood, and fenders. It takes about 30 minutes to lean up. It's possible that at 35 degrees there is enough air flowing in and around the GT's motor that it never does make it to the full lean of summer, resulting in a richer idle friendly mix all the time.

I suspect the high idle issue is an improper response to a certain set of sensor inputs. I can get it to happen on the way home from work on warm days. 45 min. at highway speeds followed by a 1 min. 120+ dash, followed by an offramp and a stoplight. O2 sensor probably gets loaded by the short duration full throttle position, causing the system to want to lean up. This ends up being too lean, so the computer reacts and richens up. See a confict? Probably causes the software to switch to a limp home mode. Turn bike off, reset computer, drive a way.

I'm getting the 7 upgrade. I know a guy that had the same problems with his R, 7 fixed it.

Ride on,
Jeff
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