mapping question

hi everyone, loving the bike and the superb beetle map...

One thing I've noticed in town,

On my old carby tontis I could be in 2nd gear and let the motor spin almost all the way down and just gently bring the power back in with a subtle twist of the wrist. very nice and smooth.

On the GRiSO, this same action invariably results in a sort of jerk to the drive train.

Questions,

does everyone experience the same thing?

is this an inevitable consequence of FI?

or an inevitable consequence of a lighter flywheel?

is my right hand just not sensitive enough? (oo-er)

is there anything that can be done in mapping?

or do I have to slip the clutch each time?

thanks everyone

Have you minimised the free play in both the opening and closing throttle cables? Any excess free play results in overcompensation of the wrist and changes from negative to positive throttle will be liable to imprecision.

Fuel injection being so much more precise than the sloppy, 'Gob-a-dollop' spit and hope of carburettors that very small throttle openings will require a bit more care, (Flywheel weight plays a part too but the 8V flywheel is pretty massive.) with decent tuning though you should be able to go from negative to positive throttle without issue. My POS will chug away from sub 1,300 in first or second with a bit of care. Tune and practice and you'll be golden!

Mine does same (Beetle map, throttle slack adjusted, balanced TBs) so I just avoid letting it run down to very low revs in high gears....I think part of cause is the 'slack' in the drive train - if I stick bike on stand, engine off & stick it in gear then rotate the rear wheel there seems like a lot of 'slack' when you change direction...I also try to avoid 'part-throttling' on slow corners else I need clutch

Quote :

does everyone experience the same thing?

No.

The throttle response on the 8V is rather impressive. One must learn to use the throttle with a delicate panache.

A slightly fatter grip, I like the grip puppies, seems to help with the sensitivity.

What the other, more learned Guzzisti above said.

Now, I have to add -- awaiting contemptuous flames from above said learned -- that I have wondered if the phenom you mention (and all of us have, I suspect, experienced) is also not a result of the CARC engineering and its "anti-jacking" function, thus leading to abrupt response from throttle input at lower RPM.  

OK, back to sipping some 1783 and reading about Hadrian.  

Bill

It might be something else. If a bike has decent engine braking, and you back off the throttle, and then you twist the throttle open again ... you are going from tipped forward, engine braking, back to booming power ... so lurch forward, lurch back, etc.

I asked Beetle for a "low engine braking" map for my GRiSO which it seems he had handy. So when I back off the throttle I get a wee bit of engine braking, but mostly free wheeling along, then back on the throttle, and off I go again. Felt like a 90% reduction in lurch forward lurch back.

Maybe try that map out?

I love the engine braking of a big V-twin.  It's what started my interest in Guzzis.

Riding on throttle only, not touching the brakes is my goal.  Sure, you will get around the bends faster if you use the brakes, but lose all the fun!

And it's the same reason why I got rid of my I-Convert.

Lazlo, would you like to try the low engine braking map?

Thanks very much for the offer,

I've got some benchtime in my friends workshop lined up later this week, so I'm going to reset the valves, check the TBs reset the TPs etc and make sure that the free play is totally zero on the cables...

I'll report back, if the jerk is still there, I'll take you up on the map

I've been piling on the miles and I'm getting more and more used to it.

Dropped the forks through the yokes to 5 bars showing the other day, transformed the bike!

could still initiate the turn quicker though, how about 6 or 7, any experience?

I was at 6 for a long time, but have gone back to 4. Tyre profile and pressure have a big effect, and I have found with my current setup, I prefer a bit more rake.

Check the front torque arm bush.

little750 wrote:

Check the front torque arm bush.

Good call, I done one on a 1200 Sport years ago that was very sloppy.  Made a huge difference.

I am confused.  Please let that go.  

No, seriously, I am not sure which beetle map I have on my GRiSO, but sure sounds as if I do not have "low engine braking" version.  

I am likely missing something obvious, but I very much prefer a measured decel over an "on-off" switch.  In fact, the last thing I want is "free wheeling" when I back off the throttle, especially of the immediate sort when entering a curve.  

IMO, that unpowered coasting is the sort of thing that destabilizes the machine that quickly leads to me screaming in my helmet as my squirrel brain frantically assesses the options of "Stand it up!" or "Low side it now!" and other choices, if any. Yet -- at least with the present beetle map (whatever it is!) -- map-driven throttle maintenance keeps everything (metal and rubber, at least  ) cool, calm, and collected and leaned over for a smooth roll-out.  

Lurching?  Yes, occasionally, especially while loafing at very low engine speed.  Even then, that lurch is, in my case, at least, almost always when I forget to caress the throttle as if it were a cyclic in a helo.  

Bill ... while sipping the morning's first cup of coffee, said caffeine deprivation being my excuse for any gibberish above.  

Bill - not sure all the non Guzzi bikes you've ridden ... but if you ride something like a Japanese 4 cylinder bike, most of those feel "low engine braking" to me. But sure if you have it at 8,000rpms and shut the throttle completely you'll get plenty of engine braking even from them.

The flip side is something like a KTM 990 with stock fueling ... at say 3,500 rpms if you shut the throttle you really get moved forward a lot. That bike has very light flywheel effect so I think that makes it even more pronounced.

On the GRiSO, the two maps aren't crazy different ... with the normal engine braking map it isn't like you back off the throttle at 4k rpms and get tossed over the bars vs. the low engine braking one just freewheels along with the riding screaming "stop, please stop"

With the low engine braking one, I love it at higher rpms ... back off at 5K or 6K and you get engine braking, lovely sounds, etc. But if you back off at 3.5K or 3K rpms it is much softer then ... not like a 100% free wheel at all, but much less of the shift forward.

On single cylinder 4 strokes with carbs (like a motard) some guys turn up the idle to reduce the engine braking ... kind of a cheezy "fix", but it works.

^^^^^

Appreciate all of that.  Very understandable.

I have little experience with non-Guzzis, tho a few hundred miles (total!) on ST1300, VFR, GXR1000, and another one or two I've forgotten.  Other than that, three Yams in the '60's (gasp! ), my brother's Duc M/S 1200, an RT1200, and that's about it.

Thanks for going to the trouble of explaining all of that.

Best,

Bill