Jumpy at low RPMs? - Wrist Twisters
 
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post #1 of 18 Old 05-26-2015, 06:03 AM Thread Starter
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Jumpy at low RPMs?

Hey All,

Big time lurker here on the forum. As this is the 3rd summer I've owned the niner I have decided to fully make it my own with a decent amountt of customization and now I'm looking to get in in top shape.

My question to you all is it normal to have my bike respond pretty jumpy at low RPMs? I ride a lot with passengers who are inexperienced and although it's not too big a deal for me it sometimes freaks them out. I have yoshi cans with a Power Commander. I have yet to fool around with any maps since I purchased the bike with the Power Commander already on it. Should I re-load a map? Are there different maps I should use to customize my ride or would a generic map slated for a power commander work just fine? Is getting it dyno'd just a costly method for this?

Thanks for any help!

Brian

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post #2 of 18 Old 05-26-2015, 06:30 AM
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I have a bone stock 06 and I've pretty much gotten used to it being jumpy at low RPM. I don't know if the PC can change it or not. I ordered but haven't installed the popular 17/44 gear/chain kit that lowers the freeway RPM a bit, so I don't know how much difference it makes but don't expect too much change.

I guess it's the trade off we get for having a bike with more mid-range torque.

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post #3 of 18 Old 05-26-2015, 06:44 AM
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My stock 02 was jumpy at low throttle openings in 1st gear as well. I've always heard that was kind of common for FI bikes, but it could be made worse because your map is wrong. A lot of others on here have Power Commanders and can chime in I'm sure. I thought there was some maps being passed around as well?

Dyno'ing it is the best way to get the perfect map, but it's pretty pricey I think.

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post #4 of 18 Old 05-26-2015, 07:24 AM
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MIVVs seemed to make it worse. I learned to ride around it long ago.

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post #5 of 18 Old 05-26-2015, 08:43 AM
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Welcome to the wonderful world of fuel injection!

The abrupt throttle response you are describing is very common when making a transition from carbureted bikes to fuel injected for the simple reason that carbs respond comparatively slowly when opening the throttle, requiring more twist to get the acceleration you want, and are by their nature inaccurate fuel metering devices when compared to fuel injection. When opening the throttle, especially with CV type carbs, there is an inevitable delay because the air has to start moving faster to create a negative pressure above the slide diaphragms to raise the slides in order to draw more fuel from the float bowl into the venturi, then to the cylinders. On average it can take as much as 30 to 60 milliseconds (ms) to respond. A fuel injected motor, on the other hand, responds in about one tenth that time, resulting in getting more power than you want / expect. It's just a characteristic that can take some getting used to for the average rider. Frankly I like the response time, and it took me less than a minute to adjust to it due to extensive road racing experience where accurate throttle control is absolutely necessary. I realized it wasn't "snatchy", just deadly accurate! Give it 1/16 throttle and that's what the engine does with only a negligible 5 to 8 ms delay.

The question then is how to adjust to it. It's all about physiology and is relatively simple. Hands have the greatest concentration of nerve endings of any area of the body, enabling extreme accuracy of movement, and by taking advantage of that fact it is easy to make the adjustment. All I needed to do is what I learned to do when racing: keep my index finger lightly resting on the front brake lever to act as a reference to abet consistency. In this way when the throttle is turned you are comparing the position of one finger to the rest of your hand instead of trying to determine position by the bending of the wrist, very approximate at best. When turning the throttle with that reference it is easy to apply just enough throttle to get the result you want without overshooting and having to change the throttle position, resulting in a smoother ride. The best part of adjusting yourself to the bike instead of the reverse is it costs nothing to do and actually increases your riding skill set: always a good thing.

Give it a go -- I think that after a couple of days riding under a variety of conditions you will find that things have gotten considerably smoother and enjoyable.

Rob

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post #6 of 18 Old 05-26-2015, 09:37 AM
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In my last bike shopping bout I test rode only fuel injected models. I immediately noticed the twitchy throttle response and embraced it - conquered it. Now I actually enjoy it. My 919 seems downright docile now. I would sure hate to have to go back to a carbureted bike.
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post #7 of 18 Old 05-26-2015, 10:04 AM Thread Starter
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Great stuff guys, thanks. I've gotten used to it and frankly like it but unsure if this was an anomaly with just my bike.

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post #8 of 18 Old 05-26-2015, 01:21 PM
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Robtharalson laying down that knowledge as always.

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post #9 of 18 Old 05-26-2015, 09:30 PM
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The PCIII fixed that herky-jerkiness for me...it was one of the huge benefits of fitting it. But, of course, not everybody reports the same way about them...I didn't have to agonise over maps, as mine was a bone-stock Asia-pacific-spec bike. I loaded that map up and away I went...

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post #10 of 18 Old 05-27-2015, 03:54 AM
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With two 919's I found that removing the slack in the throttle cable was helpful in reducing the "snatch'" which is especially noticeable when coming off the throttle and back on in a corner. My ST1300 was even worse. Some riders have had good results with the Throttle Tamer. I would suggest changing only one thing at a time when looking for the remedy.

Rob's suggestion is a good place to start.

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post #11 of 18 Old 05-27-2015, 10:05 AM
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Quote:
Originally Posted by ST-DocLizard1 View Post
With two 919's I found that removing the slack in the throttle cable was helpful in reducing the "snatch'" which is especially noticeable when coming off the throttle and back on in a corner. My ST1300 was even worse. Some riders have had good results with the Throttle Tamer. I would suggest changing only one thing at a time when looking for the remedy.

Rob's suggestion is a good place to start.

G2 Street Tamer Throttle Tube - G2 Ergonomics
Wow! That's one of those "I wish I thought of that" things. Cool!

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post #12 of 18 Old 05-27-2015, 11:38 AM
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some day i want to have a 1/4 of the knowledge of rob.


+1 to what doc said, make sure the play is out of you throttle. you shouldn't be able to wiggle it without it affecting your rpm. rob explained using the finger as a reference for the rest of the hand, but you also want that position to be consistent ride to ride. if you have play, sometimes 1/4 wrist turn is a lot of throttle and sometimes it's less, and the transition from off throttle to on will be rough because you hit it at an unexpected spot.

I definitely still snap my neck on occassion, and maybe it's a mapping thing or that might help, but i've found just having consistent and smooth throttle makes a big difference. if you're not sure, there's two cables comining out of the control, it's the top capable.

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post #13 of 18 Old 05-27-2015, 04:23 PM
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One trick I've gotten used to is more lean forward on take off. I didn't do it once and almost lost it on the pull back. I prefer the arms to be bent in a bit anyways, it tends to force me to use a lighter touch on the bar.

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post #14 of 18 Old 05-27-2015, 05:39 PM
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1
Technique matters. Be smooth.
2
Make sure there is not excessive cable slack as this has a big effect.
3
You have a PC, but who knows what map is in it, or if it was synch'd.
I suggest you synch the PC, and load in either the 'mori4 or Ben W Map as found in the Drop box.
My 919 was aweful in 1st at small throttle openings, more so when the engine was hot in slow creepy crawly traffic. With the PC installed, synch'd and with either of the above mentioned maps, it's like a rheostat down to below 1000 RPM.
4
The mush soft front spring aggravate things to some degree. The springs are not a cause and not a remedy. But they aggravate all the above effects.

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post #15 of 18 Old 05-28-2015, 08:00 AM
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I adjusted mine by shifting in to second. No more jumpy's.

Robert

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2003 Honda CRF450R
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post #16 of 18 Old 05-28-2015, 08:07 AM
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There's also a lever on the left handlebar that you can use at low speeds to dampen out any jumpiness. Looks almost like a brake.

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post #17 of 18 Old 05-28-2015, 01:12 PM
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Quote:
Originally Posted by marylandmike View Post
There's also a lever on the left handlebar that you can use at low speeds to dampen out any jumpiness. Looks almost like a brake.
Ohhhh you mean the 'wheelie popper'

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post #18 of 18 Old 05-28-2015, 02:30 PM
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Quote:
Originally Posted by TheBeeDeeGee View Post
Ohhhh you mean the 'wheelie popper'
Yes....aka "The Laxative" if you let it out too fast.

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