The Jerkiness of Jerky Motorcyle Throttles

Yamaha FJR Motorcycle Forum

Help Support Yamaha FJR Motorcycle Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

zenwhipper

Well-known member
Joined
Jan 16, 2008
Messages
583
Reaction score
16
Location
Seattle, WA
For your reading enjoyment.
coolsmiley02.gif


"In these high tech days of electronic fuel injection, you would expect motorcycle throttle response to be smooth as. However many of the latest bikes have a snatchy and jerky throttle response; especially around town at low speeds — feeling more like a switch than a throttle."

https://www.asphaltandrubber.com/columns/motodna-jerky-throttles/#more-56067

 
Thank God I drive an 05 Gen 1. No payments to make, no required insurance to carry (gotta love them Florida laws), and a throttle that's smooth as butter. No unwinding of springs, no special throttle cams needed. To borrow a little something from the late Jackie Gleason, "How sweet it is."

 
Last edited by a moderator:
My 2013's throttle is quite smooth. Works very well at slow speeds and friction zone maneuvers

 
I think my '12 is jerky enough to try the Acelerator Module (results soon). I recall my first ride on an FZ1 -- horrid throttle transitions. Next year they had it fixed, so it is possible.

 
Explains a lot.

Thanks for posting.

PC V and some filing of the throttle tube and my '06 is smooooth as can be :)

 
Thank God I drive an 05 Gen 1. No payments to make, no required insurance to carry (gotta love them Florida laws), and a throttle that's smooth as butter. No unwinding of springs, no special throttle cams needed. To borrow a little something from the late Jackie Gleason, "How sweet it is."
Same with my '99 St 1100, except for the insurance part...

I was (unpleasantly) surprised at the difference when I got the FJR!

But, not being a 'sniveling whiner and more of a doer' ;-) I got it fixed.

Very happy now
smile.png


 
Explains a lot. Thanks for posting.

PC V and some filing of the throttle tube and my '06 is smooooth as can be
smile.png
Gents:

Apologies for jumping in, reviving, or jacking . . . . The title of the thread showed up in my search for "Gen 2 fuel injection issues" . . . so I'm asking a question on this "filing of the throttle tube" process . . . . Just got my '09 a month and a half or so back, just about have a thousand miles on it . . . . Today, which was a tad windy in the canyons, I took the black space dragon out for my default run through my local canyon and down to Mulholland . . . and, for the most part I'm not the fastest guy thru the canyons, but I can usually stay ahead of cars . . . . This is the ride I've been doing for my entire riding career . . . 25+ years riding the same road. Today I was being pressured by a freaking Mercedes Sprinter van . . . when the road opened up and I could hold the throttle I could leave him behind, when the turns got tight, tight, off camber decreasing radius . . . this "off idle throttle response" issue became, I would have to say, intrusive . . . to forward motion. In comparison to my well sorted Concours carbs this bike is "jerky" in the on/off throttle response department . . . . It's not at the top of the list, but I would like some insight into how to smoothen the throttle issues . . . .

I have seen some other comments about filing something to fix what is quite apparent in tight twisties that a van could push me . . . kind of a problem . . . . If all my roads were high speed turns, like PCH . . . would not be an issue; but sometimes the road tightens up . . . not sure how the PO didn't notice it enough to mention it . . . he obviously did not address it. Any thoughts or links to the fix appreciated, thanks.

GX

 
Last edited by a moderator:
...I have seen some other comments about filing something to fix what is quite apparent in tight twisties that a van could push me . . . kind of a problem . . . . If all my roads were high speed turns, like PCH . . . would not be an issue; but sometimes the road tightens up . . . not sure how the PO didn't notice it enough to mention it . . . he obviously did not address it. Any thoughts or links to the fix appreciated, thanks.

GX
Your '09 hasn't got the abrupt throttle cam of the '06s and '07s. However, maybe you could still use either an after-market throttle tube such as a G2. But what you are referring to is where the original throttle tube is adjusted. I did my '06, drew a profile and used a hacksaw (others have used a Dremel):

(Click on image for larger view)



More pic here.

 
Your '09 hasn't got the abrupt throttle cam of the '06s and '07s. However, maybe you could still use either an after-market throttle tube such as a G2. But what you are referring to is where the original throttle tube is adjusted. I did my '06, drew a profile and used a hacksaw (others have used a Dremel):(Click on image for larger view)



More pic here.
@mcatrophy:

Thanks very kindly for the reply, and the photo gallery . . . looked through them several times . . . it's not exactly clear what is before v after . . . . I'm getting that it is a top end throttle cable issue, rather than a FI mapping or throttle body issue?? Are you slathering lube all around . . . the green stuff? Is this picture showing the line that basically is planing off the "accel" side cam of the cable turner?? (whatever that white item is) . . .

Or, you mentioned after market throttle tube . . . "G2" ?? G2 meaning whatever the proper after market throttle tube for Gen 2, or that is some name of specific throttle tube???? But, point being, that this off idle "lean" condition or seems like loss of of fuel flow control until revs can get up over . . . 3K . . . is due to throttle cable restriction??? And the OEM cable tube is too tight, and replacing the tube would be the more ultimate fix? If so, that might be a little easier than dealing with the lower end or throttle body mods . . . which I thought is where the problem is . . . . What about slathering a bunch of ye olde cable lube in there???

GX

 
I too thought that the lurch was only evident on the 2006-2007's ...

I wouldn't suggest putting any lube in the throttle cables; that will mess with the teflon sheath.

Here's the G2 he's referring to: https://www.g2ergo.com/store/g2-street-tamer-throttle-tube/

What that does it change the ratio of how much cable is pulled when you turn the throttle. The G2 changes that ratio so it's easier to feed in just a little bit of throttle so it isn't as abrupt.

But the real problem is the fueling, and in my experience with the 2006, the Power commander is the only thing which fixed it good enough to keep the bike.

Although the complete fix is to get a different bike (I hear the '14 FJR's solved it too).

 
Your '09 hasn't got the abrupt throttle cam of the '06s and '07s. However, maybe you could still use either an after-market throttle tube such as a G2. But what you are referring to is where the original throttle tube is adjusted. I did my '06, drew a profile and used a hacksaw (others have used a Dremel):(Click on image for larger view)



More pic here.
@mcatrophy:

Thanks very kindly for the reply, and the photo gallery . . . looked through them several times . . . it's not exactly clear what is before v after . . . . I'm getting that it is a top end throttle cable issue, rather than a FI mapping or throttle body issue?? Are you slathering lube all around . . . the green stuff? Is this picture showing the line that basically is planing off the "accel" side cam of the cable turner?? (whatever that white item is) . . .

Or, you mentioned after market throttle tube . . . "G2" ?? G2 meaning whatever the proper after market throttle tube for Gen 2, or that is some name of specific throttle tube???? But, point being, that this off idle "lean" condition or seems like loss of of fuel flow control until revs can get up over . . . 3K . . . is due to throttle cable restriction??? And the OEM cable tube is too tight, and replacing the tube would be the more ultimate fix? If so, that might be a little easier than dealing with the lower end or throttle body mods . . . which I thought is where the problem is . . . . What about slathering a bunch of ye olde cable lube in there???

GX
I'll try to answer your specific points.

In your original post you asked about "filing of the throttle tube" process, I was trying to answer this.

When Yamaha introduced the Gen II in '06, they altered the cam profile at the throttle body end to give a very rapid response of the throttle from off to on. (My personal guess is so that it felt as lively as the Gen Is in spite of the higher gearing.) Combined with the fuel cut-off on the overrun that the fuel injection gives, this meant for a nasty lurch as you rolled on the throttle coming out of corners.

To help compensate for this throttle body cam profile, you can change the profile of the hand-grip throttle tube. This is originally circular, no variation in radius of the cable groove during the rotation. This is where "filing" comes in, you can alter the tube cam profile, my first posted picture shows my drawing on the end of the end of the cam plastic of my wanted profile for the groove, that I subsequently filed down.

Aasland is correct about the commercial G2 throttle tube replacement. ("G2" is their name, not to be confused with our referring of the 2006-2012 FJR as "Gen II".)

As you infer in your second post, this is doesn't address the FI fuel cut-off, but that wasn't what you appeared to be asking about in your first post. Your 2009 has a sensible throttle body cam profile, but still has the FI cut-off; a power commander or similar can fix that, and is probably your best option if you can't control that off-on transition.

Oh, yes, the "slathered green lube" was what I found when I dismantled the throttle tube mounting, apparently one place where Yamaha put on sufficient lubrication in the factory.



 
Last edited by a moderator:
The best thing against the jerkiness is the Power Commander 5 from Fuel Moto, they can supply it with the smoothness map for you if you ask for it. It made my FJR smooth as butter, before it it was as bad as you describe. The G2 did not help much, I installed that also before went for PC5 .

 
GhidorahX, be sure your cables do not have too much slack in them. A 3k kick in indicates something is up. Maybe cam profile, but I'm betting cable adjustment has a lot to do with it. My '07 really smoothed out when I properly adjusted them.

 
Gents:

Thanks to each of you for the replies, much appreciated . . . after I posted here and saw the first reply I was re-thinking, "Is it jerky throttle" that I'm talking about or is it "FI cut-off" . . . and I don't think it is the throttle tube, that more or less seems "OK" . . . but what is happening seems to be with the FI map in on/off the throttle jerkiness; so it's still "jerkiness" that is the problem. But . . . anything that is less than $100 in motorcycling is a "steal of a deal" . . . so the G2 might be too good to pass up . . . just because it's not $100 . . . . : - )

@aasland: . . . so thanks for that link to the G2, mentioning the PC . . . and the suggestion to get a new bike to being the "ultimate solution" . . . . Kind of funny, this FJR decision took me at least 5 years to make . . . but my first bike was an 82 Sabre, and I went into the dealer for something about 5 or 6 months into the ownership . . . and they were like, "Sell it, now!!!" . . . and I was just digging the reostatic power delivery of it . . . kept it for 4 or so years . . . but, they were right . . . it was a lemon. But, I like this bike overall, there is no perfect bike in motorcycling . . . I live on a shoe string budget, and if I can get the windshield, rack, and now this FI mapping thing straightened out for less than a Grand . . . I'll be happy with it for any number of years . . . .

@mcatrophy: And thanks to you for the further clarification . . . I got it now, filing the groove . . . might be an option. Probably I'll be looking at the PC 5 direction . . . in the past the PC thing was about max power on the top end, which I never had any use for, but since a lot of my riding is the local twisties I need to be able to keep the Mercedes peace sign out of my mirrors . . . at whatever cost necessary . . . .

@ENN: Thanks to you for the "smoothness map, if I ask for it" . . . that has always been what I'm looking for, rather than nutz out power or acceleration . . . which quickly winds up in the "road side chat" . . . expensive, just because.

&@Hotrodzilla: Right on the cable adjustment as a possibly issue . . . did just have it in for some servicing, my buddy didn't mention anything about throttle uptake, although I feel it hesitates as I first turn the throttle . . . . As far as the "3K" . . . I actually don't know what it was . . . like I said, I was more watching the the "peace" sign ramming up my buns as I was struggling to keep the bike going through the turns . . . yowza . . . . I would probably have to be spinning the back tire to keep it smooth, which I don't do . . . too many bicycle riders hanging out in the middle of the turn to run it like a race track . . . . Obviously a cable adjustment would be the cheapest fix of all mentioned, but, don't think it would cover over the "lean" spots . . . .

Thanks again for the feedback,

gX

 
The G2 tube will help some, and the PCV will smooth out all the lean conditions to eliminate hesitation and stumbling from low rpms on up, and can be programmed to provide more power (at the expense of fuel economy)....... however, none of that addresses the fuel cut-off that occurs when you roll off throttle to 0%. This occurs below a certain pre-programmed rpm (I think 4500 on an R1, don't know what the FJR is)...... so when you roll off to 0, the fuel injection is cut off, no fuel. When you roll back on, the system must 're-wet' itself, thus the delay.

One tip might be to alter your technique, i.e., downshift to a lower gear into aggressive corners, roll off but roll on a slight bit of throttle as you go into the corner, then the hesitation will be gone as you accelerate out of it. I know one guy who slips the clutch as his technique, but that doesn't somehow appeal to me.

I would get the PCV even with Fuel Moto's regular map, at least it will fix lean conditions that cause stumble at low rpms, particularly from 0 to say 3000 rpm. That in itself is what has made PCIII or PCV users much happier.

 
Top