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Reducing throttle effort


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The return spring on the throttle is stiffer than I'd like.  It doesn't need to be that stiff, it's only operating a TPS.  And it's got a return cable to pull it shut should it stick.
Has anyone looked into reducing the tension from the return spring?
 
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The return spring on the throttle is stiffer than I'd like.  It doesn't need to be that stiff, it's only operating a TPS.  And it's got a return cable to pull it shut should it stick. Has anyone looked into reducing the tension from the return spring?

Personally I like the firm bite of a well-sprung throttle, the snap is kinda like the motorcycle equivalent of a well-made Volkswagen door being firmly shut. 

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I agree that the FJs throttle spring is stiffer than other bikes I've owned in the past, and after having this put in:
 
1.2.826.0.1.3680043.1.2.119.708060245.20140226.91236.0.0.13_zps8ggnl3fr.jpg
 
I needed to reduce the tension on the spring to do multiple day trips.
 
Disclaimer: do this modification at your own risk!
 
With the help of my friend we came up with this.
First off remove the throttle bodies, the cable wheel and stop plate and you should have this:
 
IMG_20160205_141425_zps1s4pnulo.jpg
 
We tried this position but it didn't have enough spring to it.
 
IMG_20160205_141434_zpsbpnoyrrs.jpg
 
Next up was to drill some holes in the stop plate.
 
IMG_20160205_144438_zpsrb5lqfmj.jpg
 
And install a screw, the double nut ensures that the screw can't back out and has a valley that the spring sits in.
 
IMG_20160205_144451_zps4vx1rv4l.jpg
 
This position has the absolute minimum amount of spring needed to close the throttle with cable drag. It'll close the throttle but it can be marginal if you let the throttle snap back or don't fully roll it closed. The next time I'm back in there i'll probably move the screw to the next highest position. In practice on the road it has never been a concern because the only time I let the throttle snap shut is after turning on the cruse control.
 
 
 
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I helped Deadstiff reduce the preload on the throttle return spring. I drilled 3 holes for a 4-40 allenhead with 2 nylocks. The purpose of the 3 holes was adjustable preload via trial and error. Basically try the lowest preload, assemble the throttle body and see if the throttle would snap shut. If not, try the next hole. When you find what you like put everything back together. Deadstiff was installing new cables, so it was the perfect time to mess with the return spring. It's going to take you a couple of hours to do this. I've done this on my XR600 desert and it worked great. So far Deadstiff has had luck with this.
john
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I helped Deadstiff reduce the preload on the throttle return spring. I drilled 3 holes for a 4-40 allenhead with 2 nylocks. The purpose of the 3 holes was adjustable preload via trial and error. Basically try the lowest preload, assemble the throttle body and see if the throttle would snap shut. If not, try the next hole. When you find what you like put everything back together. Deadstiff was installing new cables, so it was the perfect time to mess with the return spring. It's going to take you a couple of hours to do this. I've done this on my XR600 desert and it worked great. So far Deadstiff has had luck with this. john
 
Thats good advice, thanks for sharing
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  • 1 month later...
I just performed this procedure on my bike. The only difference is mine has a little more throttle preload than Deadstiff's set-up. Deadstiff has a right wrist injury so strength and range of motion are less, so we set his preload to a bare minimum. Very nice with a solid clunk when the throttle snaps back.
john
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  • 4 years later...

Just wanted to bump this for anyone looking to do this for a 2019+.
The only real difference is the stop plate is cast aluminum.
So what I did differently is tapped the cast and used a flat head screw to hold the spring end.


Things I learned:
1. I should have added a little more spring. There's a little casing mark that I used on the stop plate to drill my hole.
Should have used the red dot placement in the attached picture below.

2. The rod that you remove all the springamagig things off of, that moves in and out of the throttle position sensor at the other end. Took me forever to figure that out, which seems silly now since I kept running out of thread to re-assemble.

3. You pretty much need a 1/4 flexible extension (10inch is what I used) and a good 4mm allen round end socket in 1/4" with max 25 degree angle on the ball head. Turns a headache into a in and out job to remove the throttle bodies.

50868639326_298e8eb308_b.jpg

50868062722_21c8478789_b.jpg

This is about as bear minimum as I could stand, I'm guessing with a little warmth, aka not 12 degrees F in the garage, it will be a little more snappy.

 

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  • 1 month later...

I'm finding the return spring too strong also. Not that I can't turn it, it's just too much. Interferes with smooth feeling.

Looks like I'll be doing this mod to my 2015. Too bad I just put it all together from the big maint. I did over the winter.  Looks like I have at least a week, the weather is going back downhill.

Shouldn't have to remove TB's to fix something Yamaha should have right in the first place. They seem to be too worried about lawsuits then normal function. Torque specs. and return springs. I wonder what else there is.

I know this mod was big on the FJR 1300.

Edited by peteinpa
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Just did this, same as above. Works great!

1/4 in. drive flex extension and 1/4 in. drive 4mm ball end hex are MANDATORY to pull TB.

I don't even think you can replace the throttle cable without pulling the TB. It's too close to the frame rail.

20210317_112900.jpg

Edited by peteinpa
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  • 1 year later...

Going to do this mod shortly. Thanks everyone for the tips on here.

I accessed all throttle body clamp bolts (lower of the two on each boot) from left side/below, as shown in photo (1/4" extensions and a long 4mm ball-end... all I had). Pretty painless actually. A short 1/4" 4mm ball-end would work better on #1. I might pick one up and use that to assemble.

tbody_access.thumb.jpg.cde9312b1d46bd35ffdcbbb44941f0c0.jpg

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canada.gif.22c5f8bdb95643b878d06c336f5fe29f.gif - IBA #66956 - 2015 Yamaha FJ-09

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  • Supporting Member
11 hours ago, duckie said:

There are quite a few clever people on this forum…… way cool and thanks for sharing….

Agreed.   I've always felt that the throttle felt a little stiffer (harder to turn) than it it needed to be.  Should have known that someone here would have found a 'fix'. 🙂

It's now on my ever shorter list of things to do/change when I'm back under the hood.

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11 hours ago, dazzler24 said:

It's now on my ever shorter list of things to do/change when I'm back under the hood.

F'sure!!!

I've known about this mod since I became a member but kept forgetting to do it.  I won't next time I have the tank and air box off, and am printing out the instructions and taping them up over my shop desk!

My poor right wrist (previously broken with an occult fracture, carpal tunnel syndrome, broken thumb and now worsening arthritis) has suffered long enough!!!  

 

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17 hours ago, 2and3cylinders said:

F'sure!!!

I've known about this mod since I became a member but kept forgetting to do it.  I won't next time I have the tank and air box off, and am printing out the instructions and taping them up over my shop desk!

My poor right wrist (previously broken with an occult fracture, carpal tunnel syndrome, broken thumb and now worsening arthritis) has suffered long enough!!!  

 

I too suffered from a bout of carpal tunnel syndrome (both sides) a couple of years back that lasted what seemed like the duration of the pandemic! The McCruise paid for itself in that time.

Just thinking about this mod, I'm wondering if those that did it had to re-check their APS mod (if they'd done that too) which would then lead to re-checking the McCruise calibration (again, if they had that also)?

I'm not certain if the APS is touched when this spring mod is done or not so may be a moot point.  I know it didn't take much movement to change those APS numbers though.  I'll probably re-check them anyway before buttoning up just to satisfy my paranoid tendencies. 🙃

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