Caution with Throttle Spring Unwind Mod

[MikeS]

Have been visiting the forum almost every day since buying my 2006 fjr in January 2007 and love it (both FJR and this site).

I need to share my experience regarding the much talked about throttle spring mod.

I have always thought that the throttle return was stronger than it needed to be and have used a cramp buster on long rides (1200km in a day is my longest).

Last week I removed the tank and performed the centre throttle spring unwind. Seemed like a good idea after reading the positive feedback on this forum.

I Lifted the spring and let it unwind one turn. Then noted as others have that it no longer contacts the tang on the throttle at idle. Fine I thought!

I opened the throttle several times and closed it again with the bike shut off to check for correct return to the idle stop and all seemed fine.

Unfortunately it was not. I took the machine out for it's first run after the mod and noticed immediately that when cruising at 120kph if I removed my hand from the throttle it would not immediately return to idle but would slowly do so over a period of 5 seconds!! This is not good I thought. After experimenting with it for a while I found that every time it was released from a partly open throttle setting it was very slow to go to idle. This was obviously due to removal of spring.

This morning I rewound the spring and reset to the original tension and what a PITA that was.

Just thought I would put a warning out there as nearly all feedback re the mod on this site is positive and for me it was not so. Just wondering if anyone else has noticed this problem after releasing the throttle spring? Maybe will look to pursuing the G2 mod.

 

[Silent]

Check for your grip rubbing on the bar end, or the throttle housing. This causes friction that may have been overcome with the 3rd spring, but not with just the 2. I had to readjust my throttle grip and Throttlemeister after doing the mod.

 

[Motorad]

Mine behaves the same way. At first I was concerned too but now I kinda like it that way. You can take your hand off the throttle briefly and you loose speed gradually not immediately. I can't find any binding anywhere. It seems to return better when the bike if off. Not sure why. I have also added the G2 throttle tube.

 

[FJRocket]

I have TWO throttle springs completely removed from my AE. It's slow to return, but not THAT slow. Sounds like something is binding.

Only thing that worries me about the slow return rate is the possibility of getting dinged on tech inspection if I go do a track day. Otherwise, the function as is doesn't bother me a bit.

 

[Fairlaner]

While Smitty was doing my CC last year he unwound mine 2 turns and it still snaps back to idle no problem.....

i 2nd the binding theory.

R

 

[MikeS]

The first thing I checked for was the grip or anything else binding.

I completely removed the throttle grip assembly from bar and no problem there, all super smooth and free.

Strange thing is that there seems to be absolutely no problems returning to the idle stop when the engine is not running.

The problem only appears with engine running which makes me wonder if airflow through the butterflies on the throttle bodies is holding them open a little??

It returns perfectly now because I have refitted the spring.

 

[road runner]

The first thing I checked for was the grip or anything else binding.I completely removed the throttle grip assembly from bar and no problem there, all super smooth and free.

Strange thing is that there seems to be absolutely no problems returning to the idle stop when the engine is not running.

The problem only appears with engine running which makes me wonder if airflow through the butterflies on the throttle bodies is holding them open a little??

It returns perfectly now because I have refitted the spring.

I did the mod & experienced the same thing.(slow return to idle, only when running)

Checked for something rubbing & found nothing.

I even left grip off and made sure cable routing was OK. The 2 cables were twisted around each other, so I unhooked one and untwisted it so now both run from TB to grip as straight as possible without wrapping around each other. This seemed to make it better while not running, but still have slow return when running.

It works great when not running, so I don't think there is a friction problem. It seems to me like there is something vacuum related that is making it slow to return. I never had these TB's apart and do not know all the inner workings of them so I can't say but, it seems like there is a dashpot or similar circuit in there somewhere. In the car world some used it to keep from stalling on quick deccel.

Maybe a tech could chime in and confirm or deny this theory.

Next time I have tank up I may unhook the cables & try it , that will tell if it's a friction issue.

My .02 A.C.

 

[zzzzip]

I noticed the same with mine after doing the spring thing. I removed the Vista Cruise, checked cables, throttle tube, gave more slack on the cable, etc. but still haven't figured out what the deal is.

I also noticed when I released the grip and it did not do an immediate return, if I blipped the throttle and released it from the same rpms once or twice in a few seconds, it usually immediately returned on the second or third grip release, just like it did before the mod.

So far, with 15,000 on the clock I've not had a problem with the 3 second slower return from highway speeds/rpms, and hardly notice the difference. It does close completely, but just takes it time doing it-- similar to my old V-twin.

It will be interesting to know the cause and possible cure, although I have gotten to like the loss of abruptness.

B)

 

[cougar8000]

You people are Munsters. I was about to do it just for the heck of it and now I would have to wait another year before I decide again if I should or shouldn't.

Safety wise I would think it is a bad idea to have throttle still applied while you are trying to do an emergency stop. because it sure does not take that long to stop.

 

[Fred W]

The first thing I checked for was the grip or anything else binding.I completely removed the throttle grip assembly from bar and no problem there, all super smooth and free.

Strange thing is that there seems to be absolutely no problems returning to the idle stop when the engine is not running.

The problem only appears with engine running which makes me wonder if airflow through the butterflies on the throttle bodies is holding them open a little??

It returns perfectly now because I have refitted the spring.

Didn't you grease the throttle body pivot bearings? All you need to do is dissassemble the entire thgrottle body and apply some moly paste. Sheesh...

[SIZE=8pt]Just kidding...[/SIZE]

Have you always owned the bike? Maybe the PO already unwound the spring(s)?

 

[SLK50]

I too had a throttle that wouldn't "snap" closed after I released the throttle spring and installed a G2 throttle tube.

I checked my workmanship: throttle tube clean and lubed, no binding, etc.

The solution was so simple, almost unbelievable, yet irrefutable.

I merely adjusted the throttle cables. Apparently it takes just the right amount of slack in the cables to maintain

the fine balance between throttle control and tube binding. Only a quarter turn or so on the adjuster and my throttle was

snapping closed just as you would expect. If it was me, I check cable tension first, before anything else.

 

[Duff]

I'm beginning to think that there is more to this than "one bike doesn't return and the others do".

I have done this mod on both of my bikes (05 & 08) and on several other bikes for people who were not so sure of how to do it. I am thinking that maybe people are unwinding the wrong spring in some cases. This is only a theory, but it would account for a couple things I have seen in this thread:

First, I have never had my throttles stick after doing the unwind unless something was binding. In my case, it was my Vista-Cruise that needed to be readjusted. After that, it snapped right back... just as some others have said.

Second, I have never seen "slack" in the spring after the unwind when the throttle is at idle. This, to me, ndicates that a DIFFERENT spring is being unwound for some of you.

I know there are several springs in different locations on the throttle-bodies and there is only one that should be "unwound" and it should only be unwound ONE turn. If you have the correct spring, you can just flip it off the tang that holds it and it will spin around one turn and re-attach itself. It should STILL have tension on it after the unwind. You are only unwinding it ONE turn.

Anyone else think this sounds right?

 

[Duff]

<SNIP>Apparently it takes just the right amount of slack in the cables to maintain

<SNIP>

+1 I have had this same situation after trying to get TOO much slack out of the cable.

 

[adaniel]

Unless mine went around the world twice....it happens fast, and with the tang and loop configuration, not sure it can happen....mine ended up looooose.

Center thorttle spring under after unwind:

Lubed, loosened, tightened cables and nuts to no avail. Engine would over rev on shifts and slow to settle down on decel.

Ended up going back and fishing the spring back around one turn.

 

[jjsC6]

I unwound mine over a year and a half ago and it's always snapped back just fine. I agree that you might try to adjust and lube the cables.

 

[Last Chance]

SNIP
I know there are several springs in different locations on the throttle-bodies and there is only one that should be "unwound" and it should only be unwound ONE turn. If you have the correct spring, you can just flip it off the tang that holds it and it will spin around one turn and re-attach itself. It should STILL have tension on it after the unwind. You are only unwinding it ONE turn.

Anyone else think this sounds right?

I second the motion. There was no slack and it unwinds (in an instant) and re-attaches itself to the tang. All other suggestions sound logical.

LC

 

[Motorad]

I have a question for those of you who's spring returned to the stop tang. When running, does it return to idle like it did before you unwound the spring? I fiddled with mine again today and it returns with a nice snap when the bike not running. When it's running it returns to idle gradually. My throttle range of motion is very smooth and normal feeling. Based on an earlier suggestion I adjusted cable tension and added back a little free play which did improve it some. Intake vacuum must be the cause (I think someone already said that). Maybe that's why the spring comes wound so tight from the factory.

 

[vabrzn]

I attached a thin wire to mine before I released it to make it easier to put back on if I wanted to reattach it. I released the tension sowly and the spring didn't make a complete revolution and isn't attached to the tang anymore; appears some springs maybe wound tighter than others from the factory? My throttle snaps back without delay.

 

[DaveFJR]

I have not yet done the spring mod on my bike but probably will during TBS. My opinion on a loose return spring is it may not be as safe but will sure be more comfortable.

One of my previous rides was a K100RT. That BMW had an adjustible throttle cable tension spring on the grip assembly. I kept it set so loose that it would take a second or two to return to idle (no cramped throttle hand ever and didn't make it harder to turn on gas, unlike a friction lock. )