Re: Throttle return spring removal, tweak & reinstall - guidance please
Thanks Tobers for adding the pics. I tried to integrate them with his text from his original post to place them into context. Might have gotten some of the order wrong, but hope it helps those who want to do this mod.
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So as usual I dived in and had a go at it. Here's the sequence of events:
1) Remove side panels, lift the tank & prop up. Dont forget to unclip the two vent hoses that run down the front left of the engine to the bashplate so they dont pull off under the tank.
2) Undo the throttle housing on the handlebar and remove the ends of the throttle cables from their notches. This gives you free play of the cables at the engine end which you'll need.
3) Looking at the left side of the bike, remove the little black cover below the airbox which is hiding the throttle pulley. You will need a special torx bit for this - one with a hole in the middle. They are called tamperproof torx bits. I use a set like this:
http://www.abbeypowertools.co.uk/torx-and-tx-star/torx-insert-bits/showitem-6155-38716.aspx
4) With that black cover removed, you can see the throttle pulley and cables:
5) Carefully undo the nut on the end of the spindle holding the throttle pulley, and also undo the nut on the spindle holding the linked arm, and slide off the various bits on the spindles. NOTE THE WAY THEY ARE ORIENTATED BEFORE REMOVING THEM AS SEVERAL ARE ONE-WAY (ESP THE WHITE PLASTIC WASHER). The first on the front spindle was a bit reluctant to move for me but a little encouragement had it sliding off nicely. Watch for the tiny thin washer on the back of the rear linkage. Below are the spindles with all but the throttle pulley removed.
6) Before removing the throttle pulley, be sure to confirm to yourself how the spring behind engages with the tang on the pulley so you know how to put it all back later.
https://c1.staticflickr.com/1/352/18954378184_253b87b200_z.jpg
7) Then remove the throttle return spring. NOTE how the straight end engages behind the plate next to the engine as you need to put it back the same way. Here's the set of parts laid out in the order they came off. The throttle return spring is the bigger one on the right. The smaller one goes to the linkage.
8) Here's the engine view without any of the pulleys or linkages on. At this point you may have noticed that the front throttle spindle pushes in an out by about 5mm. This will cause problems and swearing during reassembly, but continue in blissful ignorance for now.
9) Now to trim the spring. I figured I'd be cautious and cut a third off it rather than a half. In retrospect, half would be more like it as the throttle resistance is still firmer than I'd like. I cut it with a Dremel tool. I then bent the cut end open at the same place and to the same degree as the bit I'd just cut off. Obviously make sure you cut it in the right place so there is enough spare to bend out like this.
Removed bit on the left, remaining bit to go back on the bike on the right.
10) With the main spring cut, replacement is sort of the reverse of removal, but with lots more swearing. Firstly, slide the return spring onto the spindle, and engage the straight end back to where it came from. So far so good. The slot the white plastic washer on the correct way around so the flat face is facing outwards and it is engaged into the spring.
11) Now the fun bit! I did this with the cables on but it should work with them off. Check you've got the throttle pulley the right way around, and slide it back over the spindle. Rotate it so the curled end of the spring engages with the tang, and then rotate it to take up the tension on the spring and align the oval-shaped centre hole with the matching lugs on the spindle. At this point you'll wonder why it wont engage. You'll start to get madly frustrated until you realise that, in putting the tension into the spring, you've pushed the spindle inwards and you cant engage the pulley properly. Try for about 30 minutes in vain to get it to engage properly.
12) After a cold beer and some contemplation, screw the nut onto the end of the spindle to give you some purchase. Keep the spindle pulled out whilst you align the pulley, whilst simultaneously using a small screwdriver or similar to ensure the wite washer is pushed back far enough to reveal the full engagement notches on the spindle. Do this about 10 times before getting it right, and then watch as it pops off again. Then repeat and do it properly.
12) With the pulley finally on and located, start refitting the remaining components. Nothing too tricky, just ensure you get them the right way around. The outer spring has 2 ninety degree bends in one end. This end goes through the little hole on the throttle pulley. The free end gets sorted in a minute.
13) Tighten the nuts on both spindles so everything is secure and the bastard pulley wont jump off its notches again. Ensure the cables are on if they aren't yet.
14) Now push the free end of the outer spring around until you can get it engaged with the tang on the outer pulley (the one with the hole in). Some needle-nosed pliers should help you get the end into the hole.
15) Refit throttle cables. Check everything operates smoothly. Then run the engine and check again. Lastly, refit the black plastic cover and secure the tank & side panels.
16) Go check it runs OK.
The result - the throttle is a bit lighter, but still not light enough for me. That is one strong little spring. The throttle is very nice and smooth and free, so nothing is binding or rubbing, so it must be just the spring that is to blame.
I'm going to repeat this exercise and cut another couple of winds off it. From start to finish this took me about 3 hours, but now I know what I'm doing I reckon it'll be 60-90 mins if that. I'll report back on further progress.
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Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr
Yamaha Super Tenere throttle spring mod by Tobers, on Flickr