Time for new throttle cable? '08 GSA

andeebee · Aug 4, 2018

Tried looking at the throttle cable adjustment to get my TB's balanced and although I had noticed the rather ragged finish to my throttle cable adjuster at the bars, I had never adjusted it.

I have zero free play at the throttle so I assume I need to make the cable shorter? To do this I expected to turn the adjuster up towards the throttle grip.

But as you can see I have only a few threads left and the adjuster barrel wont turn anymore in that direction. I guess this is what a previous owner/mechanic had tried and goosed the adjuster whilst trying.
Also noticed my cable is binding on full right hand lock and the bike revs rise to 2K.
Time for a new upper cable? Motorworks dont list a new part and web searches dont show up any options for 08-. Can an earlier upper be used?

Can I also confirm the cable is exiting at the right place on right hand side? It seems to be hard against the inlet snorkel.

I do have risers on and re-routed cable under bars recently as it was rubbing on top of bars previously. Maybe a longer cable could be purchased to sort these two problems?

andeebee · Aug 4, 2018

Looking at RealOEM, it appears the same upper cable is used 06- through to -13, so that answers the new cable question.

Steptoe · Aug 4, 2018

andeebee said:
I have zero free play at the throttle so I assume I need to make the cable shorter? To do this I expected to turn the adjuster up towards the throttle grip.
?

You adjust throttle cable free play at the throttle bodies.
Adjusting the cable at the throttle grip doesn't have any effect on the free play at the two throttle body cables. it just takes up slack in the main single cable between twist grip and cable junction box.

andeebee · Aug 4, 2018

OK, thanks Steptoe. So the throttle end of the cable is just to adjust out any cable stretching in the upper cable?
In that case I need to introduce some slack at the TB end.

duds · Aug 5, 2018

If you haven’t looked already it may be worth checking the cables are seated correctly in the junction box

andeebee · Aug 5, 2018

Yes, I might have to do that. I cant get any free play on the left hand cable, I have the adjuster down onto the locknut as far as it will go and a slight tug on the cable still raises the revs .
I may have to invest in a Twinmax or similar also as my efforts to construct a manometer using tubing and fluid have failed and causing much frustration. I used some light weight fork oil I had lying around and it seems to viscous so as not to let any air pockets move around. Ive spent longer trying to get the fluid in the tube centralised than I have balancing the TBs.

Bendy toy · Aug 6, 2018

I made a manometer with two small thinners tins. They were linked at the bottom with a fine neoprene tube and each had a neoprene tube as a level gauge. When the balance was well out, the fluid (paraffin) would be all sucked into one tin. The little connecting tube stopped it flowing too fast. As the balance improved, the vacuum difference became small enough for it to work like any other manometer.

It cost 2p for the brass tubes and some solder. I already had the clear model engine fuel hose in the shed.

Pukmeister · Aug 7, 2018

As Steptoe and Mikeyboy said in a recent thread on balancing IIRC, its all in the pickup from closed throttle, you can almost find the sweet spot by feel/ear when balancing (although I much prefer the visual way).

FWIW my 2008 GSA has ran like shit for years but the combination of new lower coils, posh petrol with techron fuel cleaner added, plus time spent balancing it perfectly has made it beautiful to ride again.

The time invested in the perfect balancing was the major factor in its smoothness and pickup from a closed throttle (rideabilty).

Back to your original point: I would replace those chewed up cables if it were my bike with new (or a good used set from a breakers like motorworks/sherlocks). They look knackered.

Steptoe · Aug 7, 2018

Pukmeister said:
As Steptoe and Mikeyboy said in a recent thread on balancing IIRC, its all in the pickup from closed throttle, you can almost find the sweet spot by feel/ear when balancing.

I do all the old airheads by ear and feel and get it spot on each time..

. I can get the idle on the 1100/1150 spot on by ear and feel, but can't quite get it spot on off idle, very close but not perfect. Another year of daily practice and i might just have it.

Can't get anywhere near as close when doing the 1200 by ear and feel, but give it time.

Pukmeister · Aug 7, 2018

Steptoe said:
I do all the old airheads by ear and feel and get it spot on each time..

. I can get the idle on the 1100/1150 spot on by ear and feel, but can't quite get it spot on off idle, very close but not perfect. Another year of daily practice and i might just have it.

Can't get anywhere near as close when doing the 1200 by ear and feel, but give it time.

I'm about 20 years behind you.....

After a career fixing Paxman diesels I have tinnitus so bad I have no chance of setting by ear. :rob

andeebee · Aug 7, 2018

Thanks for votes of confidence I am persisting with the job, although my clear tube and oil manometer still has all the air pockets in it. Should have used a thinner solution.
Took tank off to check bowden box and inside was as clean as a whistle and all cables in good order and seated well in their notches.
I found a part of the upper cable that wasnt routed to its correct position against the loom and headstock so repositioned that and hope that cures the binding throttle.
Im struggling to get the left cable to get any slack in it. Cant tell what is 'tight' and what is 'loose' - both feel the same, wherever the adjuster is.

This position allows me to pull the outer cable upward by 1 or 2mm - does this look right?

Having a lot of problems with this, but I like to make a meal out of things :blast

.
Where would be a good starting point for both adjusters? I read another post where I should only be adjusting the right cable but I have a feeling the left has not been set correctly due to its tightness.
Dont mind putting the time in to fully understand how stuff works and should be setup.

Pukmeister · Aug 7, 2018

My understanding is that there should be slight slack in the main cable from the throttle to the splitter box to prevent unwanted opening of the throttle during handlebar turning. I believe about 2mm of throttle slack is normal.

I don't think there should be any noticeable slack in the individual cables from splitter box to the throttle bodies but the throttle cables should be sufficiently set to ensure the throttle butterflies remain closed against the factory preset stops when the throttle is fully shut. (When cable ends get disturbed by owners the forum often gets hit with 'uneven running' posts asking for advice as one unseated cable holds one throttle part open.

Idle control is taken care of by the idle stepper motors under the action of the engine management system. A GS911 tool can be used to 'park' the idle steppers during throttle synchronisation and also reset them to their base setting (they can wander out slightly over time). I have previously carefully removed my idle stepper motors and cleaned a trace of dirt and emulsified oil from inside the throttle body castings, then refitted and reset the base settings.

Synchronisation is best set on the right hand throttle adjuster as the TPS gets in the way on the left hand throttle. Adjustment is very slight steps (typically one flat at a time) and not big movements. Never adjust the preset factory throttle stop screws, they used to have small domed black plastic anti-tamper covers over them but many are now missing.

If any of my perceived wisdom above is actually bullshit or half-truth, I'm sure Steptoe or the other forum experts will be on hand to correct me.

andeebee · Aug 7, 2018

Puk, thanks for reply, you may have something. Looking at earlier posted photo, on the upper cable the throttle end adjuster is obviously shagged so if nothing else could do with renewing.
While I had the tank off and the bowden box open I repeatedly twisted the throttle slowly and watched the effect on the bowden box and the take up in the inner cable reel was immediate to the two attached cables. There is zero slack at the throttle, even with the adjuster at full extension.
I wonder if the upper throttle cable is putting unwanted tension on the right hand cable because I cannot introduce any slack in that cable?

Pukmeister · Aug 8, 2018

The main cable in your photo is goosed and ideally needs replacing. Fit a new one, ensuring just a little initial slack on taking up throttle and then set your two lower cables, initially slightly slack to ensure throttle butterflies fully shut then adjust excess slack out. Finally balance using RH adjuster, leave LH set fully closed against the stop with TPS output signal to ecu at zero.

andeebee · Aug 11, 2018

Sorted!
Had to order new cable for 08 on GSA from local dealer. Motorworks didnt stock them and the chap on phone confirmed there was a part change for 08 on bikes, which they didnt stock so a dealer order had to be made. Motorworks suggested they would have a word with their parts department to start stocking these in future, so still worth a try if you need one.

Picked up new cable from the new Cheltenham Cotswold dealer in exchange for £63 on Friday -

Fitted to bike and the new cable immediately introduced the desired slack on the throttle. I can now get onto the throttle balancing...

Took bike out for quick spin to bring upto temperature and setup my workplace on driveway.

Using step ladder to bungee the new Carbtune Pro (it was shaking when hanging off the handlebars), two fans to keep engine temp down, bodywork is all off at spray shop (should be back soon).
Balanced it at around 1500 - 2500 range using a bungee on the throttle to hold it at steady revs.
Had a problem getting the 10mm locknut to tighten up on the adjuster as the nut is a slim one. Luckily I had assembled some Ikea furniture a day earlier so had a slim 10mm spanner left over with that stuff.

Got a pretty close balance after a few minutes, so set it all and took for another spin. Really pleased with the pull in 3rd and the bike is now steady at 20 - 30 mph where before it was surging and coughing.
Thanks for all your help guys. MOT soon and new paintwork and I can get out on the damn thing.

Pukmeister · Aug 11, 2018

A nice result, glad its now all as it should be, but £63 for a simple bowden cable!

I despise the blatant rip-off pricing structure of genuine parts from dealers, I appreciate the need to turn a profit when running a business but even with overheads, manufacturing costscand supply chain considered, I can't see where the £63 worth of value is in that part ?

They have us all by the balls and thats the way they like it. I hate being taken for a mug over parts but sometimes we have no choice.

Time for new throttle cable? '08 GSA

andeebee

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andeebee

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Steptoe

What a waste.

andeebee

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duds

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andeebee

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Bendy toy

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Pukmeister

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Steptoe

What a waste.

Pukmeister

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andeebee

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andeebee

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Pukmeister

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andeebee

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