R1200S throttle pulley modification

[gus]

Hi all
Old thread i know, but while i have the bike in pieces i thought i would show a few photos and a little experiment i did in reference to the OP.
even with a quick action throttle i still found that getting on the throttle met with a delay to getting any power to pull the bike out of tight corners.

I marked some positions on the throttle housing and noted that with the standard setup at the throttle body, half throttle at the grip was giving less than 1/4 throttle butterfly at the throttle body. You will see that the black plastic pulley has a flatfish shallow profile at the start then goes into a steeper curve further along. Removing the roller and adjusting the black plastic stop screw and adjusting the slack in the cable allows the pin to sit on the start of the steeper curve. Missing out the flatter first section. Result being it gives a linear action and half throttle at the grip equates to 1/2 throttle at the butterflies in the throttle body. Don't know how this will affect wear on the plastic pulley as yet. Its a solution but i,m still looking at other options.

[URL=http://s905.photobucket.com/user/bmwgusr1100s/media/DSC04582.jpg

You can see that the pin sits closer to the start of the curve in this pick. With the roller fitted and as standard it is sat further back on the flatter portion of the black pulley.
gus

[Droptarotter]

Thank for the great explanation Gus. I never understood how removing that roller would give us a quicker throttle pull.
Now I do!

What about fitting HP2 throttle bodies? Or is that just cost prohibitive?

I did try one of the gizmo's that attach at the grip area, but it only decreased the pull marginally.

Cheers

[f90x]

How easy/difficult is it to do this Gus? (The throttle body casings I mean as I can see the roller bit is easy) Also , I'm guessing that this won't be too extreme and perfectly acceptable for the road. Given that there is no longer a roller, is the throttle any harder to 'twist'? . I'm sure someone posted this mod a while back (with a Pic of that roller) but he didn't do the mod himself. I'm sure he said that it was great on the road. I'd like to do this. It would make a big difference to my wrist and I want the 'instant grunt' back that I had with the 11S.

BTW I already have the plastic insert at the twist grip end. I should imagine it would be an idea to remove this with the roller mod.

[gus]

How easy/difficult is it to do this Gus? (The throttle body casings I mean as I can see the roller bit is easy) Also , I'm guessing that this won't be too extreme and perfectly acceptable for the road. Given that there is no longer a roller, is the throttle any harder to 'twist'? . I'm sure someone posted this mod a while back (with a Pic of that roller) but he didn't do the mod himself. I'm sure he said that it was great on the road. I'd like to do this. It would make a big difference to my wrist and I want the 'instant grunt' back that I had with the 11S.

BTW I already have the plastic insert at the twist grip end. I should imagine it would be an idea to remove this with the roller mod.

Hi
It's quite easy to do. The clips holding the throttle bodies come off easy and can be reused. Disconnect cables and remove injectors. A throttle body synch will be needed after. You have to adjust the cables quite a bit to take up the slack. The throttle seems to be no harder to twist. I would still keep the insert at the twist grip. You will see when you have it apart just how non linear the action is.
All the best
Gus

[gus]

Thank for the great explanation Gus. I never understood how removing that roller would give us a quicker throttle pull.
Now I do!

What about fitting HP2 throttle bodies? Or is that just cost prohibitive?

I did try one of the gizmo's that attach at the grip area, but it only decreased the pull marginally.

Cheers

Hi
Too much money for the HP2 throttle bodies
I,m still looking into some other way of solving this problem. I may ask about having the throttle bodies modified to take a different pulley.
Gus

[f90x]

How easy/difficult is it to do this Gus? (The throttle body casings I mean as I can see the roller bit is easy) Also , I'm guessing that this won't be too extreme and perfectly acceptable for the road. Given that there is no longer a roller, is the throttle any harder to 'twist'? . I'm sure someone posted this mod a while back (with a Pic of that roller) but he didn't do the mod himself. I'm sure he said that it was great on the road. I'd like to do this. It would make a big difference to my wrist and I want the 'instant grunt' back that I had with the 11S.

BTW I already have the plastic insert at the twist grip end. I should imagine it would be an idea to remove this with the roller mod.

Hi
It's quite easy to do. The clips holding the throttle bodies come off easy and can be reused. Disconnect cables and remove injectors. A throttle body synch will be needed after. You have to adjust the cables quite a bit to take up the slack. The throttle seems to be no harder to twist. I would still keep the insert at the twist grip. You will see when you have it apart just how non linear the action is.
All the best
Gus

Nice one, thanks Gus.

[Neil178]

Delorto.
I reckon that the Italians put this cam action in on purpose to give Ducati the edge.

[Spider001]

Does anyone know where to buy this kit from?

[SyRexx]

thread digging

so does anyone have a step by step or images on which parts to remove? i can see that some rollers are removed but not sure how to do it myself

im interested in having a more 'linear' throttle pull as sometimes it feels like the bike has a '2 step' throttle

[Corvus]

Wouldn't a twist grip with a larger actuating radius be an answer? It wouldn't solve the problem of the non constant radius action at the TB, but it would result in less angular movement at the twist grip translating to more movement at the TB. So for every degree you move the twist grip, you'd get more degrees movement at the pulley. A heavier feeling throttle would result. There's no way out of that bit. A change in mechanical advantage is what's needed to get to where you want to be.

An intermediate compensating lever would also work. As would making a new pulley!

Cheers.

[f90x]

Wouldn't a twist grip with a larger actuating radius be an answer? It wouldn't solve the problem of the non constant radius action at the TB, but it would result in less angular movement at the twist grip translating to more movement at the TB. So for every degree you move the twist grip, you'd get more degrees movement at the pulley. A heavier feeling throttle would result. There's no way out of that bit. A change in mechanical advantage is what's needed to get to where you want to be.

An intermediate compensating lever would also work. As would making a new pulley!

Cheers.

I've actually come to this answer as a side effect of using the rather naff 'grip puppies'. They actually make the (too skinny in my opinion) grips about the same girth as the 1100S grips. This gives more throttle opening for the same amount of twist in the grip. This in conjunction with the plastic insert at the twist grip has actually made a noticeable difference and has helped my dodgy wrist as I am accessing more power earlier than before.

[Corvus]

Wouldn't a twist grip with a larger actuating radius be an answer? It wouldn't solve the problem of the non constant radius action at the TB, but it would result in less angular movement at the twist grip translating to more movement at the TB. So for every degree you move the twist grip, you'd get more degrees movement at the pulley. A heavier feeling throttle would result. There's no way out of that bit. A change in mechanical advantage is what's needed to get to where you want to be.

An intermediate compensating lever would also work. As would making a new pulley!

Cheers.

I've actually come to this answer as a side effect of using the rather naff 'grip puppies'. They actually make the (too skinny in my opinion) grips about the same girth as the 1100S grips. This gives more throttle opening for the same amount of twist in the grip. This in conjunction with the plastic insert at the twist grip has actually made a noticeable difference and has helped my dodgy wrist as I am accessing more power earlier than before.

Ay up.

I meant a larger radius from theoretical centre of rotation (that's a brilliant topic in it's own right!) to the centre (theoretical, of course) of the cable nipple.

Increasing the diameter of the grip itself is an interesting one as the angular movement doesn't change. But it does make one wonder how much hand/finger input is truly angular and how much is tangential.

Cheers.

[Corvus]

In fact devising an intermediate pair of levers would not only allow complete control over the amount of "magnification" but, by changing the angle at which the levers sit, would allow a degree of control over how much of the non linear action is kept. Sitting on bearings the throttle would feel smooth and accurate (rotary things generally are low stiction). Cunning design could allow accurate balancing. Return springs could be added or subtracted easily.

Just how madcap is this idea?

[gus]

thread digging

so does anyone have a step by step or images on which parts to remove? i can see that some rollers are removed but not sure how to do it myself

im interested in having a more 'linear' throttle pull as sometimes it feels like the bike has a '2 step' throttle

Hi remove all wiring to injectors and tps. Remove injectors. Undo the metal clips which hold throttle bodies to intake stub and air box connector. Remove throttle body. Slacken off cable on each throttle body. Remove circlip on protruding pin which sits against black pulley. Remove rollers. Remove black plastic cap off throttle stop screw. Adjust throttle stop screw virtually all the way in. Make they are the same on both sides. Adjust cables so that there is a little play. Make sure throttle butterfly's close full when throttle closed and are fully open when throttle is open. Lube all moving parts.
Reinstall throttle bodies and do a throttle synch procedure.
Gus

[dave the german]

Concise as ever Gus. What's you opinion of the mod?