Foot vibes and cable slack

[Cobbster]

Hi all,
I've recently noticed strong vibes through the foot pegs on my 03 twin spark R1100S. I've tried doing a throttle body sync with my twin max but it has not made any difference. I took it to a local BMW specialist who was too busy to book it in but he took a quick look at it and said that there was no free play at the throttle and that the cable at the throttle bodies was tight, when you pull the outer sleeve theres no free play and the cable starts to pull the throttles open straight away. He reckons there should be about 2mm play before the cables start to open the throttles. Although this may not be the cause of the vibes it still needs sorting out.
Has anyone done this free-play adjustment job and could you give me some hints and tips.

Thanks, Cobbster

PS. He reckons that the free play at the throttle is adjusted at the cables on the throttle bodies.

[Cobbster]

As an update. I checked the throttles on each side and found that the right one opens slightly before the left. About 1-2mm before the left one operates. Obviously not good. Think I'll have a fiddle tonight to try to get them operating at the same time.

Cheers, Cobbster

[snavetrauts]

There should be at least 1mm free play at the throttle body end.... hold the outer cable and pull up.

However regardless of how much play there is , they must pull together at the same rate and at the same time. This is best done on a Morgan tune or twinmax or other such device.... it makes all the difference to the smooth running of the bike.

PS. If you still get vibes after setting up the carbs.... try your engine mount bolts...unusual to be loose .. but they could be.

Good luck

Stuart

[Cobbster]

Thanks Stuart,
Iv'e re-set my tappets tonight, not out by much if anything, and I'll give it a run on wednesday to get it hot enough to set the TB's. I set the throttle play to about 2mm and got the throttles to operate in sync by listening and feeling when they close at the same time. Cable sleeves now pull up freely giving about 1.5mm of free play.
I'm at a loss at the moment on why the vibes should be so bad. In 4th gear doing about 70mph at 5k RPM the vibes are pretty harsh through the pegs. The only thing that I have noticed tonight was the lead balance weight is missing from the rear wheel. Don't know if this would produce such bad vibrations but its something to eliminate.

Thanks, Cobbster.

ps hope you all enjoyed Wales, hope to make it to Hawes this year, Mal.

[Cobbster]

Hi all,
I discovered where the majority of my foot vibes were coming from. Simon came accross the other night and we changed his gear box and final drive oil for MOBIL 1 fully synth stuff. I noticed his Y peice seemed to fit better than mine so after he left I made a few investigations. The cross member that I trimmed down to fit turned out to be still too long and was making contact with the frame on both sides. Rubbing was found on both sides of the mounting locators. Took it off, hacked it down a bit on each side and refitted. Bingo, better from the start. Its still not as good a fitting as Simons but hey, its a pattern part. Did a TB balance and things are sweet again. The vibes are back to normal, lets not kid ourselves these things can buzz a bit.
Out of interest, when I did the TB balance instead of using the left cylinder as the reference and adjustng the right, I used the right as reference and adjusted the left. It was easier to balance the twinmax on the seat and see the difference on the scale. When I got it right the engine sounded great with no lumpy tick over.

Cheers, Cobbster.

PS, thanks Simon for showing me how a Y peice should be fitted,

[plivez]

I've been running without the cross member for the last 3K, seems secure enough.

[Cobbster]

Yeh mate I thought that. If it starts to touch again due to expansion then I'll be taking a hacksaw to the lot of it.

Cheers, cobbster