Poor tickover and throttle sync tip

[kfrogzx7]

My KRS has not been ticking over consistently recently so I thought a throttle butterfly sync session was called for.
On removing the little rubber blanking plugs from the vacuum take off points I discovered that they were all slightly perished and cracked !
I balanced the throttles which needed doing anyway and then replaced the blanking plugs and now she ticks over perfectly.
So it could have been that the little blanking plugs were allowing an air leak and causing the poor idling , worth just checking them when you're down there .

[airhead]

Yes, perished plug rubbers can allow air leakage.
I hope you didn't touch the throttle butterfly adjustments, they are all balanced at the factory for total airflow over the rev range and shouldn't be touched ever again. All adjustments are done with the brass screws on the body.

Bill..................;-)

[kfrogzx7]

Yes, only touched the brass "air bleed" screws. Again I was mighty impressed with how easy this job is on a K -- compared to the carbs on ZX7 and my VF1 , which are almost ALMOST completely inaccessible !!!
On the K the whole job took about an hr and that was mostly taking side panel off and warming her up .

[Pete Rihoy]

These little sods rot in next to no time, I have now replaced mine with short lengths (about an inch) of silicone tube, as used on fish tank airators. I plugged the open ends by pushing in small screws with a little silicone sealer on the threads. They have been on for nearly three years and are as good as new .

No need to take off the side panels. Remove the knee pads (two screws at the top, one at the bottom) fold-up the foam insulator and you have all the access you need. A long screwdriver helps to get at the two front "air-balance" screws (through the vents in the side of the fairing) but you could struggle with a short one by reaching inside .

This works on the LT at least, and I don't think the RS is significantly different. I should mention that removing the side panel on the LT means that you have to "mess" with the radio box. It could be that, on the RS, there is less to be gained, but I think it will still save time and hastle

[BMGraeme]

I have noticed my K11RS getting gradually "rougher", certainly not as smooth as before so I have just ordered a Carbtune to balance the throttle bodies. It seems to be quite an easy thing to do. Is it just the small brass screws which are used for adjustment? I have the BMW service manual but this doesn't help in locating the correct adjusting screw(s) and I don't want to adjust what I should'nt!

[kfrogzx7]

Yes, it's the brass, more or less flush, slot headed screws that face up towards you as you look at the bodies , ie very easy to access. They are very slightly offset to the left side of each throttle body.

Yes PR I've, like you, replaced the BM plugs with short lengths of fuel pipe doubled over and cable tied to blank them off.

[BMGraeme]

Got the Carbtune so decided to see what it was made of. Boy is this the easiest thing to do ever! Took about 10 minutes of tweaking (after the engine warm up) and all 4 steel bars are now within a gnats whisker of each other. OK, I know I really should have done the valve clearances first but I couldn't help having a go.

Now, fitting a new clutch cable thats a different story. For some reason my new cable from Motorworks has doubled the required pressure required to operate the clutch. No kinks or snags and I even took the exhaust off the get all the dimensions set correctly as per BMW. Can't explain that one - can you?

[metal ken]

Now, fitting a new clutch cable thats a different story. For some reason my new cable from Motorworks has doubled the required pressure required to operate the clutch. No kinks or snags and I even took the exhaust off the get all the dimensions set correctly as per BMW. Can't explain that one - can you?

If it is in the correct cable path, you could try taking it off and pulling the cable while it is not attached to see if it is stiff, if it is a stiff cable usually some lube like wd40 does the trick. Also lube up the clutch lever pivot bolt area and make sure the lever can move OK, Also check the freeplay in the clutch lever when the cable is on, it should move just a fraction before 'biting' the cable.

Another thing i done with the brass screws before synchronising was to one at a time take them all the way out, give them a good clean with some brake cleaner or lube, the put a smearing of copper or aluminium paste round the threads (to stop them from ceasing in the future), Then put them all the way in (back them out a bit if engine is going to stall), once they were all done back them out a bit at a time till you got the correct engine tickover, then do a final tune to get them synchronised.

[BMGraeme]

The advice from others is definately not to lube this cable as it's nylon coated. If I disconnect at the clutch arm I can move the cable freely although not as freely as the old one. The problem I have now is telling what free play at the lever end I have as no matter how I adjust it at the lever, I get instant movement on the clutch arm. I have the clutch arm and cable end set to the lengths as per the manaul. I going to have to ride the bike and manually adjust the clutch lever erring on the side of more leverage to disengage the clutch than less to avoid slipping.

[Richard Todd]

Is the replacement cable a pattern one or a BMW?

I recall that I had similar scenario many years back when I replaced the clutch cable on my K11. I did the job a 2nd time using a pukka BMW one and it was far lighter in operation than the copy version.

[Andrew]

There is also adjustment on the clutch arm itself. That needs to be set correctly before you start to adjust the cable.

[BMGraeme]

I got the cable from Motorworks avoiding the "pattern" part so assumed it was OEM. I have adjusted the clutch arm and set the distance correctly at the clutch end of the cable. I just can't set the 4mm free play at the clutch lever as the cable has enough internal resistance to make that impossible. I have fired the engine up and run through the gears using the rear brake to provide resistance and think the point where the clutch bites is fine but it's all guesswork.

I think I can live with the increased pressure and it may loosen up with age but I would like to make sure I'm not riding around with a slightly slipping clutch.

[Douglas C]

I just can't set the 4mm free play at the clutch lever as the cable has enough internal resistance to make that impossible.

Not quite sure what you are saying here.....

With the adjuster at the handlebar end fully screwed in, is the cable still tight?

[BMGraeme]

Yes Douglas - there's no freeplay. However, actually using the clutch with the adjusting screws all the way in won't fully disengage the clutch even with the lever all the way to the bars. Unscrewing the cable the other way results in the clutch starting to work, and there is a point at which it seems to be working correctly but again there's no discernable free play so I can't be sure. I have made my mind up now to put the old cable back on leaving the new one in situ ready for use as a roadside repair if necessary.

Having written this I have just confirmed this is a BMW OEM cable as per the part number so this is even more mysterious. I know the cable length is supposed to me 151cm so maybe I should take the cable off and measure but still don't think that will solve the problem.

This should be a simple job and I'm really stumped on the answer now.

[mark c]

Maybe the clutch arm on the back of the gearbox is stiff, therefore making the free play difficult to feel. I have always found that with the correct 75mm of exposed cable at the gearbox end, the handlbar adjuster has to be wound out a long way to get the correct free play. With the adjuster screwed right in I doubt whether the clutch would disengage at all.
If you are using a OEM cable, length should be right.

[Andrew]

I think that Mark may have hit upon it there. The pivot pin on the release arm is quite capable of seizing if it is not greased occasionally. They tend to get stiffer and stiffer until they seize completely. The symptoms would be very similar.

When it happened on my K100RS, firstly the clutch cable got stiff, then the clutch started to slip when pulling away and it gradually got worse until the clutch would not engage at all. I assumed that the clutch had gone but I didn't get far into the dismantling before I discovered the problem.

[BMGraeme]

The clutch actuation arm is fine. Not seized and free moving. The old cable I removed was fine other than a bit "notchy". Free play was fine with this and the lever movement quite light. All I have done is replaced this with another new OEM cable which should have been an easy swap. The only thing I can think of now is if something has popped out of place when I released the old cable, but I can't think what. The clutch actually works OK it's just very heavy.

I'm going to put the old one back on and keep the new one on the bike as a spare. If anything was out of place, the old cable should have the same symptons.

[BMGraeme]

So I have now fitted the old one back on and having snipped off a few mm's of nylon inner which was catching the cable, the action is like a knife through butter. So it is only the new OEM cable which is stiff, nothing else. Motorworks was puzzled as I am. Oh well - live and learn.