Pre-amble.
I have 200 miles under my belt with a K-series bike - so wet behind the ears doesn't even come close to describing my experience level with this bike.

I bought an 87 RS just before Christmas - nice looking, but needing some TLC.

I put the bike back together yesterday and rode for 100+ miles or so. I have a harmonic vibration (Buzz) at about 3,500rpm, any gear - too fast for tires (I think) and the feeling is consistent, regardless of speed.

I did lube the clutch splines - is there a balance point with the drive shaft? I just pushed the drive shaft back on to the click, is this a balanced system, I didn't see any marking.

Is this just throttle bodies out of sink a little or
is this just a normal bike?

My normal ride is a single cylinder which makes balancing the carbs or throttle bodies a little easier.

Cheers, M

They all do that.......... Having said that, a good adjustment with a bike in good nick will take away most of it.

I found once I sync the throttle bodies the buzzing is at its lowest.

Rjtrucker wrote:I found once I sync the throttle bodies the buzzing is at its lowest.

I just ordered a set of vacuum gauges, so I'm going down that road. I've come this far...

#4 port needs a 'T' in it for the fuel pressure reg. to maintain its vacuum during the test - is that correct?

yes it does. I only do mine 2 at a time. I do 2 and 3, then adjust one and 4 to #3. Do not adjust the brass screws. let me repeat that DO NOT ADJUST THE BRASS SCREWS!!!!!.

Sorry Sir, what did you say?

Inge K.

Rjtrucker wrote:yes it does. I only do mine 2 at a time. I do 2 and 3, then adjust one and 4 to #3. Do not adjust the brass screws. let me repeat that DO NOT ADJUST THE BRASS SCREWS!!!!!.

I think that you're telling me not to touch the brass screws - yep, got that -I'll write it down on the manual as sometimes it can be difficult to remember my name! - thanks RJ

I have to wait for the vacuum gauges to arrive. I'll check the valve clearance again in the interim. All rubber is replaced at the moment, so now's a good time to proceed.

Cheers, M

It`s the brass screws that is the adjustement screws (throttle butterfly bypass).

The screws you should keep your hands off is the linkage screws between the throttle bodies,
locked with a nut which is secured with blue paint.

Inge K.

Just wanted to comment: "touch the brass screws!!"

Can also be found on forums being described as the BBS (Big Brass Screw or Butterfly Bypass Screws)

Mike

Inge K. wrote:It`s the brass screws that is the adjustement screws (throttle butterfly bypass).

The screws you should keep your hands off is the linkage screws between the throttle bodies,
locked with a nut which is secured with blue paint.

Inge K.

OK, I'm headed to the Clymers manual...
But the idea is to balance the vacuum between the bodies and then set the idle speed for tickover.

On my old 4 carb'ed bikes, I remember something about... balance vacuums between 1 & 2 and then 3 & 4 and then between pairs at 2 & 3. - but this was a long time ago when vacuums were just holes in the air and a heated jacket meant one stuffed with newspaper.

Cheers, M

Moto Smith wrote:On my old 4 carb'ed bikes, I remember something about... balance vacuums between 1 & 2 and then 3 & 4 and then between pairs at 2 & 3.

Done like this in the time before the CV`s, and then at the linkage......
which you are supposed not to touch on this one.

Inge K.

T-piece doh! I just disconnected balanced the bodies and reconnected all sweet even found the rev limiter works after accelerating from 1600 rpm like usual except with them balanced it takes off

No synchonisation before the comlete inlet system recieved new rubber

don´t start with the second step

all items needed:see pdf here

zonenfeile wrote:No synchonisation before the comlete inlet system recieved new rubber

don´t start with the second step

all items needed:see pdf here

I have new rubber - I've pretty much replaced all the rubber on the bike, aside from the front forks as they seem quite decent.

What I haven't replaced is the bungs on the vacuum lines to the throttle bodies, so I think that I'll get those coming before I start.

Thanks for your input.


Cheers, M

I am so sorry I said the wrong screw. It is the large brass screw. It had been a while and the first time I did it i adjusted the wrong ones. I am so glad this group is so active it was caughtn hopefully before the mistake was made.

Rjtrucker wrote:I am so sorry I said the wrong screw. It is the large brass screw. It had been a while and the first time I did it i adjusted the wrong ones. I am so glad this group is so active it was caughtn hopefully before the mistake was made.

RJ- no harm done - I did a quick read in the Clymer yesterday and confirmed the adjustment is the brass screw and 'DON"T TOUCH THE LINKAGE' - They seem quite adamant about that particular bit.

I'm still waiting for the vacuum gauge to come in - I'm also going to order the rubber bungs for the throttle body nipples - I should think that once I touch those, they're never going to be much use to anyone.

It's not much of a vibration, but it does feel like the bike is trying to fight itself a little - right at 3,500 rpm.
I'm new to this bike, so I'm not sure what is normal.

It sure is a nice ride though...


Cheers, M

Moto Smith wrote:It's not much of a vibration, but it does feel like the bike is trying to fight itself a little - right at 3,500 rpm. I'm new to this bike, so I'm not sure what is normal.

They are all like that, sir.............3500-3800 rpm.
But anyhow a sync. could do some improvement.

Inge K.

Inge K. wrote:
They are all like that, sir.............3500-3800 rpm.
But anyhow a sync. could do some improvement.

Inge K.

Thanks Inge.K
And I could use the experience - so nothing to lose, right??

Thanks to all for your input.

Cheers, M

Yes i must admit when i first rode my K the vibration was i bit of a worry, but after reading some posts on it here all was ok.

I did notice however that after i had done the clutch/spline lube and put my new muffler on the vibration doesn't seem as bad.

Problem is i don't know which one changed the vibration, or maybe a combination of both.

caferacer62 wrote:Yes i must admit when i first rode my K the vibration was i bit of a worry, but after reading some posts on it here all was ok.

I did notice however that after i had done the clutch/spline lube and put my new muffler on the vibration doesn't seem as bad.

Problem is i don't know which one changed the vibration, or maybe a combination of both.

Funny you should say that,

The bike came with an aftermarket exhaust - which I swapped back to stock - and I just lubed the clutch splines.

This bike has to be trip ready by the 25th of next month - she has her first overnight trip scheduled.

Plaskett Creek park, BigSur, California - this is a trip with the galactic-tupperware-bike-crew of the local BMW club - so she has to look pretty and ride well.

Cheers, M

If anybody wants a night out...

Galactic-tupperware-bike-crew! Where the hell did that name come from?

Sounds like a great trip Moto, your bike is white so it is already good looking (no fancy red colours here)

Would be great to come for a ride............Bit of a long way though.

I thought the PC800 was the Tupperware bike.

Rjtrucker wrote:I thought the PC800 was the Tupperware bike.

But it takes the new GT or RT to get Galactic status...

Mind you, This is the first time that I've had a bike where you couldn't see the engine - perhaps I had best keep my mouth mmmmm

going to try a few mods to perhaps change the vibrations .....i have a suspicion its to do with the tuned lengths of the ram tubes in the plenum .and perhaps the exhaust lengths ...which will effect induction and resonances ..time will tell

charlie99 wrote:going to try a few mods to perhaps change the vibrations .....i have a suspicion its to do with the tuned lengths of the ram tubes in the plenum .and perhaps the exhaust lengths ...which will effect induction and resonances ..time will tell

I was think the miss-matched exhaust lengths - but I think that's all I'm going to do about it. I don't fancy bending a new set of headers.

Cheers, M

from memory ...i think the bmw exhaust does some internal length management ...from what cafe was saying when he did some modifications ...

in any case having different length exhaust pipes would blend the vibrations accross a wider range ....or thats what makes sence to me as i have a staintune and its got the same issues (not actually sure whats going on inside the staintune though )

whilst ram tubes are usually designed to make intake efficiencies at certain revs ....im thinking that as they come into resonance or just before, there is a null spot ...this is complicated with the cam timing and lift of corse ..its verry hard to get a cam timing right for a full range of engine revs ...usually 4 cylinder engines these days have mooved onto variable valve timing to extend the torque curves over a wider range (honda toyota etc ) these engines usually have a null spot as the revs approch the change of breathing timing

but ram stacks have been known for ages to complement a range of torque ....usually designed for a specific rev range eg track work ....at the higher end of the rev range ... inlet runners have been extended in many vehicles ...especially fitted with auto gear boxes , to produce best power at the "working" range of revs.

lower working revs increase in power usually requires longer runners concidering the k ...the runners are all of 2 inches, maybe , but by putting the ram stacks on, it effectivly lengthens the intake path ..(well really only when throttles are almost wide open ) but its there anyhow .

i hope to get another plenum to experiment with ...maybe to cut the lengths and see if the vibrations change where they sit in the rev range ...of corse there are many more factors involved ...with large rotational dynamic mass of all the engine drive train , output shaft , clutch etc

well this is what i think and worth while playing with at least ...if i can quickly go back to standard plenum it would be great

yeah, im mad but,,,hey !!!

Not mad at all Charlie , well worth playing with . variable length intakes i suspect would be best for a touring bike and you (i think ) previously mentioned intake air cooling. This is where a few more ponies and mallee stumps are available in my humble .

Correct Charlie the headers are tuned length. you just cant see it on the stock system as the rest of the shorter runners are inside the first part of the muffler.

I too have been looking at how i can remount the whole airbox up in the r/h side if my fairing. If i delete one of my glove boxes i reckon it would fit(with a bit of fiddling).

I suspect that those K owners it colder climates would see no gain in this modification or for those without fairings. But for those of us in warmer areas the fact that the airbox sits in the main hot air flow from the radiator and the heat dissipation from the engine block, i think it would benefit from being moved. It would probably also let the hot air flow straight out the back instead of coming out from around the tank and onto your legs.

Haven't gone too far with this yet, but the cooler the charge air going in the better the combustion is. Probably not for everybody but i still like to tinker with things. I reckon these engines are capable of much more.

Well you're going way further than I want to go.

I'm going to attempt to balance the throttle bodies and then I'm going to sew it shut.

Riding singles for the last little while, I can put up with a little vibration - if it's the norm.

Thanks again for your troubles.

Cheers, M

I'm not sure moving the air box would do much for the temprature of the inlet air. Given the huge volume of air used by an engine I would be supprised if there was a rise of more than a degree or so.

As an example look at the huge intake coolers on hotted up turbo cars. They have a huge surface area are are made of very heat conductive material. We only have a small surface area in an air box and its no were near as good a conductor of heat.

ill do some measuring on that pj .... but recently i had temps around the tank area in the high 50s c ...ill put my remote sensor down the inlet tube and see what i get whilst running ....but as you say ...the volume through it wouldnt get much time to heat the air .....



the thing that i and other have discussed is mooving the mass of the filter box from the above engine area and creating a path for the air to flow between tank and back of motor . i have noticed that mine ...whilst side fairing less collects a huge amount of heat ...and im certain that the fairings certainly suck air out of the behind radiator area ...

but hopefully we can cut a few corners out of the airflow path through the filter and afm so that it becomes more straight into the plenum ....i figure the gains would be quite noticeable overall ...well anything above a couple of grand ...anything that has to change direction suffers from some form of resistance ...whilst air doesnt carry weight it has a mass and velocity

i still think the area in and around the plenum where the air has to do 3 turns before going down the ram tubes is prone to some form of gasping ...call it what you will ...and i recon some form of unwanted resonance ...

When i am building intercooler pipework or exhaust systems the more bends the more resistance(although with turbo's its not as bad) 1 x 90 degree bend is equal in resistance to 9 foot of straight pipe approx. (there is a formula for it).

Yes Pjjms i agree with you in some ways but the issue i think with the K's airbox isn't so much about being a conductor of heat but a heat trap. Also most hot turbo cars run there intercoolers out front in the air stream so as to disperse the heat created by the turbo itself. Compressing air creates a lot of heat(just put your hand on a air compresser tank thats been running for a while).

The main benefit i could see from moving the airbox is more to do with getting it out of the heat trap under the tank and as Charlie says allowing the more air to flow over the motor and out through the back.

As i said, i dont think its for everybody. But i like to tinker with these things, i'm going to run my temp probe in the intake before and after the airbox and see what readings we get. You still cant beat ambient air temp though(unless you run a dry ice cooler box) .

hmm just thinking aloud again .....kfreak ...does the k1100 have the same vibrations at 3500 ?

just wondering as the 1100 has a different air path to the throttle bodies no big plenum with ram tubes ..and no afm

it would be interesting to find out huh ?

charlie99 wrote:hmm just thinking aloud again .....kfreak ...does the k1100 have the same vibrations at 3500 ?

just wondering as the 1100 has a different air path to the throttle bodies no big plenum with ram tubes ..and no afm

it would be interesting to find out huh ?

Sure does, at 3800 thru to 4000 and then as smooth as.

well that sort of tears a hole in that theory huh ? giggle ...smacks head ...interesting to note though that it has mooved up the rev range from the k100 signature vibrations .. still learning stuff ....



our mate "guest in the house" was interested to see if he could moove the vibration thang off the 4300 -4500 area and i had the thought that the air path might be a significant contribution to the effect ...

doesnt detract from the airbox relocation thing ...and i believe ill chase up the flow improvements and ram stack/plenum adjustments

so anybody with a spare k100 plenum (read cheep ) and or a spare k1100 airbox ...with tubes (also cheep ) ....pm me huh !!!

should i try our friend in blighty ? emlyn ...he had a stack of stuff or maybe rjtrucker ?

charlie99 wrote:well that sort of tears a hole in that theory huh ? giggle ...smacks head ...interesting to note though that it has mooved up the rev range from the k100 signature vibrations .. still learning stuff ....

My K100 had the shakes at 4000-4300 so that tears the fork out of that nightie Charlie.

I have air boxes for k100s and afm. I do not have for the k11.

could be kfreak ...but i seem to get a few in the range above 3500..like you , possibly harmonics of the prime frequency,

in all things. the third harmonic is the winner ... 3500 /2 /2 =875 + 3500 =4375 i would imagine this is the third harmonic ...or close enough which just by coincidence happens to be around the next noticeable buzz fequency on mine.

i believe rs have a different cam setup although slight to the rt ...at least in my mind that explains a few things ...i better shut up and go do some work on this .

puts on full face helmet expecting rotten fruit to land nearby ...grin

cool rj ..im interested in a plenum for the k100 (airbox above the throttle bodies) ...not the filter holder -air intake or afm

ill pm you ok?

rick ---kfreak has a couple and thats kinda local ..so i think ill take up his offer and go and collect one ....as soon as i can get ol "gerty" on the road again ...that rear tyre is in need of replacement before i get "booked "

Hello all Would it not be benificial to replace the three solid mounts with rubber same as the front two, it seems to me who rode a three cylinder that the solid mount on the Alternator would transmit more of the vibs than anything else? My K75 has no rubber mounts anywhere though. I'd also be interested in what happens to the air box with Charlie and curious if a cooler in front of the radiator would help the air path rather than straight behind the radiator, didnt the 1200's have two radiators most probably for the heat ducted into the engine department problem Keith

STUPID QUESTION THEN. Would it change if someone removed the alt bolt and maybe jammed in a peice of rubber to quell any buz? would it buz more or less before he fell off.???

update

as pj suggested ...i have measured the air temps whilst riding ....ambient was around 33 d c ...heat at the side cover interface to the tenk at 49.7 d c and air temp down level with the air filter inside the box was a nice 31 d c

I was thinking you could probably put a small hole to suit a rubber bung into the rear of the plenum just below the tank This would allow the temp probe to be put inside the plenum to check the air temp there. You could seal around the probe with a bit of blue tac or similar.

Wonder if there is much difference in the plenum at 60 kph compared to 100 kph. Just my rambling thoughts .anyway.

So Charlie that seems like a 18 deg diff between airbox and outside of plenum. Am i reading that right?

i would e surprised if it went more than a couple of degrees higher cafe .... what im saying is that the flow of air through the air filter box etc should be close to ambient ...and rightly so .....my ideas are for evacuation of the hot air to rider after the radiator ...i think it has been well discussed that in warmer climates this becomes rather harsh ...and things like fuel rail under tank etc dont have the flows that the air has .......our last trip around kingaroy we all noticed the increase in fuel tank temperatures ..( mine probably hotter than the rest )

the idea of freeing up the flow through the under tank area has the ambition of keeping the rider and fuel supply loop also cooler ....the air cooler on the fuel rail seems an ideal way to acheive the tank temp decrease ....yes ?

Yeah Charlie, The one Bushy showed us would be great I wonder whether there is similar room for an RS to have one????

Agreed Charlie, i have yet to get out for run since i have now put the insulation on the fuel lines.

There definitley was a difference in temp of the tank after i had done the fuel cooler. As soon as i have a chance to go for a run i will check the fuel tank temp to see how much the insulation has helped.

I concur with you on the air flow situation. If we can acheive more air flow past the air box rather than trapping the heat as it does now. In theory this should keep rider cooler as well as fuel rail and plenum etc.

I was surprised by your comment of yours being hotter than others seeing as you dont have the bottom of your fairing on. I would have assumed that there would have been less heat due to not being trapped inside the fairing.

K75cster wrote:Yeah Charlie, The one Bushy showed us would be great I wonder whether there is similar room for an RS to have one????

The RS has a radiator cowl doesn't it? If so there should be room. Thats were i have mine mounted.

Bert 2.0 is yours beside the radiator or forward of it?? Sorry to ask but I haven't got an RS in the shed to stick me head in and see. Keith