Hi Guys

My bike is vibrating accross most of the rev range; when accelerating and even more so on engine braking. The only spot where there are not vibes is around 3500-4000. The vibes are through tank, bars and pegs.

I have checked all frame/engine mounting bolts for tightness, all exhaust bolts (there was a loose nut on the baffle box the 16 valve has but tightening it has made no difference); front wheel bearings OK, and generally gone over the bike checking things for tightness/interference. There is also a spacer at the rear wheel as there should be and tyre balance weights seem to be present and correct.

I have already had some good advice to check shaft alignment - the shaft was changed by the PO. Before I embark on this is there anything else to check first? I have not checked valve clearances (partly because remedying them if they are out on a 16 valve looks truly intimidating for someone of my mechanical knowledge!) but also would they cause such a lot of vibration? Also I have not synched TBs as this I believe only affects idle so would not generate vibes through most of the rev range.

Any advice on what to tackle first or any other root cause I should consider appreciated.
Thanks
Dave

Hi there, to isolate a possible cause, need to know if the vibration varies with the bike on the centre stand and in neutral.
Also revving on gears on the centre stand.
Best regards
JAP

Hi Jap,

Thanks for the reply. I have just done as you describe. As far as I can tell the bike vibrates the same amount on the centrestand in neutral and in gear as it does on the road. i.e. it always vibrates.

Cheers
Dave

Ok, then transmissión, steering and wheels seems not guilty. Suspects are engine and attached accessories. I'll start checking the exhaust system, you already did but are the supports and the shield (if any) sound, also the side stand, then the alternator.
Hope this helps
Best regards
JAP

Thanks Jap, much appreciated.
I'll revisit the exhaust but am pretty certain it is sound.
I have not looked at the alternator before. What am I looking for?
Cheers
Dave

The alternator can cause vibration due to bearing and/or rubber damper failure.
You can try to feel it while revving the engine, but the best way is to extract it and check the rubber and bearings, also try runing the engine without the alternator looking for the vibration. There is at least one post regarding this matter on the forum.
Remember to check the side stand, does the vibration changes while it is extended or retracted, if the rubber docking is not working properly ,the springs are weak or the bushing worn the resulting looseness can induce vibration too.
Best regards
JAP

Exhaust and sidestand OK. This is a significant mechanical vibration. I tried feeling the alternator - it buzzes, but placing a finger on it no more or less than the the and gearbox engine casings. If anything, the buzzing is strongeest on the left side of the engine (valve gear etc) and at the front of the engine. Just a thought but could a worn oil/water pump ( I know it is worn as it weeps a little oil) also cause vibes?

Next step will be to pull the alternator and run woth and without.

Thanks Jap
Dave

Hi, normally the pump should not be able to induce such kind of vibrations, however valve clearances out of allowance and/or air leaks/out of sychro might be the cause. Pity you're a bit far away; happy to check clearance and sync the bike for you. Family visit close to Glasgow in order???



PS I'm due a visit with friends in Old Rayne, where does your house live?

MT350Explorer wrote:...could a worn oil/water pump ( I know it is worn as it weeps a little oil) also cause vibes?Dave

Hi Dave, a very worn impeller could cause vibration, but you should also have temp. problems. Once the engine accesories are discarded is time to examine the engine.
Best regards
JAP

MT350Explorer wrote:Hi Guys, My bike is vibrating across most of the rev range; when accelerating and even more so on engine braking. The only spot where there are not vibes is around 3500-4000.
I have not checked valve clearances (partly because remedying them if they are out on a 16 valve looks truly intimidating for someone of my mechanical knowledge!) but also would they cause such a lot of vibration? Dave

Dave,
I'd like to toss a coupla things in to the mix regarding valve clearances and their effect on an engine: If valve clearances are too loose they're not a terrible detriment nor contributing much to a poorly running engine which feels out of sync and is vibrating. Way out of spec, perhaps a bit but not to cause the running vibes you're describing. The old adage is that it's better to 'hear' your valves than not to; a slight valve clatter due to too wide a clearance is not a really big deal in the scheme of things. The other direction on the scale isn't so good, however.

If they're too tight within their specification this causes the valve to not fully come to rest on the seat, which they need to do for proper wicking of the heat into the larger area of the cylinder head and away from the relatively fragile exhaust valve face and seat - a heat sink of sorts. This is especially true on the exhaust side where there is obviously more heat generated. If left tight like that it will lead to premature valve & seat wear over the long run, but more immediately, causing that or those particular cylinders to not generate their potential compression since the valve never closes entirely against the seat. This of course drags down the other cylinders as they're not all in sync and smoothly pumping as they should be, and this can cause a vibration.

With much too tight valves in one or more of the four cylinders, and loss of compression causing imbalance, the engine will always (at all rpm) feel quite sluggish and unwilling to rev properly, the idle will be lumpty, rumpty and irregular, like a tired, worn out old bomb.

A valve clearance check and subsequent adjustment is the first part of any proper tune up (or thorough diagnosis of an obviously imbalanced engine), followed by a check of the ignition components for proper spark/timing. Only then does the fuel mixture/TB or carbie balance get adjusted. But, having said that, a quick look-see if it's way out is not a bad place to start. You just have to consider the other items with some scrutiny. It's often easier to get out of the way what's not causing it first. The problem just might be found in that basic search.

In addition, these motors are incredibly susceptible to air leaks (especially within the post TB intake system), even with tiny cracks in the rubber components that aren't readily apparent. The bottom (and top) rubber intake sleeves and their air tightness is a very good place to start looking. At the base of 16V intakes, right on top of the aluminium cylinder head, are thin rubber O-rings set in a groove. Suspect them too. A few good squirts of your favourite combustible cleaner like carby or brake parts (or ether) as the engine idles, directed at the TBs and intakes to see if there's a noticeable change in the idle, up or down, will be a giveaway that there's an air leak. Some also use a gas like butane or propane - but not lit, of course!





Good luck and let us know how you go.

Hi Rene

[/quote] PS I'm due a visit with friends in Old Rayne, where does your house live?[/quote]

Old Rayne is close to me away so if you had the time and onclination that could be a winner!

Hell that could be the first Scottish meet!

Cheers
Dave

Thanks GITH mate, really appreciate the advice! I have tested compression and it's 150 on 3 cylinders and 145 on one. Based on Clymer range this is 'good' so suggesting the valves are not too tight maybe? If I can link up with rene and check the valves properly that would help confirm.

I've got a propane torch so wil try it around the TBs. Have previously replaced all rubber components here including manifold stubs and 'O' rings. Possible I have not fitted something properly and it is letting in air.

Ignition is a good suggestion mate - not sure where to start here but will look in to it after looking at the alternator. I have serached other posts on alternator and replacing the rubber monkey niuts seems to have cured vibes a few times so if the allen nuts come off OK (!) then it should be an easy check to run the engine with the alternatror off the bike to see if bthis is causing a problem but will do TB rubbers propane check first.

Thanks for all the help - owe a few guys here a beer!

Cheers
Dave

Mate, that's excellent compression (and really they're close to each other in psi too) and my guess would be that your valves are close to spec if not right where they should be. The clearances do change but are notorious for their valve train reliability, those 16V motors.

Once the covers are off and you have easy access the alternator comes out without much drama.
I replaced the monkey nuts in mine when I did a clutch recently and although they were slightly 'squared off' they didn't need changing. Use a light grease to aid sliding the new ones in, oh and note which direction they face!
Cheers.

Thanks GITH!

I just did the propane test and no change to idle, stayed steady at 900; it's a touch lumpy at idle but basically fine and didn't change notcieably with a generous squirt here, there and everywhere.

Just re checked the exhaust mountings - all of them. The onluy one I had not looked at before is the 16 valve silencer hanger circular 'hoop'. It was tight and the rubber looks undamaged. I had all of this apart to repalce the exhaust a coupleof months ago so am fairly confident it is OK.

So, onto the alternator now......

Cheers
Dave

Well doesn't seem to be the alternator. Took it out and ran the bike in neutral and in gear on the centre stand. Still very vibey - my feet were tingling when I got off. I wonder if when I changed the exhaust I messed up - I think I'll take it off and run the bike without it for comparison.

If there isn't one I'll post up a thread on the alternator removal with pics in the tutorial section as I took photos.

Cheers
Dave

Well I have been through the exhaust and removed and fiddled and checked for clearance. All seems fine; a possibility of contact with the clutch release arm but I can get a bit of paper through between it and the baffle box so I think it's clear although very difficult to see how much.

So I'll replace the monkey nuts on the alternator as I'm in there but currently a bit stumped.....

Cheers
Dave

ReneZ wrote:air leaks/out of sychro might be the cause.

Is this synchronising the TBs Rene?
Thanks
Dave

What about the breather hose on the 16 valve? It's diffenet to the 8 valve isn't it. I have never checked it - dunno where it is but will check manual and take a look. Would it cause vibes if knackered?

Answering my own question here YES it would cause it run like a bag of spanners. Here is the link....

http://k100rt.aforumfree.com/t3842-k100rs-breather-hose-replace

Dave, yes it is, after you have ensured you haven't got any airleaks.

Have a look at some pictures on the various fora or in realoem.com, which has equipment lists with sketches.

Have a read HERE, about a K1100, but similar to yours I think.

OK after a full shift in the garage I've removed the airbox and associated hoses and checked inside and ouside. One internal 'trumpet' had dropped off and there was a split on the crankcase breather where it enters the box. Full of high hopes about the latter I fixed it up and put everything back - not a job I want to repeat in a hurry - fiddly! No change. B*****D!

Thanks Rene, I am now certain there are no air leaks. To what extent will a DIY idle TB synch mimic the full BMW Dealer synch? Gotta be worth a go at the DIY? After that it's finding someone who can synch them properly - not sure even BMW Motorad could do this now and then perhaps checking and setting the timing - or vice versa!? Plugs are new - I will check they are correct type....

Cheers
Dave

Plugs are correct. 16 valve owners manual says Bosch XR 5DC - this is equivalent to what is fitted (NGK 7912 D7EA). Useful Bosch/NGK comparison site here http://www.sparkplugs.co.uk/pages/technical/Bosch-to-NGK-cross-ref.htm

Dave

MT350Explorer wrote:Plugs are correct. 16 valve owners manual says Bosch XR 5DC - this is equivalent to what is fitted (NGK 7912 D7EA). Useful Bosch/NGK comparison site here http://www.sparkplugs.co.uk/pages/technical/Bosch-to-NGK-cross-ref.htm

Dave

Nothing to do with your vibration problem but......your ignition system might not be fond of incorrect resistance.

The equivalent to Bosch XR 5DC is NGK DR7EA, D7EA is used on 2V which have resistor caps, 4V using resistor plugs.

Odd one Inge as it is from the 16 valve/K1 handbook that would have come new with the bike. I will check and cross check. Thank you for pointing it out!
Dave

MT350Explorer wrote:To what extent will a DIY idle TB synch mimic the full BMW Dealer synch? Gotta be worth a go at the DIY? After that it's finding someone who can synch them properly - not sure even BMW Motorad could do this now and then perhaps checking and setting the timing - or vice versa!? Plugs are new - I will check they are correct type....
Cheers Dave

BMW dealers won't touch the between-TB adjustments, either, Dave. Mainly because most are not equipped to do such a job. The best you'll get is a good balance at idle and just above as the air screws no longer have an effect.

Inge is correct, as I discovered when I used resistor plugs in my 8V and
noticed it wasn't terribly happy to rev freely...subtly. I use NGK 5K Ohm resistor tops on the leads so the additional resistance of the sparkies isn't required and is a detriment. I swapped back to a
non-resistor plug and not only did my fuel mileage go back up a bit but the engine
generally felt better, and not just in my imagination. Charlie99 clued my dense brain into that misstep whilst in conversation about the subject.

As an aside, I use NGK DP7EA which have a slightly longer reach
but do not interfere with the piston tops. The P means projected tip. In
Summertime OZ when it is much hotter I use DP8EA which in NGK language
is a one step colder heat range. There is no apparent noticeable
difference in the running (other than smooth running and typically great
fuel mileage) so why not stick that lovely blue spark as far into the combustion
chamber as possible?! The difference is less than two millimetres.

Interesting stuff GITH mate.

Well I might as well change the plugs - what the hell!

Just so I'm clear what you're saying (it's late and I'm tired!) on your 16 valve you are using DP7EA or in the summer DP8EA?

Cheers
Dave

MT350Explorer wrote:Interesting stuff GITH mate.
Well I might as well change the plugs - what the hell!
Just so I'm clear what you're saying (it's late and I'm tired!) on your 16 valve you are using DP7EA or in the summer DP8EA?
Cheers Dave

No. no, I have an 8V. You would use an NGK DPR7EA in your 16V, if you decided to follow my lead. I have no experience with projected tip spark plugs in a 16V motor. You would need to use caution and my advice is to simply replace the plugs with a known quantity...DR7EA or the Bosch equivalent XR5DC.

Get some rest, dream a little, and you might wake up with an epiphany as to what is causing your bike to vibrate so. It's not the sparkies causing it, though.
Cheers.

Cheers Guys

Well, I've a set of the correct plugs on the way and a Morgan carbtune, so we'll see if setting the TBs makes a difference.

I'm usually a big fan of Motorworks but their price for a single spark plug was two thirds the price of a set of 4 on Fleabay.

Cheers
Dave

Some progress.

Although no change to the vibes when static I took the bike for a run since I fixed the induction leak on the crankcase breather. Much better, smoother idle and generally smoother running. Still some way to go but I'm starting to grin again!

Cheers
Dave

MT350Explorer wrote:
. Still some way to go but I'm starting to grin again!

Cheers
Dave

Get at it with the carbtune and see if that gets you another bit along the road Dave. Are you planning on doing the timing too? I've read that can help a lot.

88

Hi 88

Yep, I have high hopes for the carbtune. the vibes got worse after I changed the TB rubbers etc, one of which leaked so I think they may have been adjusted with an air leak. Now it is airtight they are a bit out of synch. It's a theory anyway . timing after that...

Cheers
Dave

H Dave,

As you may be aware the carburation/injection is the last adjustment that needs to be performed.

Timing, valve clearances, then injectors.

Mike

Hi Mike

Thanks, that's a good steer. I am doing it a little arse-about-face due to availability of timing equipment - will mean I will do TBs twice but 10 min job.

Cheers
Dave

just a thought dave ...have you actually tested the resistance of the high tension leads from the coils out to the plug tops ?

whilst measuring ...move the leads around as well ( there may be a sectional or joint issue) aligator clip leads are a great aid for this .

might be a good idea to also test the resistance of the secondays of the coils as well whilst you in there (somewhere between 10,000 to 12,000 ohms ).

i have noticed that even with one plug just slightly missing , you can notice the difference .

whilst on a ride around our part of the world ..(over to drake actually with gith to meet rickg ) i noticed some vibration start after a bumpy section of road ...at about 4 grand the engine sounded fine but you could certainly notice a little more vibration than usuall ....we stopped and i reseated the high tension leads at the coil ..problem solved ...later i got a couple of new leads (about 2.5-5000 ohms for the length of them ) and replaced a couple of them that seemed to be always starting to mis periodically ...

since doing the throttle body rubber resealing and vacuume balence the bike has been far better as well

Hi Charlie

Good thought mate, soemthing was niggling me there about the HT leads. Cylinder 1 and maybe one of the others just doesn't snap home like it should. I did clean both ends of all leads and the plug ends look a bit past their best.

Unfortunately whilst I agree with what you are suggesting the majority of your post means nothing to an electrical bufoon like myself. I can change torch batteries but that's about it! I have a multimeter - so am armed and dangerous and will seek further instruction on the internet!

Just thought - the resisitance on the 4 v is in the plugs not the caps like the 2 v so I could get some bog standard HT leads and swap them out and look for improvement? Is this right?

Thanks mate
Dave

its pretty easy dave

perhaps you have time to post a pic of your multimeter specifically of the ranges that it has a available ..i can guide you from there huh ?

we have seen a couple of times that folks were measuring things with multi meters but had the range set wrong for the job at hand ....and observing a failed result when actually it was an over range measurement leaving a big 0 as a result .

Cheers Charlie. I reckon I can have a stab at the leads (talke a lead off the bike and stick a probe in at either end) - but what are the secondarys please and where would I measnure them?

hang on mate i have a pic in my resto thread ...

i got some coils from blighty ...but they proved to be on their last legs

these are pics taken of then upside down and off the bike ...but you get the idea i guess

the secondary sections are the recessed sockets the primary connectors are the spade terminals

the terminals should be bright and shiney and clean as ....not green like in this shot

use a probe ...maybe a straightened paper clip attached (wound around the probes ) to get enough depth to touch the copper bits .....if they arent clean make them so before starting



set the meter for 20,000 ohms or 200,000 ohms if it is a manual range meter you are going to measure between each of the copper bits on each coil ...report back with what you find huh ?

http://k100rt.aforumfree.com/t1833-85-rt-resto-my-attempt-hey-im-not-into-making-a-show-bike#17691

Beware that the 4V got different coils than the 2V.
Primary: 0,5 ohm. Secondary: 13K ohm.

bless you inge ...good info !!

OK so I have the following readings..

HT1 6500
HT2 6500
HT3 6500
HT4 6500

S1 15000
S2 15000

All looks good I think? No corrosion at coil end of things.
HT1 at the plug end was very loose on the plug; in the ensuing action to try and tighten it up I ended up breaking it; I reapaired it by fitting a different plug cap I had lying around - but it is now too short by about 3mm to reach the plug! So, I'll get a new HT lead tomorrow or Monday and try that. My hope is that HT1 was not making good contact with the plug..

Cheers Inge and Charlie - thsi is what makes this forum so great
Dave

It could be the source to your problem, keep in mind to get a HT lead with the same resistance as the one connected to cylinder 4.

BTW, the genuine HT leads is from Beru.

Cheers!

Good thought Inge. On reflection I might buy an OEM. If the OEM's weren't such a high price I'd replace all 4 straight away. Will sleep on it but if I get a motor factors item will take the multimeter to check resistance! Thanks

good find dave ...

hope you can get a replacement and it solves some of the issues .

wow those numbers for the high tension leads are amazing ...dont think i have ever seen so close a reading between each one before ...

makes me think that they are copper cores with resistive plug tops rather than the typical silicon leads we see so often these days

I think I have some brand new OEM 4V cables laying around,
just for fun.......where`s my multimeter........10-15 minutes...

I can vouch that they are copper core Charlie having just cut teh end off one. I would take the readings with a pinch of salt as I may not have read them correctly but for sure they were all the same!

thanks dave .....and here was me assuming that all of us had the new style silicon types

always learning something new it seems ....cheers

The brand new ones is a bit lower, but that is quite normal with copper wires I think.

1. 5570 ohm
2. 5770 ohm
3. 5710 ohm
4. 5980 ohm

Ok, Ok, OK - so like I say they were all the same according to my multimeter (found it in a christmas cracker last year) . even WITH reading glasses it's a bit of a struggle....

By the way are 2 valve leads definitely incompatible with 4 valve set-up?

Ì use double glasses when I read my analogue meter .
Some of the deal was also to test out the difference between used and unused cables.

Way back when only copper was used for these ones, it was said that one of the reasons to change them after this and that amount of km`s, that the resistance in the copper did rise over time due to the high voltage passing.

But have never tested if this was true, or just hear say.

On the other hand, my multimeter also isn`t a expensive one, so I don`t know how accurate the readings is.

.........OK, next test.....#4....measured with different meters.