While I'm making a few (ahem) other mods I wondered how often the timing chain and tensioner should be renewed.
The bike has a genuine 42,000 miles or 72,000 kilometers for our colonial cousins. Going to re-shim a couple of valves and balance the carbs, sorry injectors, and thought it might be worth doing. Thats what you get when you are raised on Hondas.
Anyone any ideas on the longevity of K timing chains?

Mine potentially has 84000 miles on it and looks brand new with no tensioner movement. No idea if it's the original but I can tell the previous monkey didn't change it as there are no hammer marks on the chain and the tensioner bolts aren't stripped.

My 8V K100RS now has just over 110,000 kilometres on the clock, with its service history records not well-kept, though I believe the mileage shown to be accurate, and two of the timing chain's three plastic guides were quite scored and worn. I've covered the last 35,000 kms of the total mileage (in 15 month's time). I had an extra used tensioner assembly and compared the two springs against one another, selecting the longest, as well as the cleanest or least worn-looking of the various pieces, and replaced them too. I also measured the old chain against the new chain and it was 'stretched' ever so slightly. They've all been replaced and the very slight slapping/grinding noise I'd heard previously has now gone away. There were no tell-tale marks of an excessively loose chain on the timing cover.

A workmate of mine who commuted primarily and rode quite gently had well over 200,000 miles on an '85 K100RS before he replaced the timing chain and guides. Lifetime of the components can vary.

According to BMW, the chain and the tensioners should be replaced every 60K.
I believe this is a bit excessive and consider 100k would be appropriate.

Again, a mate of mine in Newcastle, NSW, had a K100 from brand new, 240,000Km later recently sold it. The timing chain was still the original, but he rode it every day, commuting, tripping etc, didn't miss a beat.

Not sure I want to be holding a ticket in that lottery though...they will continue to not miss a beat until the day the chain lets go.

With 124k km under the wheels of my '86 K100RT, I'll ask the previous owner if it was done during the 22 years of his ownership and if not, start planning for a camchain replacement.

I heard that BMW did not give the course after which we should changes the timing chain in K100. What is that mean?
Other engines, have specified course.

I have a 133kkm bike, I am sure that the chain has not been changed.
What causes little worn chain?

It is a durable arrangement, guided well, tensioned well, and sitting in oil as it whirs round and round. Mine was in pretty good nick but the guides had enough scores in them to warrant changing the lot. I could see no real 'visible' length difference between the chains (perhaps a fraction of mm's), old and new, but a twist from side to side revealed that the original was worn out.

Recently went for a ride to Phillip Island for the Superbikes. Up the hill from My Beauty to Falls Creek (approx 35Km) Gave the old girl a bit of a hammering. At the top, the rattling noises from the bowels of the engine were incredibly loud, and I thought the motor was about to self destruct.
I don't know if it was the timing chain or clutch or what. Took it easy for a while and it all settled down, got home OK with absolutely no dramas.
Checked the timing chain/guides about 6000Km ago and all looked pristine. What would have caused these noises? She has 80,000Km at the moment.

Ulrich_Grabau wrote:Recently went for a ride to Phillip Island for the Superbikes. Up the hill from My Beauty to Falls Creek (approx 35Km) Gave the old girl a bit of a hammering. At the top, the rattling noises from the bowels of the engine were incredibly loud, and I thought the motor was about to self destruct.
I don't know if it was the timing chain or clutch or what. Took it easy for a while and it all settled down, got home OK with absolutely no dramas.
Checked the timing chain/guides about 6000Km ago and all looked pristine. What would have caused these noises? She has 80,000Km at the moment.

I would bet that the oil got a bit thin with the temperature increase. The fact that you got home ok should give some credibility to this. I tend to use 20W-50 in summer because of this. In fact I have 20w-60 Penrite (Syn 20?) in it now, and still, at high temperatures when the fan is on, the rattle tends to get louder.

Thanks! I'm currently using Castrol Activ 4T 15W-50. I think I'll give the Penrite 20W-60 a go. What you suggest re: oil getting a bit thin makes perfect sense to me! If something was going to fail it would have failed by now.

When you're in there have a squiz at the guts of the timing chain tensioner, a simple, oil pressure and spring thingy, for any signs wear or scoring, too. I had two secondhand tensioners and took the best bits from both and made up a nice 'new' one. I use 20W50 in the warmer weather too. I was using Castrol's Activ 15W50 4T but reckoned the added price for motorbike-specific oil which isn't required in this separate gearbox/engine arrangement is not worth it, so I'm back to 'car' oil.

I strongly favour high quality diesel oil because the extra detergency and film strength of diesel oil makes them a good choice for the K. Look for one listed for mixed fleets and that will be fine. The further benefit is you are extremely unlikely to get the sprag clutch problem with diesel oil because of the extra cleaning power it has.
Regards,
K-BIKE

Good point, K-Bike, and I too use diesel oil about every third change, which I also reckon helps keep the sprag clutch clean. I'm a fan of always changing the oil filter with the oil, even though it adds time and expense to the change. I would say that I change the oil at 3 - 5,000 kilometre intervals, depending upon the type of riding I'm doing. If out on a long trip where I know the bike's warmed up fully and going the distance, I'll leave it in there for that extra bit. But if I am only doing the stop-and-go commute day in and day out and taking short hops (never fully warms up) then it gets dropped quickly. Cheers.

That is so true many a person gets swayed by what oil is used in a formula 1 car but that oil has a better life than the oil in the average family car or bike what with stop go motoring, heavy condensation and irregular changes plus the use of rubbish oil filters some either use or get fitted by their service agent. I always change the filter it is cheap insurance, oil and a filter is cheaper than premature wear.
Regards,
K-BIKE

diesel oil? what you are talking about?
my English is not so good, or I do not understand the context

I ordered chain and small timing wheel

Hi LifeGuard,
Our bikes have the clutch separate from the engine just like a car does whereas most motorcycles have the clutch inside the engine/gearbox and submerged in engine oil. That means unlike the K the average motorcycle gears are in engine oil rather than gear oil which is not so good for gear life.

Given our clutch is separate we do not have to use motor cycle specific oil, almost any high quality car oil is fine since our engines are closer to car engines than motorcycle engines.

One problem we have with our bikes is that if poorer quality oil is used the sprag clutch gums up and the starter motor will not engage. One certain way of preventing that is to use a high quality oil intended for a diesel engine because they are better at cleaning up deposits and have a high TBN (Total Base Number) so are also good at beating corrosion inside the engine.

So a number of us use diesel engine oil (of the appropriate viscosity) either full time or once every 3 changes as does TWB.

I hope that makes my earlier rambling a bit clearer and by the way your English is 100 percent better than my Polish to my eternal shame.
Regards,
K-BIKE

Lifeguard, you might want to have a close look at the timing chain's plastic guides for any wear marks. There are three of them. All three suffer when the timing chain begins to slap a bit as it wears.

Thanks for clarifying the engine oil issue too, in case anyone missed it, K-Bike! In fact, I reckon my bike's due for a change, it's bucketing down outside, the garage is a warm and dry refuge, and this time we're due for some good ol' Diesel oil.

TWB makes an excellent point about chain and guide wear, the Merc is infamous for destroying engines if the timing chain guides are not replaced.

On our K's they seem not to fail so catastrophically as the Mercs but loose timing chains are a bad thing as I am almost certain our engines will be interference engines. So the consequences of the timing getting out will be fast moving pistons hitting valves = expensive sounding noises coming out the engine.

As an old friend used to say there is nothing wrong with expensive sounding noises in an engine as long as they stay completely inside, it is when they come out you know you have got trouble.

A bit like the magic smoke which is contained within integrated circuits as long as the pressure seal is maintained they are fine, when the seal fails due to a problem the smoke escvapes and they are then useless
Regards,
K-BIKE

Keep the smoke (and the noises) inside!

Ok, K-BIKE thnx for the clarification of this oil.

I know the construction of K engine, because I almost completely dismantled it. I read a lot about K100 engine

I ordered about 50 parts to repair only engine...
oil seal, gasket, bolts, springs, shim, orings, etc, etc (almost $500)

TWB I ordered also two plastic guides (top, bottom) The side guide is not consumed at all

You should have a fine-running motorbike once this job is completed. Goodonya! Have you been taking photos of the operation to share with us?

Two Wheels Better wrote:You should have a fine-running motorbike once this job is completed. Goodonya! Have you been taking photos of the operation to share with us?

I am planning to do photos from the assembling. I didn't take many pictures of the disassembling. hands in oil and grease and temperature near 0 degrees in the garage do not enable me to do photostory

Good man LifeGuard,
The photos you take will be very useful to help ensure that when we have to do "the big wrench dance" as they call it, the photos that you and others have taken will guide those of us who will follow your path.
Regards,
K-BIKE

Ulrich_Grabau wrote:Thanks! I'm currently using Castrol Activ 4T 15W-50. I think I'll give the Penrite 20W-60 a go. What you suggest re: oil getting a bit thin makes perfect sense to me! If something was going to fail it would have failed by now.

I tend to use Penrite 15w-50 diesel in winter and syn 20w-60 in summer. It is the matter of how hot the engine gets in slow traffic at 40C I will be going back to 15w-50 soon as the average temperatures are dropping. On a long trip where uphill and hard riding is expected, higher viscosity is required IMHO.
I am using Penrite 20w-60 specifically because Penrite guarantee that viscosity loss in these particular synthetics is minimal. So they say.

Just replaced my original 107,000 km timing chain, tensioner and guide rails.
I could find no signs of where on the tensioner or chain. Some light to medium grooves on the guides and rails.

In regard to oil viscosity it's each to their own of course, but I did a little study in January 2009 in Victoria (2weeks before the bush fires there) when we had 9 days in a row above 40 degrees C. Touring fully loaded 2 up and trecking up over Mt Hotham from Bairnsdale was a big pull, as many here will appreciate.
Remember, the K engine holds 3.75 litres of oil in a finned aluminium sump which is well exposed to the air. I run 15W40 all year round and on that trip the oil temp did not get above 80 degrees when checked with a Raytek heat gun (infra-red thermometer).
Car engines run approximately 85 degrees oil temps constantly. The thing that was copping the load was the rear drive, which topped out around 80 degrees and this has never been that hot previously, in fact my inboard oil seal gave up and beagan to weep, so it was replaced when I got home, no problems since.
Heavier oils tend to be very slow to reach some engine components when cold, pressure will be high but flow will be low, and this is when the damage occurs.

Dennis,
You are a hero that is EXACTLY (yes I am shouting) the sort of quality scientific data we need. Raytek make a high quality product and to have that data is most useful. Interesting the amount of heating on the rear drive, that's quite hot. It would be worth knowing what the gearbox gets up to as well.. I recall Dow Corning used to recommend that on hot running gear drives that up to 5% of the oil be replaced by their MolyKote molybdenum disulphide additive. The quoted some interesting temperature drops in industrial applications when the 5% was put in.
Regards,
K-BIKE

I didn't worry about the gearbox because some heat dissipates through to it from the engine, but the bevel drive is isolated and it just shows how much energy is lost in heat when the drive gets turned through 90 degrees (that's why chains are actually more efficient for power transmission than gear drives).
As for the oil additives, yes there are plenty of friction modifyers which definitely help, but enless the loads are extreme they really aren't required. We have used pure sulphur powder as an additive in large kiln support rollers (plain) bearings to reduce excessive temperatures, also tried the Wynns products and they helped too, but since the last 15 or so years we have used Kluber Syntheso HT 1000 and it is incredible stuff, but dear as poison ! But, as usual, I've strayed off topic a bit again,.....
We'll be touring in Victoria over the easter and I've just ordered some Fluke 62 mini guns, going to take 1 with me and do some more checks.

The data you collect will be top stuff, thanks so much.
Regards,
K-BIKE

and heres me using blutack and a theromocouple back to my multimeter...lols

Returning to this topic - there are so many advices, so I'm a bit confused: I ride all year (no winter pause) my 1989 K 100 LT, regularly serviced, 74.000 km on the clocks. No strange noises - but when should I start feeling unsure about my timing chain???

BMW recommend every 60,000km but I have seen a few with well over that and no problems. My attitude to them is have a look at the tensioners and the chain.
Mind we are better being a bit cautious considering the costs associated with a head full of bent valves.

Agree. At a cost of around AU$100 for parts its worth doing. Its on my short list atm. Will be seeking advice shortly when I find a break in my schedule.

RicK G wrote:BMW recommend every 60,000km but I have seen a few with well over that and no problems. My attitude to them is have a look at the tensioners and the chain.
Mind we are better being a bit cautious considering the costs associated with a head full of bent valves.

Thanks for advice, Rick.
reading the posts at this and other BMW forums, I have a feeling that the tensioners are first to go anyway - several guys describing worn out tensioners with still intact chains

Kaptain Holister wrote:Agree. At a cost of around AU$100 for parts its worth doing. Its on my short list atm. Will be seeking advice shortly when I find a break in my schedule.

Well - I am considering finding a 16-valve K 100 RS engine (in Europe may be found for ca. 400 €, plus costs for the electronics) and replacing mine, in order to get 10 HP more - and Bosch Motronic for which I can actually FIND a diagnostic unit here in Bosnia which can "read" it. With existing Jettronic, it's a fruitless task.

Not chain, not tensioner, but tensioner spring is first issue, usualy

ffbikersa wrote:

RicK G wrote:BMW recommend every 60,000km but I have seen a few with well over that and no problems. My attitude to them is have a look at the tensioners and the chain.
Mind we are better being a bit cautious considering the costs associated with a head full of bent valves.

Thanks for advice, Rick.
reading the posts at this and other BMW forums, I have a feeling that the tensioners are first to go anyway - several guys describing worn out tensioners with still intact chains

I have seen some where the chain is not worn or stretched but the tensioners are worn out and need replacing.

It's not the timing chain, but the plastic face on the tension rail that BMW recommends
being changed every 60K km.
Did change mine at 190.079 km (and the timing chain), it was worn less than
halfway through the plastic face (this may vary with driving style, and oil changes).

I was reading something (might have been a post on another forum) a while back that said that there waas a part in the timing chain tensioning setup that if left out, reduced the whirring noise that eminated from the front end. Anyone know anything about this?

Inge K. wrote:It's not the timing chain, but the plastic face on the tension rail that BMW recommends
being changed every 60K km.
Did change mine at 190.079 km (and the timing chain), it was worn less than
halfway through the plastic face (this may vary with driving style, and oil changes).

Ah so that's what it is Thanks Inge not that I have ever done what BMW say.