Engine slap

[tanneman]

This might be a stupid question but here goes.

I started the bike the other day and heard a knock which I didn't hear before. It is not the valves because that got adjusted just right. It is not the oil because that is fresh oil all over, in fact the garage looks like Opies store room. It is not the big end or small end or main bearings because the knock doesn't increase with the increase in rpm, in fact it stops. But what is apparent is the slap on the over run when you close the throttle and this then settles as the knock I can hear.

Now, I looked at the parts fiche. There are 3 chain tensioners. One for each side cam chain and another for the timing chain. The oil pump is gear driven and we all know the alternator is belt driven.

Is the camchain tensioner pressured by oil or spring and how do you adjust it? Is the timing chain tensioner pressured by spring or oil and can it be adjusted and if so, how?

When the rocker covers were off I had a look down the side to spot any abnormal wear on the camchain guides but to be honest from what I read is that the guides break on the long side which you cannot really see from the side.

Another question. Can the oil pump delivery pressure be adjusted or shimmed like on the R1200S/HP2S?

This engine lives on the track and I won't take it out until I satisfied my concerns have been addressed. That said it hasn't turn a wheel this year yet. First outing is Cadwell in June with the BMW club. Yada, yada yes I know. I should ride it more. The suspension is off to MCT.

[nab 301]

Is the camchain tensioner pressured by oil or spring and how do you adjust it? Is the timing chain tensioner pressured by spring or oil and can it be adjusted and if so, how?

.

The tensioner is Hydraulic with a light spring , not adjustable. Upgrades are available which will stop the rattle at start up ( until oil pressure builds ) .
http://www.maxbmwmotorcycles.com/fiche/ ... &md=199810
I can't really offer any useful advice on your bike but mine has had ( to me) a specific rattle ( R/h side) since '08 with 65k miles but is still running well with approx. 113k miles . Like you I've looked at the cam chain guides but haven't removed the head. Research suggested the old style 3 piece push rods apparently can rattle when warm ( the hardened ends come loose )I did replace mine but no difference, and the cam carriers can wear , mine looked ok and I bought a new used one but never got around to fitting it...although I did replace a follower and camshaft.
You could try checking the rocker shaft end float too?
My original thread here.
http://www.boxertrix.com/phpBB2/viewtopic.php?t=6480
Continued here
http://www.boxertrix.com/phpBB2/viewtop ... ight=noise

[tanneman]

Cheers Nigel. I'll have a read. Bike is a twinspark with 22k on it. Due to the unusual use it gets I'm a bit more attentive towards it. I know on high mileage engines the camchain guides wear and break but you won't see it from the side. In the future I can just as well swap out the sprockets for lennies if I do feel the need to check more closely.

[boxerscott]

Does the engine run smoothly on idle? albeit noisy?

can see the train of thought that the chains may be wrongly tensioned at low revs but a faulty oil pump/circulatory can create noise issues. Is it temperature related? ie cold starting, gets warmed up and noise goes? does it run smooth under load on the road? Look for oil warning light, kill if it illuminates, (goes without saying) but that is a practical test that you can do and I would do that with the missus following behind me in van.

PITA. for sure.

[tanneman]

Ok, took the front of the engine off. Chain drive, camchain guides and tensioner checked ok. Same on each cylinder after careful scrutineering with flash light. Tension being held by the spring and chain in good condition, can't see any stretch if there is. End float of rocker shaft within tolerance (min 0.05, max 0.40 according to online manual).

So none the wiser but now happy that the critical bits have been checked. Will need new gaskets for the return oil line and new sparkplugs and an air filter cause only the oil has been changed last year before winter. What sealant goes on the front cover? Manual says 3-Bond 1209? but will ask the dealer. Seems Loctite 5900 is an alternative.

[tanneman]

A friend of mine who has a garage gave me the 3-Bond stuff that Ducati uses. So hopefully it will be a little bit quicker.

Regarding the engine knocking noise and slap noise on the overrun I have some good news. I spoke to Steve Nash from Wollaston BMW. I have known him for a long time and he is a top bloke when it comes to engines having worked on these machines for a large part of his career. He tells me that the knocking can be from a ball thermostat valve to the oil cooler and these can rattle a bit when cold and the oil is pumped through on idle. Regarding the slap noise and my description of what I have done and checked he reckons that the best way to set the end float on the rocker arms is to slack off the bolt a little, tap it till there is no clearance and just back off a little so there is a very small gap, enough for the oil to flow through. But he added that if you have had the bike stood for a long time like mine did then it is best to take it for a ride to warm up every bit.

Some bloke once told me the best way to care for these machines is to ride it often. Very true.

Next up is the forks. I have noticed that the one leg can be compressed a bit more that the other one so I'll take them apart and make sure everything is hunky dory before fitting them to the bike. Just for reference I'll post the links to past threads about forks and oil. SAE 10 is the recommended viscosity but we know it is there for lubrication duties..

http://www.largiader.com/articles/sforks/

http://www.boxertrix.com/phpBB2/viewtop ... ight=forks