Ticking top end
 

I've just re-built the top ends on my R80 GS Paralever. Everything de-coked, new valve springs, gaskets, o' rings and grommets & stainless push rod tubes. The bike starts and runs fine but there is a persistent ticking noise from both cylinder heads that increases in line with engine speed. The rocker gear is in good condition, everything was lubed on re-assembly and the valve clearances were set at Inlet 0.1mm & Exhaust 0.2mm as per the Haynes manual. I averaged 46.5mpg or 16.4kml on a 300mile trip a couple of days ago at 75-80mph mainly on motorways, so I do not feel that the problem is too serious.

Any ideas etc, all help appreciated.

Thanks

Steve

Steve,

I have had the same problem with my G/S after and extensive re-fit. Apparently, the noise we are both hearing is a result of the rocker arm's not being properly shimmed. In talking with other owners, I was told by some the accepted method is to use a 'c' type clamp to pull the pillow blocks together prior to torqueing the heads down.
*A WORD OF WARNING*
I have not substantiated this with a BMW Mechanic, so I would talk to someone experienced with Airheads before doing this. According to my Haynes repair manual, this proceedure was only necessary with the older /5 series, and the newer bikes have 'self aligning' pillow blocks. It may be that shimming of the clearence is in order, to what clearence I don't know. I have discussed this with people that performed thet c clamp trick on newer bikes, but look into it further before you attempt this, as I will. I wouldn't want to be responsible for any damage due to false advise!

However, as to the cause of your noise, it does sound like this is it. As to damage caused by the gap in clearence, it is unlikely.

Correct rocker arm end play is .05mm +- .02mm. or between .03 - .07mm

If it's more it will make a racket that sounds like valves out of adjustment.

Shims are available from BMW dealers, in .20, .25, .30, .35 and .50 mm thicknesses. (Note: the accuracy of the shims from the factory is suspect, some are a little thicker some a little thinner, e.g. a .20 is actually .22, and some have a burr on the edge which should be sanded off.) The shim is on top of the rocker arm. Don't try to squeeze with a c-clamp, doesn't work on the later models.


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Grant Johnson

Seek, and ye shall find.
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One world, Two wheels.
www.HorizonsUnlimited.com

Slackened off the heads earlier & re-torqued them to 28ftlbs and re-set the valve clearances. Both left hand clearances were about 0.02mm loose and both right hand side clearances were tight by the same amount. Once re-assembled, the ticking was still present but slightly quieter.

Thanks for the advice on the rocker gear shimming, unfortunately I don't have time to do this at the moment but will report on the results when I do.

Thanks

Steve

Hi Grant

Interesting, I though that the clamp method worked OK on later models. There is some clearance in the rocker block stud holes on my '93 and I've certainly squeezed them together swith some degree of success. In fact, our local BMW dealer couldn't remember ever having sold any shims - but he probably can't remember selling an airhead either. Is it maybe a question of the amount of play that can be corrected? Alignment certainly isn't an issue on the later bikes.

Cheers

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Sean

Problem with the squeeze method is getting the clearance right. On my own I found that squeeze only varied it by .01mm at best, (once tightened down) so pretty hopeless. Others may be different. Dealers don't sell shims cause they're too dumb fat and lazy to do it right, imho. http://www.horizonsunlimited.com/ubb/smile.gif

"They all do that sir" is the usual response to a complaint of valve noise.

Properly set up ones don't. Mine is remarkably quiet compared to almost all others I've heard except brand new ones, and mine still sounds new.

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Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

Just ordered a selection of all size shims from Sherlocks. I've two GS Paralevers to do when I return from two weeks in Europe (we leave this Friday).

I've ordered 4 of each shim (£10.00) as I'd rather be able to measure the clearance and remedy the situation immediately rather than have to put the bike back together and then do it again after ordering the required shims.

Looking forwards to a quieter engine, will post results in a couple of weeks or so.

Steve

Steve,
i agree with what has been said,
i did a similar rebuild.....i had to re shim the valves....not a big job...i agreewith grant re dealers....it isn't their bike ..it isn't their problem !!!

So what were your results Steve? http://www.horizonsunlimited.com/ubb/smile.gif

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Grant Johnson

Seek, and ye shall find.
------------------------

One world, Two wheels.
www.HorizonsUnlimited.com

Carried out the work last Sunday. Had the shims for a while but laziness had taken a hold on me.

All four rocker arms had clearances on the tight side. I expected the clearances to be loose, not tight?

Interestingly, all four arms had 2 x 0.3mm shims fitted. I expect that this is the standard BMW fitment upon leaving the factory? On both inlets I only had to remove one of the shims. On the exhausts, I removed both shims & replaced them with a 0.2mm shim in each arm.

The result is a quieter running engine, Worth doing, took about 2 hours in total, taking it easy. Easy to carry out as long as you have Verniers & a Micrometer. The shims are only 60p each from Sherlocks.

This bike is now for sale, see my posting in the relevant section, full spec on contacting me.

Steve