Author Topic: Noisy B29 engine  (Read 4672 times)

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Offline hoejmark

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Noisy B29 engine
« on: 11 Dec 2015 at 08:19 »
Hi All.
My B29 engine produces a noise that I best can describe as a clatter or a rattle that is too hard to ignore. More guys have helped listening, but it is difficult hear what it is or from where it comes.
The noise cannot be heard when the engine is cold but first begins when the engine is warmed well up. The tappet clearances are adjusted to 0,006”. When idling at very low revs, the noise disappears, then leaning the bike towards the chain side, the noise starts and leaning it back again and towards the timing side, it stops again. A little bit more revs and the noise starts again.
For a longer period the timing gear had suffered from bad lubrication due to a drilled drain hole in the bottom of the timing gear housing. There were heavy wear on the bronze worm wheel for the oil pump drive and on the oil feed nozzle as well as the spur gears were well worn.
What I did on the first hand was to  block the drain hole in the bottom, so that the oil level should now be ok, and cleaned up the entire oiling system. The crankshaft was rebuild with new gudgeon pins. Then I made new worm wheel and nozzle. When turning the engine by hand on the workbench, there was a distinct click from backlash in the timing gears, that I thought was the reason to the noise. I then got new timing spur gears (except for the magneto) from HPC Gears, adapted them and had the local tool maker to Wire EDM the cam profile holes and pressed the cams into.
This summer I attended the “Skagenløbet”, which is nearly 1000 miles around in Denmark, constantly accompanied by that noise, and surely everybody could hear. Otherwise the engine runs smooth and lovely, and I finished without problems, but the noise was still there.
Some days ago I had another look at it and made new distance collars behind the cams to ensure equal play between tappets and spur gears and removed the breather disc and the curved spring washer and  then it happened, that the noise had disappeared!
I then fitted back the breather disc and the curved spring washer and after a new test run, the noise was back again.

Can it really be so, that the rattle and clatter noise is related to the breather disc system??

The distance behind the back of the centre spur gear and the breather disc, where the curved spring washer operate, is 2,3 mm (3/32”). The spring washer seem a bit weak to me, and when in place, the breather disc can fair easy be lifted from the housing with a hook. The breather disc starts to open well before TDC and is closed again at BDC.

Does any of you have similar experience with this problem - any ideas and suggestions should be welcome.

Regards
Soeren

Offline hoejmark

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Re: Noisy B29 engine
« Reply #1 on: 12 Dec 2015 at 16:21 »
Hi again
Perhaps I should also mention, that the noise depends on the revs, but is not affected when the bike is loaded (uphill) or relieved (downhill).

Does anybody know wich type of spring is suitable together with the breather disc, and how much (or little) space is needed for the spring.
Soeren

Offline Doug

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Re: Noisy B29 engine
« Reply #2 on: 25 Dec 2015 at 04:07 »
Hello Soeren,

It sounds like quite an unusual problem that you have. Rattling in the EW-B29-A31-Aero 350 type engines is not a problem that I have ever heard reported.

The fact that tipping the engine to the flywheel side can induce the noise is interesting. It suggests the crankshaft is moving side to side, which of course is ominous. One way to check would be to tip the bike over to the timing side and operate the clutch. The clutch release mechanism will push the crankshaft to the flywheel side. If this too can induce or influence the noise, then that is a pretty good indicator that the crankshaft can move too much and has some contributing factor to the noise. As to figuring out where the noise is originating from, a stethoscope is handy. A long screwdriver with one end applied to various parts of the engine and the the handle applied to the cranium adjacent to the ear makes a good substitute. This could tell you if the noise is originating from the timing side or the drive side.

One problem that I have noticed with these engines is scant clearance for the primary chain. I wonder if chain thrash is causing it under certain situations to just barely touch the primary chain cover? A light push or pull on various areas of the cover should demonstrate audibly if this is the case.

The crankshafts in these engines are not particularly robust, and gudgeon pins and big end bearings are always suspect. However these tend to make more of a knocking noise, and tend to make more noise under load versus on the over-run. So I do not think these are the problem in your case. I have seen EW engines with a lot of radial play in the main bearings (probably due to the ball bearing(s) becoming loose in the crankcase), which while not a good situation, do not see to make a lot of noise!

The rotary breather shuttling on and off the face of the valve could make a clicking noise, but I find it hard to believe you would be able to hear it while the engine is running.  I just cannot imagine it being that loud. I have the rotary valve components from a 250 Aero engine, which uses the same design.







The dimensions for comparison are as follows. 
Rotary valve disk: 0.055 inch thick
Wave washer (spring): 0.140 inch free height, 0.010 inch compressed height.
Unfortunately I cannot provide an assembled dimension, since the crank is not in the crankcase.

It is a very light spring, but as it is a timed valve, it is generally open when the valve would otherwise see pressure. So it only needs a light spring to maintain the seal against the crankcase face.

Hope this helps,
Doug


[update image links 02May19 Doug]
« Last Edit: 02 May 2019 at 14:24 by Doug »

Offline eddie

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Re: Noisy B29 engine
« Reply #3 on: 25 Dec 2015 at 07:01 »
Doug,
         I agree with your theory that it is crankshaft endfloat. Many years ago, I bought a BSA Road Rocket with a rebuilt engine for next to no money - the owner had got frustrated with it because it still had a knock. That turned out to be excess crankshaft endfloat - an 8 thou shim cured it!!
  Regards,
                Eddie.
P.S.    Hope everyone has a good Christmas - but don't make it so good you cant remember it tomorrow!!

Offline hoejmark

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Re: Noisy B29 engine
« Reply #4 on: 26 Dec 2015 at 15:53 »
Hello to Doug and Eddie
Thanks for your respondings to my question. You have interesting points af wievs, but please allow me another day or two for replying, as the house is still crowded and busy due to Christmas celebrations.
Regards
Soeren

Offline hoejmark

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Re: Noisy B29 engine
« Reply #5 on: 28 Dec 2015 at 17:21 »
Ordinary days again! And today I had a longer ride to thoroughly warm up the engine. With the disc valve an the spring still taken out of the engine, the noise didn’t appear, not even when activating the coupling when tipping the bike to one side or the other.
The noise is surely not coming from the chains. I have not yet tried the stethoscope, but I have tried the trick with the screwdriver, and was not able to localise the noise. I have also tried to listen through a flexible hose hold in various positions outside the engine, and even here I couldn’t localise, but the noise tended to become louder when the hose was nearer to the breather tube opening on the left side of the engine. If weather keeps reasonable tomorrow, I shall have another ride with the disc valve and spring back in the engine, and then try the tip the bike to the sides while also activating the clutch, to see if this make any changes. If not, I will try to make a distance collar behind the small timing pinion, leaving a minor distance of 0,001 inch allowance for the spring to operate. If this doesn’t help either, the next step, I believe, will be check the crank shaft end play.
Soeren

Offline hoejmark

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Re: Noisy B29 engine
« Reply #6 on: 30 Dec 2015 at 14:06 »
Had another ride yesterday with the breather disc valve, spring and a distance collar in place - unfortunately the noise was also back in place.
Next step will then be to chck out the crank shaft endfloat.
Thanks to Doug and Eddie for bringing ideas.
Soeren

Offline Doug

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Re: Noisy B29 engine
« Reply #7 on: 30 Dec 2015 at 14:19 »
Soeren,

That is really bizarre that the breather disk could make that much noise. But your comparison with and without proves it is contributing.

The endfloat of the crank is determined by the fit of the crankshaft in the crankcase. The presence of the breather disk should not have an impact. However if the crank does have too much endfloat, perhaps the breather valve is then coming into play and is the next thing that is 'making contact'. That would be a lot of endfloat and also the crank would be sliding about too freely in the bearings.

To quickly test, you should be able to just grab the flywheel and push and tug back and forth. If you can feel an appreciable shuffle, something is wrong. the endfloat should be so slight that you ought not to notice it by that method.

-Doug



[fix typo.  -Doug, 30Dec15]
« Last Edit: 30 Dec 2015 at 15:06 by Doug »

Offline Edin

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Re: Noisy B29 engine
« Reply #8 on: 30 Dec 2015 at 14:55 »
Hej Søren
Nice to see many advises and comments from other members.
My advise to you are:
Bring your self and your B29 to my shop,- when holidays - the flu - weather and so purchaser - for a long week end , and together solve your problems using advises an comments from the members to you.
Regards and happy new years from Edin DK

Offline hoejmark

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Re: Noisy B29 engine
« Reply #9 on: 30 Dec 2015 at 15:06 »
Hello Edin.
Yes, seeing you soon then.
Soeren

 

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