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D3 flywheel one cover plate missing
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rhi010
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July 13, 2021 - 3:50 pm
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Another thing to bear in mind is that these are not sealed, peened over as stated,

Once an engine has stood many years an oil deposits are gone an rust has made a start on the internals then these plates can trap debris, this was the case in my D1, it was quite bad and I was surprised how must debris was in the cavities.

This would have found its way out eventually I thought. 

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Number6
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July 13, 2021 - 5:08 pm
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That is a good point that hadn't occurred to me http://livinginthepast-audioweb.co.uk/imagex/misc/screaming-face.png

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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Ringting
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July 15, 2021 - 12:41 am
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Hi, just take a look at my B175 crank (in my d14) behind the plates in this link. Probably worse because there's a dirty great hole in them to allow the pin to be pushed out but none of them are really sealed around the edge.

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D1, D14/4, Guzzi LeMans, Guzzi V35, Triumph Trident 900, Maserati 160 t4. Mk1 Mini Traveller, Berkeley T60.

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cocorico
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July 15, 2021 - 7:44 am
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Your post number 7 with the pictures is very similar to what I found under the D1 and D3 plates I removed due to detachment from their flywheels. Plus a much more comprehensible explanation of their possible function.

Crank case packing I understand. Thin, ventilated, plates - no...

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larryc
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July 15, 2021 - 7:02 pm
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The pics of what muck is under the plates should make us all think of removing, cleaning and re-fitting (or not as many seem to prefer) when we have an engine in bits.

Larry

D1 plunger 2 x D3 plunger projects and a 1953 Hungarian Csepel 125 plunger

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mike p5xbx
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July 16, 2021 - 5:53 pm
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cocorico said
plates I removed due to detachment from their flywheels. Plus a much more comprehensible explanation of their possible function.
Crank case packing I understand. Thin, ventilated, plates - no...  

I thought I had put this question to bed 2yeas ago
The plates have nothing whatsoever to do with Increasing crankcase compression. !
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Number6
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July 16, 2021 - 7:31 pm
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Thanks for that! thumbs-up

Mike H --

Murphy's 4th law of motion states that any small object that is accidentally dropped will immediately hide itself under a larger object.

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Stoo63
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July 16, 2021 - 10:14 pm
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I thought I had put this question to bed 2yeas ago

  If only , Mike......... rolleyes

 '55 D3 Battery; '58 Square Four (project); '59 D1 direct lighting plunger; '59 Tiger Cub; '60 5TA;  '76 FS1-E; '91 GTR 1000;  '97 Honda Sky SGX50.

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cocorico
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July 17, 2021 - 8:15 am
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mike p5xbx said
The plates have nothing whatsoever to do with Increasing crankcase compression. !
 

I didn't say they did - must have expressed myself badly. I'll try to remember your sleuthing for the next time the question comes up. tip-my-hat

I still don't think they make any 'real world' difference to a D1 / D3, but that's just my choice.

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sunny
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July 17, 2021 - 8:47 am
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its  not  ezy  for  folk  to  understand   the  2 stroke  cycle         ,the  4 stroke    suck , skweez  , bang  and  poo ,     2 stokes   twice a  complycated   witch   macks  it   moor  like [  suck  it and   see   ]  and   confusing    to    ALL  GOOD  FUN   

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Mike E.
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July 31, 2021 - 10:35 pm
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I have a D3 and have followed this topic with interest. Forgive my ignorance, but from looking at the exploded view schematic of my spares manual, I can't see which part you have referred to as the "cover plate" ?

If possible, a photo or part number would be appreciated. ?

1954 Vintage 150cc D3 Major - Direct Lighting - Plunger

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Nick_S
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July 31, 2021 - 11:41 pm
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Mike E. said

Sponge said
Good advice. The consequences of a bad fitting cover plate are dire. I have always used an ex BSA trained mech to fit mine.....there is a special tool I believe ?  

I have a D3 and have followed this topic with interest. Forgive my ignorance, but from looking at the exploded view schematic of my spares manual, I can't see which part you have referred to as the "cover plate" ?

If possible, a photo or part number would be appreciated. ?  

Item 111 in this link.

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Mike E.
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August 1, 2021 - 12:12 pm
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Ahh, part number 90-0748, Thank You. thumbs-up It doesn't show up clearly on the photo copied " BSA SPARES " parts schematic booklet I purchased.

1954 Vintage 150cc D3 Major - Direct Lighting - Plunger

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Stoo63
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August 1, 2021 - 12:36 pm
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There are also hundreds of previous posts on the subject, Mike.

 '55 D3 Battery; '58 Square Four (project); '59 D1 direct lighting plunger; '59 Tiger Cub; '60 5TA;  '76 FS1-E; '91 GTR 1000;  '97 Honda Sky SGX50.

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rhi010
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August 1, 2021 - 8:03 pm
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Just so happens I have an engine in bits on the bench today, history of the engine is unknown but I believe it had been a racer.

Interesting to see how these plates have been secured an sealed, I think this could be replicated quite easily at home.

162784444453943991925.jpg

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cocorico
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August 1, 2021 - 8:39 pm
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Those don't look like original plates. Drilling and tapping the flywheel has been discussed before. (See Spaced Marine's extensive coverage on the subject)

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Stoo63
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August 9, 2021 - 11:47 pm
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These don't appear all that often...

 '55 D3 Battery; '58 Square Four (project); '59 D1 direct lighting plunger; '59 Tiger Cub; '60 5TA;  '76 FS1-E; '91 GTR 1000;  '97 Honda Sky SGX50.

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