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Grub screws in twins

jim burgess

Well Known and Active Forum Website User
Non-VOC Member
So I have put back together my Shadow engine. Remaining on the bench is a grub screw. I took out two screws from the back of the timing cover to clean the galleries. I put 'em back. So where else could I have removed a grub screw from? This is not a trick question. The screw is slimmer than those in the timing chest. About 8mm long. It could have come from some electrical application, but age and decrepitude have the better of me and I cannot fathom from whence it came. Any suggestions?

Cheers
Jim Burgess.
 

youngjohn

Well Known and Active Forum Website User
Non-VOC Member
Is it the one on the underneath of the engine below the timing chest which blanks off a gallery near the oil pump?
 

Big Sid

Guest
There are two grub screws , no. 221 , 5/16 in. BSW , 3/8 in. Long listed in the hard ware . The very early B timing cover may have taken the other to plug a drilling at one end of the big veins . Sid .


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davidd

Well Known and Active Forum Website User
VOC Member
I am with YoungJohn. I started someone else's rebuilt Rapide without the grub scew in the oil pump galley and the oil began to flow on the ground. Much better with it in.

David
 

Big Sid

Guest
An important point I'm sure most know . The grub screw found in the case bottom beneath the oil pump above serves not only to plug off the drilling preventing oil loss , but more importantly it prevents entry of air trying to enter there . This is seeking to fill the vacuum or depression created by the pump that serves to lift the sump oil into the pumping system . A weakened depression , poor lift , the sump overloads causing more oil to enter the bores , smoking and fouled plugs .
The grub screw threads must be well sealed but don't gob up the passage for obvious reasons . Sid .


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ogrilp400

Well Known and Active Forum Website User
VOC Member
If air can get in, then oil can get out. The give away being a large pool of oil growing under the bike whilst it is parked in the shed.
An important point I'm sure most know . The grub screw found in the case bottom beneath the oil pump above serves not only to plug off the drilling preventing oil loss , but more importantly it prevents entry of air trying to enter there . This is seeking to fill the vacuum or depression created by the pump that serves to lift the sump oil into the pumping system . A weakened depression , poor lift , the sump overloads causing more oil to enter the bores , smoking and fouled plugs .
The grub screw threads must be well sealed but don't gob up the passage for obvious reasons . Sid .


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chankly bore

Well Known and Active Forum Website User
Non-VOC Member
I could well be wrong, but on a Twin, Series "C" at least. 2x item 221 blank the rear ends of the camshaft oil feed galleries. I believe item 30 is a 3/8" bsw x3/8" grub screw keeping the garage floor free from gravitating oil as previously mentioned. Anything slimmer should not be in the plot unless it is some dastardly malfeasance.Is the offending item the brass grubscrew from the brakelight switch?
 

jim burgess

Well Known and Active Forum Website User
Non-VOC Member
Gentlemen, I thank you all, Before I put the motor together I had a damed good look around to find the hole i had taken it out of and could find nuthin. I did remove the timing cover screws, I couldn't extract the oil pump blanking screw, just too damn tight. It's just that, I now have the thing together, and am building up the frame, this little screw is still left over, so I am hoping and prayin' that I have everything correct, from what you say I feel much more reassured.
Cheers
Jim Burgess
 
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