Mystery dowel

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brf1957

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May 15, 2009
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Hi all ,Decided to check and adjust cam chain on the 73 850 today , when i pulled the cover away a hollow dowel tapered at one end fell from the left side i am assuming it came from the oilway between the cases maybe someone can clarify this for me, question is i cant see picture of this dowel in any of my manuals or the parts list, also i cant remember seeing this dowel on my other 850 when i did the chain on it some weeks ago, so is it supposed to be there and could it be that it is missing from the other bike ,any help with this would be most welcome.
 
Can you provide some dimensions? I have the timing cover off my 850 right now and would be glad to have a look. I can't say right off that I know what it is.
 
Hi, its about 10mm long about 5mm at one end tapering to about 2mm hope that makes sense and appears to be made of aluminium
 
Could it be a bodged oil pump spigot, as there isn't any hollow dowel in the timing cover joint that I can think of?
 
From the oil junction block? How would it have gotten inside?
 
rvich said:
From the oil junction block? How would it have gotten inside?
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If that was a reply to me, then I meant the one between the pump and the timing cover?
 
rvich said:
From the oil junction block? How would it have gotten inside?
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I just sorta tossed that out there as thinking out loud. I would have to pull my oil block to see if the dimensions where even close.
 
Hi LAB you mention between the pump and casing would this mean it could have made its way to the oilway between the cases as im convinced thats where it seemed to come from when i parted the cases it seemed to come with the flow of oil coming from crankcase side
 
brf1957 said:
Hi LAB you mention between the pump and casing would this mean it could have made its way to the oilway between the cases as im convinced thats where it seemed to come from when i parted the cases it seemed to come with the flow of oil coming from crankcase side
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It couldn't get past the OPRV. And I'm not sure why anyone would have deliberately put it in the OPRV to crankcase drilling-unless the intention was to increase oil pressure if it is only 2mm at one end?
 
When i find camera i will post photo of the offending part to see if you recognise it
 
photo
Mystery dowel
 
Unfortunately the photo is too blurred to be much help.
 
Hi again ,been trying for the last 2 nights to post a clearer photo of mystery item but not having any luck ,i must have got the first one on by sheer luck ,been studying it and i am convinced it is the end from a pen, what someone had it in the oilway for i dont suppose i will ever know ,anyway bike is running fine been using it the last couple of days .
 
Some foriegn object must of got in there as closest item would be the oil pump nipple but all the ones I've seen are grey steel not a brass like yellar. Check to see if magnetic as photo lighting can fool us. Any sediments to give a clue?
 
brf1957 said:
been studying it and i am convinced it is the end from a pen, what someone had it in the oilway for i dont suppose i will ever know
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Perhaps a PO/mechanic removed the timing cover and jammed a pen in the crankcase drilling to stop the oil draining down from the tank (presumably unaware the drilling is threaded so a that timing cover screw can be used as a temporary oil plug) and managed to leave the end behind when they pulled the pen out?
 
It could be the shroud off a LED penlight! Somebody left it behind, closed up the case, and then later wondered where the hell the tip of their light went. Go ahead, ask me how I thought of that scenario!

Whatever it is, put it someplace you can find it when you discover you need it. I recommend out the back door, past the garden.

Russ
 
I think you have hit the nail on the head there LAB, the more i look at it i am convinced thats what it is , which way is the oil traveling at this drilling and would it have starved any vital parts of oil
 
brf1957 said:
which way is the oil traveling at this drilling
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Excess oil from the OPRV is sent back to the inlet side of the feed pump through the drilling*, so a blocked or partially blocked drilling could result in excessive oil pressure (at least when the engine was cold).


brf1957 said:
and would it have starved any vital parts of oil
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It's unlikely anything would be starved of oil-just the opposite in fact, although excess pressure can blow the crankshaft oil seal, and could perhaps blow the standard plastic rocker oil feed pipe off one of its fittings?


*The 850 Mk3 models (or any Commando that's had a Mk3 timing cover fitted) do not make use of the drilling-even though it is still there in the Mk3 crankcase, as the Mk3 cover vents the oil from the OPRV directly into the timing chest.
 
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