Cylinder Lubrication

Tug Wilson

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Non-VOC Member
Thankyou for this, what a brilliant response demonstrating the value of the internet and the wealth of knowledge within our club. Thanks again.

See you at Liphook?
 

Matty

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VOC Member
Thanks David - for your excellent description of the lubrication systems for Comets/1000cc models, it says exactly in essance what I was going to reply to Tug Wilson's comment ie leave the 170 jet to provide lubrication to the cam spindles, but blank off the other feed which is a now unnecessary supply to the cylinder wall. However if it all works OK leave it as it is - and if you have a re-sleeve don't drill the angled feed hole in the cylinders and this will automatically block the feed from the timing cover.

Matty
 

bmetcalf

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VOC Member
My liners are undrilled and I soldered up the holes in the discs because I didn't want oil to escape from any gap there might be between the liner OD and the crankcase mouth.
 

Matty

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VOC Member
Yes I agree Bruce, blanking the cylinder feed at the timing cover is best, because this removes any risk of oil leaking from the crankcase mouth and therefore losing a little from the crank bearings and cam spindles.

Matty
 

Chris.R

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VOC Member
There are three feed screws in the Timing cover of the Comet. I have been able to remove OP39 the top centre one that is in front of a casing screw it has a 170 jet. I have removed OP38 oil relief valve plug a large brass nut and the spring behind it but OP37 the relief valve has not fallen out, I assume it is stuck in the oilway so how to remove it? At the top left there is a slotted screw so tight that I cannot undo it do I need to take it out can heat be used safely and what is the part number as none seems to be listed? I notice in the Instruction Sheets page 68 Examining Components it say`s the piston gaugeon pin should be an "easy push fit when cold" it is not, it is a tight fit and had to be drifted to remove the piston. Should the pin and small end be replaced? is removal and replacement of the small end something that can be done in-situ at home?

I welcome any comment that will help me.

Chris
 

Robert Watson

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VOC Member
First the easy one. The slotted screw is a plug in the end of an oilway drilling, there should be nothing in behind it.

The relief valve little plunger can be a bit of a bugger to get out. There was just a thread quite recently on doing this exact little task but of course I can't find it right now. I recall doing one a year or two ago by getting a drill that was a tight fit in the spring hole in the back of the plunger and gently hand turning it in until it "bit" and then pulling the plunger out.........

The gudgeon pin should be a floater in both piston and small end. What piston is it and when was it last apart? Then start measuring!

I have seen small end bushes replaced in situ but getting it right can be tricky and sizing it after is almost not an option.

I am sure you get lots of advice on all of this from people much closer to you that I am!
 

Chris.R

Well Known and Active Forum User
VOC Member
First the easy one. The slotted screw is a plug in the end of an oilway drilling, there should be nothing in behind it.

The relief valve little plunger can be a bit of a bugger to get out. There was just a thread quite recently on doing this exact little task but of course I can't find it right now. I recall doing one a year or two ago by getting a drill that was a tight fit in the spring hole in the back of the plunger and gently hand turning it in until it "bit" and then pulling the plunger out.........

The gudgeon pin should be a floater in both piston and small end. What piston is it and when was it last apart? Then start measuring!

I have seen small end bushes replaced in situ but getting it right can be tricky and sizing it after is almost not an option.

I am sure you get lots of advice on all of this from people much closer to you that I am!
1. OK Robert the screw can be left and does not need removing so that's ok.
2. I will try the plunger in the way you describe it is obvious the plunger must be stuck.
3. The bike has been rescued after standing in a museum for thirty years, much work has been done already with a view to getting on the road again. The piston is marked E7/7 STD ID83 inside the piston it is marked AE so don`t know the make, I am having help from a couple of brothers in the local Surrey section. No doubt will have to think on the gaugeon pin how to deal with that The Instruction sheets do mention using a 7/8" reamer I do not have one of those in my tool box.
Thanks for your comment from a distant shore.
Chris
 

Matty

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VOC Member
The gudgeon pin should be quite a tight fit in the piston when cold but will be sliding push fit if the piston is hot.
I have blanked off the oil feed to the rear of the cylinder with a plastic disc years ago and all has been OK after many runs on motorways etc
 

davidd

Well Known and Active Forum User
VOC Member
You can put a lot of heat to OP39. I have always relied on a TIG welder to loosen bolts or take out broken bolts. I did a freshly painted cover recently and was able to extract the screw.
DSCN3271.jpg

I think Matty knows what he is doing, but when racing I found that I had to have a slightly larger small end bush or the pin would blue considerably. Carleton Palmer had Carillo increase the size of the clearance and the bluing stopped. It was a half a thou increase, as I remember.

Pat Manning has a jig to hold the reamer to do a proper job on the bushing in place, which can be a complicated job.
DSCN0245.JPG


David
 
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