72 750 Combat Roadster project

Fast Eddie said:
From time to time there are a lot of threads on here about exhausts, poor quality chrome, not fitting properly, etc.

How did your RGM pipes fit Richard and wadya think to them so far?
Click to expand...
Hi F E - The pipes fit good - some tweaking on the right side - pulling in pipe closer to frame rail with temporary cable ties before tightening up clamps & exhaust roses - to gain more clearance for kick start . I will also need to reduce the diameter of the washer under the acorn nut at the top of the kick starter as this comes close to silencer. Left side silencer needed rubber mounts backed off to align with plate but all drew up ok.
The chrome looks good but only time will tell . I live at the seashore so they will get a good test. The clamps are stainless and they were not as highly polished as some other stainless bits I have gotten from them but a few minutes on the buffer took care of that.
While I have never been disappointed with any of the UK suppliers , this bike has been my first experience with RGM and I am delighted with their products and exceptional service.
 
Lit it up today - fired on the first kick & on the second kick - then nothing for two-three more.
opened up the air slides half way and off it went ! Settled into a nice idle but I shut it down because in the bright sunlight I could not see into the oil tank to check return . The return is piped to the former breather location at the top center as per CnW instruction.
72 750 Combat Roadster project

Sorry Ben - no video as I had my hands full but I'll work on it
Happy Day - RT
 
Last edited:
Congrats, I like your remote fuel feed.
When you say air slide, are you referring to the choke?
 
Can you explain a bit about your comment:
The return is piped to the former breather location at the top center as per CnW instruction.

I tried to look at the CnW site for clarification of where they suggest the return oil line should go.
 
Bob Z. said:
Can you explain a bit about your comment:
The return is piped to the former breather location at the top center as per CnW instruction.

I tried to look at the CnW site for clarification of where they suggest the return oil line should go.
Click to expand...
Hi Bob - I have installed the CnW crankcase breather and the instructions have you pipe the breather to the spigot at the filler neck - the one facing forward . I also had CnW perform their magic on the oil tank . As part of their service they pinch off and weld up the internal and external spigots on the overflow/vent tube which runs down the back of the tank - this by default leaves the central spigot at the top of the tank as the only spot for the return . Before anyone takes this as gospel I should state that I arrived at this on my own - not by direct instruction from CnW. Poor choice of wording on my
part . Probably best for me to contact Matt to be sure I did the right thing - glad you brought this up .
As noted this makes it difficult to see the return flow.
72 750 Combat Roadster project
 
Richard,

The cNw instructions you post clearly state to pipe your breather hose from your engine breather, to the same oil tank spigot as standard, ie the forward facing spigot on the tank neck. If that’s what you’ve done, that bit is good.

I don’t know if Matt has changed his design since he did my tank, but on mine the branch off to the chain oiler was blanked off (this is where it is labelled ‘oiler’ on the oic posted by LAB), but the oil return pipe / spigot was still in place, and is piped up to the oil return line as standard.

They way you have it piped up currently seems wrong to me. Can you get a picture of the rear of the tank for us to see?
 
Thanks F E - The original return tube ( which I incorrectly referred to as overflow/vent ) at the back of the tank has the chain oiler branch spigot pinched off and welded up on the outside of the tank . It is also pinched off and welded closed on the inside of the tank on the rear side of the filler neck. In seeing this I thought that this was done as an improvement by CnW but perhaps not. I have just blown air through it from the bottom and there is flow so is the exit hole for returning oil blind between pipe and tank wall ? This may be where I went wrong . I'm sure there is no harm done as I don't see what difference which hole the oil returns to the tank from but it will certainly be easier to monitor return flow from original location. Is the return tube on your tank pinched off and welded inside the neck ?
Thanks for the help _ RT
72 750 Combat Roadster project

72 750 Combat Roadster project
 
Richard Tool said:
The original return tube ( which I incorrectly referred to as overflow/vent ) at the back of the tank has the chain oiler branch spigot pinched off and welded up on the outside of the tank . It is also pinched off and welded closed on the inside of the tank on the rear side of the filler neck. In seeing this I thought that this was done as an improvement by CnW but perhaps not.
Click to expand...


That's how the standard return should look on the inside of the filler so it hasn't been modified.

The oil tank must be capable of venting to atmosphere or not only would the oil tank become pressurised but so would the crankcase so there must be a return (rear spigot), engine breather inlet (filler spigot) and tank vent.


https://coloradonortonworks.net/cnw-specialized-modifications
"cNw Oil Tank Modification

Details:

    • The oil tank gets completely boiled out to remove any sludge and build up. This also strips all paint off.
    • The lower tank mount gets cut off and a plate is brazed over the area to ensure any hairline cracks are covered up.
    • The rear mount is beefed up for added strength. This rear mount is also shaped to give it a better fit with the thicker than stock mounting rubber
    • The spigot to the chain oiler (if equipped) is closed up
    • The oil tank is finished in a gloss powder coat
    • The finish is removed to bare metal where it is needed to ensure proper sealing when installed.
    • Included are two rubber mounts that are far stronger than the original.
    • Stainless steel hardware to mount is included.
    • A high density foam pad to install between the battery cover and oil tank is included"
 
Hi Richard,

Yes, as LAB has already said above, as standard the oil return to the tank is pinched off with a small hole then drilled in it.

Don’t worry though, you haven’t harmed anything. You would have if you’d not caught it though as the open pipe would have emptied frothing oil all over your rear tyre !

Just swap the pipe work over and you’ll be fine, and yes, checking the oil return is then much easier.
 
Thanks again gents for helping me clear up my misunderstanding.
Had to drop the oil filter to re route the oil lines and now it looks like I will have to remove the tank as well to wiggle the return line on . Had to walk away from it and start fresh tomorrow with a better attitude. Just found out that my older brother - an insulin dependent diabetic- has tested positive for covid 19 . Fortunately it looks like he has turned the corner an is starting to feel better.
 
RT
Very nice build. Home today for the obvious common reason! Scanned 11 Pages. It's kind of like a review of my 1987 combat restoration before internet and forums. I learned a lot on my own with only a few tidbits from local club members. My combat is still my favorite!!! I was sorry in thinking you left the cam and bushes as original. In around 2002 or 04, I saved my engine from a seized oil pump due to a broken intake valve spring jamming it up and breaking the gear and shaft OFF..
I had come off the highway blast approaching 100mph followed by a slow homeward bound cruise for a few miles when I heard a clunk and saw my oil pressure gauge instantly plummet to ZERO. I immediately pulled off the road and shut the engine off.
Oil gauge save the day. No general damage from the broken intake valve spring being eaten by and killing the oil pump.
Retrospecting the incident 5 miles prior... during the 100MPH blast and no oil pressure gauge.
New valve springs, new oil pump, new 850 style cam bushings...still alive to tell the story due to pressure gauge. :)
 
Thanks dynodave for the compliments.
Oil tank plumbing all re routed- if dry tomorrow I will try to run it again and check for return flow.
 
Can i ask a question with regard to the oil line schematics some posts above... with regard to the breather line coming of the top of the tank at the front, it appears to go into a separator of some description with a out let at the top to which looks like it goes into the air filer and one at the bottom which looks like it goes into one of the inlet manifold balance tubes???
I also cant see any think like this on AN or similar parts supplier pages??
 
That drawing shows the oil tank breather line going to a small separator that was on the black box air filters.
Earlier ham can filter boxes had a tube on the back plate that the breather line went to.
Sometimes caused a gooey oil/water/air emulsion that dripped out the bottom of the filter element.
 

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