Please clarify re oil in the combustion chamber

Information relating to the Matchless G9 or AJS Model 20 500cc twin
User avatar
dave16mct
Member
Posts: 3234
Joined: Mon Jan 01, 1990 12:00 am
Location: LANCASHIRE UK

Re: Please clarify re oil in the combustion chamber

Post by dave16mct »

Its illustrated on page 16, an in-line view of the sprocket, cam etc bolt,valve housing, spring and diaphram. Description listed on page 19.
dfarchives.jampot.dk/book/Spares_lists/1954_Spares_List_M_G9.p

Dave.
Carson
Posts: 31
Joined: Tue Sep 08, 2015 10:04 pm
Location: British Columbia Canada

Re: Please clarify re oil in the combustion chamber

Post by Carson »

Great info on the parts, and where to find them. There is just no substitute for experience. Breaks me up though having to take apart my non-leaking chain case to see check out that valve, but "let's git her done".

If you guys are ever in the Vancouver area, beer is on me....Carson
Carson
Posts: 31
Joined: Tue Sep 08, 2015 10:04 pm
Location: British Columbia Canada

Re: Please clarify re oil in the combustion chamber

Post by Carson »

My frustration is now at 8.9 on the Richter scale...took off the chain case and there is one large bolt holding the shock absorber spring etc. Took out the bolt and NOTHING behind it, no valve, Nothing and the crankshaft DOES NOT have a hole in the end of it, absolutely solid at the bottom of the threads.
Comments, please!!
User avatar
Duncan
Member
Posts: 2118
Joined: Thu Jul 10, 2003 1:00 am
Location: HAMPSHIRE UK

Re: Please clarify re oil in the combustion chamber

Post by Duncan »

Carson

Sounds like you have an early crankshaft, the timed breather was on the drive side end of the inlet camshaft, what is the date on your crankcases? I believe there should be a boss cast/tapped in for the vent just behind the drive side cylinder and primary chaincase.
User avatar
clive
Member
Posts: 5657
Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Please clarify re oil in the combustion chamber

Post by clive »

At last you seem to be making progress and this could be the explanation of your problem. 54 crankcases with no vent and an earlier crankshaft with no vent either, hence no venting of the crankcase pressure. The solution is less clear. I wonder if there is a way to fit a vent to your crankcases, it's either that or look for the later correct crankshaft. Perhaps better engineers than me can comment. After 61 years of previous ownership this is unlikely to be your only challenge.
clive
if it ain't broke don't fix
Carson
Posts: 31
Joined: Tue Sep 08, 2015 10:04 pm
Location: British Columbia Canada

Re: Please clarify re oil in the combustion chamber

Post by Carson »

The numbers on the front of the crankcase are 54/20/21489?

On the drive side behind the cylinder there is a funny looking circular fitting (about 1 1/8" diameter) with 4 about 1/8 diameter round dimples in it, and just to the left of that is a small screw/bolt with a slot head and above those is a bolt head about 1/4 Whitworth?

Lol...I have restored several vintage cars, and just finished a 1942 Harley but all together not as frustrating as this "beast" but I am in love with it because it is an example of the first motorcycle I ever owner 52 years ago.

Carson
JimFitz
Posts: 663
Joined: Thu Feb 27, 2014 9:27 am
Location: Kent, England

Re: Please clarify re oil in the combustion chamber

Post by JimFitz »

Some very interesting reading about breathers here http://www.a7a10.net/forum/index.php?topic=8292.0 Back in the day the standard mod on Nortons was a piece of 3/4" clear pipe routed vertically from the crankcase vent and then back along the frame to end at the rear numberplate. The beer can oil catch on the end was optional as any oil never made it as far as the top of the vertical section of tube (unless, as I did, you tried to start with a sumpful of oil which had gathered over the winter). Still used today on Manx Nortons.

Jim
Too old to Rock and Roll but too young to die.

1952 G80 rigid, 1960 G12 DL / Watsonian Monza, 1954 G80S.
User avatar
clive
Member
Posts: 5657
Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Please clarify re oil in the combustion chamber

Post by clive »

Carson some photos are going to be more helpful than the description.
clive
if it ain't broke don't fix
User avatar
Duncan
Member
Posts: 2118
Joined: Thu Jul 10, 2003 1:00 am
Location: HAMPSHIRE UK

Re: Please clarify re oil in the combustion chamber

Post by Duncan »

Carson

I have copied the pictures from the 1950 parts list, as you have later cases it is a bit arbitrary:
1950 case.PNG
1950 Breather connector.PNG
1950 Breather.PNG
I would probably try and provide an additional valved breather (bunn? type) if one has not already been installed, there are several inventive locations in the historic forum, from hollowing the mag stud to tapping the rocker boxes.
You do not have the required permissions to view the files attached to this post.
Carson
Posts: 31
Joined: Tue Sep 08, 2015 10:04 pm
Location: British Columbia Canada

Re: Please clarify re oil in the combustion chamber

Post by Carson »

Thanks Duncan, I guess it is pretty clear that I have the part #011648 breather, God only knows why that is on cases marked 1954, some weird things happen to machinery over time. Looks like you would have to dismantle the clutch etc to pull that breather out for a look-see. Not going to happen, at least no now. I will have to assume it is working, and you know what happens when you assume something.
Clive, would love to attach a photo but my computer skills have not improved passed regular typing so in short I don't know how.

Gotta take a break from this #%^&, so am going now to pour a large Scotch.

Thanks, everyone...Carson
Locked