Chunk of gasket flew out!

Helpful information and requests for assitance and advice
Locked
User avatar
JemzieAJS
Member
Posts: 6
Joined: Mon May 13, 2019 3:17 pm
Location: Dorset UK

Chunk of gasket flew out!

Post by JemzieAJS »

Hi all, I am very new to the club and vintage motorcycles in general but many thanks for welcome.
I own a 1961 AJS Model 31 650 Twin
Riding along quite happily and a ticking noise starts, gets louder into a blowing noise.
I bend down to have a look at the engine and it appears a chunk of gasket has flown out!? - Picture attatched.
Apologies for the many questions,
Could there be a specific reason this has happened or is it just old Gasket- It appears to be the composite type - (feels a bit plasticy and flexible)
Is there anything in particular I need to know before I attempt to fix it? (never done it before)?
Am I going to have to replace pistons or do something with the barrel?
Do I need to do anything to the carb if i need to remove it?
AJS GASKET.jpg
Thanks in advance for any help!
You do not have the required permissions to view the files attached to this post.
User avatar
clive
Member
Posts: 5657
Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Chunk of gasket flew out!

Post by clive »

Head gasket on the twins are usually composite and do need some care with tightening down. Someone more knowledgeable on the procedure will comment but my process is to crank the gasket down, run the engine then leave it overnight and crank down again then check the tappet clearance, followed by a further crank down at 100 miles with further clearance check. You will probably be wondering about the correct setting for your torque wrench, its medium size spanner!!!!
your gasket is available from the club spares 026039 CYLINDER HEAD GASKET; 1960-63
clive
if it ain't broke don't fix
User avatar
les ward
Member
Posts: 380
Joined: Mon Jan 01, 1990 12:00 am
Location: WILTSHIRE UK

Re: Chunk of gasket flew out!

Post by les ward »

I live quite close to you. If you want a hand let me know. (Private message sent)
MalcW
Member
Posts: 626
Joined: Tue Oct 24, 2017 12:05 pm
Location: DEVON UK

Re: Chunk of gasket flew out!

Post by MalcW »

clive wrote:Head gasket on the twins are usually composite and do need some care with tightening down. Someone more knowledgeable on the procedure will comment but my process is to crank the gasket down, run the engine then leave it overnight and crank down again then check the tappet clearance, followed by a further crank down at 100 miles with further clearance check. You will probably be wondering about the correct setting for your torque wrench, its medium size spanner!!!!
your gasket is available from the club spares 026039 CYLINDER HEAD GASKET; 1960-63
I agree with all of this, plus I would suggest another torque down at 500 miles or so. You'll see two different torque values in the owner's manual, 16ft lbs and 22 ft lbs. The generally accepted value in this knowledgeable forum is 22 (I know because I've asked the same question). Later bikes have larger head studs torqued to 25 ft lbs.

You'll need a thin walled socket to fit in the recesses in the head; I have a feeling the club may sell one. I use a double ended box spanner of unknown antiquity, with one end on the head nut and the socket and torque wrench on the other.

Malc
User avatar
JemzieAJS
Member
Posts: 6
Joined: Mon May 13, 2019 3:17 pm
Location: Dorset UK

Re: Chunk of gasket flew out!

Post by JemzieAJS »

Many thanks for the help and advice. I have managed to find the workshop manual and instruction manual also. New digital torque wrench ordered to help correct tightness. Thought it best buy some decent feeler guages too. :P
Locked