1955 AJS Model 20

[Eric the chicken]

Was there a problem with the crankshafts on AJS/Matchless twins? Something about nodular iron hovering in the back of my memory, although probably got it all wrong.

 

[Rannsachair]

Was there a problem with the crankshafts on AJS/Matchless twins? Something about nodular iron hovering in the back of my memory, although probably got it all wrong.

I believe it was mainly the 650's as the power increased and folk gave them a hard time there were some breakages.In think in 1961 they switched from a Cast Iron to a Nodular Iron crankshaft to reduce failures.

I think in general the 500's were not seen to have this as a significant cause of failure.

 

[Seadog]

Noddy cranks were introduced to prevent failures. However, it seems that the alignment of the centre Web, which supported the centre of the crankshaft and also provided the oil supply, was none too accurate. Meaning that the crank was flexed from assembly, thereby causing the crank to oscillate as it rotated.

 

[Rannsachair]

Noddy cranks were introduced to prevent failures. However, it seems that the alignment of the centre Web, which supported the centre of the crankshaft and also provided the oil supply, was none too accurate. Meaning that the crank was flexed from assembly, thereby causing the crank to oscillate as it rotated.

I just read an article in Jampot that there were no significant failures on the 500 and 600 engines bar when reground without suitable corner radii.

In 1961 there was a large batch of crankshafts manufactured in an incorrect material resulting in many failures. AMC then changed the crank material to nodular or spheroidal cast iron.

The same article recounts an AMC dealer saying the 500 twins were smooth and long lasting.

 

[Seadog]

Commandos were another case in point.

 

[Seadog]

I'll just leave you to ponder this.

 

[Rannsachair]

The upgraded pump arrived today, "both pumps are stripped base plate bleed stripped. Pump faces ground flat and recessed for viton o rings. An alloy cap with reservoir is fitted to the feed pump. The o rings are NOT designed to stop oil bleed only to slow it right down. You must never ever aim to seal the pumps as some try because the cam drive and gear spindles require lubricant or that'll wear real fast. The base plate bleed is cleaned of crud and a new ball, spring and grub screw are inserted and pinned in place."
Fitted:

The original design:

Bike back together:

 

[Rannsachair]

Had never finished getting my "Indian tank" fettled, so spent some time on it today:

Mounting holes were 3/8" out:

I redrilled the rear mountings and tapped the original BSCY thread, the fronts were well out say I went down a size and turned two diameter studs to suit:

I decided just to tack weld the on:

A coat of paint and ready to fit. taps are owners club with viton seals to resist the ethanol in the petrol.

I cross drilled the studs to wire them and made up new petrol hoses. (still to swap that head.

Trial fit of the twin exhausts too.

The tank does set the bike off, think despite the work to get it to fit, it was a great buy:

 

[nickk]

Have you ridden two up on your AMC’s ,always thought their dual seats were short.

 

[Rannsachair]

Have you ridden two up on your AMC’s ,always thought their dual seats were short.

No, my wife will only go on my BMW's for some reason!

 

[Rannsachair]

I am sad, painted the engine lettering:

Matches the tank badge blue

 

[Eric the chicken]

Frequently done back in the day.

 

[redlig]

I'll just leave you to ponder this.

View attachment 392681

Looked like a winner but was overshadowed by the G50 for various reasons . shame really.

I am sad, painted the engine lettering:
View attachment 393835
Matches the tank badge blue
View attachment 393836

Back to Siamese pipes I see. I always thought my super rocker sounded better on Siamese rather than twin pipes especially after I fitted a genuine Goldie 'silencer' complete with Twitter.

 

[Robotstar5]

I am sad, painted the engine lettering:
View attachment 393835
Matches the tank badge blue
View attachment 393836

Got to be done, I highlight the lettering on some of my engines

 

[redlig]

Got to be done, I highlight the lettering on some of my engines

View attachment 393871

You will be painting the makers name on the tyres next.

 

[Rannsachair]

Looked like a winner but was overshadowed by the G50 for various reasons . shame really.

Back to Siamese pipes I see. I always thought my super rocker sounded better on Siamese rather than twin pipes especially after I fitted a genuine Goldie 'silencer' complete with Twitter.

I went to fit the twin pipes and realised Armours have sent the wrong downpipes, mounting in wrong place. I emailed them last night as the pipes were a Christmas present and this was the first I tried them.

I prefer the look of the original twin pipes.

 

[redlig]

Apologies for quality of photo .photo of a 60 year old photo.

Taken before Goldie silencer fitted.

 

[Seadog]

 

[redlig]

View attachment 394434

I do wish you hadn't posted that . Is that Hugh Viney if not he is wearing the classic H.V. anti dab coat . So called because it was thought that you could dab without the marshals seeing.

 

[Seadog]

Too late. You can never unsee it