The Famous James motorcycle 1897-1966

Keeping the old British Motorcycle manufacturer alive.


The AMC motors

Posted by Kelvin_20T on January 9, 2011 at 7:41 AM

Hello everyone.

I just wanted everyone's thoughts on the AMC units.

Lots of people cast a black light over them, are they really as bad as people say they are?

Or do we say their bad when compared to the villiers units?

I for one think it's good unit, a fella on the Francis Barnett told me that providing you have a good bore and use quality two stroke oil you should be fine.

Anyone elses thoughts?

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Reply derek
7:23 PM on January 9, 2011 
It seems the original engines buit by AMC suffered from build quality and later Villiers built the engines for them and these were better. These engines that villiers built have a v in front of the engine number ie V25T.
I quite like the AMC motors and proving you dont thrash it they should be ok.
The last one I built hadnt run for many years and bought it in bits.
I fitted new crank seals which you can get at any bearing supplier had the piston turned back round fitted new rings, cleaned the clutch plates, fitted new gear change return springs. Engine started second kick.
Done four engines now and they all have been the same , start second kick.
Its worth noteing that although the 20T and 25T look very similar very few parts interchange between the two. I think the 17 and 20 are basicly the same but dont hold me to this.
The charging / ignition system on the amc I think is better than the villiers and a bit easier to follow if electrics are not your thing.
All you realy need to do on the amc is fit a new coil and condencer and a soild state rectifier and you should have a run.
Reply Kelvin_20T
7:40 PM on January 9, 2011 
Hi Derek

Yes I totally agree with what you say, my 20t is a superb starter.

The only thing that will interchange with the 25t and 20t is the clutch plates, the 25t has one more plate than the 20t (I think)

The 17t and 20t are similar up to a certain engine number, then the 17t pistons had a cutout in the skirt, you cannot use these pistons but you can use the ones without the cutout I believe.

Regards, Kelvin
Reply falconer87
3:41 PM on January 19, 2011 
i think the villiers engine were so good at that time,so when amc made there own unit they did not have the skills that villiers had. the engines proved less reliable.with hindsight they should have stuck with villiers.but they had capacity to make there own engine .piatti desighned 3 units that looked good so they when for it with modern oils bearing seals ect they should be well up to the job they are at least 46 year old now so most are just big boys toys.of course like derek says later units were skrewed together by villiers but by now most are skrewed together by previous owner.villiers or amc dont matter just enjoy them for what they are.
Reply Kelvin_20T
3:47 PM on January 19, 2011 
I agree Falconer, I think it was a nice idea of AMC to give it a shot. I've had no problems with mine and as Derek pointed out it starts 2nd/3rd kick everytime no matter what the weather.
Reply ian adcock
11:53 AM on March 28, 2015 
I would be grateful if you can add details of this event to your club's calendar:
Naunton Classic & Vintage Transport Show & Village Fete
Sunday 19th July 12.00 ? 16.00 hrs
Naunton Recreation Ground (SAT NAV Post Code: GL54 3AS)
Awards for Best Pre-1940, pre-1970, pre-2000 cars ; best commercial/utility/agricultural vehicle. Best in class pre- and post-war motorbikes. ?The car I most want to take home? ?Best vehicle of the day?
To register your vehicle contact: [email protected]
£5.00 entry to include cup of tea/coffee, bacon sandwich, programme/raffle ticket
Children?s Games, Tombola, Bar-B-Que, Bar, Cream Teas, Stalls, Raffle
Free entry and parking for visitors
All proceeds towards Naunton Village Hall rebuild fund

Thanking you in anticipation
Reply David scarr
5:30 PM on July 12, 2018 
Does anybody know someone who rebuilds these engines? Please send email or call 07855191466.
Many thanks. Dave
Reply tony Huntrod
3:03 AM on October 25, 2018 
Hi. I have recently bought a 1963 FB with a AMC 25T engine. I have taken off the casing on the right hand side to rewire the bike but i cannot work out how to get it back on as the gear selector springs etc. are bolted to the inside of the cover (if you have rebuilt one you will know what I mean) any tips for getting it back together?

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