Short Stroke/Long Stroke

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ian saunders
Posts: 39
Joined: Thu Jul 02, 2015 5:09 pm
Location: durham

Short Stroke/Long Stroke

Post by ian saunders »

Hi All,
Just coming “back into the fold” after several years absence and looking to buy a heavyweight single. Have had a couple for many years back in the past and looking to acquire another to get back on the road. My previous bikes have all been long strokes but I am considering buying a short stoke which has come up for sale near me. Is there anything of major difference between the long and short stroke and anything I should be wary of with the short strokes. I’ve heard engine parts may be difficult to source (Which is only to be expected given the relatively short production run).
jmbradford
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Joined: Mon Jan 01, 1990 12:00 am
Location: MIDDLESEX UK

Re: Short Stroke/Long Stroke

Post by jmbradford »

Short answer for short strokes is yes ! Unless competition or 350 models everything is post 63 which means Norton 18inch wheels, brakes and forks.To me it feels like you ride on top of the bike rather than in it , the steering feels different but has good road holding , use TT100 tyres.The gear oil pump means it will wet sump if left for a while , as the piston/bore wears oil will be lost via the oil breather , rig up a catch bottle.Also fit an air filter to extend the life of the piston/barrel. Spares are reasonable although barrels are a little scarce. 500s come up more regularly now but are still not that common , they go better than long strokes and are a little different to the normal 50s amc fare. Pre 63 350s had variations in bore/stroke which can make spares difficult and pre 64 500s had timing roller bearings which are very difficult to source replacements for , stick to post 63 for an easier life.

John B.
Reynard24
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Joined: Mon Dec 16, 2013 2:27 pm
Location: CAMBRIDGESHIRE UK

Re: Short Stroke/Long Stroke

Post by Reynard24 »

I would agree with much of Mr Bradford’s observations in that the “short strokes” do go better than their long stroke siblings.
It should be noted that none of the AMC output in 350 or 500 form is a true short stroke, i.e. where the bore is larger than the stroke, but all thrive on revs and will bog down if ridden in the manner one would ride a long stroke machine.
Top speed, if that is really important on 50+ year old machinery, is not that much higher than the long stroke version but you will get there much more quickly.
1964 on machines do have the feel of sitting on top of the bike rather than being part of it and I found that a little disconcerting. In my view Norton forks and brakes are not a patch on AMC forks and 1963 interim brakes but you will only find these on the 1963 350 ultra-short stroke of 74x81 dimensions, which incidentally are the same as the 7R. Pistons for these are supplied by the club and although barrels are scarce I have had one fitted with a new liner to match the club standard piston by T&L.
1963 350s also have 18” (AMC) wheels but use journal bearings which again are available from the club.
1962/3 350s should have the large knee knocker badges on the tank ( different tanks for ‘62 & 63!) whereas ‘64 on should have the smaller plastic badges - not a huge problem but some don’t like the bigger badges.
I have ridden all the 350 & 500 variants and would happily go for the earlier 350 or the 500 with the later 350 (72x85.5) as the least favoured but any of these bikes will raise a grin very easily.
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clive
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Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: Short Stroke/Long Stroke

Post by clive »

jmbradford wrote: Sun May 22, 2022 11:58 am Short answer for short strokes is yes ! Unless competition or 350 models everything is post 63 which means Norton 18inch wheels, brakes and forks.To me it feels like you ride on top of the bike rather than in it , the steering feels different but has good road holding , use TT100 tyres.The gear oil pump means it will wet sump if left for a while , as the piston/bore wears oil will be lost via the oil breather , rig up a catch bottle.Also fit an air filter to extend the life of the piston/barrel. Spares are reasonable although barrels are a little scarce. 500s come up more regularly now but are still not that common , they go better than long strokes and are a little different to the normal 50s amc fare. Pre 63 350s had variations in bore/stroke which can make spares difficult and pre 64 500s had timing roller bearings which are very difficult to source replacements for , stick to post 63 for an easier life.

John B.
Blimey John B on the website, retirement must be suiting you. 🤣
clive
if it ain't broke don't fix
ian saunders
Posts: 39
Joined: Thu Jul 02, 2015 5:09 pm
Location: durham

Re: Short Stroke/Long Stroke

Post by ian saunders »

Thankyou both for your comments.
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