Britbike forum

Classic British SparesKlempf British PartsBaxter CycleThe Bonneville ShopLowbrow CustomsGirling Classic MotorcycleLucas Classic MotorcycleHepolite PistonsIndustrial tec supplyJob Cycle

Upgrade your membership to Premium Membership or Gold Membership or even Benefactor


New Sponsor post
Triumph 650/750 High-Output Alternator Kit
by The Bonneville Shop - 01/13/23 11:29 pm
New FAQ post
Missing edit button
by wrench136 - 05/30/22 2:57 pm
News & Announcements
Premium members! 🌟
by Morgan aka admin - 01/31/23 2:14 pm
Buy BritBike staff a coffee ☕️ or pint 🍺
by Morgan aka admin - 01/15/23 9:29 am
Benefactor ✅
by Morgan aka admin - 01/08/23 8:38 pm
Gold members! ⭐️ ⭐️ ⭐️
by Morgan aka admin - 01/03/23 6:30 pm
How to guides - Technical articles
British Fasteners Specs
by Morgan aka admin - 01/03/23 1:29 pm
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Member Spotlight
AussieDerek
AussieDerek
Wangi Wangi, NSW, Australia
Posts: 25
Joined: November 2022
Top Posters(30 Days)
Lannis 77
DavidP 74
Top Likes Received (30 Days)
Kev. 36
DavidP 25
Newest Members
BSA A65 rebuild, Dan Haggard, Padsdad, sam keller, Raz
12,386 Registered Users
Forum Statistics
Forums35
Topics76,525
Posts783,968
Members12,386
Most Online204
Jul 10th, 2022
Random Gallery photo
Photo posting tutorial

Previous Thread
Next Thread
Print Thread
#844496 03/29/21 5:49 pm
Joined: Apr 2020
Posts: 5
Britbike forum member
OP Offline
Britbike forum member
Joined: Apr 2020
Posts: 5
Hi. Does anyone know of pistons for the above model ? The UK club claims there was no such model, but there definitely was (A friend has one). The club sent him later model 650 pistons, which are entirely different, and could not possibly be modified to fit. They were a US only model, along with the 20 B 550 (I have one of these)
Cheers, Dale.

AJS & Matchless on eBay
Joined: May 2002
Posts: 136
Likes: 1
Britbike forum member
Offline
Britbike forum member
Joined: May 2002
Posts: 136
Likes: 1
Hi Dale, I must admit to not hearing of a ‘58 AJS M31, however more than once have heard of the ‘58 Matchless G12, so no reason why the AJS didn’t exist.
I am fairly certain the pistons are the same as the 1959 model which is a domed top piston, this changed in 1960 with the redesigned head. I have seen these earlier pistons come up NOS at times on eBay, though I believe JP Engineering in Australia manufactures both types and they know the difference.
I believe this is their website https://www.norndaautomotive.com.au/jp-pistons/product-information.html .
Goodluck
Adrian

Joined: Jun 2005
Posts: 99
Britbike forum member
Offline
Britbike forum member
Joined: Jun 2005
Posts: 99
Hi Dale,years ago I also got the same claim from the UK club that this model doesn't exist. I was very lucky a few years ago and acquired one of these "no such model" bikes. It is unrestored and had very low mileage when I got it.I've ridden it about 30,000 miles and it is just great.
The pistons are special as I believe that to make the model 30 a 650(or 31) they stroked it ,so the piston skirts are very short ,and these pistons are hard to get . The Hepolite part number for this series is 15242,with a bore size of 2.8346 or 72mm.
I found a set on Ebay that no one was bidding on as they didn't know what they were for .The 59 pistons are not the same ..
If you want you can email me at [email protected] for more info.I'd post a picture of the bike but I don't know how to do it on this site.
As Matchman says JP might be able to help you out ,maybe by sending them a sample ..

Joined: Apr 2020
Posts: 5
Britbike forum member
OP Offline
Britbike forum member
Joined: Apr 2020
Posts: 5
Thanks for the replies. I'll pass the suggestions on to my friend.
Cheers, Dale.


Moderated by  Matchman62 

Link Copied to Clipboard
British Cycle SupplyMorries PlaceKlempf British PartsBSA Unit SinglesPodtronicVintage MagazineBritBike SponsorBritish Tools & FastenersBritBike Sponsor






© 1996-2023 britbike.com
Powered by UBB.threads™ PHP Forum Software 7.7.5