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Bullet 500cc piston dimensions
Posted: Sun Apr 26, 2015 10:51 pm
by steverat
Hello Gents,
Can anyone help me with the vital dimensions for a 500cc Bullet piston?
I confess - I need to know in order to decide whether I can use one in my AJS.
The diameter of a Bullet piston at +0.020" oversize is just right for my (already grossly overbored) old Ajay.
However, I need to know:
**Compression height**
**Gudgeon pin diameter**
Many thanks for your generous help
Steve
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 2:24 am
by Tim NZ
Totally difference deck height: about the only other old brit single your could consider swapping a RE piston with would be the B33/34 BSA.
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 7:03 am
by simon
A decent engine rebuilder should have a book that gives you the various piston sizes as a searchable list. My mate discovered that an Isuzu diesel light truck had a piston that suited his 1935 Panther 600.
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 8:22 am
by papasmurf
steverat there are at least three suppliers of AJS pistons in Britain. It is going to cost you an arm and a leg wherever you get one from.
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 2:52 pm
by Nettshubby
Tim, he doesn't want to swap an Enfield piston, he wants to replace an AJS piston!
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 3:03 pm
by Presto
Why doesn’t someone answer the man’s question – instead of answering questions he never asked! The piston pin dia is ¾ inch and the distance from center of piston pin to top of piston crown is 52.5 mm – this is for the 38504A piston.
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 4:13 pm
by Mark M
Thanks Presto, my thought exactly, I was just off to find a piston to measure!
REgards, Mark
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 9:46 pm
by steverat
Thanks so much gents, particularly Presto for the precise dimensions.
The piston height is fine, crown is 4.6mm lower than the Ajay.
However the Ajay pin is 7/8" so I will have to think about that, means making up a new small end bush too.
An alternative would be to just use Enfield rings since I can get a piston albeit without rings.
Hitchcocks sent me some but they are 0.5mm deeper radially than the old Ajay originals - using them in an old Ajay piston would be asking for seizure I think.
Are there any +0.020" rings out there with a radial depth of about 2.5mm?
Best wishes
Steve
Bullet 500cc piston dimensions
Posted: Mon Apr 27, 2015 10:42 pm
by Adrian
Try a piston specialist! Here is just one, there are others.
www.imdpistons.com . A.
Bullet 500cc piston dimensions
Posted: Tue Apr 28, 2015 7:44 am
by Bullet Whisperer
Hi Steve,
I recently bought piston rings for a 350 AJS and a 650 Panther from these people, they will probably have what you need. Cheers, Paul.
http://www.classiccarwebsite.com/cox-turner-engineering