Hitchcocks Forum

Has anyone any knowledge of gaining a little hp to the 500 twin motor(1963)?Perhaps interceptor cams,head porting etc?I just would like 7-8 hp,get it closer to 40Hp?Budget and stockish is a factor.

Hi, what trim is it in at the moment? Standard or sport! Vince

Going by that picture I would say Meteor Minor Sports pistons will be lumpier than what you have at the moment and would probably help.

If it was a bullet I would say tune it there's plenty of parts available at a reasonable cost
But it's not a bullet and to be honest your looking at about a 25% power increase that's going to cost both in money and reliability
As Paul said super sport pistons are also the way I would go
Would I go any further? probably not
One of the sweetest bikes I've ever ridden was a speed twin I think it was a 1962 it may have been earlier (half bathtub) that bike was set up well but all stock it just worked

Your bike would probably be a nice ride if you build the engine more or less stock
The money saved could be spent on shocks forks and tyres

The other option would be to send it to Paul let him build it

Hope this helps Dai

Thanks for the input,im in the states so Paul might not be an easy option,although worth it.Aint no royal enfiels gurus here,lol!

I wouldn't let comment that get back to the US forum!

A.

Meteor Minor pistons have a very high dome as standard in order to achieve the correct compression ratio (17mm from apex to main body, as opposed to 12mm on a Constellation piston).

As far as I'm aware, there never were any 'sports' pistons for the MM, (in fact fitting the MM pistons to a Connie is a good way of bumping up the CR by 1 atmosphere). Early versions of the MM used head gaskets of a thinner material in order to achieve a CR of 8.5:1, though this was changed to reduce it to 8:1 by using Super Meteor spec gaskets.

The MM Sports used a Constellation inlet camshaft on the exhaust, and this is supposedly the way RE achieved the extra 3hp of the sporty model. However, despite having 2 original Connies and several sets of camshafts, there's not a single Constellation-spec cam among them, as every one I've checked out is to Super Meteor spec - even those supposedly marked with the 'correct' Connie stampings..... so good luck finding one with the correct profile!

The MM I owned was indeed a gentle performer, but none the worse for that. I would urge you to keep it standard and enjoy it as it is; if you tune it, I'm pretty sure you wouldn't enjoy it anywhere near as much.

There is always what was known as "blueprinting", i.e going through the bike with the engineering equivalent of a fine tooth comb and making sure everything was finished and assembled according to how the bike was actually designed. Manufacturing expediency often meant that what was wheeled onto the showroom floor didn't quite live up to what was supposed to come off the drawing board.

I read the story that in the latter days of BSA somebody came to test an A65 twin at BSA/Triumph's R&D facility and found that the thing ran much better than a normal production bike. The comment of the development engineer was that that one was "built to drawing".

Our hosts may even have some MM factory drawings available.

A.

Thank you.Thats some information i can use.I am currently still trying to free the pistons fronm the cylinders.I will heed your advise,my 03 bullet runs great,the spec performance,coupled with a little simple tricks,will probably feel much faster than the bullet,cheers.