Allspeed/Gibsons Exhausts - The Classic Expansion Chambers of The Day

Gibson Exhausts advert

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I was looking for some time for a decent set of expansion chambers for my model A. Micron had made the final run of their 'Allspeeds' and shipped them to Germany some two years earlier, when I came across the advert above in Classic Motorcycle Mechanics. Intrigued, I rang Pete and arranged to go and see him to talk about the history of 'Allspeeds' and see if he would make me a set to the spec he used to do in the way back when. I knew that they had been around since the seventies and there were a couple of different styles (early and late) but Pete took the time to tell me the story. When I get sometime I'll put it here. However Pete has asked me to make it clear that Allspeed is a registered trade mark that is registered by a company not in anyway related to Peter Gibson Exhausts. Unfortunately, as with common use of the trademark Hoover that became a word to describe a vacuum cleaner , Allspeed has become a word used by most in the UK to convey a description of the style of 3 into 3 expansion chamber set up and use of the word here is in that context.

After quite a few months waiting in line, (the LC owners club beat me to it!) Pete phoned me to say he was now in a position to jig it and go on GT750s.

This weekend I'm going for a fitting and hopefully to collect them, their construction is exactly the same as originals, mild steel but unfinished. I'm probably going to polish them and get them chromed but I understand that there is an excellent exhaust paint available and not just black, but blue, red and even white, so I'm going to get some and experiment, watch this space!


Original ad from Motorcycle Mechanics 1979 when Pete Founded and produced Original 'Allspeeds':

Hy-performance ad

A very nice GS conversion with original 'Allspeeds' made by Pete:

GS conversion leftGS conversion right

Saturday 1st December

Went down to Pete Gibsons with Stuart (Club mag editor), really wet, windy and slippery so we both chickened out and went in our tin boxes. Picked up the 'pre production' set of spannies (see pics) to fit them tomorrow to my bike.

Three pipes

Micron 'Allspeeds' currently fitted:

Micron Allspeeds

Sunday 2nd December. First fitting. Original style 'Allspeeds':

Allspeeds right

Centre stand tucks up nicely

Allspeeds centre leftAllspeeds centre right

Touch Down. Near as I can tell both sides on mine clear 45% both sides. Bike is not standard, has early forks (J/K) and Koni shocks on the back but I don't think that changes any overall dimensions. (Photos are without baffles, I forgot to pick them up!!)

Allspeeds leaning

Right side-pipe touches down first, beats the footpeg by about an inch. Left side side stand followed by center stand the then pipe then footpeg.

Fitting. First time and if it was not for the center stand that would be it. I know the scratchers over this side of the pond do away with the stand but I want to keep mine if I can. (I'm no scratcher!) With minor dimple knocked in to clear the inner center stand nut the spring would still be tight so its back to Petes soon to see what can be done. The extra small panel welded to the surface in the left picture is to strengthen where the stand contacts the pipe. I'll probably bond a silicon rubber ring in the center stand cross piece to protect whatever surface I decide on, paint or chrome.

Centre nut and spring

Saturday 22nd December

With the offer of a standard 'M' from a willing volunteer, Tim Broome from Thurrock (thanks again Tim), we met up today to do some provisional comparisons between standard exhausts and Gibson Allspeeds. Pete is determined to get these right so wants to do full evaluation and road tests before going into 'production'. Tim machine is well turned out with still lots of TLC waiting to be lavished on it this winter. Objectively it is what I would call average in mechanical and electrical turn out. Still has points ignition, (not for much longer Tim has Newtronic kit to fit this winter) that look a bit jaded, sort of going gray all over. Nothing was done to the bike as far as setting up, it was running fine with no problems as far as Tim was concerned so we went straight in and ran a few baseline runs warming it up as we went. The last two are shown on the graph.

It took a little time to get the Allspeeds on, a little thread cleaning on the clamp bolt holes and a few notes taken on alignment of brackets but no big deal. Unfortunately I missed what I should have checked, but more on this later!! ( See the second graph)

From these first tests it confirmed that 10% increase in BHP that MCM reported back in the 70's is there. Additionally there is a considerable weight saving with all three pipes weighing less than one original outer.

I have to admit one thing, for me its the head turning sound I love most, so have a listen to the runs.

Graph 1

The graph shows 5th gear roll on runs, 001 and 002 were about typical with the standard pipes

with 46.8 bhp (SAE adjusted) the recorded maximum. Runs 005 and 006 were the only two runs we did with the new spannies with 53.9 BHP the recorded maximum.

Now just when it was getting interesting, and going for the third run of the set , the engine note changed and the graph showed all was not well!

Graph 2

To cut a long story short, don't trap the ignition points loom between the center pipe and the frame Malcolm, it welds all the ignition wires together and ruins a fun day. (the only reason I've posted this is because I promised Tim I'd give concrete evidence for his wife to see to explain why he was late home!!!)

The 'A' Team. Pete Gibson and Tim Broome. (I must read the instruction book for this camera! Section under Focus.)

Next stage, fit to my bike and do as many miles as I can. This could be a problem cos its bleedin' cold with snow forecast.

Update July 2002

I never did get around to fitting the prototypes but so far 8 sets have been sold (including one to Hong Kong!) and all feed back is very positive. One set was fitted by Pete to a K model (bracket fitting is different for early models J & K) belonging to Stuart (the Kettle Club editor).

Stuart 1Stuart 2

Before picture

Stuart before

Stuarts comments........

I got my new pipes a couple of months ago, had them chromed near Leeds, and they got their first airing (lovely sound) at The Blue Haze Rally at Baskerville Hall. I must say that I was staggered by the increase in power. The combination of shedding something in the region 15 kg in weight and increased power is quite awesome. For the first time the old girl felt like she had been let off the leash and was at times quite frightening. Not for the handling or stopping reasons, but for the sheer acceleration from 3000 upwards. What fun!!!!

Other modifications????? None.

I’m one of these people who, if she’s running well and nothing feels wrong, then leave well alone.

I think most people on the run out at The Blue Haze experienced the acceleration of my bike (I hope the speed camera was off when I passed) as I was playing catch-up with Pete Smith helping to marshal the field.

Anyone who needs a set of pipes, or even if you don’t, I can highly recommend the increased fun and grin factor these pipes can bring. My original pipes certainly won’t be back on my Kettle for a while.

Stuart (Editor)

Why have I not fitted mine? Well I've been waiting for Pete to make me a set in stainless steel and now they are ready I'll put them on as part of a rebuild with box section swingarm CMG alloy wheels and upgraded disc brakes all round. Watch this space!

Anyone interested in stainless? Give Pete a call, they work out £500.00 per set as opposed to £375.00 for mild steel. I'll post pictures shortly.

August 1st 2002

New bits

Still lining up some final bits for the 'new' look for my pride and joy. Not shown are the A model forks and GS880 front calipers. Refurbishing a set of model B clocks , and that should be a part from all models J through to B. (That should wind up the anoraks!!)

Master

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