The Imp Site

Imp powered motorcycles

Every so often one hears of motor bicycles that were treated to an Imp engine... On a few of those I received addictional information:

Edward Newman:
My father recently told me about a very interesting imp special.
When he was younger, one of the guys who worked with dad used to run an imp engined motorcycle combination. He believes that it was the same one that broke the British flying quarter mile record.
From what he remembers it was very successful and the guy who owned it was sponsored soon after he started racing it. The firm who sponsored him was called Neuros (I think that's the correct spelling). The bike was then called Neuros Impus. The firm supplied him with complete engines. The engine that he was eventually given was a twin cam race tuned imp engine. The twin cam head was apparently made by Neuros. In this setup the bike went down to the Brighton Seafront. On it's fastest run over the standing quarter mile it came within 1/100th of a second of the world record for a one litre motorcycle combination. Which is fairly impressive. However, it was found out that the world record was held by an American bike which had been running on 'dope' whereas Neuros Impus was only running normal petrol.
(21 May 1999)

World record

In October 1966 Victor Phillips took a 998cc Imp powered motorcycle/ sidecar combination to a British National Record of 119.86 mph for the flying quarter mile. The next day they averaged 97.32 mph over a two way run (an average of 36.99 seconds improving the record by almost two seconds)

Ken Horwood

From: "ken horwood"
Date: Thu, 31 Jan 2008


Back mid 70s I built an imp engined solo motorcycle. I used a Norton wideline frame, Norton commando clutch, & Norton gearbox. Plus all sorts of other parts!

To keep the engine weight symmetrical I used a countershaft supplied by a guy in Bristol called Stoke Gifford Engineering.

I rode the bike all over uk & Europe, mainly to bike rallies & sold it in 1979.

I never heard of it again & presumed it was scrapped. Then some years ago I was waiting at the docks to cross the channel & there it was!

I told the guy riding it I Made That! He looked baffled & off we went.

A few years later I was at the docks again & there he was. I checked the DVLA entry for VPU4S Norton today vehicle enquiry

& it is still taxed!

Not bad for a 31 year old homemade bike.

I have pictures if anyone is interested.

I can also write a lot more tech stuff about it if needed,


In Essex

Norton Commando

Malcolm Irving:
Here are two photos I took of a bike, back in about 1988 at The Festival of 1000 bikes, Brands hatch. It would appear to be a Mark three Commando with a Hillman Imp engine shoe-horned in!

Notice the extremely professional looking 'one of' casting to drive the Imp camshaft off the end of the crank. I was able to talk to the owner briefly at the time and he told me that it retained the standard Norton/Lucas alternator and Prestolite starter motor. The rear brake/ gearchange levers had been transversed so they are the 'proper' way round again as on earlier Commandos, although the Mark 3 hydraulic read disc brake has been retained using a special rear brake lever/ master cylinder arrangement.

It would appear to be fitted with twin Stromberg carburettors and some kind of sump extension to help with oil cooling. I did hear it running if a little muted through the single Norton 'bean can' silencer.

The big question is of course, where is this bike now ? Does it still exist?
If anybody knows, email me at

(Copied with permission from Malcolm's page on bike stuff - no longer in existence)

At National Weekend 1991 there was an Imp-engined BSA motorcycle combination. This had been prepared by Tim Berry (member of the Bath & Bristol area centre).

The Limpet

The Limpet is a racing motorcycle sidecar combination with a Hillman Imp engine.
The original Limpet was driven by Dave Lawrence and it proved very succesful with many club championships to its credit.
December's Impressions of 1985 features a Limpet owned and ridden by John Anson. Originally it was built for John Oakley in 1975, who had some success with it. John Ansom used it in 1985 for classic racing. Anson's first outing with his Limpet gained him a 3rd, two 2nds and a 1st place - all in one meeting. His second meeting resulted in a sidecar passenger with a broken wrist and a slightly bend Limpet. It was rebuilt and displayed at the '85 town & country show, Stoneleigh on the Imp Club stand. It attracted a lot of attention.

The Impressions article by Tim Reshaw has an x-ray drawing, a photo and graph (x = rpm, y = power (bhp corr.))
A review of the Stoneleigh show in the October issue features a photo, too.

Compression ratio
Valve sizes
Coil & distributor
Max. power


998cc Hartwell
12.1 : 1
inlet: 1.4; exhaust: 1.125
2x Weber 40 DCOE
R.P.3 (lift: 360;  50 80 80 50)
Castrol R.40
Twin front single, rear 8" discs;
single drum on sidecar
Aeroquip (all around)
Norton 4 or 5 speed box
purpose built G.R.P.
113 bhp @ 8,500 rpm

First Impression

First IMPression; sidecare side   

Reg. no.:

Doug Smith: "Hi, I was surfing on the web and came across The Imp site, and especially, an Imp-engined Norton motorcycle. Mention was made of a sidecar outfit which reminded me of one called 'First Impression', which I saw about 1979 at the B.M.F. show in Peterbourgh.
I still have two colour photos of it, which I will send to you if you are interested."
17 - Nov. - 2000

First IMPression; engine side

Thaxter Imp powered bike - seen from above


Another Imp bike, again pictures and info supplied by Doug Smith.

The Imp-engined chopper was featured in issue 164 of Back Street Hero's, a custom bike magazine.
According to the article it was built by a guy called Simon Thaxter.

Thaxter's bike

a V8 motorbike with 2 Imp engines, actually the two imp engines run side by side: it's got two crankshafts.

The Imp Site
   Imp Specials
      Sunbeam S7 - the engine that Walter Hassan looked at for inspiration to build his fore pump

Links outside of this Imp site:

  • Bert Clewits' site features two photos of Imp motorcycles in his gallery
  • On the site of the Stevenage A.C. of The Imp Club, there's a page on Imp powered bikes, like the Bettson V8
  • Norton "Imp"
© Franka