Reversed head Manx

Hi Michael,

   I have not seen this one before, but have seen a couple of them from the 1960s. I think the most notable one was done by Ray Petty, but as you say, there was no real benefit of the air flow going in, but several disadvantages. The risk of grit and fine stones going straight down the bell-mouth is the most obvious, but if you fit a substantial air filter, that would completely negate any pressure boost. Just to make matters worse the hot exhaust area will lack the air-flow and get even hotter, as will the oil with the exhaust pipe running very close to the tank.

   This bike looks like it has been built recently for a talking point. With the fins being extensively cut back, it would need to be on alcohol fuel or drop the compression ratio for petrol. The other issue is the frame, what the hell has happened to the front down tubes and the head-stock ??

that the down-tubes were too close for the inlet tract and carburettor to pass through, so the frame may have been widened at bit.  It looks rough.

I remember some period comments that the straight exhaust pipe had advantages.  It would be interesting to get power comparisons for this and a similar engine with the ports 'right way round', as well as temperature readings.

If pressure on the inlet tract is the goal, a front-fed cold air box would be a simpler / better idea.  It was fashionable in the late '90s.  Did it yield results?

Was it a Joe Craig quote: "I've never found the exhaust gases to be reluctant to leave the engine"?

Joe Craig is quoted saying that.

I am interested in the snakes of rubber pipes on the left side of the engine.  Are they breathers?

Hi Micheal/all,

   The NOC camshaft specialist Barry Stickland has contacted me to identify this bike as the original Ray Petty machine which has been owned by classic racer Adrian Sellars for many years. This jogged my memory as I had seen it about 15 years ago, but didn't have a camera with me that day.

   What the thinking was behind this mod was, I think, "grasping at straws" as any tests could have been done by simply ducting air from an air scoop from the fairing into a pipe direct into a rear facing carb and comparing it with the standard set-up. Also having to ruin the front end integral strength of the frame to accommodate this set-up is difficult to understand. 

Paul, yes the pipes are breathers leading to a tubular catch tank with a mist feed to lubricate each valve guide. 

1. The respected Barry Stickland is correct.

2. The engine was  developed by Ray Petty and extensively tested by Derek Minter mostly at Brands [I have the photos.

3. It was raced with some success by Derek Minter [ I have the programmes ].

4. In it's last incarnation [ as it is now ] higher revs were achieved and some power increase was noted [I have the build sheets with Ray's comments ].

5. The progressive reduction in the finning was to maintain engine heat it was too cool with standard finning.

6. The "rough' frame amendments were carried out by an internationally respected frame builder who is no longer with us to answer the insult.

7. Oil temperature and proximity to the oil tank was not an issue , don't you know Manxes thrive on hot oil which does it's best to escape !

8. There are several photos that plot  it's physical changes as development progressed .

9. The project was abandoned not because it was going nowhere but the arrival of Yamaha 2 strokes lighter and quicker.

10. To suggest that the machine was built recently and "as a talking  point"  is inaccurate in the former but seriously correct in the latter.

" That's all folks" Porky Pig - Looney Tunes.

Adrian Sellars has provided a definitive response to the Ray Petty bike , but as a footnote… I have an old article from one of the magazines showing Lee Wing Sang and his 500Manx with reverse head arrangement. I’ll try and attach the pic to this note .  The text says that he competed with it at the Dunlop Gap Hill Climb in Singapore on 28.11.65 , and won the 500 Class with the bike .  I don’t know if this is the same ex Ray Petty bike or not .  

Twas I who accompanied Adrian at Prescott and making all that noise with 6 runs on his 500 Manx. My late father Gerry Brown ( died 2005) restored this machine although was in reasonable original condition beforehand and I can confirm the frame was very nicely modded by a recently departed master of the subject, I saw it before it was painted and can assure any naysayers it was done to a high standard. The cylinder fins were trimmed because the engine was running too cool, no dope required there! This was believed to be the result of the lack of any exhaust heat being blown back through the finning like the standard engine.To quell any fears of the carb gulping any debris, the bellmouth was fitted with a nicely adapted mesh tea strainer, standing off by a small distance, offering no or indiscernible restriction to air passage so no need for a ‘substantial’ air filter. In fact a standard Manx was not unknown to digest the odd stone from the back tyre- again the Manx wizard came up with a solution: a fibreglass rear mudguard that infills the frame behind the oil tank and extends over the swinging arm cross tube and beyond was conceived by Ray. He was one of the greatest tuners and thank goodness he was still providing a service when the Classic racing scene emerged. He also built a 250 Manx that he raced himself with more than a modicum of success. He was a great support to me also when I campaigned a 500 Manx for quite a few years and any suggestion of any bodgery by Ray is quite insulting to his memory.