400 pistons

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Re: 400 pistons

Postby 72degrees » 13 Feb 2018 13:00

Omega could make a batch of 12 if you could get hold of those drawings. 3D machined, and I suspect phenomenally expensive though.

"Three Dimensional Machining.

The best way for a very small batch (currently 12) of pistons to be made that have to have no compromise or, for prototyping to finalise a design before a forging tool is manufactured is 3D machining. The piston is designed using our state of the art 3D modelling software and each piston is individually machined from a solid billet. This takes approximately ninety minutes depending on the complexity of the final internal shape. After this process it is then passed on to the workshop for wet blast cleaning, and all of the external machining. Though expensive it is sometimes the only way a customer can get exactly what they want for a small production batch. To the untrained eye it is very difficult to tell a 3D machined billet piston from a forged piston."

https://www.omegapistons.com/technology.php
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Re: 400 pistons

Postby pedro » 13 Feb 2018 13:05

Further message from the Italian guy

"he had them produce 6 pieces forged, but the price was 220 euros plus VAT each!

if you want you can contact them, as I told you they already have the drawing"

That doesn't sound terrible for unobtainium!
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Re: 400 pistons

Postby 72degrees » 13 Feb 2018 15:33

pedro wrote:Further message from the Italian guy

"he had them produce 6 pieces forged, but the price was 220 euros plus VAT each!

if you want you can contact them, as I told you they already have the drawing"

That doesn't sound terrible for unobtainium!


If I remember correctly (OK I cheated and searched the forum), when harrymuffin got Omega to make a batch of 500 pistons the cost was £130 each, which with inflation from 2011 prices would possibly be nearer to £160 now?
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Re: 400 pistons

Postby norbert » 13 Feb 2018 15:37

I´m sorry but have no idea about the 400 pistons. I only remember a friend of mine looking for one piston for years (don´t know wether he found one). The original ones must be very very hard to find. I don´t think that the VW Lupo pistons enter plug and play in a 400 Dart motor. If they have nikasil barrels, the pistons have to fit exactly to their size. I think the Lupo pistons serve for boring a normal iron cilinder, but maybe you have to manipulate the pockets for the valves (I´m not sure about that, never did it).

I allways wondered why the valves of the 400 heads were smaller than in the 350 Darts (and probably the last 350 enduro motors). The explicacion from Tom (japanese market) may be the reason.
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Re: 400 pistons

Postby mgelder » 13 Feb 2018 18:14

I'm pretty sure the Japanese market restriction for 400cc bikes was 60bhp-ish; all those NC30 / ZXR400 / FZR400 / GSX-R400 bikes made about the same power because of this.

There used to be (not sure if there still is) a German market licence band at 27ps which sounds more likely for a slightly restricted Dart.
Morini stuff on RealClassic.co.uk: http://www.realclassic.co.uk/profiles.html#morini
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Re: 400 pistons

Postby morinipete » 13 Feb 2018 19:08

Hi Pedro.

Do your pistons look like this? I have a set of barrels with piston like these and I'm pretty sure they're Guzzi. I have never run them and my main concern is that the Gudgeon pin is central, when in a morini, obviously, it is not. As such I guess the bad thing is they'll add some vibration. The good thing is they're available and were designed to run in nikasil, not iron, liners.

Oddly, though Guzzi ran heron heads in all but the 4-valve small block-Vs, they kept with very simple combustion chambers like this. They obviously thought the fancy design wasn't worth any measurable power advantage?

Have a look at Gutsibits. They sell them second hand https://gutsibits.co.uk/pr/TheShop/inde ... 4&q=piston

Cheers

Pete
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Guzzi 66mm.jpg
Guzzi 66mm.jpg (62.9 KiB) Viewed 344 times
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Re: 400 pistons

Postby pedro » 13 Feb 2018 19:28

Similar, but not quite, I'm hoping that Mark will let us see some photo's of his (I don't actually have any, yet)
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Re: 400 pistons

Postby harrymuffin » 13 Feb 2018 22:39

I had a batch of 20 500 pistons made by Omega about 10 years ago. They still have the dies from when they made the pistons for Devimead. They are much better - being squeeze forgings, than the original 500 pistons as they have narrower rings and less radial pressure and therefore less friction losses.
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Re: 400 pistons

Postby harrymuffin » 13 Feb 2018 22:44

P.S. Just seen 72 deg reference to the piston I had made,that price was for the pair. I did recently have them quote for piston, for another engine and minimum order is 12 and they worked out at about £650/set of 6, but unlike NLM that is inclusive of pin and rings, might have gone up a bit now.
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Re: 400 pistons

Postby MarkB » 14 Feb 2018 17:11

After giving up on Photobucket in disgust some time ago I no longer know how to post photos here. I've posted a picture of them on the Moto Morini Motorcycles facebook group so you'll see them there.
"I'll have a V please, Bob."
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Re: 400 pistons

Postby 72degrees » 14 Feb 2018 17:33

MarkB wrote:After giving up on Photobucket in disgust some time ago I no longer know how to post photos here. I've posted a picture of them on the Moto Morini Motorcycles facebook group so you'll see them there.


The what now?

Oh, I see. If I'm granted membership I'll grab a copy and host it on my web space or FlickR if that's OK with you. There's a whole alternative universe of Moto Morini pages. Whilst exploring this popped up. I used to have an SWM.

https://www.motorcycle-magazine.com/moto-morini-chinese-v-twin/
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Re: 400 pistons

Postby 72degrees » 14 Feb 2018 17:55

Or you can add them as an attachment like I just did.

400 pistons.jpg
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Re: 400 pistons

Postby pedro » 14 Feb 2018 23:20

This is the type that I have seen, Mark thinks that Alex at NLM fitted them, so it seems unlikely to me that they are VW pistons, but I don't know, what I would like to know is the various merits between the two types, are these able to take advantage of 500 sized valves more easily than the Morini type for instance, the theoretical performance differences between the two types etc. Someone out there must know.
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Re: 400 pistons

Postby morinipete » 15 Feb 2018 05:44

Hi Pedro,

I'll add my two penny-worth. It may cloud the waters further, but does at least come from the horses mouth. A few years ago, interviewing Franco Lambertini (nice name drop there) for a magazine I asked him about the difference between the combustion chambers in the 500 and 350 pistons. Since they are completely different .

I assumed the 500 design was an improvement on the 350 design - as coming several years later - which he confirmed. But this was not for an improvement in power. Solely one of fuel efficiency. This was a disappointment to me at the time, as I saw the logical progression to be making 350 pistons with the 500-type combustion chamber pattern, particularly if using 500 heads (in fact it meant if you were remanufacturing 500 pistons you'd be best off using the earlier 350 type combustion chamber design. Quite the opposite!). As such I didn't question further.

This does lead to the question though of whether the fancy combustion chamber work was always about MPG rather than BHP, and why, as on my previous post, Moto Guzzi kept with plain combustion chambers in their own Heron head engines, even though these were developed well after Lambertini's?

I don't know the answer but in truth I think the only way of finding out is for someone to bench test an engine with standard pistons then do a swap for 'dish' versions and run the same test again. May be it's worth 1 or 2bhp, max, and in Guzzi's case the extra manufacturing costs didn't justify the advantages? It's also worth noting the original 350 engine was developed with machined pistons, to ensure accuracy in all the critical compression dimensions, but very quickly these went over to cast ones in production. Again may be this swap lost any initial advantages measured?

All speculation, so perhaps others have some more concrete evidence?

Cheers

Pete
PS. Looking at the photos above, my 400 pistons are also of the last type posted. Very close to the Guzzi 66mm pistons (I posted earlier), but just a little different.
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Re: 400 pistons

Postby pedro » 16 Feb 2018 17:30

Mystery solved it seems, Wee Vee imported a number of sets of barrels and pistons from Italy with the bowl type pistons, I have this from Benjy himself. If Wee Vee imported them it is not unlikely that NLM also did so. They are not Guzzi or VW pistons but who the supplier was Benjy cannot recollect.
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