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Author Topic: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350  (Read 9337 times)
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fordboy628
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« Reply #15 on: January 05, 2018, 04:52:23 PM »

Patrick,

Way cool restoration!   And double way cool on the newest find/project.

I suspect your French friend is correct, this bit of history is now in the right hands.    Please keep us informed of the process.

 cheers cheers cheers
Yourchoiceoflibationboy
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« Reply #16 on: January 05, 2018, 05:21:06 PM »

I will, Fordboy...

At the moment, TT 2 is sitting in my trophy cabinet, waiting for stuff to arrive and assemble themselves in a timely fashion...



I did open my already restored sidevalve to compare the castings and cams, yes, TT 2 is pukka racing parts, different castings with reinforced bearing locations, with cams with about 100 degrees of overlap and 9mm lift, not shabby for 1931 engineering!!!







The racer was fitted with a Bosch racing magneto, type FF1 A L, found one for dirt cheap in Poland.
One of my mates at work, Marek, is Polish, he handled the purchase and should be back from holidays on Monday with it!!!



Patrick
« Last Edit: January 06, 2018, 05:38:51 AM by thefrenchowl » Logged

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fordboy628
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« Reply #17 on: January 06, 2018, 07:27:39 AM »


I did open my already restored sidevalve to compare the castings and cams, yes, TT 2 is pukka racing parts, different castings with reinforced bearing locations, with cams with about 100 degrees of overlap and 9mm lift, not shabby for 1931 engineering!!!

Patrick


Hi Patrick,

You know, one of the falsehoods that is unwittingly perpetuated on the internet, and other places, is the idea that engine engineers of early 20th century (post WWI through the late 1950's) didn't know what they were doing.   This idea however, is far from the reality.   When you read the papers and books from these pioneers, it becomes obvious that they were hard working and very astute engineers and scientists, who advanced their projects using the scientific method.   And in many instances, it was these pioneers who invented the methods and technology that we use and take for granted today.   It is on the shoulders of these giants, and the ones who followed, that we now stand.

To be sure, these pioneers were handicapped by the metallurgy of their times, the infancy of production hot forging, the tediousness of hand calculation(s), and the lack of standardization, as well as other issues.   But then, as now, there is little that restrains persistence coupled with ambition.   And it is important to also note, that Postwar racing definitely benefited from the technological advancements of WWII.

Knowing what I know about the material specifications of the times, I'd say 100 degrees of overlap and 9mm lift would have been pretty cutting edge and quite racy for the 1930's.   Quite probably near to the limits of their valve springs . . . . . .

I'm sure you already are aware of this, but it is always worth repeating.  Re-manufacturing of the critical parts of these assemblies using "modern" materials, bearings, etc, can add life and reliability to these restoration projects.   Especially where no reliability may have existed before . . . . . .

 cheers
Mark
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« Reply #18 on: January 08, 2018, 12:10:58 PM »

Yes Fordboy,

The OHV has double hair pin type valve springs well out in the air flow and also had coil springs on the push rods at the bottom of the cylinder...

But the sidevalve only have a single coil spring per valve, also enclosed, I'll check if I can fit a slightly stronger one there cause the cams are indeed hairy...

Stuff is also starting to drop at the front door...

Tubes for bits of fabrication today and

Last week, Saddle, a rubber backed fabric item by Dunlop, named Drilastic, on an Ideale licence, and a Speedway spool hub for the front wheel:





I also put a nice sum on eBay for a sport carburettor, a one inch bore AMAC 15 MDY, to no avail, it went elsewhere...



So long...

Patrick
« Last Edit: January 08, 2018, 12:28:58 PM by thefrenchowl » Logged

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« Reply #19 on: January 08, 2018, 03:42:28 PM »

Patrick,
I am always in awe of your kind of project. I love old motorcycles and to take one and bring it back to life and then race it is a true test of stubbornness!  Can't wait to see it finished!!

Rex
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« Reply #20 on: January 08, 2018, 04:26:15 PM »

Thanks Rex...

Yes, I never choose the easy way!!!

The records I'm looking at, depending on category, are not too shabby for an 85 years old SV bike to beat, 250cc M-VF = 79.55mph, M-VG = 77.306mph, MPS-VF = 82.486mph and MPS-VG = 81.418mph

I've had a chat with the SCTA/BNI MC Tech Committee, it appears the balsa filler and sticky tape on the Webbs type forks put the bike in PS category...

Cheers, Patrick
« Last Edit: January 08, 2018, 04:28:27 PM by thefrenchowl » Logged

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« Reply #21 on: January 08, 2018, 09:47:33 PM »

An expert can make digital profiles of your cams, weigh the valve train components, and use computer calculations to tell you exactly what springs are needed - both for strength and resistance to harmonic irregularities.  Then, they can suggest a reasonable safety factor to use in the design.  Another fix is to use ceramic coatings on the ports and cylinder head to keep the springs cool.   

This work sounds expensive.  It isn't when the cost of hard to replace parts is factored in.  An additional plus is the information you get can be used for other things, like optimizing the cam timing or having custom springs made. 

A source for good quality mousetrap springs are those folks in the UK who supply parts for the racing Nortons and Matchlesses.  The matchbox G-80's I had used those springs. 
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thefrenchowl
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« Reply #22 on: January 09, 2018, 07:46:42 AM »

 grin Wobblywalrus,

I'm running the side valve version, not the OHV, hence I'm stuck with using coil springs.

I'll check how far I can shim the OEM ones to improve seating pressure without going ""coil bind + 40 or 60 thou" at full opening...

I have a few coils springs from various Harley OHV heads, I'm sure I can find some harder ones in there!!!

As you might have seen, I'm not one for much testing!!! But I can make a quick jig to check their tension under a certain weight.

Patrick
« Last Edit: January 09, 2018, 01:28:29 PM by thefrenchowl » Logged

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« Reply #23 on: January 09, 2018, 11:25:46 AM »

Happy Birthday Patrick.

It looks as if you have already received your present (some assembly required).    cheers

  Don
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« Reply #24 on: January 09, 2018, 12:06:25 PM »

Thanks Don!!!

Yes, Christmas, New Year and Birthday all within 2 weeks, the fun never ceases!!!

Patrick
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« Reply #25 on: January 09, 2018, 04:00:29 PM »

grin Wobblywalrus,

 

I'll check how far I can shim the OEM ones to improve seating pressure without going ""coil bind + 40 or 60 thou" at full opening...
Patrick

Very nice project you have there. If I can add a few cents worth of experience to your build. Many racing cylinder head porters and builders try to not go closer than .100" before coil bind because it wears the springs out much faster due to over compressing them. I know people do and will continue to do it even when faced with facts and evidence it will. But maybe longer valves can help your valve spring selection and find a stiffer spring from more modern engines and possibly give you a much wider selection to choose from.
« Last Edit: January 09, 2018, 04:03:52 PM by CNC-Dude » Logged
thefrenchowl
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« Reply #26 on: January 09, 2018, 07:01:31 PM »

Thanks, CNC-Dude,

I sensed I couldn't shim modern springs that tight, but you should see these OEM 85 years old springs, they nearly look like out of a retractable ball pen!!!

Patrick
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« Reply #27 on: January 16, 2018, 01:38:49 PM »

Too cold here to do anything decent...

But Marek's luggage was back from Poland after his holidays there at Christmas...

Nice bloke, nice magneto!!!







More news soon I hope!!! Gotta make some room in the garage, too many bits everywhere!!!

Patrick
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« Reply #28 on: February 16, 2018, 06:21:00 PM »

Hi, a bit of movement... Not before time!!!

Went to the St Pancras railway station in London today, 320 miles round trip... Met in a hurry a Belgian friend of mine, Yves Campion. He donated a racing/period AMAL type 27 for this project and I gave him this magneto as grateful thanks...





Yves always travel with this souvenir:



It's a lapel pin from Rene Milhoux, another famous Belgian rider who broke numerous records at Montlery in the 30s on Gillet d'Herstal and F.N. motorcycles. All successful record breakers got one, but I have never seen another one...

I also found a 2nd Bosch FF1 AL magneto, this time in Australia... Should arrive home here in GB by the end of this month...



Weather is getting better, I'll soon start dismantling the donor bike... Promess, cross my heart!!!

So long, Patrick
« Last Edit: February 16, 2018, 06:24:31 PM by thefrenchowl » Logged

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« Reply #29 on: February 16, 2018, 08:17:36 PM »

Patrick, two magnetos is nice.  it is always a good idea to have an extra one ready to be quickly installed. 
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