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Author Topic: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350  (Read 27698 times)

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Offline thefrenchowl

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 :-D



 :-D



Patrick
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...What exactly are we trying to do here?...

Offline Harold Bettes

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Patrick,

What diameters are the valves? What is the overall length of the valves? And of course, what is the stem diameter?

What is the CR of the thing? Approx 6:1 or so?

Regards,
HB2
If it was easy, everybody would be doing it.

As iron sharpens iron, one man sharpens another.

Offline thefrenchowl

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Hi Harold,

Valves are both the same dimms, but the inlet is more tuliped than the exhaust.

They used the same valves on the OHV version...

Head diameter 44.5mm, 1"751, length 121mm, 4"763, stem diameter 9mm, 354 thou.

Not too restricted then for a 70mm bore and 90mm stroke

The head has no "Ricardo" squish, I doubt there more than 4.5 CR... I'll measure it soon.

Thanks for theyour interest,

Patrick
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...What exactly are we trying to do here?...

Offline thefrenchowl

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Exhaust pipe...



Curve retouched and small extension to get it to 38" from valve to end like my KHK...



Recycled stainless brackets:





Welded back to back:



Frame bracket:









So long,

Patrick

« Last Edit: August 11, 2018, 10:37:13 AM by thefrenchowl »
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Offline wobblywalrus

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That might be a good place to put a rubber mount between the header and the bracket on the frame so the pipe can grow and contract due to thermal expansion and not overstress the bracket.

Offline thefrenchowl

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Hi Everybody,

Not too much enthusiasm these last weeks, two funerals, old friends of my wife Susan... Plus a few difficulties to visualise the braketry needed for the saddle...

The vertical supports are easy enough to do...







After that, quite challenging, space geometry with the saddle suspended precariously above the tyre!!!



It stayed like this for about a week, time and rest needed to decide where to start the rest.

Started with the front, A Frame, don't quite see where the word stemed from!!!





Above these was a bit Gaudiesque, branches in every direction towards the saddle frame. I started with the lateral ones.





Just enough support to allow spot brasing...



I'll continue with the front branches tomorrow.

Patrick

« Last Edit: August 23, 2018, 05:35:07 PM by thefrenchowl »
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Offline thefrenchowl

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Hi...

Finished saddle frame, just needs a good seance of filing...





Then rear fender, there were none on the original bike, but SCTIA/BNI who run Bonneville Speed Week insists it's mandatory...





So long, Patrick
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...What exactly are we trying to do here?...

Offline thefrenchowl

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Hi,

Needed sommat to relax this weekend... Nothing like monotonous stuff to do that!!!

Swiss cheese endeavour for the rear sproket!!!!

I started with this boring part:



Central portion thinned out:











Cheers,

Patrick
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...What exactly are we trying to do here?...

Offline Koncretekid

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Nice work, Patrick!  Do you plan to bring the bike to Bonneville?

The valve sizes sound huge for the 70mm bore.  44mm intake valve is the same as for the 84mm bore BSA B50.
How did they ever fit the same valve sizes in the overhead valve version?

Tom 
We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!

Offline thefrenchowl

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 :-D With great difficulty, Tom!!!



And yes, the plan is to bring this bike to Speed Week next year if all goes well...

Patrick
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...What exactly are we trying to do here?...

Offline thefrenchowl

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Re: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350
« Reply #115 on: September 05, 2018, 04:07:17 AM »
Hi,

Finished the saddle frame...







And did a 18/14 reducer for the spark plug:



Choice of modern super cold NGK:



Of NOS Harley KR Champion plug:



Patrick
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...What exactly are we trying to do here?...

Offline thefrenchowl

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Re: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350
« Reply #116 on: October 26, 2018, 04:02:44 PM »
Hi...

Still waiting for a retired panel beater to get in touch with me about the tank...
While waiting, why not try???

Big sheet of duct alloy













Another friend has a wheel for the curves...

Bye for now, Patrick
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Online Stainless1

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Re: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350
« Reply #117 on: October 27, 2018, 09:38:54 PM »
Are those retracted gap plugs...  :cheers:
Stainless
Red Hat 228.039, 2001, 65ci, MSA Bockscar Lakester with a little N20 
MSA Bockscar Lakester #1000 my fastest mile 245 and change, 84 ci turbobusa motor... but Corey's 233 MPH H/BFL record is still 3MPH faster than mine.

Offline thefrenchowl

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Re: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350
« Reply #118 on: October 29, 2018, 08:02:12 AM »
 :-D

After that photo, I remembered I had some super strong  hard drive magnets so I used them, more discreet!!!





Patrick
« Last Edit: October 29, 2018, 11:17:03 AM by thefrenchowl »
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Offline thefrenchowl

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Re: New Vintage Project, 250cc M-VG, Reconstruction of a 1933 French Jonghi 350
« Reply #119 on: December 24, 2018, 11:41:51 AM »
... Ah, Christmas is upon us...

So just in time to start work again on this Jonghi!!!

Just a little appetizer to begin with...

There is an OEM complex brass bush on the right main shaft to allow the oil to pass from the pump to the rod rollers:





As soon as there's a bit of play, oil takes the easy way and returns directly to the timing cavity, hence starving the rollers, not good...

I did redo the same exact brass bush on my other TJ 4, but it's a pain really...

Thankfully, there is enough width to fit 2 back to back lip seals to improve oil transfer:









So long, I hope you all have a good end of year...

Patrick
« Last Edit: December 24, 2018, 11:50:05 AM by thefrenchowl »
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