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Author Topic: Vr 360?  (Read 6391 times)

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Offline VR250

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Vr 360?
« on: December 03, 2011, 08:33:55 pm »
Has anyone heard if its possible to modify a vr250 engine into an open class (300cc +) motor using pre 1975 sleeves pistons etc?
Got a spare motor lying around and curious if it can be done.
Im sick of running a 250 against open class bikes and need a little boost to help carry my ever increasing waistline over the finish line.
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Offline Slakewell

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Re: Vr 360?
« Reply #1 on: December 03, 2011, 08:44:21 pm »
The only thing I know of was a GP 360 motor in a VR running chassis
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Offline cappra

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Re: Vr 360?
« Reply #2 on: December 03, 2011, 10:13:28 pm »
Next to impossible to do with the existing VR cases (34M cases) An extreme overbore on the
VR cylinder, still does not give you an over 300cc displacement. Stud placement of the VR cases
makes the use of the 360GP cylinder a no go. Montesa just did not offer any pre 75' big bore motors
except for the 360GP engine, which can be swapped in easily, but is not a suitable option for what
you have in mind. As a side note, the 77' VB 250 can use a Cota 348 piston which will yield a 305cc
displacement.
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Offline Stan S

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Re: Vr 360?
« Reply #3 on: December 03, 2011, 10:56:48 pm »
This is the VR360 (VR 250 frame with a GP 360 engine) built by Lyall O'Brien that his son Gary won the 1973 Grand National on. I will restore it next year hopefully in time for CD9.

Stan.



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albrid-3

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Re: Vr 360?
« Reply #4 on: December 08, 2011, 10:26:54 pm »

Gary O`brien on the Montesa 360GP VR 1973 winning the Grand National.
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Offline evo550

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Re: Vr 360?
« Reply #5 on: December 09, 2011, 06:24:53 am »
....are they the same bike??
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maico police

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Re: Vr 360?
« Reply #6 on: December 09, 2011, 06:34:47 am »
Yup! ;)
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Offline cappra

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Re: Vr 360?
« Reply #7 on: December 09, 2011, 12:25:02 pm »
Sorry for the poor quality of the picture. Lyall sent me this pic of the VR 360 some years ago.
Of note is the sprocket cover.
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Offline Canam370

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Re: Vr 360?
« Reply #8 on: December 09, 2011, 12:38:57 pm »
He must have been worried about throwing the chain with the LTR. Is there a fair gap between the swingarm pivot and countershaft?
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Offline cappra

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Re: Vr 360?
« Reply #9 on: December 09, 2011, 01:52:43 pm »
Yes, there was a long distance between the sprocket and the swingarm pivot.
Was alway's a problem with Montesa motors. A byproduct of using a dated engine
design well in to the eighties.
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Offline VR250

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Re: Vr 360?
« Reply #10 on: December 10, 2011, 05:49:51 pm »
Sorry there are 2 different bikes there.
The one of Gary racing is an early Vr.
The 2 others are late Vr's.
So someone out there has an early Vr with a 360 motor hiding in their shed somewhere in oz!
Come out, come out, wherever you are.
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Offline cappra

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Re: Vr 360?
« Reply #11 on: December 10, 2011, 05:56:18 pm »
They could be the same bike only with the addition of lay down shock mounts and other minor changes.
The bike appears to have been "enduroized" in it's last incarnation.
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SPANISH ARMADA

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Re: Vr 360?
« Reply #12 on: December 10, 2011, 07:13:03 pm »
the other vr 360 still lives with its owner and its not me and he doesnt want to sell it thats all i can tell you cheers
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Offline Stan S

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Re: Vr 360?
« Reply #13 on: December 10, 2011, 09:11:57 pm »
Quote from: VR250 on December 10, 2011, 05:49:51 pm
Sorry there are 2 different bikes there.
The one of Gary racing is an early Vr.
The 2 others are late Vr's.
So someone out there has an early Vr with a 360 motor hiding in their shed somewhere in oz!
Come out, come out, wherever you are.

VR250, the three photo's are the same bike which I have in the shed. In 1974 Lyall up dated Gary's 73 bike with a 74 tank seat and wheels. In late 74 the rear suspension was modified. The bike was sold later through Ryan's in NSW to the guy that is pictured in my photo. He then modified it to race enduro's and that is the state that I bought it in.
I have spoken to Gary O'Brien recently and he confirmed the history as he remembers it. When I get around to it I intend putting it back to the same as it was when Gary won the 73 Grand National on it. I hope one day to intice Gary into doing some laps on it at an Demo event somewhere, but that's sometime down the track.

Stan.
« Last Edit: December 10, 2011, 09:15:01 pm by Stan S »
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SPANISH ARMADA

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Re: Vr 360?
« Reply #14 on: December 10, 2011, 09:15:06 pm »
stan your right but there still live one more that was built by lyle
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