Author Topic: Yamaha YZ360 B  (Read 1686 times)

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Offline GMC

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Re: Yamaha YZ360 B
« Reply #30 on: April 19, 2020, 11:19:39 PM »
Some of my shots;

The late Ross Campbell, YZ 360 B


YZ 250 A


And one of the Herbert boys
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Offline sleepy

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Re: Yamaha YZ360 B
« Reply #31 on: April 20, 2020, 09:32:24 AM »
Geoff thanks for those photos. My favorites are the "A" model YZ's with the DT1 based motors and the "B" had the same motor. The early Mono's would have been so much better if they had a decent shock and spring combination. What was Yamaha thinking when they made a rear suspension with the down travel controlled by the spring going coil bind and no effective bump rubber and as the spring sagged with age the owner would wind up the pre-load only reducing the travel. I recall racing a 125C in my youth after coming off a TM125 and thinking how much better it was until you bottomed the rear end only to find the seat coming back up at a great rate trying to drive your backside up your spine. Only raced it twice then bought an RM125S which was way better again.

Well pointed out sleepy , that is exactly what I am working on . Bumpstop in combination with spring travel and stroke . A couple of weeks and I have a solution to present . I will upload the pics on the FB site , when finished

Probably the only good bit of the stock shock is the accumulator on the rear, well ahead of it's time. I have done a couple of shocks where I welded that bulb onto a cut down later YZ shock with the floating piston removed. Worked extremely well only drama was fitting the larger spring up through the middle of the bike. Works Performance also did a shock but it's travel was to suit about 7" wheel travel and turned out to be difficult to travel limit for pre75 and still work ok.
A YZ360B with a good designed 4" limited shock would be a nice pre75 machine.

Offline cr4ever

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Re: Yamaha YZ360 B
« Reply #32 on: April 22, 2020, 08:58:01 AM »
I believe there was also a YZ125B ( almost identical to the A model) in 1974?
The MX125C has laid down twin-shocks. I never saw or heard of one back in the day but saw a mint original one recently here in SA.

Offline Iain Cameron

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Re: Yamaha YZ360 B
« Reply #33 on: April 22, 2020, 08:53:56 PM »
Ross Campbell . I miss that silly bugger . RIP my fashion deva mate .
Yamaha tragic ; dt1, rt1, dt2, rt2, dt2mx , rt2mx , mx250, mx360,sc500, 74dt125, yzx125, yzc250, yzc400, yzd250, yzd400, yzh250, yzh80 , dt100 , xr75 ko xr80 03 , it175 82 . Not a member of any club

Offline bazza

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Re: Yamaha YZ360 B
« Reply #34 on: April 23, 2020, 01:23:44 PM »
Was Ross a Kiwi? or does my memory fail again.
Once you go black  you will never go back - allblacks
Maico - B44 -1976 CR250- 66 Mustang YZF450,RM250
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Offline geoff

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Re: Yamaha YZ360 B
« Reply #35 on: April 23, 2020, 02:14:50 PM »

Not sure if Ross was a Kiwi, had been around and lived over here in Perth W A and was one top bloke with an array of riding gear that you had to see to believe. He certainly livened up the VMX scene and several Forum members will vouch for that.
Taken way to soon Ride in Peace Ross.

Offline Wasp

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Re: Yamaha YZ360 B
« Reply #36 on: April 23, 2020, 05:11:37 PM »
Do the YZ 360 share the same frame and bottom end as the YZ 250 ?
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline GMC

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Re: Yamaha YZ360 B
« Reply #37 on: April 24, 2020, 10:14:25 AM »
Do the YZ 360 share the same frame and bottom end as the YZ 250 ?

Others will know better than me but I would have thought they are different strokes and therefore different cases for different size cranks?
G.M.C.  Bringing the past into the future

Shock horror, its here at last...
www.geoffmorrisconcepts.com

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http://www.geoffmorrisconcepts.com/8/news/

Offline sleepy

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Re: Yamaha YZ360 B
« Reply #38 on: April 24, 2020, 10:54:40 AM »
Do the YZ 360 share the same frame and bottom end as the YZ 250 ?

Others will know better than me but I would have thought they are different strokes and therefore different cases for different size cranks?

The cases are slightly different but the frame mounting holes are the same. The main difference is the barrel mounting spigot and studs are different. Cranks have a different stroke but the diameter of the crank wheels are the same.

Offline Wasp

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Re: Yamaha YZ360 B
« Reply #39 on: April 24, 2020, 11:13:01 AM »
Thanks , so a 360 barrel will fit ?  Or can a 250 be bored to 360 ?
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline sleepy

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Re: Yamaha YZ360 B
« Reply #40 on: April 24, 2020, 03:35:03 PM »
Thanks , so a 360 barrel will fit ?  Or can a 250 be bored to 360 ?

No on both. The 360 stud spacing is further open and wouldn't fit on the 250 case and the 250 barrel can't be bored more than about 2mm without the need for a custom sleeve and a lot of other work.
The 250 is 70mm bore and 64mm stroke with the 360 being 80mm bore and 70mm stroke.
 
It would be possible to modify a 250 out to 360 but you would need a 360 crank (RT1-3 or YZ360) and either weld / reposition studs and machine cases to take a 360 barrel or custom re-sleeve and lengthen a 250 barrel.
I have done the later to a DT1 to make it into a 360cc for pre70. Main reason there was to get a much lighter motor as an RT1 barrel is ridiculously heavy.
Quite an expensive exercise though but it ended up winning a Pre70 title recently.   

Offline Iain Cameron

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Re: Yamaha YZ360 B
« Reply #41 on: April 24, 2020, 08:08:10 PM »
The Frames are interchangeable .
Yamaha tragic ; dt1, rt1, dt2, rt2, dt2mx , rt2mx , mx250, mx360,sc500, 74dt125, yzx125, yzc250, yzc400, yzd250, yzd400, yzh250, yzh80 , dt100 , xr75 ko xr80 03 , it175 82 . Not a member of any club