Author Topic: Yamaha YZ360 B  (Read 1684 times)

0 Members and 1 Guest are viewing this topic.

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Yamaha YZ360 B
« on: April 09, 2020, 09:53:17 AM »
Looking for a YZ 360 B , restored or not . Preferably restored or in good shape but will consider anything .  (I edited the model from MX to YZ ,sorry )
« Last Edit: April 14, 2020, 05:01:09 PM by Wasp »
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline drums'n fins

  • A-Grade
  • ****
  • Posts: 340
    • View Profile
Re: Yamaha 360
« Reply #1 on: April 11, 2020, 03:45:06 PM »
Good luck with your search Mr Wasp, if you do get lucky and end up needing some parts I ended up with some NOS and repo stuff that I didn't really need that may come in handy for a resto.
OMG,NOS,OEM,RMT,CDI,NLA,WTF!

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha 360
« Reply #2 on: April 12, 2020, 03:15:49 PM »
Got it , thanks . I am on to it .
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha 360
« Reply #3 on: April 14, 2020, 02:40:13 PM »
It is the first  mono shock YZ I am after , to be more specific .
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Online Momus

  • Legend
  • *****
  • Posts: 622
    • View Profile
Re: Yamaha 360
« Reply #4 on: April 14, 2020, 04:35:43 PM »
Perhaps alter your title mate?

MX360B would be a 1974 twin shock bike.
If you love it, lube it.

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha YZ360 B
« Reply #5 on: April 14, 2020, 05:02:03 PM »
YZ 360 B it is now . Thanks for letting me know .
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Barra

  • C-Grade
  • **
  • Posts: 110
    • View Profile
Re: Yamaha YZ360 B
« Reply #6 on: April 14, 2020, 11:21:22 PM »
 
I had an MX250B.  It was the first model cantilever and it was '75 (on sale late '74). And it was an MX B.  Alloy white tank with red sides and vertical black stripe. The 360's I think had yellow instead of red.  Got it registered so i could get my "L"s!!! Universal rear tyre really hooked up on the bitumen, mono's out of every corner!! Unreal fun, cant have been too many cops around Geelong back in the day, never got picked up. Ha ha.

This is interesting as maybe the first year model cantilevers were MXB and then Yamaha designated them YZ after that? It's odd as i think the first YZ was a C model in '76?   

     

Online Momus

  • Legend
  • *****
  • Posts: 622
    • View Profile
Re: Yamaha YZ360 B
« Reply #7 on: April 15, 2020, 05:47:06 AM »
 
I had an MX250B.  It was the first model cantilever and it was '75 (on sale late '74). And it was an MX B.  Alloy white tank with red sides and vertical black stripe. The 360's I think had yellow instead of red.  Got it registered so i could get my "L"s!!! Universal rear tyre really hooked up on the bitumen, mono's out of every corner!! Unreal fun, cant have been too many cops around Geelong back in the day, never got picked up. Ha ha.

This is interesting as maybe the first year model cantilevers were MXB and then Yamaha designated them YZ after that? It's odd as i think the first YZ was a C model in '76?   

     
The MX400B was the big brother to the cantilever 250. It had yellow styling  accents.
The YZ360 is a completely different and much rarer and more valuable animal.
« Last Edit: April 15, 2020, 05:48:44 AM by Momus »
If you love it, lube it.

Offline Barra

  • C-Grade
  • **
  • Posts: 110
    • View Profile
Re: Yamaha YZ360 B
« Reply #8 on: April 15, 2020, 09:03:17 AM »
Quote
The MX400B was the big brother to the cantilever 250. It had yellow styling  accents.
The YZ360 is a completely different and much rarer and more valuable animal.

Oh yes in '75 it was the 400 not 360.  So Wasp must be after the first YZ monoshock, not the first ever monoshock?

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha YZ360 B
« Reply #9 on: April 15, 2020, 09:52:35 AM »
Now I am confused .  :o  . I always thought the YZ B where the first mono shock model.
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Hoony

  • Legend
  • *****
  • Posts: 4238
  • Melbourne, Vic.
    • View Profile
Re: Yamaha YZ360 B
« Reply #10 on: April 15, 2020, 05:24:08 PM »
Now I am confused .  :o  . I always thought the YZ B where the first mono shock model.

Yes i think they were as well. 1974 YZ80/125/250/360 A models were all twin shocks
Long time Honda Fan, but all bike nut in general, Big Bore 2 stroke fan.    http://www.youtube.com/watch?v=XJoKP6MawYI
1985 Honda CR500RF "Big Red"
1986 Honda CR250RG
2005 KTM 300EXC "The GruntMeister" ( I love that engine)

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha YZ360 B
« Reply #11 on: April 15, 2020, 07:21:38 PM »
Would that mean 360 and 400 ran parallel in 75 or consecutive ?
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Barra

  • C-Grade
  • **
  • Posts: 110
    • View Profile
Re: Yamaha YZ360 B
« Reply #12 on: April 15, 2020, 07:41:55 PM »
Quote
Yes i think they were as well. 1974 YZ80/125/250/360 A models were all twin shocks
I'm pretty sure all those models were MX not YZ.

I'm very sure the first ever mono-shocks were the 1975 MX 250/400B.  Yamaha ran a prototype works cantilever in late '73 and developed it through '74 before the production MX B cantilevers hit the market in '75. (works bikes were called YZ before the factory bikes went to OW in 76?)

I reckon the first mono-shock "YZ" was in '76 - which were the YZ C's - unless someone can disprove any of that?     

Offline GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #13 on: April 15, 2020, 09:20:57 PM »
Yamaha models got a bit confusing in the 70's as they produced the MX & YZ series side by side and their model designation letter was all over the shop as well.
Not to mention year models that were available in Aust were different to the US

To the best of my knowledge;

1974
MX 125 A - twinshocks, yellow
MX 250 A - twinshocks, yellow
MX 360 A - twinshocks, yellow

YZ 125 A - twinshocks, grey
YZ 250 A - twinshocks, grey
YZ 360 A - twinshocks, grey

YZ 250 B - monoshock, white, possibly the first monoshock, a 74 model in Aust but a 75 model in the USA
YZ 360 B - monoshock, white, possibly the first monoshock, a 74 model in Aust but a 75 model in the USA


1975
MX 125 B - twinshocks
MX 250 B - monoshock
MX 400 B - monoshock

YZ 125 C - monoshock, white


1976
MX 125 C - rare to find

YZ 125 X - yellow - airforks
YZ 250 C - yellow - airforks
YZ 400 C - yellow - airforks


1977
Designation letter now in sync
YZ 125 D - white, first plastic tank, steel swingarm
YZ 250 D - white, first plastic tank, steel swingarm
YZ 400 D - white, first plastic tank, steel swingarm

Now updated
Now updated yet again!
« Last Edit: April 19, 2020, 09:03:49 AM by GMC »
G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline Iain Cameron

  • Legend
  • *****
  • Posts: 2019
    • View Profile
Re: Yamaha YZ360 B
« Reply #14 on: April 16, 2020, 10:40:24 AM »
Geoff there was no MX250/ 400 c in 1976 . 1975 was the last year of the 250 and open class MX series .
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 Iain Cameron

  • Legend
  • *****
  • Posts: 2019
    • View Profile
Re: Yamaha YZ360 B
« Reply #15 on: April 16, 2020, 10:53:47 AM »
The first mono's available to the public where the YZ series Designated the 75 model but released in Australia  at Easter in 1974 so called the YZb  only the 250 and 360 were mono the 125 remained twin shock till the YZc came out in late 75 . the YZx125 came out in 76 to match the YZc 175 , 250 and 400 . but as Yamaha had used the "C" the year before for the 125 it was called the X .
The MX series ended for the 250 and 400 in 1975 but the 125 lasted one more year as the 125c and was a twin shock bike .
the DT/MX designation was used in Europe and the US for the trail bikes range were as in Aust we called them the DT range .
todays useless information from the Yamaha tragic .
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 GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #16 on: April 17, 2020, 10:22:06 PM »
Geoff there was no MX250/ 400 c in 1976 . 1975 was the last year of the 250 and open class MX series .

Ah, yes
I was trying to put some intelligent information together, only ended up confusing myself :o
G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #17 on: April 17, 2020, 10:37:15 PM »
todays useless information from the Yamaha tragic .

Talking of useless information;

The MX 100 went for many more years

And the YZ 100 D  was based on the C/X models,

G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha YZ360 B
« Reply #18 on: April 18, 2020, 11:57:11 AM »
thanks , so everybody in agreeance with the updated GMC list ?
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Barra

  • C-Grade
  • **
  • Posts: 110
    • View Profile
Re: Yamaha YZ360 B
« Reply #19 on: April 18, 2020, 03:06:12 PM »
Looks good to me, although i'm no expert.  I had always thought the '75 MX B's were the first production monoshock, I'd never seen the first '74 YZ monoshocks, they must have been a limited run model like the RH Suzukis for selected riders only??

So Walter, is it strictly a YZ 360 you are chasing? 

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha YZ360 B
« Reply #20 on: April 18, 2020, 03:46:08 PM »
Yes they only made 1400 of them globally ,so I have been told , but I was confused of the year . The MX 360 also threw me off . Now it makes all sense . Yes Barra , that is the one I am chasing for a friend .
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Barra

  • C-Grade
  • **
  • Posts: 110
    • View Profile
Re: Yamaha YZ360 B
« Reply #21 on: April 18, 2020, 06:24:02 PM »
Quote
1975
MX 125 B - twinshocks
MX 250 B - monoshock
MX 360 B - monoshock

Actually Geoff shouldn't that be MX 400 B?

Offline GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #22 on: April 19, 2020, 09:02:14 AM »
Quote
1975
MX 125 B - twinshocks
MX 250 B - monoshock
MX 360 B - monoshock

Actually Geoff shouldn't that be MX 400 B?

Doh!
My enthusiasm to look knowledgeable has brought me down again, curse you copy and paste.

I also accidently deleted the MX 125 C which I know exists, just that they are rare, well in Oz anyway, think they were 76!
G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #23 on: April 19, 2020, 09:11:34 AM »
Lets see if i can't bring myself undone again :o

I believe this is what Wasp is chasing, the YZ360B;


Not to be confused with the MX 400 B

G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #24 on: April 19, 2020, 09:14:07 AM »
And just for the hell of it...

The MX A series


And the YZ A series
G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline sleepy

  • Legend
  • *****
  • Posts: 656
    • View Profile
Re: Yamaha YZ360 B
« Reply #25 on: April 19, 2020, 10:23:38 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. 

Offline Hoony

  • Legend
  • *****
  • Posts: 4238
  • Melbourne, Vic.
    • View Profile
Re: Yamaha YZ360 B
« Reply #26 on: April 19, 2020, 10:24:12 AM »
Good Work Geoff........for a surgeon of steel   8)
Long time Honda Fan, but all bike nut in general, Big Bore 2 stroke fan.    http://www.youtube.com/watch?v=XJoKP6MawYI
1985 Honda CR500RF "Big Red"
1986 Honda CR250RG
2005 KTM 300EXC "The GruntMeister" ( I love that engine)

Offline Wasp

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: Yamaha YZ360 B
« Reply #27 on: April 19, 2020, 07:08:23 PM »
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
362 shocks , We don't just sell them - I designed and make them individually for you since 1989.

Offline Iain Cameron

  • Legend
  • *****
  • Posts: 2019
    • View Profile
Re: Yamaha YZ360 B
« Reply #28 on: April 19, 2020, 10:33:28 PM »
Well done Geoff . Not bad for a rider of the Green ones . only missing the MX 175 1974 and the YZc 175 1976 if you think a MX175 1976 is rare in Aust try finding a YZ175c .
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 GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
Re: Yamaha YZ360 B
« Reply #29 on: April 19, 2020, 11:10:04 PM »
They were just some photos I stole from the net.

I remember seeing the YZ 125 C on the front of Trail and Track and thinking it was the coolest thing.
It would be another year before I could gather enough money to buy a second hand MX 125 A

Well done Geoff . Not bad for a rider of the Green ones . only missing the MX 175 1974 and the YZc 175 1976 if you think a MX175 1976 is rare in Aust try finding a YZ175c .

Well I started off with Yamahas before I turned green

And I just sold a airbox and chamber to the US for a YZ 125B
G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline GMC

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
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
G.M.C.  Bringing the past into the future

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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline sleepy

  • Legend
  • *****
  • Posts: 656
    • View Profile
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

  • C-Grade
  • **
  • Posts: 66
    • View Profile
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

  • Legend
  • *****
  • Posts: 2019
    • View Profile
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

  • Legend
  • *****
  • Posts: 2306
    • View Profile
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
Embrace patina

Offline geoff

  • C-Grade
  • **
  • Posts: 65
    • View Profile
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

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
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

  • Legend
  • *****
  • Posts: 3693
  • Broadford, Vic
    • View Profile
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

For the latest in GMC news...
http://www.geoffmorrisconcepts.com/8/news/

Offline sleepy

  • Legend
  • *****
  • Posts: 656
    • View Profile
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

  • A-Grade
  • ****
  • Posts: 321
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
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

  • Legend
  • *****
  • Posts: 656
    • View Profile
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

  • Legend
  • *****
  • Posts: 2019
    • View Profile
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