1979 Mugen air cooled ME125RZ Restoration

Bearuno
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2/10/2026 7:57pm
Bluelion wrote:
Every single 1979 factory air cooled 125 Mugen I have seen the shocks are mounted this way. So I think they were engineered to be mounted...

Every single 1979 factory air cooled 125 Mugen I have seen the shocks are mounted this way. So I think they were engineered to be mounted this way? I like the look of them mounted the other way but this seems correct?
14AECED0-82FF-4654-B5C9-32A680C74544.jpeg?VersionId=0qk9RbSJBb

I think the Same as you as to the Orientation.

But,  I'm a great fan of Checking things.

The Resi end / Valve travel a Looooong way, what with the travel within that shock - looking to compress  right level with, or perhaps, past the spring / clip interface.

And, the Shock mounts don't appear to be 'outwards' much, if at all, from the actual swingarm 'leg'. And, no 'pocketing' for clearance - which, of course, indicates there's no need for such a thing. 

With the geometry of 'laid down' shocks, mounted far back on the swingarm, the angle formed at the Shock to Swingarm won't open much, if at all. Indeed, I'd be surprised if it didn't 'close', as into a more acute angle.

 Cripes. on one of my early XRs, that I modded to take 17.5" Fox Factory shocks ( that I made about 1/2" longer to suit the frame mods I did, and the DG Aluminium +1" Swingarm I got for it, and  the Fox 44s I fitted to various bikes - those all sit behind / above my Lathe now)   , that , went in effectively, falling rate, had me trying some very strange dual and Triple springs. And Spring Engagement alloy sleeves( that went into the short 'helper spring(s)', to try to engage the a particular spring earlier).

It probably clears by a bit, but, if you are actually going to ride it, it would be wise to check it. Heck, years ago I'd deal with shock shafts that were bent when a rock / debris got stuck between a shock and swingarm, in tight clearance areas. 

An opposite thing, is many bike / shock combos, having the resi / resi arm being able to contact Various 'things' when mounted to the top. Though, it looks to be buggerall chance of that with those Showas - such long resi arms and resis! They are quite the Cool blast from the past. *As were the original Kayaba Airshocks it came with.

So much nastiness happened years ago during the Suspension Revolution / Suspension upgrades, from just lack of checking. 

2
Bluelion
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2/11/2026 4:23am

My Mugen’s. 
3914F1AE-8FB1-46AC-9F01-7B819F635148.jpeg?VersionId= JP GqG1Pt4AF Q2tr9J4UF 0te

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Bluelion
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2/11/2026 4:24am
8260565E-9D9C-46BC-BDF7-E127536C3D7D.jpeg?VersionId=kRm
1
Bluelion
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2/11/2026 4:27am Edited Date/Time 2/11/2026 4:27am

I will do a detail photo, shoot and description of this bike and it’s history in an upcoming post on here.
 1977 mugen 250.m

CE88FED4-8A44-445F-9196-3055A9C887BE

 

4

The Shop

PN27416
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2/11/2026 5:36am
Bluelion wrote:
Every single 1979 factory air cooled 125 Mugen I have seen the shocks are mounted this way. So I think they were engineered to be mounted...

Every single 1979 factory air cooled 125 Mugen I have seen the shocks are mounted this way. So I think they were engineered to be mounted this way? I like the look of them mounted the other way but this seems correct?
14AECED0-82FF-4654-B5C9-32A680C74544.jpeg?VersionId=0qk9RbSJBb

Bearuno wrote:
I think the Same as you as to the Orientation.But,  I'm a great fan of Checking things.The Resi end / Valve travel a Looooong way...

I think the Same as you as to the Orientation.

But,  I'm a great fan of Checking things.

The Resi end / Valve travel a Looooong way, what with the travel within that shock - looking to compress  right level with, or perhaps, past the spring / clip interface.

And, the Shock mounts don't appear to be 'outwards' much, if at all, from the actual swingarm 'leg'. And, no 'pocketing' for clearance - which, of course, indicates there's no need for such a thing. 

With the geometry of 'laid down' shocks, mounted far back on the swingarm, the angle formed at the Shock to Swingarm won't open much, if at all. Indeed, I'd be surprised if it didn't 'close', as into a more acute angle.

 Cripes. on one of my early XRs, that I modded to take 17.5" Fox Factory shocks ( that I made about 1/2" longer to suit the frame mods I did, and the DG Aluminium +1" Swingarm I got for it, and  the Fox 44s I fitted to various bikes - those all sit behind / above my Lathe now)   , that , went in effectively, falling rate, had me trying some very strange dual and Triple springs. And Spring Engagement alloy sleeves( that went into the short 'helper spring(s)', to try to engage the a particular spring earlier).

It probably clears by a bit, but, if you are actually going to ride it, it would be wise to check it. Heck, years ago I'd deal with shock shafts that were bent when a rock / debris got stuck between a shock and swingarm, in tight clearance areas. 

An opposite thing, is many bike / shock combos, having the resi / resi arm being able to contact Various 'things' when mounted to the top. Though, it looks to be buggerall chance of that with those Showas - such long resi arms and resis! They are quite the Cool blast from the past. *As were the original Kayaba Airshocks it came with.

So much nastiness happened years ago during the Suspension Revolution / Suspension upgrades, from just lack of checking. 

Post pics of whats around your Lathe, xr-75 sounds trick!

Bearuno
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2/11/2026 8:17am
PN27416 wrote:

Post pics of whats around your Lathe, xr-75 sounds trick!

Not an XR75 - at that point, it was a 200. That ended up with a Poweroll 249 kit, and, then it went into a 83 Floater chassis, then, in a '89 CR125 chassis. The engine is in a cupboard below my computer,  the (both) chassis, hanging on the wall behind endless Dirt Bike and Ducati parts.

It is a complete shemozzle of a workshop. It's Not a Pretty Garage...... but, I love it. 

Though, as to XR75s : I converted my next door neighbour, Tyrone's,   XR75 to a Monoshock, with a CR125 front fork, sometime around 1976?. And, his little brothers MR50 to a Monoshock, with the XR forks on it. Wish I could find those 2 bikes - I lost track of them when Tyrone died......  I was a crazed Modifier and Builder, at an early age. 

 

2
moto9
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2/11/2026 11:59am
Bluelion wrote:
8260565E-9D9C-46BC-BDF7-E127536C3D7D.jpeg?VersionId=kRm

Really awesome 👍

What are the plans for the two bikes?

Do you race them in vintage, take them to shows, or put them on a wall in your house?

I have a friend that has a brand new 74 cr 250 mounted on his wall in the living room on his house.

Bluelion
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2/12/2026 4:03am
Bluelion wrote:
8260565E-9D9C-46BC-BDF7-E127536C3D7D.jpeg?VersionId=kRm
moto9 wrote:
Really awesome 👍What are the plans for the two bikes?Do you race them in vintage, take them to shows, or put them on a wall in...

Really awesome 👍

What are the plans for the two bikes?

Do you race them in vintage, take them to shows, or put them on a wall in your house?

I have a friend that has a brand new 74 cr 250 mounted on his wall in the living room on his house.

I will lightly ride these bikes just to see how they run. I will not race them. They will be display bikes. I will take them to bike shows and things like legends of heroes displays. I have other vintage bikes to race.

4
Bluelion
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2/12/2026 4:06am

So my next project will be this number 12 1977 Mugen Honda that Steve Wise raced. Stay tuned for that. I will be doing a complete blog, step-by-step restoration build of this bike. A2E4C66B-4F1B-46F9-BDE4-078D7D13C0D8.jpeg?VersionId=SKeSC5Ls
 

7
PN27416
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2/12/2026 6:23am
Bluelion wrote:
So my next project will be this number 12 1977 Mugen Honda that Steve Wise raced. Stay tuned for that. I will be doing a complete...

So my next project will be this number 12 1977 Mugen Honda that Steve Wise raced. Stay tuned for that. I will be doing a complete blog, step-by-step restoration build of this bike. A2E4C66B-4F1B-46F9-BDE4-078D7D13C0D8.jpeg?VersionId=SKeSC5Ls
 

Will be looking forward to that!!!

PN27416
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2/12/2026 6:24am
Bluelion wrote:
8260565E-9D9C-46BC-BDF7-E127536C3D7D.jpeg?VersionId=kRm
moto9 wrote:
Really awesome 👍What are the plans for the two bikes?Do you race them in vintage, take them to shows, or put them on a wall in...

Really awesome 👍

What are the plans for the two bikes?

Do you race them in vintage, take them to shows, or put them on a wall in your house?

I have a friend that has a brand new 74 cr 250 mounted on his wall in the living room on his house.

Bluelion wrote:
I will lightly ride these bikes just to see how they run. I will not race them. They will be display bikes. I will take them...

I will lightly ride these bikes just to see how they run. I will not race them. They will be display bikes. I will take them to bike shows and things like legends of heroes displays. I have other vintage bikes to race.

Any event you want to show it with the Legends & Heroes. Please let us know!

pete@legendsandheroestour.org

Bluelion
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2/16/2026 11:08am
moto9 wrote:
Really awesome 👍What are the plans for the two bikes?Do you race them in vintage, take them to shows, or put them on a wall in...

Really awesome 👍

What are the plans for the two bikes?

Do you race them in vintage, take them to shows, or put them on a wall in your house?

I have a friend that has a brand new 74 cr 250 mounted on his wall in the living room on his house.

Bluelion wrote:
I will lightly ride these bikes just to see how they run. I will not race them. They will be display bikes. I will take them...

I will lightly ride these bikes just to see how they run. I will not race them. They will be display bikes. I will take them to bike shows and things like legends of heroes displays. I have other vintage bikes to race.

PN27416 wrote:

Any event you want to show it with the Legends & Heroes. Please let us know!

pete@legendsandheroestour.org

I sent you an email.

Bluelion
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2/24/2026 3:45am

So I’m one of the very last things I need to do to this bike is put a chain guide on it. I could not find one that would be correct for this bike. So I just had to make my own and I worked off of pictures I first made one out of cardboard to get the pattern. Alot test fits to get it right. But I finally got it and I’m very happy with it.

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Bluelion
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This is the chain guy that was trying to copy.
C5704F99-17F0-465A-B81A-8D7F67934D0E

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Bluelion
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2/24/2026 3:48am

The cardboard pattern. I came up with to cut the 2 chain guides half’s out of aluminum.

40F6B221-7BCE-4A5B-81BF-4029BB3D0FA6
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Bluelion
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Aluminum blanks cut to shape.

FD4F836D-7F3C-421E-BB2B-CDFDDC2834AF.jpeg?VersionId=4601wdiB YTocMU.U49hwJjEqELrY2b
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Bluelion
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Finished product installed on the bike.
63786C88-E2EE-4B9C-B2E2-81C2D933265D

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Bluelion
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Bluelion
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PN27416
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2/24/2026 5:03am

Well done!

Bluelion
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2/27/2026 3:25am

So I have decided to try to make an aluminum brake lever just for fun. Something trick to put on the Mugen project. Hand made parts are always cool.
69DD668F-2C82-48EF-9BC8-1CB6C6A11B52

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Bluelion
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Bluelion
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I have the lever refined, and all of the parts made so I did a mock up to see how everything fit’s before I tig weld it up.

F7065107-3439-42AF-A2C0-2DE278B8E598.jpeg?VersionId=B57Uuoteae.yPcTicaIWNjZpoaOc60
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Bluelion
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Bluelion
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2/27/2026 3:32am

I will tig weld it up this weekend.

335A058F-2895-4740-A2E0-8FD62A411876
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Bluelion
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Bluelion
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3/2/2026 5:53am

It was a beautiful day here last Friday, so I got the bike out for a little photo shoot. Here are the pictures.
C630E576-17D9-4BEE-8124-5199389B3123D8DEB00F-E50E-463F-829F-80C8A60BA252.jpeg?VersionId=RvOk4sfocUKswK2qE

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bbitunjac
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3/2/2026 6:20am

Bluelion, that thing turned out fantastic, good job. I hope IF you decide to ride it a little to come to Red Buds grass race and let it sing.

Bluelion
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Bluelion
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