XR500 Mugen Baja Commander 1979-82 exhaust header

[eric318]

Yes, I know, I might just as well be looking for the philosopher's stone... But the internet has already brought me its share of surprises.

So here is the deal.

I am rebuilding 2 C&J XR500, to get them as close as possible to the Al Baker's bikes.
Back in the day, Al Baker built an handful of racing bikes with Mugen parts, ensured Honda's domination in US desert races and then started selling his success in the form of the "Baja Commander Mugen power kit".

It had a whole bunch of goodies in there (valve springs, clutch basket, S&W carburetor, 503cc piston, exhaust, etc...). Most of the inside parts can be emulated with more modern and easily accessible parts (Megacycle etc.) with similar performance results. The pieces that are proving elusive though are the exhaust headers and y piece. These are also very visible, so i'd like to get them right. Luckily, I already have the Mugen/Al Baker megaphone!! and I am using a Lectron which is as close as one can get to the EI Blue Magnum / S&W of the time.

So, it is up to you all. I am taking anything, rusty, damaged, photos, measurements. One of you has to have one of these things either on a pristine machine or in a box waiting for a project.













Thank you!!

[LWC82PE]

If you go to www.vintagefactory.com there is a couple photos/sales adds for the XR500 Mugen/Baja bikes & parts. Also i think i have some photos somehwere showing the Cibie light kits they had on these too. I know for sure those lights were sold on mounts by Malcolm Smith as they show up in their catalog. The kit was usually just Cibie Super Oscar driving 8" driving light which you can still readily buy and are exactly the same as they were back then. If you want you can even take out the globe socket and fit a H4 socket so you can run hi/low beam in it. When Baker actually raced he had one of those plus 2 of the smaller normal Oscars on each side if your replicating his bike to taht degree. Also you might want to check out www.bajadesigns.com as they were selling those 8" light kits up till a few years ago but now sell a similar thing but they updated the mount and have their own light insert made which was based of the Cibie but the optics are optimised for the variation in the pitch of the motorcycles suspension as the Cibies were really only designed for cars, so now they have just upgraded things a bit.

[eric318]

Thank you sir, I had been toying with the idea of going as far as the lighting, but this was last one my list . I already have a 12V, high power stator to put in there when I rebuild motor no.2 (both with PE01 79-80 serial numbers). So this is very useful. I'd be very happy to get copies of your pics!

Incidentally, I am in touch with a guy who knows where the rolling chassis of Johnny O'Mara White Machine is... Not for sale of course (and even it if were probably at least one zero out of my range), but may come useful one day...

Since I am on the subject, I am still wondering what front fork would be the most resembling. Right now I refurbished, painted and stickered a 43mm Showa from a 83 CR480R. It looks the part  but the bulges at the top of scutcheons give the game away. I was told by a guy who actually talked to Al Baker about the White Machine in Carlsbad when Johnny raced tpook it out, that it had a factory 43mm. May be a 41mm from a 81 CR450R would take me closer? Although I am told these were not good. What you think?

[LWC82PE]

Hi can you please make it clear if you are doing a twin or single shock XR Baja replica?

[eric318]

A double shocks, like on the picture above (I use "twin" with caution as apparently in the UK what they call "twin" is a ProLInk and in the US what they call a "twin bed" is a "single bed" go figure...).

[christianB]

hello, im new here.
 
maybe i have what you need..
i think its  mugen???

[eric318]

Hi Christian B,

Indeed, if this is not a Mugen header it resembles wildly!

Would love to convince you to transfer ownership

Will send you private message.

[eric318]

Hi Christian, yes we also have the same White Bros swingarm ! This is the 3rd one I see ever!
Here is one of my XRR:



This one also has an unusual exhaust header, no idea where it comes from (White Bros too?).

Does yours have a White Power shock/spring? The fork also looks like a 82-83 Kayaba/Showa. Great bike!

[eric318]

Here are the two XR500 C&J, work in progress



Note that the Fox air shcoks cannot work like this. They are just placed like this waiting rebuild.
Also note that the shocks (Ohlins) on the white one (Mugen) are replaced with pieces of wood as they are being rebuilt too.

[christianB]

This one also has an unusual exhaust header, no idea where it comes from (White Bros too?).

Does yours have a White Power shock/spring? The fork also looks like a 82-83 Kayaba/Showa. Great bike!

may be its a ordinary XL500 exh.header?

also i thought first its a white power shock, but i´ve compared your photos in picasaweb.
now i´m sure its öhlins, the spring is just colored white.

the fork is kayaba 82. before was maico, but i sold all maicoparts.

here you can find pictures, where i bought the xr:
http://www.xr-forum.de/index.php?PHPSESSID=menftlo502dmh27fl10m4fr8140ppgu9&topic=17314.0

cheers, christian

may be its a ordinary XL500 exh.header?

ok, i was wrong.
-looks completely various...

[eric318]

The stock XL/XR headers are quite different from this.

This is so funny, we have sister bikes!
Same swing arm, same shock, same fork. Mine was a bit of a mess when I bought it though.



But it was quite easy to make nice again. Next job is the 92mm Wiseco piston waiting in the box and a better carburetor. I can choose either a Mikuni 38mm round slide or one from a Suzuki DR600.
Funny I also had a Magura 312 throttle years ago but gave it to a friend.
What carb do you have ?
The swing arm is actually a White Bros, not a Mugen, I believe but if you know better let me know!
I drew this conclusion from this photo, which I believe shows the White Brothers (were they twins?) and their machine, but I could be completely wrong. It does look like the sticker on the swing arm says "White Brothers" ...



I see yours has a XL motor? So you no longer have the rectangular valve reed box right?

Here is another one of these exhaust headers on the Paris Dakar winning XR550R in 1982:



Here is a close up of the Ohlins after restoration by Ohlins so you can be certain of what you have:



I would love to see a close up photo of yours: the piece of plastic that protects the shock from stone projections by the rear wheel. This is missing on mine.

Thanks,

EF

[eric318]

Also, any chance you could measure the diameter of the twin pipes on the exhaust header?
Thanks,
EF

[eric318]

Here is where the Al Baker replica project is at this week. All nicely repainted, all new bits everywhere.







As for the exhaust header, I found a local artist who is on his second attempt with this:



Getting there...

[eric318]

... and here is the bike on the starting line of the Baja 250 in San Felipe, Mexico in March. Project complete! Well not quite, I still need that Mugen header! Saw one on a bike for sale in the UK a few months back, but was gone before I placed my bid...

Any other option?

Thanks,

EF

[firko]

... and here is the bike on the starting line of the Baja 250 in San Felipe, Mexico in March.

Does the 'Clam Man' still sell clam tacos and burritos down on the beach in San Felipe? They were unbelievably good mmmmmm

Nice bike by the way.

A few minutes later: Well I guess the Clam Man's no more.http://www.blueroadrunner.com/clamman.htm San Felipe's a great little party town with plenty good desert riding. We used to ride from San Felipe to Ensenada, all off highway....drink Margaritas and Modelo beer at Hussongs Cantina, camp the night and ride back the next day. Great riding country .