XR500 Mugen Baja Commander 1979-82 exhaust header

[sudman]

Used XR600 headers on hot XR500 and work well as header is bigger than 500, I have two C & J but XL350 models.

[eric318]

Well, this was my first shot at the race and I did not really have much time for tourism!!
Here is a little race report... http://www.xr500only.com/baja-250-san-felipe-2012
Next year I will do the Norra instead, I am told it is better for dilettantes like me

[eric318]

Ah yes, a XR600 header... that might be a good place to start. Will try.
Thanks,
E

[FourstrokeForever]

Ahhh, I am in envy with your bike. Very nice job! I am currently in the middle of building a 1976 C&J framed centre port XL350 that will be 410. I just finished fabricating the seatbase and foam last night at around 11pm....I intend the bike to look like the Works 76 XL250 (305) that Marty Tripes rode so will pretty much look like a 76 CR250 with more suspension and a big old 4 stroke. I do however need a swingarm for it. I also have an original 79 XR500 that I am contemplating building a White Bros replica from, but then I have no original 79 XR left. I have the swingarm!!!! and a set of 79 elsinore forks that I was intending to use but I read you are using 43mm forks. Did the original Baker and White Bros bikes have 43mm forks? Is the tank you use from a 79 elsinore? I also have a set of White bros XR600 headers that I will be fitting up. Should get more than enough flow from them I think. Once again, nice job!

[sudman]

TBM my side port C&J had no swing arm, so fitted a TS250ER which works well

[eric318]

Ahhh, I am in envy with your bike. Very nice job! I am currently in the middle of building a 1976 C&J framed centre port XL350 that will be 410. I just finished fabricating the seatbase and foam last night at around 11pm....I intend the bike to look like the Works 76 XL250 (305) that Marty Tripes rode so will pretty much look like a 76 CR250 with more suspension and a big old 4 stroke. I do however need a swingarm for it. I also have an original 79 XR500 that I am contemplating building a White Bros replica from, but then I have no original 79 XR left. I have the swingarm!!!! and a set of 79 elsinore forks that I was intending to use but I read you are using 43mm forks. Did the original Baker and White Bros bikes have 43mm forks? Is the tank you use from a 79 elsinore? I also have a set of White bros XR600 headers that I will be fitting up. Should get more than enough flow from them I think. Once again, nice job!

I there, beautiful work you are doing there. well done!

Your swingarm: are you saying that you want to build a WB replica from a stock XR79 swingarm? Do you mean that you want to put something like this on your C&J frame? http://www.ebay.com/itm/WHITE-BROTHERS-ALLOY-SWINGARM-XR-500-AHRMA-VMX-GP-/230813853144?pt=Motorcycles_Parts_Accessories&hash=item35bd93e5d8&vxp=mtr. Otherwise stock XR swingarms are in abundance on eBay (I will even list one there myself today, need to start making room...).

The fork: I do not know for certain what Baker used and I suspect it varied with the years, 39mm factory, 41mm or 43mm... Since I wanted to ride, I went for the biggest Showa. One chap who had actually seen the White Machine in MX guise in Carlsbad told me that it had to be 43mm, but memories... It turns out that the Showa 43mm from the 83 CR has the upper part of the scutcheons enlarged, so it does not really cut it visually, although I managed the trick by using the right rubber fork boots. The more I think about it, the more I believe that Baker used the 39mm for certain and you know how hard these are to come by: there was one on a "ex Al Baker" XR500 C&J for sale last month (with magnesium engine covers), not sure if it sold already (I will pass, too many projects...). He may also have used a 41mm... I eventually got one from a 81 CR450R, one day I will get to that one...

The tank: I first went with a 79 CR250R and then discovered that the fuel petcock had to be moved to the left side and forward to avoid fouling the frame. Then I changed direction for the whole bike and went the route of the "Baja Commander" version on which Baker used a plastic Vesco tank. Got one easy off eBay and did a complicated paint job that worked well. See here: http://www.xr500only.com/restauration-tips/how-to-paint-a-plastic-tank-and-use-it-normally

The exhaust header: isn't the XR600 header a dual pipe one?

Re the "White Bros* bikes, sorry, I know nothing.

[sudman]

TMB this is my 75 Baja bike it was raced in Baja 1000 in 1975, it's Bill Bell bike made by Long Beach Honda, I also have the MR250 tank for it as well.

[eric318]

Superb, I love it!

[Zakk]

i've got an new Megacycle race cam for the single carb XR500 plus about 12 Champion race plugs, send me an offer via PM if anyone's interested.

[FourstrokeForever]

Hi Guys,

Sudman, that's a lovely Bell bike you have there. My frame looks similar to the Bell bike although the upper shock mounts look to be a bit further forward.  While I can appreciate the TS swingarm, I want to retain the lay down shock positioning. I have a 77 XL350 swingarm that does the job of giving the bike 8.5 inches of travel with Marzochii MX580 piggy back shocks. However, I badly want the original C&J box section swingarm if for no other reason than having the bike look correct. I have the required travel with the XL swingarm and my wheelbase is spot on at 57 inches so maybe I can get an arm made out of box section to the same specs as the XL arm. What are the forks on the Bell bike? I've settled on 1977 RM370 kayabas as they are 39mm and have 8.5 inches of travel to match the rear and they were pretty much the bench mark fork for 1977. I do intend to ride the bike in Pre78 class racing so I need to stay within the rules. I'm not entirely happy with the suzuki clamps, but hey, what else is a man to do and where do I stop spending? Beside which, the front end geometry is spot on with 28 degrees rake and 4 inches of trail.....  I will however try to adapt a Honda XL / MT brake hub to the suzuki fork. Not only is the Honda brake so much better (in my opinion at least), It will also look like Honda!
Eric318, Thanks for your information. I have a White Bros "banana" swingarm for my 1979 XR 500. I'm just not sure I want to bastardise the XR as it is very much an original survivor bike apart from 38mm Mikuni and SuperTrapp silencer. Even has the original 23 inch wheel with the "claw action" tyre still on it!
To my way of thinking, the Baker bikes would have used 39mm forks as I'm not sure there were 43mm forks available in 1978,79. I think even the "factory" Honda's of the day only had 41mm forks but where do you find them?, let alone the cost. There are the Yamaha 41mm Kayabas.....Maybe he used them and put Showa stickers on them?
The swingarm I refered to as needing is a C&J for my 1976 Frame. Any help in obtaining one of them would be much appreciated. I will have to get some pics of my build for you guys to check out.

[eric318]

Hey TBM,

I'd love to see pics of your banana WB swingarm.

I have been thinking of letting go my C&J straight swingarm (from XR500 frame) to replace it with a Thor repro.
Here is a photo. I am not sure it would fit a XL350 frame, but we could check dimensions.
Interested?
It is the white one in the photo. This is an authentic period C&J, hardly ever used judging by the condition of the paint. not even holes for the chain guide

[FourstrokeForever]

Eric,
I will take some pics for you and check the dimensions with my stock 79 XR swing arm

Cheers