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Old Brown

Discussion in 'The Garage' started by Team Junk, Jul 5, 2019.

  1. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Getting pretty close. working on carbs right now.

    Attached Files:

  2. halfmile

    halfmile XS Builder XS650.com Supporter Top Contributor

    Very interesting front end. What is it from?:umm:
  3. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Mid 80's tariff bike. XJ700
    Mailman likes this.
  4. nhsteve

    nhsteve XS650 Addict XS650.com Supporter

    Had never noticed that the XJ had kind of a built-in fork brace. That is pretty neat!
    Was the installation straight-forward, or did you need to hunt down different steering bearings, etc.? I notice the triple clamps do not appear to be from an XS650, as far as I can tell (?).
    Superjet and MaxPete like this.
  5. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    I never liked the original forks on my 650s. My race bike had a rather lumpy idle and I could see the front axle making a 1 inch orbit. Kinda like having the front wheel mounted to wet spaghetti. I was going to use my 78 special forks when I came across a good deal for the XJ .

    The neck on the XJ and on my 650 were roughly the same length. So….. turns out the top XJ roller bearing fit the 650 neck and the lower 650 roller bearing fit the XJ triple tree. I had to freeze the triple tree and heat the bearing in the oven.

    Then I got the bad news. Turns out the 86 Maxim was the first Yamaha designed from scratch as a special. To get the long tube look they moved the steering head higher and stretched the fork legs To keep everything straight they went with 38 mm tubes and the fork brace. The triple trees are interesting because the top tree is much higher above the top of the neck . I have the tubes higher up in the trees to try and get the axle closer to where was with the stock forks.

    I don't know if it's going to work out or not but it's worth a shot.
  6. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Check fork tube/triples to gas tank clearance at full turn also. Those triples will have much less "forward offset" because the axle sits in front of the lowers instead of below them.
    madmax-im likes this.
  7. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    It’s been a few years but if memory serves when I compared the trees they were similar except the distance between the fork clamps vertically. I think Yamaha compensated for the leading axle by steepening the steering neck angle. My plan is to adjust the tubes in the trees to get the wheelbase close.
  8. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Carburetors put back together today. They look much better at least. A funny discovery I made was the cavity next to the main jet on the underside of the bowls was packed with sand. The bike the carbs came off of belonged to my mad late friend Ted. As I was scraping the sand out a memory came to me. Ted and I were at a bike week party in Daytona and at 2:30 in the morning decided it would be a really great idea go ride on the Daytona drive on beach. That’s when I discovered the 650 is no Yamaha enduro. We spent 30 minutes turning up sand to try and extricate ourselves from the beach. My R5 race bike had a similar issue. My buddy Ned crashed it entering the bend before turn 2 at Oak Hill. After I bought from him, for years later anytime I worked on it red dirt from Henderson would come out.

    Now I wish I would of left the sand in the float bowls.

    Looks like wit a little luck Old Brown will run this weekend. I was surprised at how much the carbs had evolved between my 74 and the 78 carbs I’m using now. Again many thanks to those of you that contributed to the carb guides here. Saved me a lot of grief. I’m pretty familiar with the VM34s that I had on my race bikes as I was inside them all the time when I was racing. Only Old Brown had BS38s and after the 750 kit I never had to mess with them.
    gggGary and TwoManyXS1Bs like this.
  9. 5twins

    5twins XS650 Guru Top Contributor

    I quite like the '78-'79 BS38 carb set. I think they're about the best of the 38s. A close 2nd is the '76-'77 set but they're not quite as smooth in the lower RPMs. I attribute that to their old style slide and needle configuration. The needle is actually a bit loose in the slide and able to bounce up and down about half a MM. The spring-loaded needle in the '78-'79 carbs meters more precisely simply because it isn't free to bounce around like that.
    JAX71224, MaxPete and Machine like this.
  10. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Well hopefully I'm going to find out in a little while. I just got back from Mini Mart getting a gallon of premium fuel. I have my carb retainer hardware soaking right now, should be ready reinstalled in a couple hours. This has been a three-year journey putting her back together and I’m excited to be on the verge of getting her running. I’ve fired it off on carb cleaner so I know both sides are firing. We will see about my carb rebuilding skills.
    gggGary likes this.
  11. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Looks like the next step is to paint the gas tank and fenders. Any suggestions as to the going rate for painting tanks ? A friend that works for a body shop recommend a guy but before I go talk to him I would like to know what ballpark I’m in.
  12. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Hopefully last note on carbs. I just cleaned the rubber carb mounts and I'm amazed at what great shape they are in. I'm 99% sure they are original from new. I can only speculate it is the metal covers that extend the life span. my other bikes always had VM34s with radiator hose clamps and I was constantly replacing them. Anyone know if OEM style covers are available for the 34's ?
  13. 5twins

    5twins XS650 Guru Top Contributor

    I thought VM34s would fit in BS34 manifolds, and they would have the tin shrouds then.
  14. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    If I remember correctly I think they are different . The VMs use a smaller diameter mount I think. Could be wrong. It's what I remember from 40 years ago.
  15. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Any suggestions about oil filters ie who has good ones ?
  16. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Strongly urge someone to correct me, but I'm finding:

    BS38 spigot diameter = 48mm
    BS34 spigot diameter = 42mm

    VM34 spigot diameter = 40mm
    VM36 spigot diameter = 43mm
    VM38 spigot diameter = 43mm

    According to JBMindustries, BS34 spigots will:
    Work for 36mm/38mm VM, not the 30mm to 34mm VM carbs...

    Team Junk likes this.
  17. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    Thanks 2m. I just remember it was a pain in the ass to swap stock pipes onto my race bike to get it inspected every year. The vm34s jetted for my race pipes would make the bike spew fuel out the tail pipes so I had to change not only the carbs but also the mounts and the throttle. Of course back then most Houston cops had a short broom handle in the trunk of their patrol cars and would shove it into the exhaust to see if there was a baffle. No baffle = $55.00 ticket. Thankfully I never caught.

    The 650central floats came well packed and quickly. Installed them and to my amazement the float setting was perfect. Carbs all buttoned up and reinstalled this afternoon. Just have a couple of connections to make in the headlight bucket and can fire it up. Hope to in the morning after I watch the British GP.
    TwoManyXS1Bs likes this.
  18. Team Junk

    Team Junk XS650 Addict XS650.com Supporter

    And yes I have read it but got somewhat distracted by the flame war in the middle of it. It was a older thread so I was hoping for an alternative stock filter after all I've heard about the Mikesxs filters.

    On a side note yesterday I cut the inductive clamp off my dead timing light with the thought of hooking it up to a microphone amp module I have on my desk and then a output stage to drive a LED. Today I stumbled across your circuit, Life is funny sometimes.
    TwoManyXS1Bs likes this.

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