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new to me 83 xj900 seca - need some advice

Discussion in 'XJ Modifications' started by mario hernandez, May 5, 2019.

  1. mario hernandez

    mario hernandez New Member

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    I just picked up a clean 83 Seca 900. Sat in a guys barn for 12 or 13 years. He had the carbs rebuilt and all the fluids changed so it was a runner when I bought it. Its all there and runs really well except for a couple issues. No leaks, fork seals are good, even the tank is clean! I attached a couple pics.. 20190412_172213.jpg 20190412_172229.jpg
    I haven't been under the tank sniffing around yet, but it takes a few seconds for the idle to come back down after blipping the throttle. It may have an air leak from any of the hoses/boots, but is there anything else I should be aware of with this bike?
    Another issue is the tires are worn, so I need to get some fresh rubber on. Are there any drawbacks from larger tires? Are there any clearance issues? I generally stay with the stock sizes unless I've modified a bike. I'd like to keep this one "stocky but upgraded" if you know what I mean.

    So far I've ordered -
    new stainless brake lines - (that have the anti-dive jumper included).
    new EBC HH brake pads
    new battery
    new bake levers
    Already has a 4 into 1 Kerker exhaust

    Looking for -
    A fairing screen - actually still looking for one that's not $230.00!
    If anyone knows a place that makes factory style decals that would help also.
    I'm investigating suspension upgrades. If you have replaced the suspension, what did you use? I found tons of stuff but what worked for you. I'm 6'3" 250 lbs and ride somewhat aggressively (in my 50s) so maybe not so aggressive. LOL

    I'll be spending the next month or so polishing up parts and cleaning her up for the summer so any advice will be welcome.

    thanks!
     
    Andrew Nichols likes this.
  2. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    1. Vacuum leaks are most likely at:
    a. Intake boots (including the base gasket).
    b. Vacuum caps on said boots
    c. The petcock vacuum line
    d. Throttle shaft seals (leaks here can be hard to detect).
    Other things that can cause a hanging ilde are improper carb synchronization, air jets being put into the wrong locations, throttle cable or tube in need of cleaning and lubrication.

    2. Wider tires have no real value on older macchines (because frame geometry), and a wider rear will rub on the driveshaft housing.

    3. Start a conversation with @chacal for parts, paint, and decals.
     
  3. mario hernandez

    mario hernandez New Member

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    thanks for the info. I'll check each of your recommendations. Planning a road trip this summer to WV for a music festival. Got other bikes to ride but i want to make the trip on the XJ.
     
  4. mario hernandez

    mario hernandez New Member

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    got another thought.... I've read the anti-dive feature doesn't work very well on this model. Have you tried to disable it or bypass it? Or is this a case of the internet providing me with more ailments that don't need curing?

    thanks
     
  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Personal biases.
    The anti-dive works fine, so long as it was cared for.
    When is your trip?
    Speaking of things brake/anti-dive-related , what are the date codes on the brake lines?
     
  6. mario hernandez

    mario hernandez New Member

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    That's what I thought...probably even better with the braided lines installed.
    My trip is to a music festival in snow shoe WV. July 12 - 14. Going to take a couple extra days and ride around see what else i can get into.
    I'm certain my brake lines are original. Check it out... brake line 1.jpg brake line 2.jpg brake line 3.jpg
     
  7. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Why You NEED TO REPLACE Original brake lines w/pics

    FLush everything really good. before fitting new lines.
    I'd want to rebuld the master cylinder and calipers.
    The anti dive pistons can get sticky, but it's typically just the one on the brake-fluid side.
    I don't think we have a rebuild thread for the 900 anti-dive, but the differences are shown in the service manual and the procedures are basically the same.

    You can test the anti dive by adjusting it to the right all the way, then ride (preferably in a large, empty parking lot) and do some moderate to heavy braking. Then do the same with it adjusted all the way to the left. If you don't notice a difference, then they need to be serviced.
     
  8. mario hernandez

    mario hernandez New Member

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    I'm considering replacing the master with one from a newer Yamaha but I'll look into rebuild kits first. Any thoughts on replacing the master to a newer one?
    I've used this formula chart in the past and it work very well. see attached...
     

    Attached Files:

  9. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    No reason not to, except that you won't be able to use the original lever with a new master. You'll also have to maybe do some wiring work for the brake switch. Im not sure the newer masters use the same plug or teminals.

    IMO, brake changes don't have to look original if you're not going to show the bike.
     
  10. mario hernandez

    mario hernandez New Member

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    Agreed. I am undecided if I want to show the bike.
    I think for now I will rebuild the master to see if I like the braking once cleaned up.
    I drove this bike back in 85 while serving. I had the Honda 1000F interceptor and was riding across the country on leave to visit my folks. Met up with a couple guys on the way, one of which was riding the 900 Seca. We traded bikes for a while. I really liked it back then so I was a bit surprised to find the front brakes soft.
    Of course I'm relying on my memories but what I've read indicates the brakes were quite good.
     
  11. Chitwood

    Chitwood Well-Known Member

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    After putting braided lines on both of the bikes in my garage I can say that the brake lever is borderline too firm. I do like knowing that if I really have to grab the brakes quickly that they will be right there how and when I want them
     
  12. mario hernandez

    mario hernandez New Member

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    Agreed. I have replaced my brake lines on all my bikes. I like the feel they give. I also like the adjustable levers of newer bikes. They allow me to ride with two fingers on the lever comfortably. I haven't been able to find adjustable levers for the stock 900 Seca so I'm going through my (master cylinder) ratio tables to see if I can find a replacement that has adjustable levers, looks as close to stock (preferably from Yamaha) and better than stock feel. I'll post some pictures and everything I find in case anyone else is interested.
     
  13. Dave in Ireland

    Dave in Ireland Well-Known Member

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    For years, I was using XJ900 master cylinders on my GS850s, but eventually they got a bit tired and don't suit me quite as well as they used to. On one of them I replaced the XJ m/c with a Honda Deauville (NTV650/700) item (same 5/8" bore, from Nissin) with adjustable span on the lever and it really woke up.
    I'll shortly be replacing the other one with a Deauville m/c.
    Oh, I also used a Deauville m/c on my XS650 and with rebuilt standard calipers it's got excellent braking.
    For the moment anyway, my go-to master cylinders are Nissin/ Deauville. Just lucky the bore suits all of my bikes as standard. I don't need to replace the standard one on the XJ9 as yet, but when I do it will be... guess what?
     
  14. fardarriggerXJ900Seca

    fardarriggerXJ900Seca New Member

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    After ordering new steel braided lines for my 83 900 Seca, I realized they were so expensive because of the extra 4 fittings on the anti-dive units. Jon Fife tried for years to rebuild his, and he couldn't get them to stop leaking, so finally he just blanked them off. He's expressed an interest in European spec forks without the anti-dive. Next time I do this I'm going to just skip those hoses, and leave the original hoses to the anti-dive but use a solid bolt to attach them to isolate them.

    Your results may vary, but that's ok. They're YOUR results.

    Lauren
     

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