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76 XS650: Hardtail Project

Discussion in 'The Garage' started by Voldo, Jun 12, 2019.

  1. Voldo

    Voldo XS650 New Member

    Hey, everyone.

    First off, I want to say this forum is a tremendous resource and I am very appreciative of all the info you guys provide. That being said, I am looking for some guidance.

    Ok, so here is what I am working on. Please disregard the seat/sissy bar fitment and the messy garage. The PO had the seat pulled back to match the sissy bar but I am going to swap it out for a solo seat.

    [​IMG][​IMG]

    I picked this up kind of on a whim about a month ago after I sold my Jeep and was itching for another project. I am new to working on motorcycles but I’ve worked on cars most of my life. Different beasts but similar concepts I suppose.

    When I got the bike it was covered in surface rust. It ran but needed to be gone through a bit. Leaked fuel at the carbs and fuel had leaked back into the crankcase so I drained that and then cleaned the carbs, replaced the floats that took on fuel and rejetted since it has a Speedster pipes and cones. I did find there are different diaphragms in each carb. [​IMG] The needle slide fits tighter in the one than the other. Seems some components from other years were used during a previous cleaning…Anyhow, got the carbs back on the bike and leaks are gone. Haven’t taken the bike out since it needs tires but I anticipate I’ll need to tune it further once a road test has been completed. I need to adjust the mix screw to get the idle dialed in. Dead cylinder method is on the list.

    I checked the cam chain tension. Found some oil under the crown nut which has me a bit concerned. My gut tells me this shouldn’t be happening… [​IMG]

    After that I checked valves. Right bank needed a little adjustment but left bank was good. One thing I found odd was when I rotated the crank via the kicker (bike is kick start only and rephased) at a certain point the cam would flop, for lack of a better word, around to the sloppy TDC mark the PO made. (i took plugs out) Is this a symptom of the rephase or is something else happening here? It seems like it should not just “fall” around.. could something be loose that shouldn't be? Or is it just the piston falling? Realizing now I should check the other motor I have to see how it acts upon rotation since it is all stock.

    Plugs looked nasty. Need to replace then inspect.
    [​IMG]

    Timing has not been confirmed. I need to grab a timing light. The timing card is missing but I believe I have a template to print out that should work.

    Also replaced the shoes and cleaned up the rear drum. There is not a return spring on the lever but the rear brake pedal no longer sticks. I found a guide on here that was very helpful in this process.

    On the not so mechanical side of things: I picked up a 21” wheel from a tt250 so I can run a mini drum. Also because I like the look of a 21” wheel up front. Form and function. I still need to get the actual drum, lever, weld stay tabs, etc. and will do so as cash flow allows. Also, figure out a way to mount the thing since the axle sizes are different. I think I have that covered but it is lower on the priority list than some other items. Getting the idle and tuning dialed in and new tires is top of the list.

    [​IMG]
    Not the best angle but oh well.

    So, I supposed that brings us to present day.Thanks for reading and any input on the aforementioned concerns is greatly appreciated!
     
    gggGary and Jim like this.
  2. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Welcome to the forum, Voldo.

    Your carbs look to be '76-'77 model, but best to confirm.
    The left slide in your pic looks like an aftermarket replacement.
    Best to run projected tip plugs, like BP7ES or AP63.
    A little oil dribble from the uncapped tensioner adjuster is normal.

    Best to pretend that the existing TDC marks on your rotor are bad/wrong/missing, and re-do them properly with piston-stop method. It'll help in understanding the rephased engine.

    The "cam flop" would indicate a stretched timing chain.

    Double-check your rear brake work, using 5twins thread.

    http://www.xs650.com/threads/650-rear-drum-brake-plates.51046/
     
    Last edited: Jun 12, 2019
    gggGary and Jim like this.
  3. Voldo

    Voldo XS650 New Member

    Thanks, twomany! Also, thank you for your response.

    According to the images in the carb guide I have the 76 carbs.
    I actually just came across a thread after I posted this on the plugs so I will give that a try.
    Good to hear the oil at the tensioner is normal.

    As far as a stretched timing chain- is replacement the only solution here or is further adjustment on the tensioner ok? A stretched chain could be the source of other running woes as it messes with the timing, right?

    I used the info 5twins provided in this thread for the rear drum work. It feels way better now.
     
    Jim, gggGary and TwoManyXS1Bs like this.
  4. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    You'll want to double-check the rear brake cam alignment, the "mystery dimple", as noted in 5twins' thread, above. (Oops, I see that 5twins updated his post for that).

    I'll generally advocate replacing the camchain, and the front guide. Seem to be a common "new member" issue. The later engines can tolerate a bit more chain stretch, but that's a risk judgement thing.

    You could do a forum search on "camchain stretch", posted by "Twomanyxs1bs".
    About 18 threads there. Enjoy the eyestrain...
     
    Jim and gggGary like this.
  5. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Shouldn't run mix n match slides, the different rubber will probably result in different raise and fall rates, not good (for anything).

    :agree: oil at cam chain cover expected.

    a bit of cam movement is normal the valves pushing on the ramps change any slack from front to back twice a rev. Use the adjust while idling cam setting procedure for most consistent setting.
     
    Last edited: Jun 12, 2019
    Jim and TwoManyXS1Bs like this.
  6. Voldo

    Voldo XS650 New Member

    I was a bit concerned about the slides being different since the needle retainer disc (not positive on the exact nomenclature) is a bit more snug on the one than the other. I cleaned and "polished" the sides of the disc for good measure. It rises fine when I move the need manually so I figured it was ok to run. I could see how it may not act the same as the more loose (better?) fitting brother in the other carb.
     
    gggGary likes this.

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