XR500 thread

Discussion in 'Thumpers' started by lilsmokey, Aug 3, 2011.

  1. lilsmokey

    lilsmokey Been here awhile

    Joined:
    Jun 21, 2011
    Oddometer:
    335
    Location:
    Denver, CO
    Hey guys. Just going to start a xr500 thread to see other bikes like mine. Post your pictures of your favorite Xr500's getting down and dirty.

    Also this was the xr a while ago. I have a Cobra exhaust, the tank decals were cleaned off, plastics polished, and swingarm decals detailed.

    Enjoy
    --Lil smokey--

    Attached Files:

    #1
  2. lilsmokey

    lilsmokey Been here awhile

    Joined:
    Jun 21, 2011
    Oddometer:
    335
    Location:
    Denver, CO
    [​IMG]
    #2
    fstarocka likes this.
  3. seth0941

    seth0941 NW Adventure Rider

    Joined:
    Jun 20, 2011
    Oddometer:
    483
    Location:
    Western WA.
    My new toy

    <iframe width="560" height="315" src="http://www.youtube.com/embed/aLxCsOmPxIQ" frameborder="0" allowfullscreen></iframe>
    #3
  4. 2muchtime

    2muchtime Adventurer

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    Sep 30, 2010
    Oddometer:
    29
    Keep them coming guys !!! I got a 1983 XR500 this month. Bike has been sitting for a looong time. Engine was not turning. After taking the top end apart found the reason. Both ex valves are bend. I suspect camshaft chain skip a tooth or something a lot of slack in the chain plus one of the rails was broken in half. Bike is all original with minimal mechanical wear. The piston has four valve grooves bigger for the ex much smaller for the in . It looks like the original piston ???
    #4
  5. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
    Aug 12, 2009
    Oddometer:
    727
    Location:
    border of granite & flats
    I think lilsmokey sold his bike. I saw an ad on Craigs with a link to his thread here on ADV. FYI

    Here are my XR500Rs:

    The dual sported 84:
    [​IMG]

    The 83 built back to running from parts n pieces:
    [​IMG]

    Here is what the 83 looked like when I got it and another 84 for $100:
    [​IMG]
    #5
  6. 2muchtime

    2muchtime Adventurer

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    Oddometer:
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    Nice !!! What did you do with the reed valve ? Kept it, or mod it like the '87 ?
    #6
  7. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
    Aug 12, 2009
    Oddometer:
    727
    Location:
    border of granite & flats
    I made my heads like the 85 dual carb, by plugging the reed port holes.
    Here is a photo:
    [​IMG]
    The plugs are turned/cut from Aluminum stock. I made them to be a slight press fit. My heads had different sized reed valve port holes. So the 83 has slightly larger plugs. The right plug has a fancy groove in it done by hand with files so that the valve cover gasket and valve cover will sit flush to the gasket surfaces. I made a pattern out of wood dowels to get this right the first time.:D There are punch centering recesses in the top of the plugs to make tapping them in easier.

    The much easier way to plug up the holes is to get a newer style valve cover gasket (metal) that has the reed valve chamber closed up. I did it the hard way because I had the 83/4 XR5 Athena valve cover gaskets which were silicone coated. They seal up much better than a plain stock Honda gasket. Other builders have been using sealer on the Honda gasket to get the leak proof seal. The sealer they use is the good stuff like Honda bond, and it is applied in a thin coat to prevent excess, sealer boogers getting into your engine. Search around here on ADV and you can see photos of this for the other RFVC engine builds. There should be some photos on the XRL and XR/L 600 threads. Here is a link to Steve's (mcma111) latest photo on doing this and he has better descriptions of the process elsewhere here on ADV:
    http://www.advrider.com/forums/showpost.php?p=16926663&postcount=2555

    I ditched the 83 carb boots that lack the cross port passageway, don't plug the reed valve and also run the 83 boots, the right intake valve won't get its cooling air/fuel at idle with the 83 boots and no reed valve. I used 84 carb boots and insulators on both of my XR500s. I think the 84 XR5 insulator is the best as it has the largest port holes. Some of the newer XL/R insulators have stopped down port holes. Look at these photos, top boot on the carbs is from the 83 and lacks the cross port passageway. One insulator is from the 84 XR5, the other insulator is from an 86 XR6, with stopped down port holes. Note: the insulator is a used part only, not available new anymore.
    [​IMG]
    [​IMG]

    I also upgraded my oiling systems by using the later style pump with internal shaft seals and changed oil pump drive gears to get slightly more oil volume per RPM. Lastly I used some high temperature silicone sealer to plug up the small holes between the cam bearing and the head to make sure that all the oil went into the cam like in the newer RFVC engines.
    [​IMG]
    [​IMG]

    Probably overkill, as my 'good' 84 engine survived 24 years with original components before I took it apart.:rofl
    #7
  8. seth0941

    seth0941 NW Adventure Rider

    Joined:
    Jun 20, 2011
    Oddometer:
    483
    Location:
    Western WA.
    Anyone have a downloadable service manual? Mine is a 79
    #8
  9. 2muchtime

    2muchtime Adventurer

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    29
    Sweet ! Thank you for taking the time to expand on my question. I appreciate it. I quess I have some tinkering ahead of me .....he he
    #9
  10. 2muchtime

    2muchtime Adventurer

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    29
    #10
  11. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
    Aug 12, 2009
    Oddometer:
    727
    Location:
    border of granite & flats
    Closest I've got is a link to the Italian site that has an XL500 manual (82?) on it in English (first group in the list):
    http://www.hondaxl.it/manuali.htm
    #11
  12. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
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    Location:
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    That is the stock Honda piston.

    If its the 92.0 original piston, its probably worn past the limits. My 84 with its original piston was still running quite well when I started the rebuild, but the cylinder to piston was over the limit, and the ring gaps were way over the limit.

    I had a hard time finding a 92.25 1st oversize Honda piston and ring set. Its also discontinued, but there were some Honda parts dealers that had old stock on the shelf when I was looking. The place that I got mine from has since sold out. Do a google search with the Honda part number for the piston or just get an aftermarket slug if you prefer.
    #12
  13. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
    Aug 12, 2009
    Oddometer:
    727
    Location:
    border of granite & flats
    OK, I reread your description above and if the bike was blown up awhile ago, the perhaps your piston isn't worn out nearly as far as my 84.

    If the part checks out, then run it:lol3
    #13
  14. 2muchtime

    2muchtime Adventurer

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    Leaning towards keeping it. I Measured the cylinder sleeve ID at 91.80mm. Piston looks pretty good. Do you know the service limit #'s for sleeve and piston ? Thanks

    Bike has been sitting for at least 15 years.
    #14
  15. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
    Aug 12, 2009
    Oddometer:
    727
    Location:
    border of granite & flats
    Before you ask :D, no I do not have a soft copy of the 83/4 manual. I got mine on ebay and I strongly suggest folks get one before doing engine rebuilding. There is a soft copy of the 83/4 XL600 on the Italian site I linked to above. That will cover most of it.

    Having said that, you should also know that there are mistakes in the Factory XR5 manual. The numbers you have requested are on a page with mistakes.:roflThe clymer manual also has this same set of mistakes! In addition, the cam lobe height #s are in error in the factory XR500 manual, but its the same cam as in the XL600 and XR600, so use those numbers for checking your cam wear.

    From my factory 83/4 XR5 service manual, service limits are (after adjusting for mistakes):

    Cylinder ID: 92.12 mm, 3.627 in
    Cyl taper: 0.05 mm, 0.002 in
    out of round: 0.05 mm, 0.002 in
    warpage top: 0.10 mm, 0.004 in

    Piston skirt OD: 91.85 mm, 3.616 in
    pin bore: 22.08 mm, 0.869 in (I think that is right, but check yours)
    piston to pin clearance: 0.07 mm, 0.003 in
    pin OD: 21.95 mm, 0.864 in

    Cyl to piston clearance: 0.10 mm, 0.004 in (not sure about this number, my machinist gave me a 'small hair' over 3 thou on my over bore for clearance with the new piston, which seems to be working well at the moment. I measured 8 thou on the original piston and cylinder and decided to get the 1st over replacement).


    ring gap top/2nd: 0.50 mm, 0.020 in
    ring gap oil: no limit number, just says 0.2-0.9 mm, 0.007-0.035 in

    ring to groove clearance top: 0.12 mm, 0.006 in
    2nd: same as top

    I do have a pdf file of the 84 'owners manual'. If you want a copy, PM me a email address that will accept larger attachments.
    #15
  16. 2muchtime

    2muchtime Adventurer

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    Oddometer:
    29
    Thank you so much bud. I really appreciate it. I will send a pm. Cheers ! S
    #16
  17. 2muchtime

    2muchtime Adventurer

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    Oddometer:
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    It looks as this rebuilt is going to be a little more involved....Now I need to decide which way to go about the piston and cylinder. I don't like the wear in the cylinder sleeve. It appears minimal and even but there is a slight "step" in the cylinder wall. Piston appears to be in good shape. My preference is to stay stock but at this point the $$$ option will be the deciding factor. Trying to decide between a new piston and cylinder bore to 1st over or a new stock sleeve using the same piston. Any thoughts ? 1983 XR500 Cheers !
    #17
  18. 2muchtime

    2muchtime Adventurer

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    Oddometer:
    29
    Paging ghost_mutant.....
    #18
  19. Ghost_Mutant

    Ghost_Mutant looking for bionics

    Joined:
    Aug 12, 2009
    Oddometer:
    727
    Location:
    border of granite & flats
    Sorry bro, I was out doing something important today..........riding in the mountains:clap
    [​IMG]

    Where is the step in the cylinder? I'm gonna guess its at the top. How big is this slight step? Any other indications of wear on the side of the piston?

    Also, what is your cylinder to piston clearance? I have not had good luck with the regular telescoping gauges to measure the cylinder bore, they always compress a tad upon taking them out to measure with the calipers. The best way to estimate the cylinder to piston clearance in my garage without a bore gauge, is to put the piston in upside down and carefully use feeler gauges to measure clearance directly between the top of the cylinder and the piston skirt. Don't jam the feeler gauge in there:evil

    As far as getting Honda pistons, that will be tough. There are aftermarket pistons still available and I see them on ebay quite frequently for the 83/4 XR500s. Prices are between $140-180 for the new set which includes rings. The Honda piston with rings will cost about the same amount (or more) if you can find the piston. Rings do not appear to be a problem yet. Since I've never used the aftermarket pistons, I can't comment on their performance. Its been reported here by others that the advertized compression ratios with the aftermarket pistons are on the high side. Actual compression ratios are lower, which would be good if you are running on pump gas.

    I suppose I should get some spares since I'm going to be riding this bike for a few more years.:D
    #19
  20. 2muchtime

    2muchtime Adventurer

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    Oddometer:
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    Ha ha !!! Good one. I am glad that you are there having fun bud. I will go ahead with some measurements tomorrow and report back. Piston is in pretty good shape but i think going to a 1st over right now is the best course of action, I will start looking for a piston. Cheers !:clap
    #20