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Thread: 1985 ATC125M still smokes after rebuild

  1. #1
    Join Date
    May 2016
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    1985 ATC125M still smokes after rebuild

    Hello,

    I'm a new member but have used this site for years for great info when working on my trikes. I presently have a 1985 ATC70, 1985 ATC125M, and a 1986 ATC350X. I'm about done with the 125m and just refreshed the top end with a new piston, cylinder bore, fresh valves and had the seats reground to match. After reassembling everything according to the service manual, I still have the same smoke issues I did prior to the rebuild. I did notice the one of the channels that feed oil into the top end was corroded and i bent one of the dowels when trying to remove it. I think this same dowel may have been leaking oil into the cylinder before as I had great compression and the old piston I replaced looked beautiful. I plan on replacing the dowel once it gets here (just ordered) and I wanted to see if anyone could chime in to tell me if it could cause the smoke issue (it wasn't bent before I tore down the top end but maybe the corrosion could lead to this too). Also, does anyone know how to get the old dowels out when they are stuck in place without bending them? Thanks!

  2. #2
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    Stick a bolt in the dowel with an outer diameter that is large enough to fit snug in the dowel. Heat around the dowel with a butane or map torch and use a pair of channel locks and grab around the dowel using the bolt as a support and work back and forth. This way the dowel won't collapse while you are trying to pull it out.

    Need to be more specific about the smoking.

    Is it continuously smoking or only on startup? Are you positive there's no residual oil sitting in your pipe? Residual oil in a from a failed ring set could get hot, smoke and mimic failed rings, seals, etc.
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  3. #3
    Join Date
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    What brand piston kit did you used ? Some of the old Rocky and cycle Kraft kits had real crappy ring sets and would smoke no matter what .
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
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  4. #4
    Join Date
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    Quote Originally Posted by yaegerb View Post
    Stick a bolt in the dowel with an outer diameter that is large enough to fit snug in the dowel. Heat around the dowel with a butane or map torch and use a pair of channel locks and grab around the dowel using the bolt as a support and work back and forth. This way the dowel won't collapse while you are trying to pull it out.

    Need to be more specific about the smoking.

    Is it continuously smoking or only on startup? Are you positive there's no residual oil sitting in your pipe? Residual oil in a from a failed ring set could get hot, smoke and mimic failed rings, seals, etc.
    The smoke is there from start up and was still there after allowing it to idle for half an hour or so. I can try to run it this evening with the exhaust removed easily enough to rule out that possibility as the source of the smoke. Thanks for that and the tip on the dowel removal, will be picking up a torch asap.

  5. #5
    Join Date
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    My kit is from Cycle Kraft. If that ends up being the issue who makes a quality set of replacement rings? The kit I purchased is only .25mm over. Thanks!

  6. #6
    Join Date
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    Quote Originally Posted by Vforcebrant View Post
    The smoke is there from start up and was still there after allowing it to idle for half an hour or so. I can try to run it this evening with the exhaust removed easily enough to rule out that possibility as the source of the smoke. Thanks for that and the tip on the dowel removal, will be picking up a torch asap.

    Don't run it without the exhaust on. Just take the header and silencer off and turn them upside down over night to see if oil comes out of them.

    if you rule out oil pools in the exhaust and its smoking idle through 5th then I would say your rings are shot. Did you thoroughly wash the cylinder out with warm water and dawn dish soap after you got it back from boring? In my experience, cylinders have to be uber clean. Even after I wash them, I spray WD-40 on a microfiber, lint free cloth and light wipe the bore to see if any dirt remains.

    Dirt/cutting oil and tiny shavings will stay in the tiny grooves left from a boring machine.
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  7. #7
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    Search eBay for an OEM Honda set of rings .



    Quote Originally Posted by Vforcebrant View Post
    My kit is from Cycle Kraft. If that ends up being the issue who makes a quality set of replacement rings? The kit I purchased is only .25mm over. Thanks!
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

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  8. #8
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    May 2016
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    Quote Originally Posted by shortline10 View Post
    Search eBay for an OEM Honda set of rings .
    Do they sell OEM sets for anything above standard bore? I just had it bored .25mm over stock. The oil seems to be coming from the top end anyway, I removed the pipe to have a look and there was oil all over the place where the pipe mounts. Also, there was no smoke in the crank case when I had it running, if the rings were bad wouldn't there be some smoke in there? I think my next move is replacing the all four dowels in the top end since they were less than $2 a piece. They won't be here for a week though :/

  9. #9
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    Quote Originally Posted by yaegerb View Post
    Don't run it without the exhaust on. Just take the header and silencer off and turn them upside down over night to see if oil comes out of them.

    if you rule out oil pools in the exhaust and its smoking idle through 5th then I would say your rings are shot. Did you thoroughly wash the cylinder out with warm water and dawn dish soap after you got it back from boring? In my experience, cylinders have to be uber clean. Even after I wash them, I spray WD-40 on a microfiber, lint free cloth and light wipe the bore to see if any dirt remains.

    Dirt/cutting oil and tiny shavings will stay in the tiny grooves left from a boring machine.
    The inside of the exhaust was normal by comparison to another trike I have with no smoke issues. I did not do anything with the cylinder aside from a wipe down with a dry cloth so that could be an issue. The only thing that makes me think it could be related to how the oil circulates in the head is how it's the exact issue I had before the rebuild, and the condition of the piston that I replaced (which was excellent). When I took the clutch side case off, the oil screen had crud 1/4 inch thick so whoever had it did not take great care of it. Like I said in my other reply, the new dowels are on the way so I can at least cross the one I tore up off the list of possibilities. Thank you for the help, I'll keep posting until I get this solved. This trike was literally in milk crates when I picked it up and it's down to this and a rear brake cable issue to have it 100% so this little stuff is a pain lol.

  10. #10
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    Did you replace the valve seals?

  11. #11
    efhondakid's Avatar
    efhondakid is offline At The Back Of The Pack Arm chair racerFirst time rider
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    There should be no oil in the header what so ever. If it is residual left from blow-by from before the rebuild I would run it through a few break in heat cycles to try and burn off the excess in the pipe before tearing back into the motor if it were me. Even if the dowels in the jug/head are a bit mangled the gasket/o-rings are there to seal up everything the dowels are for alignment purposes.
    2 in the back, 1 in the front.

  12. #12
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    Depending on the amount of oil, it can take days to stop smoking.

  13. #13
    sanchez's Avatar
    sanchez is offline At The Back Of The Pack Arm chair racerFirst time rider
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    Has everyone forgot the valve guides? If their shot no seal will ever work
    Appearing since '07

    Looking for a place to happen...
    Making stops, along the way

  14. #14
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    Atc125m rebuild

    Quote Originally Posted by Vforcebrant View Post
    Hello,

    I'm a new member but have used this site for years for great info when working on my trikes. I presently have a 1985 ATC70, 1985 ATC125M, and a 1986 ATC350X. I'm about done with the 125m and just refreshed the top end with a new piston, cylinder bore, fresh valves and had the seats reground to match. After reassembling everything according to the service manual, I still have the same smoke issues I did prior to the rebuild. I did notice the one of the channels that feed oil into the top end was corroded and i bent one of the dowels when trying to remove it. I think this same dowel may have been leaking oil into the cylinder before as I had great compression and the old piston I replaced looked beautiful. I plan on replacing the dowel once it gets here (just ordered) and I wanted to see if anyone could chime in to tell me if it could cause the smoke issue (it wasn't bent before I tore down the top end but maybe the corrosion could lead to this too). Also, does anyone know how to get the old dowels out when they are stuck in place without bending them? Thanks!
    I hope this email finds it way to you. I just completed a full restoration on an 1984 125m. Started and after warm-up the atc starts to smoke like a two stroke.

    First thing I noticed is the fuel is over flowing though the float bowl greatly. ( China aftermarket carb)

    Only thing I did not touch was the valves. i did set timing and valve gap correctly.

    What could it be? thanks from VT

  15. #15
    Join Date
    Jul 2009
    Location
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    Time for a topend rebuild
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

    My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10

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