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Thread: Perplexed in Iowa

  1. #1
    Join Date
    Nov 2015
    Location
    Davenport iowa
    --
    1,144

    Perplexed in Iowa

    Okay folks need some help. We have a ATC 90 Bored 5mm over, stroked, ported head, bigger cam, heavy duty valve springs. The machine smokes bad, runs good, idles good, good compression. We’ve had the top end off 4x now. The trike is actually dripping oil out of the exhaust. We have Inspected rings (new rocky) without taking off piston and no obvious signs of breakage. We’ve inspected the valve guide with no obvious signs of breakage. We thought after our last pull off that we had found the problem with us forgetting to put in a stud guide where the oil seal goes. That didn’t solve the issue either. We did have a bad tick and that was caused by the intake valve hitting the piston we have fixed that. We have rebuilt 50 of these or so and have never had one smoke like this before. We are now leaning towards a bad exhaust valve guide. Any thoughts as to what we could be missing here?
    90 nickolson Bored and Stroked "The Good"

    Big Bore 110 Pauter frame "The Bad"

    90 Bored and Stroked “vey’s frame” "The Ugly"

    110 JSC frame Bored and Stroked
    flat track build. “Shop trike”

    1974 original 90 X 2

    1974 Original 70.

  2. #2
    Join Date
    Jul 2010
    Location
    Arkansas
    --
    2,196
    Any oil leaks besides the exhaust?

    Is the crankcase venting properly? Vent tube pinched or has it been modified with an extra vent?

    Dirt daubers here will plug any and everything up so I start looking in holes right off. Do y'all have any of those there (AKA mud wasp)?
    The story of three wheels and a man...

  3. #3
    Join Date
    Nov 2015
    Location
    Davenport iowa
    --
    1,144
    Quote Originally Posted by ATC King View Post
    Any oil leaks besides the exhaust?

    Is the crankcase venting properly? Vent tube pinched or has it been modified with an extra vent?

    Dirt daubers here will plug any and everything up so I start looking in holes right off. Do y'all have any of those there (AKA mud wasp)?
    We considered that and it did not have a vent. So we vented the head this last time.
    90 nickolson Bored and Stroked "The Good"

    Big Bore 110 Pauter frame "The Bad"

    90 Bored and Stroked “vey’s frame” "The Ugly"

    110 JSC frame Bored and Stroked
    flat track build. “Shop trike”

    1974 original 90 X 2

    1974 Original 70.

  4. #4
    Join Date
    Aug 2016
    Location
    East of Worcester ma
    --
    1,326
    Who put the 2-stroke gas/mix in the Atc 90 gas tank.......just Kidding

    shep

  5. #5
    Join Date
    Nov 2015
    Location
    Davenport iowa
    --
    1,144
    Quote Originally Posted by Shep1970 View Post
    Who put the 2-stroke gas/mix in the Atc 90 gas tank.......just Kidding

    shep
    I wish it was that easy.
    90 nickolson Bored and Stroked "The Good"

    Big Bore 110 Pauter frame "The Bad"

    90 Bored and Stroked “vey’s frame” "The Ugly"

    110 JSC frame Bored and Stroked
    flat track build. “Shop trike”

    1974 original 90 X 2

    1974 Original 70.

  6. #6
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,722
    Is it a one piece oil ring ?
    I’ve see plenty of bad sets of rings back in the day .
    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

  7. #7
    Join Date
    Nov 2015
    Location
    Davenport iowa
    --
    1,144
    Quote Originally Posted by shortline10 View Post
    Is it a one piece oil ring ?
    I’ve see plenty of bad sets of rings back in the day .
    It is Mike, also with a leaky head as in guide I would think oil would burn off after a few minutes of run time. Honestly, we have never had one of these start so well, idle and throttle up and smoke so bad.
    90 nickolson Bored and Stroked "The Good"

    Big Bore 110 Pauter frame "The Bad"

    90 Bored and Stroked “vey’s frame” "The Ugly"

    110 JSC frame Bored and Stroked
    flat track build. “Shop trike”

    1974 original 90 X 2

    1974 Original 70.

  8. #8
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,722
    I would lightly hone the cylinder and get a different set of rings .
    Back in the day we built a lot of these motors and new which ring sets not to use and the sets with the one piece oil rings always smoked like a freight train lol . Rocky and big Al’s were the worst !
    Last edited by shortline10; 11-14-2021 at 07:11 PM.
    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

  9. #9
    Join Date
    Jul 2010
    Location
    Arkansas
    --
    2,196
    That one piece oil ring makes sense to me because there's one gap with no way to stagger anything like with the three piece sets being able to stagger the gaps in both rings and the expander.

    I've worked on some older Honda motorcycles, but never came across a one piece oil ring. Was a good day; learned something new.
    The story of three wheels and a man...

  10. #10
    Join Date
    Nov 2015
    Location
    Davenport iowa
    --
    1,144
    Quote Originally Posted by shortline10 View Post
    I would lightly hone the cylinder and get a different set of rings .
    Back in the day we built a lot of these motors and new which ring sets not to use and the sets with the one piece oil rings always smoked like a freight train lol . Rocky and big Al’s were the worst !
    i would love to find a 3 piece ring set if i knew of a brand that would fit I'm wondering if Honda rings fit the Rocky pistons/
    90 nickolson Bored and Stroked "The Good"

    Big Bore 110 Pauter frame "The Bad"

    90 Bored and Stroked “vey’s frame” "The Ugly"

    110 JSC frame Bored and Stroked
    flat track build. “Shop trike”

    1974 original 90 X 2

    1974 Original 70.

  11. #11
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,722
    Some OEM Honda rings fit . Years ago I had plenty of just about every size in stock .
    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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