//ArrowChat Code
Results 1 to 14 of 14

Thread: Atc 350x problems

  1. #1
    Join Date
    Dec 2019
    Location
    Jackson MI, USA
    --
    54

    Atc 350x problems

    I am 13 years old and have partaken in fixing my fathers old 350x. I have discovered what I believe is an oil leak in the left side case where all the charging instruments are. My grandfather believes the crank seal has blown out and that is why there is oil in the electrical area of the case. It should also be noted that the electrical part was also oil soaked. Is this how it is supposed to be? Also, this motor has a bent valve. What could’ve caused this to happen? It has been noted however that this engine has had valve issues in the past. I will tear into the engine tomorrow so we’ll see what other things I find out about this engine.

  2. #2
    Join Date
    Jan 2010
    Location
    Sulphur Springs,Texas
    --
    1,005
    The stator side should have no oil in it.
    • 1985 Honda 250SX
    • 1985 Honda 350X
    • 1985 Honda 350X
    • 1986 Honda 250R



    “I Love The 350x. It’s So Bad”

    My Feedback Link!

  3. #3
    Join Date
    Apr 2006
    Location
    London Ontario, Canada
    --
    1,192
    I believe your grandfather is correct, there is an oil seal on the crank to keep the oil out. There are a couple of reasons a valve would bend, jumped time, keepers fell off the valve stem, foreign object in the cylinder to name some
    R.I.P. Sandpuppie, you are greatly missed!
    May you rest in peace Jeswinehart, deeply missed, never forgotten....
    Feedback thread http://www.3wheelerworld.com/showthr...ight=tapper190

  4. #4
    Join Date
    Dec 2019
    Location
    Jackson MI, USA
    --
    54
    Thanks for the info! My only question is will I have to split the case to change the seal or not?

  5. #5
    Join Date
    Dec 2019
    Location
    Jackson MI, USA
    --
    54
    Update: I broke a valve and bent one. One intake and one exhaust I believe. Does anyone know where I could get new ones?

  6. #6
    Join Date
    Feb 2013
    Location
    Ontario
    --
    811
    https://www.partzilla.com/catalog/ho...camshaft-valve

    Click on 8 and 9. This will show you what other models parts will fit your machine. It’s a handy site to reference part numbers.

  7. #7
    Join Date
    Feb 2017
    Location
    Corona CA
    --
    808
    Also shindy makes new aftermarket ones , an eBay search will pull them up.


    Sent from my iPhone using Tapatalk Pro

  8. #8
    Join Date
    Dec 2019
    Location
    Jackson MI, USA
    --
    54
    Thanks everyone! I finally decided I’m just going to do a complete top end rebuild. I’m going to just replace the worn out rings and all other wearable parts, to ensure that my motor doesn’t collapse on me. Plus, before the motor blew up it only had 80 pounds of compression. It needs a rebuild. Also, I’ve heard of 400ex carb swaps. Is it worth swapping the carb?

  9. #9
    Join Date
    Apr 2014
    Location
    Edmond, KS
    --
    2,531
    I thought it was. It seemed to make a little bit more power or else it just revs up quicker, making it feel like it has more power. Mine's completely stock otherwise.

  10. #10
    Join Date
    May 2009
    Location
    S.E. Michigan
    --
    1,250
    The carb swap is popular, but if I were you, I'd take it one step at a time. I don't want to discount your mechanical abilities, but at 13, just focus on fundamentals and do a nice solid job on your rebuild. Take your time, do a nice clean job, and read up the process in the official service manual. There is a lot of good info to do your top-end job correctly.

    Download it here:
    https://img1.wsimg.com/blobby/go/462...hoa_938805.pdf


    Chapter 6 is all about the top end. One of the critical areas that is highlighted in the manual is where to use hondabond sealant when you put the cylinder cover back on. There are areas around the cam journals where you need to be real precise with sealant application to avoid it getting in the cam journals and ruining the cam. The sealant is required at this particular joint since by design there is no gasket. Take a look at the picture on the bottom of page 6-17.

    ...and use a torque wrench as much as possible. The most common problem I see on these old machines is overtightened bolts that pull out (strip) the aluminum threads.
    - Frank

    1984 200ES Big Red
    1985 350X (x2)
    1986 350X
    1986 250SX
    1984 Auto-X
    1984 ATC70
    1985 ATC70

  11. #11
    Join Date
    Feb 2004
    Location
    Tionesta, PA
    --
    5,735
    ^^^As noted above, please buy the correct bonding agent - Hondabond - you can buy it on amazon or from your local Honda dealer. Do not, I repeat, DO NOT use RTV or any other silicon type sealers. Hondabond only.
    RIP - Yamahondaman!! You will never be forgotten!
    RIP - Sam Brehm!! Gone but NEVER forgotten!
    RIP - Sandpuppi101 - You will live on in my mind - I miss you friend!

  12. #12
    Join Date
    Aug 2008
    Location
    devore,ca
    --
    1,015
    Be careful on the sealant. Don't use silicone, oil makes it useless. Use just enough to do the job. If you use too much it will squish out into the inside of the engine and drop into the oil passages where it might cause problems. I've taken more than a couple apart to find the oil screens plugged with pieces of silicon.
    YAMAHA 450 HYBRID
    85 350X- RED
    85 350x -BLACK
    86 350x-WHITE (with Goki)
    85 250r
    83 atc 70
    84 atc 70
    84 atc 110
    09 yfz 450
    2006 Arctic Cat Prowler
    RZR XP 900

  13. #13
    Join Date
    Dec 2019
    Location
    Jackson MI, USA
    --
    54
    Thanks for all the helpful information! I’m glad you notified me of the sealant because I didn’t know that. It also appears that this is not the first time that a engine failure has occurred. Someone else had already gotten into it and rebuilt it in the early 90s (I think it was the 90s) because the head is already stripped out when someone else was in there. They also used silicon. I will be sure to keep you all posted!

  14. #14
    Join Date
    Apr 2012
    Location
    USA
    --
    4,114
    For the valve cover, you don't want to see the red or blue RTV, but the company makes a Gray RTV that is correct for that application. It's benefit is a slower cure time. My dad builds chainsaws up and tried a couple different gasket makers for the base cylinder gasket (base gasket delete to increase compression) and he found the Gray RTV is the easiest to work with and it always seals. Big trick is to not over apply it. The other gasket makers that are like Hondabond, Yamabond, etc set up too quick for him and he couldn't get the engine to pass a leak down test. On a 2 stroke an air leak is very bad and can make the engine burn up.


    https://www.amazon.com/Permatex-8219...a-437600037492

    Here's a couple vids.

    Not a valve cover, but it's how I've always applied RTV. Thing I have to say is, if there was originally a gasket, buy the gasket. The valve cover on the 350x is the only place I can think of where a sealant should go.

    https://www.youtube.com/watch?v=UXN4FqQH-xM


    Here's a video showing the results of someone doing it wrong and based on the guy's description, applied 10x or more too much sealant and didn't use it where gaskets should be. Gaskets have a thickness and Honda engines are designed with that gap in mind. Nothing is idiot proof, so any good thing can be screwed up by someone.

    https://www.youtube.com/watch?v=2WzELjtjslo

//ArrowChat Integreation Code //