New guy, DT175 woes

Discussion in '2 smokers' started by Chunche, May 8, 2013.

  1. Chunche

    Chunche Forever fixin things

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    My uncle had this DT175 sitting in his garage for 15 years, then one day he decided he wanted it gone. When he called and offered to just give it to me, the obvious response was a definite yes. Brought it home, drained and cleaned the gas tank, petcock, and carb (which was stuck closed). It has an auto oiling system for the gas, but my uncle thought it didn't work for some reason. So just to be sure I disconnected that and mixed up some 32:1 gas. After about ten kicks I got it to fire up and run, and then even got to ride it around the block a few times. My buddy hopped on it, took off down the street and then I got the "hey come help me push" phone call. Long story short, the throttle slide had a big gouge in it from somebody trying to pry it open with a screwdriver, and the carb body had a matching gouge. The throttle got stuck wide open and my buddy panicked and couldn't figure out how to shut it off so it ran for a few minutes wide open. Ordered a new carb on ebay, hooked it up and now it won't start at all. It won't even try and burp, not with starter fluid, not on gas, nothing. My first thought was spark, but I pulled the plug and it's got a strong blue spark. I'm fairly certain it's getting gas, but even if it wasn't it should still try and do something with the starter fluid. I got a compression tester from oreilly's and it read 60 PSI. I put a little two stroke oil down the whole and retested and got 70 PSI. I read a few places online it should have way higher compression than that? Maybe the rings fried from being run wide open? And would low compression be enough to have it not even try and start? I'm new to 2 strokes so this is all a learning process for me

    and a pic of the bike for fun

    <a href="http://s25.photobucket.com/user/driveline_13/media/6FBE2406-90A6-4A20-BB0B-27601D6AD26C-19145-000025EFB8996F6D.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/6FBE2406-90A6-4A20-BB0B-27601D6AD26C-19145-000025EFB8996F6D.jpg" border="0" alt=" photo 6FBE2406-90A6-4A20-BB0B-27601D6AD26C-19145-000025EFB8996F6D.jpg"/></a>
    #1
  2. dtysdalx2

    dtysdalx2 PITA but useful

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    I had one of those in the 125 version. Had a terrible flat spot in the jetting I remember.

    Didn't hit the kill switch?? :huh

    Those were prone to rusting the inside of the motor. I would check for that. Too late? 60-70 is around the bare minimum for pressure. Maybe the rings got fried.
    #2
  3. Chunche

    Chunche Forever fixin things

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    So when we got it started, we had unhooked the killswitch and ignition switch. I don't know why, but somehow the bike is wired to still have spark with those unhooked. Had it been me, I would have just yanked the wire off the spark plug to kill it. My buddy didn't think about this and tried to kill it by dumping the clutch but it just kept going on him. Finally got it pointed up a hill in third to kill it.
    #3
  4. Highside>Lowside

    Highside>Lowside Hairier Than Thou

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    Is the kill switch now connected and funtioning correctly??

    If not, that is your first order of business...
    #4
  5. mudgepondexpress

    mudgepondexpress Long timer

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    I love old DT's! Your is a 79 I believe...so here is what I can tell you.

    1) File that gouge down with a file and sandpaper. Done right it will make -0- difference in the running of the DT.

    2) Jetting stock sucks! Mine was way too rich and I had to go down 1 on the pilot and 2 on the main. Don't do this unless you know what you are doing.

    3) The ignition is a continuation of ground...ala it breaks the ground, not the hot side of the system.

    4) The autolube systems is awesome on these. Just disconnect the hose from the carb and plug the barb. run it on premix and make sure the autolube tank has a good supply. After a while you should see oil come out from the hose. It is a very small amount and doesn't shoot out, kind of dribbles (think prostrate problems). That is all you need! If it works hook it back up and start using straigt gasoline.

    5) Don't forget the 175 is a 6 speed. Mine could hit 80+ on a good day with no wind and flat...but throw in a headwind and 65 was the best it could do. No matter how hard I rode it (and I rode it with a light switch throttle), I would get 58 mpg.

    6) 18 hp and 216 or so lbs...it is a fun little bike. I miss mine greatly....wish I had it back.

    7) Don't forget a new spark plug...D8ES I believe.

    Kenny
    #5
  6. Chunche

    Chunche Forever fixin things

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    Yes, I hooked it back up to avoid the same problem



    I got a new carb off ebay for cheap, that functions properly.

    I'll worry about jetting when it actually runs:D

    I pulled the gear out that runs the autolube pump so it wasn't just running the pump dry in case it does function. After I get the motor back together, I'll probably test the autolube system. It would be nice to be able to fill up at gas stations with worrying about mixing oil.

    A light little bike with decent power + I'm a pretty light guy = what's going to be a very fun bike:evil

    Spark plug, check.
    #6
  7. dan-c

    dan-c Back

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    Under the tank is a 6 way connector that you can uplug that bypasses the ignition switch, lights, etc so you can take off the lights and shit like that. Unplug it and see if it runs.
    #7
  8. woods wizard

    woods wizard Been here awhile

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    Welcome to No.Va...expect delays
    I hate to say it but you prbably fried the top end. Exact same thing happened to my CT175. Throttle stuck wide open after a failed hillclimb, landed on throttle tube & held it wide open & spinning around in circles trying to cut off my feet as I tried to get it stopped. Upon teardown found it had taken a chunk out of the cylinder. Yours may not be that severe, but you will need to pull the cyl. off & inspect. Hope it didnt destroy the cyl. Good Luck.
    #8
  9. Scootern29

    Scootern29 Been here awhile

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    I concur with woods wizard. The chances are it siezed and stuck the rings. You will need to pull the top end. You may be able to get away with sanding the piston and freeing up the rings. But while you have it apart have it measured and maybe a new bore and piston is in order.
    #9
  10. Chunche

    Chunche Forever fixin things

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    Well I may have found the culprit. I pulled the cylinder, the gaskets looked good but I found this

    <a href="http://s25.photobucket.com/user/driveline_13/media/BFAE256A-820B-4AD3-89E1-2649C499DB08-20115-0000279922E856F8.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/BFAE256A-820B-4AD3-89E1-2649C499DB08-20115-0000279922E856F8.jpg" border="0" alt=" photo BFAE256A-820B-4AD3-89E1-2649C499DB08-20115-0000279922E856F8.jpg"/></a>

    <a href="http://s25.photobucket.com/user/driveline_13/media/79E9218A-C0ED-41F6-9D1C-704C3F5708EB-20115-000027992C5530D5.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/79E9218A-C0ED-41F6-9D1C-704C3F5708EB-20115-000027992C5530D5.jpg" border="0" alt=" photo 79E9218A-C0ED-41F6-9D1C-704C3F5708EB-20115-000027992C5530D5.jpg"/></a>

    The top ring had a weird bend on the front of it, to the point where it didn't want to come off of the piston without some help. As you can see the piston has a matching bend. Other than that the piston didn't have any gouges or broken bits to it. The bend was on the very front, directly in front of the exhaust.

    The cylinder didn't appear to be damaged however.

    <a href="http://s25.photobucket.com/user/driveline_13/media/613CA229-DD4D-4E2D-A809-E18F62BB3453-20115-00002799761C8F20.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/613CA229-DD4D-4E2D-A809-E18F62BB3453-20115-00002799761C8F20.jpg" border="0" alt=" photo 613CA229-DD4D-4E2D-A809-E18F62BB3453-20115-00002799761C8F20.jpg"/></a>

    That's a picture of the exhaust port, where the bent ring was. The spot on top is just an oil spot, you can see the smudge where it wiped away with my finger. No gouges or anything that can be felt with a finger. So maybe just a light hone and a new piston and rings (and gaskets obviously)?

    The only thing that concerns me is a comment on another forum I posted the same question about the crank. Someone pointed out to me I ran the bike with 15 year old crankcase oil in it because I forgot to change it. How does one go about checking if the bottom end is trashed too? The connecting rod moves side to side about an 1/8 inch, does this indicate worn bearings?
    #10
  11. Valleyrider

    Valleyrider I Survived The '60s

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    Your compression is not going to get the motor started.
    You should have around 120.. or somewhere there about.
    Woods Wizard and Scootern 29 are correct.
    #11
  12. fallingoff

    fallingoff Banned

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    brought back memories'

    same bike and colour

    could never kill it

    once you get it sorted you will love it

    cheers
    #12
  13. joexr

    joexr Banned

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    Valleyrider. What's the bike in your avatar? T500?
    #13
  14. spo123

    spo123 Man About Town

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    Your friend ruined the top end of the engine.
    Good luck.....could be worse.....Plan on $250 or so.
    #14
  15. Valleyrider

    Valleyrider I Survived The '60s

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    Yes, it was the cover of the Clymers manual. It's me from a magazine shoot at the old Orange County Raceway in Irvine Calif. Never knew that they were using me as a model!! No pay for it....
    #15
  16. joexr

    joexr Banned

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    Thought so. I had a '77 GT500. Had the Clymer manual too , but I don't remember the cover. Cool.
    #16
  17. baloneyskin daddy

    baloneyskin daddy bikaholic

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    Are you sure the throttle isn't sticking wide open.
    #17
  18. Chunche

    Chunche Forever fixin things

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    Well I may have found the culprit. I pulled the cylinder, the gaskets looked good but I found this

    <a href="http://s25.photobucket.com/user/driveline_13/media/BFAE256A-820B-4AD3-89E1-2649C499DB08-20115-0000279922E856F8.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/BFAE256A-820B-4AD3-89E1-2649C499DB08-20115-0000279922E856F8.jpg" border="0" alt=" photo BFAE256A-820B-4AD3-89E1-2649C499DB08-20115-0000279922E856F8.jpg"/></a>

    <a href="http://s25.photobucket.com/user/driveline_13/media/79E9218A-C0ED-41F6-9D1C-704C3F5708EB-20115-000027992C5530D5.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/79E9218A-C0ED-41F6-9D1C-704C3F5708EB-20115-000027992C5530D5.jpg" border="0" alt=" photo 79E9218A-C0ED-41F6-9D1C-704C3F5708EB-20115-000027992C5530D5.jpg"/></a>

    The top ring had a weird bend on the front of it, to the point where it didn't want to come off of the piston without some help. As you can see the piston has a matching bend. Other than that the piston didn't have any gouges or broken bits to it. The bend was on the very front, directly in front of the exhaust.

    The cylinder didn't appear to be damaged however.

    <a href="http://s25.photobucket.com/user/driveline_13/media/613CA229-DD4D-4E2D-A809-E18F62BB3453-20115-00002799761C8F20.jpg.html" target="_blank"><img src="http://i25.photobucket.com/albums/c75/driveline_13/613CA229-DD4D-4E2D-A809-E18F62BB3453-20115-00002799761C8F20.jpg" border="0" alt=" photo 613CA229-DD4D-4E2D-A809-E18F62BB3453-20115-00002799761C8F20.jpg"/></a>

    That's a picture of the exhaust port, where the bent ring was. The spot on top is just an oil spot, you can see the smudge where it wiped away with my finger. No gouges or anything that can be felt with a finger. So maybe just a light hone and a new piston and rings (and gaskets obviously)?

    The only thing that concerns me is a comment on another forum I posted on about the crank. It was pointed out to me that I neglected to change the 15 year old crankcase oil (stupid mistake) and possibly damaged the crank. How does one go about checking if the bottom end is trashed too? Since it's this far apart I'd rather make sure everything else is working before I put it back together. The connecting rod moves side to side about an 1/8 inch, does this indicate worn bearings?
    #18
  19. Valleyrider

    Valleyrider I Survived The '60s

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    First, something went in or out the exhaust to do that kind of damage.
    Do you have a strange rattle if you shake the exhaust pipe?
    Some side to side play is normal at the piston end of the rod.
    The important thing to look at is the crank end. Is there any discoloration of the rod? can you get any play if you lift the rod straight up and down with the rod at top dead center? If so, the crank will need freshening up/rebuilt.
    The "Crankcase Oil" you refer to is not in the crank area. It lubricates the transmission. You should probably make sure it has the proper amount of oil in it, but it is not the cause or future cause of any crank issues.
    #19
  20. Chunche

    Chunche Forever fixin things

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    I believe the crank is ok, no discoloration, no play up and down. I did however get a chance to take a closer look at the cylinder, and I think you're right about some sort of debris entered the exhaust port. There's no rattle in the exhaust so I'm not sure where it would have come from. Could built up carbon cause such damage? Because there was quite a bit in the exhaust port. I also found damage to the cylinder wall that matched the damage to the piston and ring right above the port, so I'm going to take it down to a local bike shop tomorrow and see if it can be bored out, or if I'm looking at a new cylinder.
    #20