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Yamaha DT50

Discussion in '2 smokers' started by Dave in Wi, Apr 21, 2020.

  1. Dave in Wi

    Dave in Wi Long timer

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    About 15 years ago a friend of mine gave me this 1988 Yamaha DT 50. He used it to teach his kids how to ride a motorcycle. They moved on to bigger and better things and he gave the bike to me.

    At the time I had to do a little work to it to get it to run. Cleaned the carb, fab’d up an air filter, and give it a once over. I used it for a few years as a pit bike at Mid Ohio vintage days, it worked great for that.

    It’s been sitting for probably 10 years now, in a garage up at my folks cabin. It hasn’t been run in at least 10 years. I was up there last weekend and dug it out. I’m going to work on getting it running again and then doing a light restoration (assuming I get it running!)

    Here it is as it sits right now:
    IMG_1802.jpg

    IMG_1803.jpg

    The inside of the gas tank doesn’t look great. Unfortunately I did not store it with a full tank like I should have.
    IMG_1819.jpg

    I’m going to start by giving it a good bath and degreasing. That’s going to have to wait till it warms up a little bit. Then I’m going to pull the carb and clean it as best I can. When I did have it running, it did not exactly run right. At part throttle it would stumble and bog, kind of right where you want the revs to be to takeoff from a stop. I could ride around it but it’s not ideal. That might be due to the foam air cleaner that I made. At the time there were no online motorcycle parts places that had parts for the DT50 at all. Now I see that some of them do have a microfiche and parts are available, so I can get an actual air filter. So anyway, clean the carb, new fuel lines, clean the gas tank and see if I can get it to run is the first step.
    #1
    Nobade, tex68w, Dauer and 2 others like this.
  2. Dave in Wi

    Dave in Wi Long timer

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    IMG_1827.jpg

    Imagine that, mice got into the air box. Little buggers. Not sure why they didn’t chew through the foam sir cleaner. But I’m glad they didn’t.

    IMG_1828.jpg
    #2
  3. Dave in Wi

    Dave in Wi Long timer

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    I have several gallons of Evapo-rust that I used on a project last year. I’m going to use that to de-rust the gas tank. But I need for it to warm up a little bit outside. I found that it works best over 70°, and it’s just not that warm in the garage yet here.

    I’m not planning on bringing the gas tank in the house. I don’t know if it’s me or if the formulation of gasoline has changed over the years. The smell of it never used to bother me, now I cannot stand it.

    It appears that a whole new carburetor assembly is available for a little over $100. I will pull off the carb and clean it up as best I can, but it is awfully tempting just to get a brand new one. It’s good to see that parts are available for this bike. Years ago when I checked, nothing was available. They are not very common in the US.

    At some point I’m going to pull up the YSR 50 microfiche and compare it to the DT 50. I suspect that they share a lot of common parts in the engine and transmission. I know that the YSR 50 had quite a following back in the late 80s early 90s. But you never hear much about a DT 50.

    Before I attempt to start it I will check the compression. Which reminds me, I do want to try to get a factory repair manual for it. I have no idea how much compression it’s supposed to have. The engine is free. It always has kicked over ridiculously easy, I’m not sure if that’s just the way it is or if it’s low on compression. It used to top out at about 45 miles an hour which seems about right for a 50.
    #3
  4. Anachronism

    Anachronism Lived Too Long

    Joined:
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    Cascadia, eh.
    @Dave in Wi : The YSR 50 engine is a POS air cooled 5 speed DT/GT engine from the 70's that should of been left there. Shares exactly zero parts & grenades when it feels like it, which is often.
    If Yamaha had used the DT50LC 6 speed engine in the YSR they would of really had something.
    The DT50 LC engine is not only a performer it is an anvil if you feed it clean air/fuel & Yamalube oil.
    Don't be afraid to rev it past redline, all three of mine would bury the tach needle & keep on screaming. If you are riding on the street it is your only choice to keep up w/traffic.
    The clutch lever from the YSR & DTLC are interchangeable just different colors. I would be surprised if they shared any other part #s.
    My second & third DT50LCs tank looked like yours. I just cleaned out the screen in the pet cock & installed an inline filter to catch any crap that made it through.
    The carb is super simple to work on. Just watch out for the tiny pilot jet as it can plug easy. I plugged mine w/a tiny piece of lint while cleaning it!
    DT50LC was available in the USA from 88 - 90. In Canada we had them until 95, the only thing that changed was the price & colors and the color was different EVERY year.
    I had three of these, one from new & 2 used, pound for pound & dollar for dollar the best small dual sport Yamaha ever made available in North America. Small & Light!
    Weak points would be drum brakes & spindly forks. Could use 12 volts w/fan & twin radiators for off road abuse. The 19/17 wheel combo severely limits tire choice too.
    Compression is somewhere between 7 & 9 to 1. It practically kick starts itself. You can use your hand to do it.
    On the street w/stock 13/48 sprockets & running right, on flat ground & drafting something bigger, you should hit 50 mph if you aren't too big a guy & you tuck down/in as small as possible.
    If you can still get the Yamaha service manual it will be pricey & the picture quality is crappy photocopy at best. Good info though. Suzuki made much nicer service manuals.
    #4
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  5. Dave in Wi

    Dave in Wi Long timer

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    Thanks for the info, that’s great.
    #5
  6. Dave in Wi

    Dave in Wi Long timer

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    One of the downsides to working at home is, I can go the whole day without poking my head outside. Yesterday I was on conference calls from 8am-4:30pm. Then I made dinner. As I was working on it I glanced at the thermometer- 65 degrees. I didn’t realize it was that warm.

    So after dinner I got out the hose & Engine Brite and gave it a quick bath. Looks better now:

    IMG_1846.jpg

    IMG_1845.jpg

    This is really a cool little bike. It has some nice design touches. Like this- the tool cannister has a soft rubber cap that is captured by the side cover so the tools theoretically can’t fall out. And they are still there. I also like how the oil tank is hinged to pivot out to fill and access the battery.
    IMG_1847.jpg

    I finally placed an order with Yamaha parts nation online. I ordered the air filter, and a carb bowl gasket. I believe last time I was in the carb I had to make a new one, or repair the old one. Also ordered new levers- the ball ends of both are broken off and they are pretty stabby.

    Also the cowl over the headlight is broken. And it’s NLA. Not too surprising for a beginner bike, the easily breakable parts always seem to run out pretty quickly. On the lookout for yellow zip ties to stitch it up.

    I was going to order a new battery from Dennis Kirk, but luckily I read the fine print. They ship dry with no electrolyte provided. I’ll have to hit up Batteries Plus, I think that’s where I got the old one.

    IMG_1820.jpg
    #6
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  7. Dauer

    Dauer Kicking names and taking ass

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    Really dig these little guys. I'm passively on the hunt for a black and yellow schemed one to compliment my '89 TDR 250. Seems like you have a solid foundation for a strong runner. Best of luck with the resto, keep us in the loop.
    #7
  8. Dave in Wi

    Dave in Wi Long timer

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    No progress yet. I’ve been waiting for the carb bowl gasket I ordered to arrive. It hasn’t even shipped yet. I’m trying to be understanding given current events. Hopefully it will be here soon.
    #8
  9. Dave in Wi

    Dave in Wi Long timer

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    Well I got four emails Friday and three today telling me the parts were shipped. Makes me wonder how many times I clicked “submit order”...
    #9
  10. Dave in Wi

    Dave in Wi Long timer

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    Well, progress he has inched to a halt. I found out why I got four separate shipping emails. Each part is being shipped separately it seems. Last week I got a card oring and the air filter element. I am waiting for the carb bowl gasket before I tear into the fuel system.

    Shipping is taking a long time these days. I know I’m not alone. Last week I also ordered two batteries from bike bandit. I haven’t even gotten an email that my order has been received yet. When I log into my account I see that the order is there and it’s being processed. So I’ll just have to be patient.

    Speaking of batteries, I went to batteries plus to get a new battery for the Yamaha. They did not have one in stock and had to order one. They said it would be 2 to 3 weeks.

    I also sent out my Kawasaki ZRX carbs to be cleaned. They should be back early next week. So at least I’ll have that to work on. I am planning on Jimmy-rigging my own carb balancing outfit. That should be interesting.

    It will be nice to have at least one running bike. I’m beginning to wonder if it’s time to get rid of the ZRX and get something newer. Fuel injection an ABS in a old school/standard/UJM style bike would be nice.
    #10
  11. Jmarklowitz

    Jmarklowitz Adventurer Supporter

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    I have nothing constructive to add. Just had a flashback. I got a 1988 blue dt50 brand new when I was 11 yrs old. My 1st real motorcycle. I rode the crap out of that thing almost every day after school for several years. Treated it like a mx'er. Never a single problem with it except flat tires. Still looked good when we sold it. Good luck with your build. I'm sure you'll have a blast tearing up the neighborhood!
    #11
  12. Dave in Wi

    Dave in Wi Long timer

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    There will be some action this week. I have the float bowl gasket. My ZRX is back together and running great. The levers are on national back order, but those can wait.
    #12
  13. Dave in Wi

    Dave in Wi Long timer

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    Sometimes just taking some small steps helps keep you moving.

    Last night I didn’t get out to the garage till later than I wanted. I didn’t want to start tackling the fuel system because I wanted at least a few hours to get into that.

    So I went through my old container of zip ties and picked out the yellow ones. I wish I could remember when I bought this. I’m guessing early 80’s. It must be old because they were made in the USA.

    IMG_1973.jpg


    IMG_1972.jpg


    I spent a little time with a pencil & ruler and drilled holes to stitch up the cowl. Not too bad.

    IMG_1986.jpg
    #13
  14. Dave in Wi

    Dave in Wi Long timer

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    Tonight I started in on the tank & carb. First I unhooked the fuel line from the petcock, attached a fuel line and turned it on to drain the tank. Nothing came out. The petcock must be totally plugged.

    Ok, so I dumped out the old gas through the filler. It smelled really weird, kind of sweet. I wish I could remember how long it’s been since I ran it. Obviously too long. I dumped the gas into an old vintage metal gas can. I’ll use it to start burn piles next winter.

    Unscrewed then petcock. Yikes.
    IMG_1989.jpg


    I tried sealing the petcock bung with a piece of inner tube with a hose clamp around it. Put the tank in a muck tub and started filling it with Evaporust. It didn’t hold and started leaking. Dumped it back in the jug and decided I didn’t have anything to lose, and put the petcock back in. Filled it with Evaporust and I’ll let it soak overnight. Tomorrow night I’ll dump it out, flush it, rinse it out with alcohol & spray down the inside with WD40 and maybe fogging oil to keep it from rusting till I get it all back together.

    IMG_2002.jpg
    #14
  15. Dave in Wi

    Dave in Wi Long timer

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    I also got the carb off and taken apart.

    IMG_2001.jpg

    Got the jets and little bits soaking in carb cleaner a small glass jar. Getting the needle jet out was a little challenging but I got it done. I plan to pick up a can of carb dip and soak the body & float bowl for a while. Probably not tomorrow night, the tank will keep me busy enough.
    #15
  16. Dave in Wi

    Dave in Wi Long timer

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    Watching some videos on De-rusting gas tanks on YouTube. I wish I had seen this trick earlier tonight. I bet I have tubing the right size, I could’ve made this work

    IMG_2004.jpg


    A new petcock assembly is like $22 online. Plus shipping of course. I’ll have to see if I can get the old one to work. but it might be worth it just to pick up a new one.
    #16
  17. Dave in Wi

    Dave in Wi Long timer

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    So I let the gas tank soak in if Evapo-rust for two days. I figured that should be enough. Tonight I dumped it out - holy cow was that stuff nasty. I dumped it out and it was black with all kinds of flakes in it. I rinsed it out with the garden hose for quite a while and a lot of crap came out.

    IMG_2013.jpg

    I left the shop vac run in reverse in it for a while to dry it out. I didn’t get completely dry but I could see there was still a little bit of rust inside. So I dumped the rest of my cleaning solution in the tank and I’m going to let it soak at least another day.

    I also went to Farm and Fleet and bought what I thought was a can of carb dip. Well it turns out it was actually parts cleaner, not carb cleaner. Even though the kids there told me it was the same thing. As soon as I opened it I could tell that it was not carb cleaner, it was kind of oily and he did not have any volatiles in it. It really smelled just like Gunk engine brite cleaner. So I’m going to return that I used spray carb cleaner and cleaned up the carb pretty well. I don’t think I need to dip it now.

    Not sure I will be working on the bike again tomorrow night. I think I might have to relax with a couple of beers. Saturday is the wife’s birthday, so we will be doing something related to that. Probably going downtown and look at the artwork on all the boarded up store fronts. Maybe Sunday I will be able to get it back together and - fingers crossed - maybe get it running.
    #17
  18. Dave in Wi

    Dave in Wi Long timer

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    So I’m back at it today. I let the tank soak in Evaporust for another two days. I think when I tried drying the tank out with the vacuum cleaner last time, I got some flash rust. So this time I tried a different tactic.

    I poured out the Evaporust this morning, and flushed the tank out good with the hose again. Instead of drying it out this time, I poured in some ISO-Heet. The Internet says to flush out the tank with rubbing alcohol to absorb the water. I don’t know if any of you have tried to buy rubbing alcohol lately, but you can’t find it anywhere. This product really contains alcohol is about the same thing.

    IMG_2021.jpg


    I used four containers to clean it out, one at a time. It’s kind of cool how the clear tubing I used to plug the petcock acts like a sediment bowl. A surprising amount of crap is still coming out.

    IMG_2023.jpg


    Next I’m going to dump in BBs and pre-mix and continue sloshing it around. I’m going to repeat the process until the gas comes out clean. Then I’m going to spray the inside with fogging oil to keep it from rusting. I’m not sure when I will get the carburetor back together, but it is ready to do so. I might have to take it in the house today and put it together in the air-conditioning. It’s pretty hot and muggy here today.

    I also bought a small engine fuel filter to put in line once this is all done. If there’s any crap left this should filter it out. IMG_2026.jpg
    #18
  19. Dave in Wi

    Dave in Wi Long timer

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    So after running through 2 1/2 gallons of gas 3 to 4 cups at a time, my gas can is empty. I should’ve set up my work table to do this, after two or three hours of squatting in the driveway I am pretty sore. Time for a lunch break and re-energize. I’m gonna run down to the gas station to get some more gas. It’s coming out a little cleaner every time but there still some schmutz there.As small as the pilot jet is, I want to make sure I get everything out of the change that I possibly can. One tiny particle would plug that thing right up.

    It’s hard to get a picture of the inside of a gas tank. Here it is right after I first rinsed it out. From what I could see it looks pretty good. But obviously there’s still crap in there that needs to come out.

    View attachment 2393224
    #19
  20. Dave in Wi

    Dave in Wi Long timer

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    It appears the picture didn’t work last time, trying again.

    IMG_2025.jpg
    #20