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Fixing up the DT1

  • CHUGCOFFEE
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Fixing up the DT1 was created by CHUGCOFFEE

Hey all,

Thought I would start a thread on my fixer upper DT1 project. I bought this last week with a pretty basic set up. Seat is bad shape, tank is close to being unsavable and there is no wiring harness or lights whatsoever. On the good side of things it looks like this bike used to be someones racebike. GYT kit looks to be on it and suspension is in really nice shape, just got redone by previous owners. 

 

 

 

Instead of grabbing a ton of parts off ebay for this bike at a ridiculous price; I found a 1974 DT175 being parted out locally , It has a small fire on it(from welding sparks) which was why it was being parted out and I got a heck of a deal on the whole thing. I'm going to use it primarily for wiring, lights, tach and speedo. Currently I am using the seat off of it just as a stand in until I can figure out the old seat.

 

Because of the condition of the badge tank I am using a DT250 tank I found locally. I hope to be able to save the old tank however I have been told it's not worth it to try(but il probably try anyways.

 

We decided to try and get it to start today, went through the carb which was pretty clean already but double checked the jets and whatnot. All seemed to look okay until we tried and failed to start it. It had spark and fuel. Turns out the oil pump was working(I was going to use premix) and trying to pump extremely thick oil into it. Long story short it took awhile to get it disconnected and stop the plug from fouling. Still cant get it to start yet but hopefully we can try some other things and get it going

Excited to start this thread and see where it goes!
The following user(s) Liked this Post: Quartermaster35
15 Feb 2021 14:58 #1

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Replied by CHUGCOFFEE on topic Fixing up the DT1

Ok, so an update to an issue I'm having. Sometimes it coughs but it will not start. It's completely fouling the sparkplug with oil within 3 kicks. I have disabled the oil pump and even drained the carburetor, and it still coats the spark plug with oil completely after 2-3 kicks.

This leads me to believe that gearbox oil is getting into the crankcase. The gearbox oil level has also dropped since I've been trying to start it. Does this even sound possible, and what would be causing it?
15 Feb 2021 15:11 #2

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Replied by MarkT on topic Fixing up the DT1

Crank seal on clutch side of engine could be bad. 

BUT most commonly on a bike that has been sitting the autolube oil has seeped past the check ball over the years and flooded the engine bottom end with oil.  Getting it cleared out can be a pain but doesn't require too muct effort on that model.

What I'd do is remove carb and rear fender, put piston at TDC, and then get some buddies to help tip bike up like it's wheelieing over backwards.  excess oil will run out the intake port and probably make a mess.

Or if you are changing a seal anyway, after removing old seal, lay bike down on that side for a while to let excess crankcase oil drain out through bearing.

Another way is remove spark plug, shut off fuel and drain carb, remove pipe, and have someone tow or push you around in gear to blow the excess oil out the plug hole and exhaust port

Trivia:  Puch had "Autolube" on their 250 model more than a decade before Yamaha "invented" it. 

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The Puch system was crank-driven and throttle controlled just like Yamaha's...  Puch added a drain plug in the crankcase because their pump would let the oil slowly seep into the crankcase when parked...  pump was a lot "seepier" than Yamaha's...  but they gave you an easy way to drain off the excess oil if bottom end got flooded. 
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
The following user(s) Liked this Post: Badger52, shyted, JayB, Pete-RT1, Jack
15 Feb 2021 15:36 #3

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Replied by CHUGCOFFEE on topic Fixing up the DT1

Thanks for the detailed response. I now have it hanging up and a lot of blue 2 stroke oil came out. Hopefully it's just that and my mind was playing tricks on me about the gearbox oil. Going to leave it up for a day or so and see how it goes
15 Feb 2021 16:42 #4

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Replied by Gr8uncleal on topic Fixing up the DT1

Nice project!

Just a "fyi", that nice green tank is off a 1973 DT3 (the predecessor of the DT250).
15 Feb 2021 23:49 #5

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Replied by RT325 on topic Fixing up the DT1

If its been parked up for a long time its likely the twostroke oil has drained into the motor via the feed line to the motor. They have a shut off ball & spring in the feed line that gets stuff under it. Not a problem usually in regular use but long time parked is another story. Could remove the carb & with piston at top the get a small hose into the crankcase & suck it out. If it starts then don't got giving it a big rev--or not for a while--as will throw an left over oil up top into the plug, just bring it up & down slowly till you think she's ready to rev. Pretty unlikely to be the crank seal as they're pretty bulletproof. Big thing too is be Very Sure that the crank key is good for the magneto flywheel.. If good then points at 15thou & kick it. Timing 3.2mm btdc but 15 thou gap will get it going ok initially & not be far off. l'd better go read as thought it was a std DT1 but center plug head high compression head must have some go-fast bits in it. So timing will be 2.3 btdc. not 3.2 so set points at 12 thou. My book says also a B10EN plug which is a bit over the top unless its well cleaned out & on full song around a flat track--i think. Hope she runs soon. Video would be great.
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16 Feb 2021 00:45 #6

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Replied by CHUGCOFFEE on topic Fixing up the DT1

Well after stringing it up from the ceiling and letting the oil drip out of it, it started second kick! Super thrilled about the progress. Now have to get the rust out of the green tank. I grabbed some citric acid to try getting it as nice as possible. Will update with a video as soon as the tank is clean and ready to go! Good to know its from a DT3! Thanks for the info, you guys are the best!
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21 Feb 2021 19:09 #7

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Replied by Bartman512 on topic Fixing up the DT1

I ordered a 5gal bucket of Evaporust at the start of my DT2 resto and submerged the whole tank for a couple of days. Worked great!
22 Feb 2021 06:26 #8

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Replied by shyted on topic Fixing up the DT1

Evaporust. That company does a tidy turn over as a result of this site .
Top stuff.
22 Feb 2021 12:58 #9

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