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First time post - 1974 dt250a Carb main jet

03 Aug 2020 17:39
Lafljm
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First time post - 1974 dt250a Carb main jet #1
I just recently inherited my fathers DT and for the most part all the old man ever did to it after buying it new was wax the tank in the garage. It has 5k miles on it and was taken care of immaculately. Well, got it running after unsezing the engine which was hydrolocked (I think thats the right term as the gas from the tank got into the crank case i think) and needed to clean the carb as its never been cleaned or taken apart. I asked a old motor head neighbor to give me a hand as I thought two heads would be better than one. We broke the what I think is called the "setter needle jet" which screws into something that the needle goes into. Broke the threads right off as it was a fight to get it opened. I have ordered so much shit off ebay that doesn't fit and partzilla no longer has it. Anyone have any ideas on how to go about getting this piece? Its sentimental for me to keep all original. Thank you for any help you guys can give me. I have caught the bug and understand why these bikes are addicting.

137-14145-00-00 SETTER, NEEDLE JET


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03 Aug 2020 22:36
darinm
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First time post - 1974 dt250a Carb main jet #2
Wow the externals of that bike are immaculate for the age of it. Someone here will hit you back with a solid suggestion tomorrow. From your post you are on the right track. Hopefully you can just remove the remainder of that setter and replace it with an oem one. For now I'd soak it in PB Blaster or loosening oil of choice, let it sit a day then heat it with heat gun or propane torch and then try to remove. Worse case, a new used top half of a used carburetor to fix the problem.

1972 Yamaha CT2 175
1972 Suzuki TS 185 Sierra
2016 Yamaha WR250R
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04 Aug 2020 03:22
Swoop56
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First time post - 1974 dt250a Carb main jet #3
I have checked my original DT 250 A manual ( for Oceania ) , and it shows the setter to be
part # 276-14145-00 . There is one listing on ebay # 191906370742 .
There may well be others too .
Unfortunately , half your old setter is still wedged in your needle jet ,
so you will have to replace that too . It's part # 280-14141-30 .
That one is likely more easily found .
You're very lucky to be starting with a bike , so well preserved .
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04 Aug 2020 10:03
apex
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First time post - 1974 dt250a Carb main jet #4
The jet setter screws into the nozzle (of course), and there's a washer between the jet setter and the nozzle. If you can get that washer out, you can (carefully) tap the nozzle out towards the slide bore. With the washer out soak the needle bore in brake clean, use a tool of some sort, sized right, against the bottom of the nozzle where the setter is broken off (like a deep 1/4" socket), and lightly tap the nozzle out. Once it's out, since the brass is relatively soft, I'll bet a small, left handed drill bit turns the broken piece right out.

Allrighty Then
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04 Aug 2020 21:27
Lafljm
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First time post - 1974 dt250a Carb main jet #5
Swoop56 & Apex, unbelievably helpful. Thank you. I ordered that part and I was fortunate to get the threads to come out nicely from the needle jet.

Lastly, do you think there is going to be anything else I should replace since the engine had been seized (hydrolocked from underneath) from the gas leaking through the pitcock ?
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05 Aug 2020 15:39 05 Aug 2020 18:07 by RT325.
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First time post - 1974 dt250a Carb main jet #6
Wonder if the piston was just alloy corroded into the cylinder rather than hydrolocked because if 'Hydro' you'd want to be careful kicking it over as you'll be likely trying to push the crank seals out of the case. With the jet setter thingy, if it were 'me' & dodgy methods & if stuck for that item, i'd just screw the main jet in directly to where the broken bit is. I know the thread is a little different as in fine & not so fine threads but i'd make it work. Only thing to watch is how close to the bottom of the bowl cavity it gets. Also there's a brass washer where that broken thread is sitting but i'm guessing you have that but don't lose it. The broken thread should just twirl out with the tang of a file or something as shouldn't be tight in the thread because it would have broken due to overtightening & just pulled the thread off, 'not' thread tightness where it screws in.

Welcome by the way. Also the small Oring is critical if you end up replacing the broken part as seals it into the bowl cavity so it'll then suck from the side mounted main jet.

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08 Aug 2020 07:54
Lafljm
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First time post - 1974 dt250a Carb main jet #7
Rt 325 - "Wonder if the piston was just alloy corroded into the cylinder rather than hydrolocked because if 'Hydro' you'd want to be careful kicking it over as you'll be likely trying to push the crank seals out of the case."

I'm not sure if it was corroded or hydrolocked. It took me putting a wood block on top of the piston and banging it down for quite sometime to get it to move. Once it did, we tipped the bike upside down and had a bunch of pink fluid drain out. Then it kicked over; however, we couldn't get it started by kicking it over. We pushed started it and then it took off but wouldn't idle very well.

Now that I got the carb cleaned and reinstalled with OEM parts I'm experiencing the same thing. I can't get it to turn over by kicking or by push starting. When push starting, it sounds like it is just about to run but doesn't have the energy. So couple of things. I know how to adjust the pilot screw to factory (1 1/2 turns out) but how about the screw throttle stop ( I think thats what its called?)? Any other advice or things I should be looking at? Also what size jet should I be running at 5000 feet? I'm in Denver.

Thanks again for the help

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08 Aug 2020 10:42
apex
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First time post - 1974 dt250a Carb main jet #8
If the rings were stuck to the cylinder (probably, as RT325 said), then the rings are most likely seized in the piston ring lands, and you've got low compression. If you can pick the rings out, clean them up and clean the ring lands in the piston, you might be able to get compression back, enough to start. Nothing to lose! Otherwise it's time for new parts & a cylinder bore.

Allrighty Then
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08 Aug 2020 12:15
Lafljm
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First time post - 1974 dt250a Carb main jet #9
No idea what was wrong but I primed the carb and now she starts in one kick even from cold. Idles low and perfectly. So now I think I need to figure out what size jet for my altitude. Thanks for your help guys.

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08 Aug 2020 21:45
RT325
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First time post - 1974 dt250a Carb main jet #10
Yep fully agree with 'apex' #8 but now it's come right i'm guessing the rings have unstuck themselves & popped out to give compression--lucky you--go & enjoy it.

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