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1975 yamaha dt250 carb

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Replied by Lizeec on topic 1975 yamaha dt250 carb

On the link I posted to my earlier thread if you looked at it has pictures of measurements of the intake and the air cleaner side, now this bike was a 1976 DT250C, I know the 1975 is the same, the 1974 is definitely different. So you have a couple of issues one is are you sure the year model bike you have, are you sure your carburetor is the correct model code for a 1975 or 1976 DT250? Last are you sure the vm28/49 on eBay is a genuine Mikuni, they are going for between $100-$125 if you are looking at a $35.00 eBay Mikuni it is not genuine Mikuni. Mikuni vm28/49 that I bought the intake and air cleaner side were identical 34.70mm o.d. on the intake side and 43.86 o.d. on the air cleaner side, probably a discrepancy with my cheap measuring caliper, the Mikuni website lists the specs at 35.0mm o.d. intake side and 44.0mm o.d. on the air cleaner side.
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Last edit: 29 Sep 2022 20:26 by Lizeec.
29 Sep 2022 15:40 #31

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Replied by dan on topic 1975 yamaha dt250 carb

Ok, the ones I was looking at were the cheaper ones.
The price range ones you mentioned appear to be correct.
Thank you so much.
Dan
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29 Sep 2022 20:05 #32

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Replied by Lizeec on topic 1975 yamaha dt250 carb

Pictures of rebuilt carburetor 

     
05 Oct 2022 09:18 #33

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Replied by Lizeec on topic 1975 yamaha dt250 carb

Pictures of stock Mikuni VM 28/49

     
 
Last edit: 05 Oct 2022 09:23 by Lizeec.
05 Oct 2022 09:22 #34

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Replied by Lizeec on topic 1975 yamaha dt250 carb

Pictures of Mikuni vm 28/49 with correct jets for a 1976 DT250C, still needs oil injection nozzle installed.

    
05 Oct 2022 09:27 #35

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Replied by dan on topic 1975 yamaha dt250 carb

I tried the new mikuni with the jets it came with. The bike would not even fire for some reason, the plug got soaked and it had spark. It came with a 200 main.
So I dug around and found a 150 main , put it in, with another plug and after a few kicks it fired up.
I stayed with the pilot jet that came with new carb.
It starts easilly and idles nice. I rode it around the yard a bit (the grass is wet), and got it up to 3rd and all seems in order, runs OK.
Thanks for the tips Lizeec, your info was helpful.
Now when I get laid of this winter I can putter around with making it look nicer.
Dan
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08 Oct 2022 05:34 #36

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Replied by dan on topic 1975 yamaha dt250 carb

I know, pics or it didn't happen..

dan
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08 Oct 2022 05:49 #37

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Replied by dan on topic 1975 yamaha dt250 carb

After the grass dried a bit I discovered (after honking on it a bit) the back brake didn't help stop it. I took it apart and one of the shoes had separated the the friction surface. I dug around my boxes and found a set of shoes. Also the clutch doesn't feel just rite, like some slippage up top. The fibers were crusty and the stills were rusty when I had it apart. I cleaned them up but I may have to replace the fibers. I have a bunch of them lying around somewhere I know.
But the bike started with just a slight push on the kicker, like I do to spin them a few times before I stomp on it to start it so it is set rite I think...
Dan
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08 Oct 2022 13:38 #38

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