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DT250F performance half-assary for the street

03 Apr 2018 22:50 03 Apr 2018 22:58 by fmxr47.
fmxr47
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DT250F performance half-assary for the street #1
Hello all, Ive gotten some great info from some groups on facebook as well as right here. I intend to see what i can do myself to get some more power out of this pig of a 250 with just some simple things i can do at home aside from having a family friend mill my older DT head for proper squish and higher comp. ratio.

I got the bike for $250 with my dad and the intention was he bought it, and i'd fix it and then we'd sell it and split the profit. well i decided this bike is quirky and I like it. I like things that get complicated to modify, and of course I picked this one year bike as far as engine junk goes.

-I replaced the crank seals and clutch frictions
-cleaned/soaked the carb
-cleaned the jets that were in it, needs a fatter pilot jet, undetermined on the main jet as of now
-replaced the fron tire and tube
-replaced the missing airfilter with a uni
-set the air screw to 1/8-1/4 turn out
-fuel screw to 2-1/4 or more and it still hangs like its lean until i bump the enrichener

Need To do still:
- I have new fork seals, oil and dust, and some cheap ebay for boots/gaitors that I hope fit so i can replace the tattered ones on the bike.
-replace the battery and check the electronics
-replace speedo cable/ see why its not working!

Plans:
-set squish with new 77 DT head with a centered combustion chamber
-cut open stock pipe and remove the internal garbage and perhaps fab up a cone for the end of the chamber
-uncorck factory silencer or replace with another lighter aluminum silencer like the turbine core 2 from FMF
-widen and polish exhaust port, open up transfer ports like the IT's and match the cases, I wont be raising any ports. Have some nice reference material for this thanks to some nice guys on facebook
-Im thinking about boysen ports, although ive been told they aren't necessary, I did them on an old 175 and a blaster with seat of the pants results(or so I think)
-probably find a slightly larger carb(not sold on that yet), mathing intake boot
-maybe some better reeds


If I'm happy with all of that then I may decide to start a custom type of build and ditch a lot of factory body work and maybe even the front end for a USD conversion, Maybe an oldschool take on a supermoto. Who knows!?!

Anyway, Im open to any suggestions or helpful input about my plans as I tackle this project slowly but surely. Im also restoring a square body chevy along with the XL 500 project that is in my introduction thread.



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03 Apr 2018 23:00
fmxr47
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DT250F performance half-assary for the street #2

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04 Apr 2018 07:19
Blackhat250
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DT250F performance half-assary for the street #3
Hi " , sounds a tad rich to me, also it has a loud induction noise , like the air filter is missing , thers nothing wrong with the hanging , it settles down nicely to 1400 rpm,

If you aint mixin gas " you aint haulin Ass

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04 Apr 2018 09:12
fmxr47
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DT250F performance half-assary for the street #4
The one video is especially pig rich because I forgot the Choke was on when I rode it around the lot. I’ve got several extra new plugs, I’m going to warm it up once I’m back in town on the current plug, then pull the plug and swap it for a new one and let it idle and run it to about 1/4 throttle and check the color of the plug after a bit of running.

The slight rev hang is normal you think? My dads rt1 and ct3 settle to idle much faster.

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04 Apr 2018 10:22
fmxr47
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DT250F performance half-assary for the street #5
Does anyone know if a CT3 tank will fit over the monoshock on this bike? My dad has the original tank from his CT that’s in pretty good shape and I prefer them over the ugly 79 DT tank. My side covers are in poor shape so I’m thinking of possibly making some of my own covers if I get that ambitious.

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04 Apr 2018 15:41
RT325
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DT250F performance half-assary for the street #6
Wow, you've got the good ideas so i'll follow you lol. Did fix mine though--fitted an IT400 motor, was too fast but definitely fun.
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04 Apr 2018 19:46
TerryM
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DT250F performance half-assary for the street #7

fmxr47 wrote: Does anyone know if a CT3 tank will fit over the monoshock on this bike? My dad has the original tank from his CT that’s in pretty good shape and I prefer them over the ugly 79 DT tank. My side covers are in poor shape so I’m thinking of possibly making some of my own covers if I get that ambitious.


I believe the tunnel area on the pre-monoshock bikes is significantly narrower than the tunnel on the monoshockers. Plus, the frame on the 175 and smaller bikes is smaller than the frame on the 250-400 series bikes. I would be very surprised if it would fit.
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04 Apr 2018 20:55
Chard
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DT250F performance half-assary for the street #8
If you do end up going with a different tank I'd be interested in purchasing your old one. My 79 dt250's tank is leaking pretty badly :(
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05 Apr 2018 15:46 05 Apr 2018 15:50 by fmxr47.
fmxr47
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DT250F performance half-assary for the street #9
Do any of you knowledgeable fellas have any idea if a yz/mx rear swing arm and shock would fit this frame? More or less curious, I highly doubt I’ll change it, just figured if I’m pulling it off at some point to restore it, why not put another type on. I really like the look of the square tubed swingers

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06 Apr 2018 09:09
RacerClam
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DT250F performance half-assary for the street #10
Nice project. If your serious about performance mods It might be good to contact me , its what I do. The addition of Boyesen ports isnt a bad idea but I one up that by adding a case port , and with out changing port heights you wont gain much over all.Reeds should be upgraded to v force amd carb size is too small for good performance . I can be more specific if you give me a call.. here is my web site richstaylordporting.com I just completed a 1978 dt400 for a member here also for street use

Rich

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