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DT 400 B shunting update 2

  • p.wells
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DT 400 B shunting update 2 was created by p.wells

Hello all you guys out there just thought I would let you know how the bike is performing, as the needle jet and needle were the only parts in the carb that I had not replaced with genuine parts, I took RT325s advice to replace them, and with a Mikuni stockist recommended by GR8UNCLEAL the items arrived yesterday , so thank you so very much both of you.

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  At the moment all carb parts are stock and at the correct sizes and settings, so today I went for a test ride and boy what a difference, I would say that there is a 75% improvement with a lot less shunting . Going up through the gears I could feel the bike just wanted to go, but as I am running in a new piston and ring set I had to control the revs, so I am not allowing it to go past 4,000 revs, even at that l ow power the bike feels crisp, sounds great and pulls like hell. So all I need to do now is experiment with some of the other suggestions from other readers to iron out that last bit of shunting when your slowing right up to a junction or roundabout etc. I hope my posts are helpful to other readers with this problem .
The following user(s) Liked this Post: RT325, JayB, Gr8uncleal, AirborneSilva, Ht1kid, Pete-RT1, Andy L, Jammyyammy
24 Jun 2022 12:21 #1

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  • AirborneSilva
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Replied by AirborneSilva on topic DT 400 B shunting update 2

That is good news and gives me hope that when I can get my 400 going again I have a direction to go.  Thanks for the update!
1976 DT400C
1981 DT175H
1972 DT2 250
24 Jun 2022 16:59 #2

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Replied by Gr8uncleal on topic DT 400 B shunting update 2

Thanks for posting an update.

 
25 Jun 2022 00:19 #3

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Replied by hatrick1960 on topic DT 400 B shunting update 2

Hi

Where did you buy the needle jet and needle?

Thanks
12 Aug 2022 12:48 #4

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  • p.wells
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Replied by p.wells on topic DT 400 B shunting update 2

Hi there Hatrick1960,   sorry for the late reply as I have been away, and only just noticed your question to me, I live in the UK and in the city of Nottingham there is a Mikuni stockist called Allens performance LTD, this is where I purchased all of the jets and parts for my 400 B carb.
27 Aug 2022 12:25 #5

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Replied by Andy_C on topic DT 400 B shunting update 2

Another source of genuine Mikuni carbs parts in the UK is Moto Carb www.motocarb.com/ run by a bloke called Steve.

I have found him really helpful if you give him a call.

I am told to avoid anything made by, or under the name of "Keyster" for Mikuni carbs - they are known to cause problems, certainly on Kawasaki Triples.

Just sayin'
Yam DT 400 C, Kawasaki H2B, Royal Enfield Himalayan, Triumph 865 Speedmaster - many, many more in my lifetime.....
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29 Aug 2022 11:34 #6

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Replied by p.wells on topic DT 400 B shunting update 2

Hi again to all of you out there, had to have a break from my DT for a while due to work and family commitments, but I can now tell you all that I have now managed to fix the shunting and surging on my 75 DT 400 B as mentioned in past posts, so here is my set up
. New needle and needle jet tube.
. 16 tooth front sprocket up from standard 15 tooth.
. Pilot jet up to 50 from standard 40.
. Mixture / air screw out half a turn from fully closed.
. Needle clip position 4 from top as opposed to standard position 3.
From my settings you would expect it to be running rich, but the plug is a lovely light tan colour and the bike now runs like a dream idles smoothly, revs crisp and cleanly pulls through the gears like hell, sounds great and most of all comes off the gas without any shunting nonsense, what a pleasure to now ride. My thanks to RT325, Garydean, Turbodan and Masavitt for their input and pointers on this subject, what a happy man I am Thank You.
The following user(s) Liked this Post: MarkT, JayB, AirborneSilva, Ht1kid, Jammyyammy, adguy2112
21 Nov 2022 12:15 #7

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Replied by AirborneSilva on topic DT 400 B shunting update 2

That's great news and information! Can you tell us what plug you're running? I ask because when I first got my DT400 I went to Yamaha and asked for a plug, they gave me a B8ES but book says B9ES and after asking here on the forum the consensus is to run the B9ES. Thanks and congratulations!
1976 DT400C
1981 DT175H
1972 DT2 250
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21 Nov 2022 13:12 #8

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Replied by msavitt on topic DT 400 B shunting update 2

running smooth and strong is so good to hear!

#40 pilot sounds so small to me because stock on my DT360 was #50 and going to #55 and raising the needle one slot richer from 3rd position really helped with the shunting.  And another point of reference, my 78DT400E is listed as #80 and it chug chugs less and is a beast.

I couldn't find your 75 on Partzilla, but did find 76 400 and pilot was a #40...seems so lean
anyhow, if you think you have a bit more to gain you might want to try a #55...but you have the screw in making it way richer....when I put the #55 into my 360 I had to take the air screw out to almost 2 turns out because it was much richer, but it really helped with the chug chug and really hauled ass and the plug stays a nice dark brown. My hypothesis  was that I was getting more fuel / air at a rich enough ratio into the engine...or maybe I had too much beers and just got confused.

So great that you got the bike running great, so much fun riding these up a mountain and hoping the 50 year old CDI or whatever doesn't konck out!
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21 Nov 2022 17:36 #9

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Replied by Ht1kid on topic DT 400 B shunting update 2

+1 on the beers
21 Nov 2022 17:43 #10

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