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Mikuni Carb identification

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Mikuni Carb identification was created by BDub

I am having a hard time identifying the model of this carb. It’s off of my 1969 DT1B 250. It seems to measure out to 26mm but the float bowl doesn’t seem to match any of the vm26’s that I can find. I am specifically looking for float height setting. It was set at 24 mm but was not getting fuel to the bowl. I dropped it down to 21mm and now it is leaking out of the over flow. I am also curious about recommended jet sizes. Any help is much appreciated! 
23 Jun 2022 14:15 #1

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Replied by yamahahaha on topic Mikuni Carb identification

Well, DT1B is a 26mm. What is the number on top of the carb flange? It will be on the top left side of flange. Stator side


EDIT   I think it would be 214  E2
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Last edit: 23 Jun 2022 14:25 by yamahahaha.
23 Jun 2022 14:18 #2

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Replied by JayB on topic Mikuni Carb identification

BDub said: "I am also curious about recommended jet sizes."

This is from page 4 of Series DT1 service manual, LIT-11612-14-99:
 

I hope it is legible.  You never know until you post.
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23 Jun 2022 15:58 #3

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Replied by MarkT on topic Mikuni Carb identification

Note the * in the specs by float level.  Yamaha/Mikuni changed how level was measured.  Early bikes did NOT always measure from float bowl gasket surface which is likely your issue. 

Just set the float arms parallel to the float bowl gasket surface just as needle closes and call it good.  Or look up the proper method for your carb which is measuring from "jet setter" area down to float arm.
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
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Last edit: 23 Jun 2022 18:18 by MarkT.
23 Jun 2022 16:53 #4

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Replied by MarkT on topic Mikuni Carb identification

Edit:  I just noticed you are in the 20's with your measurement...  so probably using wrong technique and wrong spec.  Just use parallel. 

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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
23 Jun 2022 16:56 #5

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Replied by BDub on topic Mikuni Carb identification

Wow, thanks so much MarkT! I will give it a shot. I still can’t seem to find anything in the SH model of the VM26…I think over the past few years I’ve had this apart more times than I can count. I had issues with a cracked phenolic resin spacer, had to strip the tank of a failed sealer, warped flange, etc. Really looking forward to putting some miles on this bike. 
23 Jun 2022 17:25 #6

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Replied by MarkT on topic Mikuni Carb identification

Kudos to JayB for posting specs!!

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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
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23 Jun 2022 18:19 #7

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Replied by BDub on topic Mikuni Carb identification

Thanks for posting that JayB. I set arms so that the pin would close just as it was parallel to the gasket surface but as soon as I turn the gas on from the petcock gas flows out of the overflow next to the fuel line. I couldn’t find any numbers on the flange until I sanded it down a little. And it is “214 E4”. I’m still unclear as to which model this is. Is there a Mikuni measurement to set the float height? 
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24 Jun 2022 08:47 #8

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Replied by MarkT on topic Mikuni Carb identification

E4 = 1969 # DT1-015830 through 1971

Service manuals in Tech Library and spec in chart.  I don't trust manuals on float level as conflicting specs are often posted in same manual.

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If overflowing with arms parallel and valve closed, likely needle and seat are bad or overflow tube in carb is cracked. 

Post a picture of your float level adjustment. 
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
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24 Jun 2022 09:27 #9

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Replied by JayB on topic Mikuni Carb identification

BDUB wrote: "Is there a Mikuni measurement to set the float height? "

Mark mentioned this, 'the old way'.

Old way of float height measurement, from page 43 of DT1 Service manual.  I believe this is how you use the 14mm measurement:

 

Newer way for later models and DT1MX (C&E) from page 91 of the same service manual.  If the floats are not attached, you measure from the float lever like the old way to the gasket surface like the new way:

 

Notice in both drawings the float lever is parallel to the gasket surface, like Mark said.

Confused?
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Last edit: 24 Jun 2022 10:13 by JayB. Reason: Added a sentence.
24 Jun 2022 10:09 #10

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