facebook1 youtube1 twitter1 instagram linkedin1 pinterest1

NOTICE:  If you are not a free registered member of the site, you will not see the photos in the forum, and you won't be able to access our premium member content. Please consider joining our community! REGISTER AND MAKE THIS BOX DISAPPEAR!

×

Pictures Posting Not Working (12 Jun 2023)

Picture uploads is again unavailable. We are working on the problem. Thanks for your patience.

Makotosun

1974 DT250A Vs DT250B

  • Camp3
  • Camp3's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 115
  • Likes received: 18

1974 DT250A Vs DT250B was created by Camp3

Hi all, had a great summer working on and riding my DT175C with a dented tank. I am setting up my winter project which is a DT250A with sand ingested in the motor by previous owner. My question relates to the 250A Vs 250B. Is the 250A a 1 year wonder? It has the unpainted engine case with a 450 prefix engine. I have a spare motor with a 450 prefix serial number and is painted black and is from a 1975 Model Year. Both years have a 450 engine model but don't look to be interchangeable which is a bummer, unless some of you can tell me different...Thanks
1976 DT175C
1975 DT100B Kid Trainer
1974 DT250A In Process
1992 FJ1200
21 Oct 2019 18:15 #1

Please Log in or Create an account to join the conversation.

  • Posts: 689
  • Likes received: 521

Replied by Steve F on topic 1974 DT250A Vs DT250B

Pic's of the differences you speak of would help.
It is my understanding that A,B & C are mostly the same.
Did you try to fit the B engine into the A frame?

And the DT250A is as solid as they come.
1974 DT250A
1974 DT250A
1977 IT175D "Alex"
1978 IT175E
1972 DT2 "Adam"
1973 DT3
"And there ya have it"
22 Oct 2019 14:03 #2

Please Log in or Create an account to join the conversation.

  • Posts: 13392
  • Likes received: 9258

Replied by MarkT on topic 1974 DT250A Vs DT250B

Curious as to what you are basing the "don't look interchangeable" question on... parts lists? Or the actual engines?

Parts lists will show a different number if the finish on the part is different (silver vs black) and sometimes for no reason at all...

I don't know much about the larger bikes but in my general experience if the model code is the same for multiple years the basic parts are the same or interchangeable.
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
22 Oct 2019 15:26 #3

Please Log in or Create an account to join the conversation.

  • Camp3
  • Camp3's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 115
  • Likes received: 18

Replied by Camp3 on topic 1974 DT250A Vs DT250B

The two motors in the post are a 1974 250 and a 1975 250. The serial numbers are on opposite sides, the paint is black on the 75, the head fins are radial Vs. the square shape in the 74. The motors look different, although that doesn't mean they wont bolt up to the frames I guess, I just don't know enough about these to know if its swap-able. I don't want to get all invested in a rebuild then try to swap in the motor just to find out there is some little piece that wont work.

1975 DT250 Motor with a 450 Serial number Prefix



1974 DT250A Motor with a 450 Serial number Prefix




The below post is related to the two motors I found in pile of Yamaha motors, one is a DT250B and the other is a YZ 250A by the looks of the serial number, which one would be better for a on/off road DT250 refurb, I can't afford a NOS type restore...
yamaha-enduros.com/index.php/forums/74-7...mx250a-dt250a-motors
1976 DT175C
1975 DT100B Kid Trainer
1974 DT250A In Process
1992 FJ1200
Last edit: 22 Oct 2019 17:10 by Camp3.
22 Oct 2019 17:01 #4

This message has attachments images.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • Camp3
  • Camp3's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 115
  • Likes received: 18

Replied by Camp3 on topic 1974 DT250A Vs DT250B

and here are the frames..it looks like it might be a possible swap.

DT250A

DT250B
1976 DT175C
1975 DT100B Kid Trainer
1974 DT250A In Process
1992 FJ1200
22 Oct 2019 17:02 #5

This message has attachments images.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • Posts: 82
  • Likes received: 49

Replied by Ctune80 on topic 1974 DT250A Vs DT250B

The DT250A, 250B and 250C for that matter are pretty much the same except for small details. '

Motor mounts are the same for all, even the DT360A and the 400B and C for that matter.

The 250A has points ignition and the straight finned head.
You can put the points ignition on the later engines and it will hook right into the 250A harness. (And probably be easier to deal with since the Hitachi CDI is "Finicky"

The 250A straight finnned head, they all interchange and I'm not aware of a performance difference. Just looks.
The Ox is slow, but the Earth is patient.....
The following user(s) Liked this Post: MarkT, sagetree33
Last edit: 23 Oct 2019 16:38 by Ctune80.
23 Oct 2019 16:36 #6

Please Log in or Create an account to join the conversation.

  • Camp3
  • Camp3's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 115
  • Likes received: 18

Replied by Camp3 on topic 1974 DT250A Vs DT250B

Thanks! That is some good news, I have 2 spare motors for this frame, I think I can make this project work. I'll have to start a separate thread to track my progress.
1976 DT175C
1975 DT100B Kid Trainer
1974 DT250A In Process
1992 FJ1200
The following user(s) Liked this Post: Ctune80
23 Oct 2019 17:53 #7

Please Log in or Create an account to join the conversation.

  • Posts: 11
  • Likes received: 3

Replied by sagetree33 on topic 1974 DT250A Vs DT250B

just thought id put this out there that the crank oil seals are bigger and share the 73s seal on the 74
250A and oem are hard to find the 75and on up are a smaller seal and you can still get them at
partzilla or other sellers
18 Nov 2019 23:15 #8

Please Log in or Create an account to join the conversation.

  • Posts: 9639
  • Likes received: 3915

Replied by RT325 on topic 1974 DT250A Vs DT250B

I'd best not confuse the issue so take it with a pinch of salt. The YZ250A [trick worksy looking bike] has the old design cases based on a DT1. So does the worksy YZ250B first monoshock & that was also the case with YZ360B. Funny thing is--Partzilla are confusing things by showing a YZ250A 1974 with crankcases showing the next generation [so a mistake]. But the YZ360A same year shows the early cases. If you go to YZ250B or YZ360B "75 it shows the old cases for both [which is right for the trick bike] "75 also had the MX series MX250B & MX400B which had the later shape motor & cases. So--umm, not sure where i'm going now. Have had all those models at some stage when new or nearly new in the case of the YZ250B & bought an MX250B new in "75 & C model in "76. Looks like the crankcase page is the only wrong one on the 250. Must be hard for Partzilla to keep up realy with so many confusing changes in those days--& now i'm confusing things more lol.
19 Nov 2019 00:43 #9

Please Log in or Create an account to join the conversation.

  • Posts: 130
  • Likes received: 41

Replied by Don Dieago on topic 1974 DT250A Vs DT250B

If I had both motors and I wanted to know I would pull it out of frame and sit the a into frame. Dont know about you but I can have the B engine out of the frame in say 15 minutes. You say full of sand! sounds like it was sunk in a river ben there done that more than once. go ahead and pull engine and flush everything several times with clean diesel. I personally think the 74 engine looks better than the radial head black engine.
29 Nov 2019 07:34 #10

Please Log in or Create an account to join the conversation.

Moderators: yamadminMakotosunDEETVinnieJames Hart