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Makotosun

ROTORS , FOTO1971 VS F1T350.

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ROTORS , FOTO1971 VS F1T350. was created by Jewelkutter

   Hello ,I gotta say that trying to find a matching rotor for my 1974 DT250A has been a challange, trying to find a rotor from another model that is compatible hasnt been easy either .After looking over Partzilla I did find that other DT250 models and i think one year 400 models used the same rotor FOTO1971 or 1M1-81350-20-00 and 1977 as well as 1978 , however when looking at the 1978 parts image on partzilla i noticed the stamp on the face appears to be F1T350 and zilla says its compatible with 1974 DT250A . I looked at  year 1977 for DT250 and the image of the rotor appears to be stamped FOTO1971. After searching on ebay for months for a rotor i found one stamped F1T350 , it was cheap and looked to be in good condition so i bought it . It just arrived today and it is similar , the differences between the two rotors that i have noticed are ,The F1T350 Rotor is aprox 1-7/8"  and the FOTO1971 is aprox 1- 3/4" thick. The F1T350 has an extra hole drilled i assume these holes are for ballance? The FOTO1971 has a aprox. 3/8" x 1/16" deep machined smaller around its diameter , the F1T350 does not have this machined edge , on the i guess you could call it the lobe the machining is slightly different on length to shoulder its longer on the FOTO1971 only about 1/8" ,possibly got something to do with the F1T350 being thicker by 1/8" , my delimina now is that the coils on my 1974 show different part numbers than the 1978 model dt250 and zilla doesnt show them being used on a 74 DT250A , the points plates are the same , so my guess now is that i need to use 1978 lighting and source coils , im not sure if anyone has advice on this i would greatly appreciate it .    
Last edit: 26 Feb 2021 04:59 by Jewelkutter. Reason: Somehow i had double pictures and text , it seemed redundant so ive attempted to edit , hope it worked
25 Feb 2021 11:58 #1

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Replied by Jewelkutter on topic ROTORS , FOTO1971 VS F1T350.

I dont have a clue how i got double of what i sad and double of my images on here , oh well sorry bout that,
oh well its out there now , if theres a way to get rid of the doubles i'll try and figure it out , thanx for everything 
john
25 Feb 2021 12:05 #2

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Replied by KennyV on topic ROTORS , FOTO1971 VS F1T350.

Just a thought for more posible options. Many years ago I was looking for a 250A stator for my 400C. Investigating all the options out there I found that early Yamaha snowmobile engines used similar stators and flywheels. Luckily I found a 250A stator and flywheel. Just a thought.
71 Z50 Minitrail
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21 CRF300l Rally
25 Feb 2021 12:29 #3

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Replied by MarkT on topic ROTORS , FOTO1971 VS F1T350.

Is the inside diameter of the magnets the same?  Are the magnet positions oriented about the same with respect to the keyway?  Points cam about in the same place with respect to keyway?

If so, bolt it on and run it.  You'll be fine. 

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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
25 Feb 2021 12:42 #4

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Replied by Jewelkutter on topic ROTORS , FOTO1971 VS F1T350.

Thanks for the quick responses. Interesting The key is centered with the magnet on both rotors and the points cams are about the same location to the right of the keway when looking both rotors
Again thank you.
John
25 Feb 2021 13:53 #5

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Replied by Jewelkutter on topic ROTORS , FOTO1971 VS F1T350.

I can't bolt it on just yet, i have issue with the lighting coil , the previous owner or someone had an issue with the original rotor , after looking at the rotor cover i noticed a crack on the outside and on the inside the aluminum is scared up from more than likely a magnet screw since the original rotor has a shattered magnet , in the process of the screw spinning around in there it tore up the wires on the lighting coil , i was thinking about unwinding it and rewinding new wire if i cant find a cheep enuf coil. I was wondering is the winding one piece of wire?
Any thoughts greatly appreciated
John
25 Feb 2021 14:06 #6

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Replied by Jewelkutter on topic ROTORS , FOTO1971 VS F1T350.

Also yes MarkT the inside dia. Is the same for both rotors , just a hair under
3- 7/8"
Last edit: 27 Mar 2022 09:45 by Jewelkutter. Reason: Somehow i got my message in there twice
25 Feb 2021 14:10 #7

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Replied by Jewelkutter on topic ROTORS , FOTO1971 VS F1T350.

Hi Everyone,  as i previously mentioned , i found an F1T 350 , but while looking on ebay i found this Flywheel and its marked FOTO 1971 just as the original one found in my 1974 dt250a , so i bought it trying to stick with the FOTO 1971 , only difference that i can see is the number of drill holes for ballance and the shouldered edge on the one i recently found as you can see in the picture is not there. I assume there is more drill holes because the shouldered edge hasn't been machined into it. the keyway in relation to the lobe look the same and measurements look same also, the magnets are positioned the same in relation to the keyway any thoughts why would yamaha make this change in the shouldered edge?
thanks for your time
john
Last edit: 27 Mar 2022 09:47 by Jewelkutter. Reason: Somehow i got my message in there twice
27 Mar 2022 09:36 #8

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Replied by Jewelkutter on topic ROTORS , FOTO1971 VS F1T350.

I also noticed the numbers on the original say D2 and on the other one say D8 but the both say FOTO1971   
27 Mar 2022 11:38 #9

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Replied by RT325 on topic ROTORS , FOTO1971 VS F1T350.

All interesing stuff to know. Thanks for the pics.
27 Mar 2022 21:53 #10

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