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Discussion Starter · #1 · (Edited)
Ok, so my DT400 suddenly wouldn't upshift. 1st and neutral only. No external reasons. Split the cases and found a complete gear tooth laying inside. Along with a partial tooth and chunk of the case. 3rd gear was missing the partial tooth. Found the busted case near the tach drive. No gear missing a complete tooth.... I can only assume the previous owner left it behind for the Tooth Fairy which cost me $55 dollars for a new 3rd gear and a gasket set. Witness marks on the shift drum stopper plate tell me one of these pieces had settled in next to the spring detent. It would rotate in one way for 1st gear but not the other way for the remaining gears. I hope my theory holds true because I don't want to go back in there.......
 

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Ouchie Mama! Looks more like a Tooth Gremlin!!>:)You wouldn't happen to have a picture of one of my all time favorite motorcycles, ever, would you? jevers
Ok, so my DT400 suddenly wouldn't upshift. 1st and neutral only. No external reasons. Split the cases and found a complete gear tooth laying inside. Along with a partial tooth and chunk of the case. 3rd gear was missing the partial tooth. Found the busted case near the tach drive. No gear missing a complete tooth.... I can only assume the previous owner left it behind for the Tooth Fairy which cost me $55 dollars for a new 3rd gear and a gasket set. Witness marks on the shift drum stopper plate tell me one of these pieces had settled in next to the spring detent. It would rotate in one way for 1st gear but not the other way for the remaining gears. I hope my theory holds true because I don't want to go back in there.......
 

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Discussion Starter · #3 · (Edited)
Ouchie Mama! Looks more like a Tooth Gremlin!! You wouldn't happen to have a picture of one of my all time favorite motorcycles, ever, would you? jevers
Here is mine, but it has been stripped down for off-road only.
The other pictures are compliments of google images.
 
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Busted case? I assume this was just an internal chip so the case was reusable without loss of compression through an external crack. As for the chipped gear - poor heat treatment?

There was some talk of reintroducing the legendary DT400 in Yamaha’s Sport Heritage lineup but with the milder SR400 motor, since two strokes are now verboten. That would spoil the DT’s ring-ding character, so hold on to your treasure, Schu.
 

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Discussion Starter · #5 ·
Busted case? I assume this was just an internal chip so the case was reusable without loss of compression through an external crack. As for the chipped gear - poor heat treatment?

There was some talk of reintroducing the legendary DT400 in Yamaha’s Sport Heritage lineup but with the milder SR400 motor, since two strokes are now verboten. That would spoil the DT’s ring-ding character, so hold on to your treasure, Schu.
Yes, the cracked case was an area next to the tach gear drive. There was a cast opening in that area that is now just a little bit larger opening. No detrimental effect at all. Lucky on that one.
The chipped tooth on 3rd gear was most likely due to the broken tooth that was left behind from a previous incident. It got caught between gears and cracked the corner off 3rd.
I have a complete collection of the old 2-stroke enduros and have yet to sell any of them. This 400 is near the top of my list. Followed only by my CT175 and my DT360.
 

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Dt400

Thanks, Schu! I bought that bike, which was my very 1st REAL motorcycle at the age of 14, back in 1978. It was only 3 years old and I believe that I only paid around $700! It looked just like those last 2 pics when I 1st got it and after a few crashes, it looked more like your stripped down version.
Here is mine, but it has been stripped down for off-road only.
The other pictures are compliments of google images.
 

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Busted case? I assume this was just an internal chip so the case was reusable without loss of compression through an external crack. As for the chipped gear - poor heat treatment?

There was some talk of reintroducing the legendary DT400 in Yamaha’s Sport Heritage lineup but with the milder SR400 motor, since two strokes are now verboten. That would spoil the DT’s ring-ding character, so hold on to your treasure, Schu.
Yeah, I miss the old ring-ding sound. My last bike before my recent SCR buy was a 1971 Yamaha 360 Enduro that was stolen while attending summer school in 1972 at the University of Texas. I loved that black beauty, as well as the two Bultacos (El Tigre and Pursang) I had just prior to that. The SCR has a nice exhaust note, but there was a certain beauty to the old ring-ding.
 

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Discussion Starter · #8 · (Edited)
Beautiful sound of a Ring Ding

Yeah, I miss the old ring-ding sound. My last bike before my recent SCR buy was a 1971 Yamaha 360 Enduro that was stolen while attending summer school in 1972 at the University of Texas. I loved that black beauty, as well as the two Bultacos (El Tigre and Pursang) I had just prior to that. The SCR has a nice exhaust note, but there was a certain beauty to the old ring-ding.
Do yourself a favor and watch the YouTube video at the very top of this thumbnail image. Jump ahead to 4:45 and try not smile when you hear this DT360 go for a ride. By far the best audio of a classic 2-stroke I've ever heard.
 

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After I enjoyed the YouTube video fate lured me to Cochise Motorsports in Sierra Vista. They are my local dealer and guess what? A pristine 1971 Yamaha 360 Enduro RT1-B with glossy black tank is on display in their vintage collection. I was surprised how small it is up close compared to our SCR950. I know, should’ve taken a picture - next time! Meanwhile, let’s see if there’s an offer the dealer can’t refuse ;)
 

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Discussion Starter · #10 · (Edited)
Got Gears!

Finally got my 400 back together after busting up my trans and it works great! Shifts nice again. First time I've split cases and did trans work. As a matter of fact, I am only one bike away from having the entire herd running. The open slot is for my 360 which has terminal carb issues. I need to acquire a better carb to work with. But a good one sells for more than I paid for the bike. The 74 DT360 was a one year bike like our SCRs. The cost of parts reflect that fact....
 

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Finally got my 400 back together after busting up my trans and it works great! Shifts nice again. First time I've split cases and did trans work. As a matter of fact, I am only one bike away from having the entire herd running. The open slot is for my 360 which has terminal carb issues. I need to acquire a better carb to work with. But a good one sells for more than I paid for the bike. The 74 DT360 was a one year bike like our SCRs. The cost of parts reflect that fact....
The picture came across as a little small and at first glance, it almost looked like you had 2 or 3 SCRs in the herd, red tank and all!!! I have bike envy.
 

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Discussion Starter · #12 · (Edited)
Recent DT400 sale

Thanks, Schu! I bought that bike, which was my very 1st REAL motorcycle at the age of 14, back in 1978. It was only 3 years old and I believe that I only paid around $700! It looked just like those last 2 pics when I 1st got it and after a few crashes, it looked more like your stripped down version.
Hey jevers
Look what this one went for.
 

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Thanks, Schu! I bought that bike, which was my very 1st REAL motorcycle at the age of 14, back in 1978. It was only 3 years old and I believe that I only paid around $700! It looked just like those last 2 pics when I 1st got it and after a few crashes, it looked more like your stripped down version.
Why you gotta be like that? Rubbing it in and all! I just got off the SCR 10 minutes ago returning from a ride to a Harley dealership with a friend to look at a used Ultra Classic. Well, it was sold so I did the next logical thing and talked/helped him into buying a NEW one! Of course I had to give him a fly by, hitting the triple digit for the first time. Surprisingly stable!

Hey jevers
Look what this one went for.
Why you gotta be like that? Rubbing it in and all! I just got off the SCR 10 minutes ago returning from a ride to a Harley dealership with a friend to look at a used Ultra Classic. Well, it was sold so I did the next logical thing and talked/helped him into buying a NEW one! Of course I had to give him a fly by, hitting the triple digit for the first time. Surprisingly stable!
 

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