1975 Yamaha DT250B (Issues?!!!)

[KamakazieX]

As I suspected the woodruff key was sheared clean in half..

Anyone know how to prevent the key from breaking all the time? Is there any fix?

Eg, Lock-tite (on the woodruff key?), Over tourqing?

[zillaguy89]

the flywheel key shouldn't break. Sounds to me like the timing is off, or your running too low octane fuel.

my DT looks like that too, but its a brownish-coppery color.

[KamakazieX]

Also-- I was using a std. key from the hardware store and the flywheel was NOT tourqed on, more or less hand tight /w a wrench. I did run 87 oct that day as a last resort. I just hope I didn't fuck my reeds up.

I'm running 2 steps hotter on the plug on 93 oct. and its runnign a little rich, charcoal color. The top end has little power- so I'm going to play with the needle clip and see if my top end opens up. This time I'm waiting for a real OEM yamaha shaft key before I shear the flywheel.

Also Bike Bandit has some good stuff on their site to shorten the gearing, Moose front and rear sprockets (for the 75/MX250). I'm probably going to invest in those as well.

[amcfeek]

bwahaha you probably have this thing running by now .
the blaster is too smal on the flywheel if i can remember its the size of the dt 125 dt 175 if that helps
if you want to swap in a cdi unit the 77 78 dt 250 will work as well as the it 250's . you can also run the mx's and the dt 360 a and dt 400 will also bolt on but i think the flywheel will be out of balance
the yz is the same but vintage yz stuff gets expensive, and hard to take the inner type flywheel of the vertex mag off the crank
i like the it's because of the headlight option , hanging out till after dark then finding the way home with moonlight aint fun
swapping in the cdi is real e=z .
grab ahold of the compete wire from cdi box down to stator . then the only 2 wires in the cdi to whole harness needed is the orange coil wire and the black white stripe wich is the kill to ground .
getting my dt3 ratbike timed was a pain . and my 71 .. but usually they were pretty dam relaible except for getting em wet. points dt's dont run in the rain .
tip seal the heck out of everything and keep the coil dry.
look on ebay sometimes this time of the year you can get a bottom end with electrics .
if you get the important stator flywheel a blaster cdi should work
also if using cdi swapp in a yamaha coil for cdi . a banshee is supposed to work on dual spoarkplug heads . i have 2 from yamaha snow mobiles 1 wire 2 coil outs will try this myself
hope it helps

[JordanM]

Looks alot like my 1976 TS 250. I gave up on it haha.

[amcfeek]

i gave up on my 74 ts250 for like 100$ profit . i have a 78 185 ts and foor a profit i will give that up too.
now about my yamaha's , better fill out the mortgage papers!

[atomicsaladbowl]

thats the weirdest problem i have ever heard, wish i could help, good luck fixin it

[KamakazieX]

nuff said - i did figure it out, used oem yama mama key, bout 5, used 93, dropped 10 on the main, plug looks cleaner than my cars!!! cant ride it as of now, winter...

sooooo sexy now... ooooohhhhh.. :-D hahaha..