1969 yamaha enduro 250 questions


14 replies to this topic
  • chrismyers67

Posted 18 May 2007 - 12:29 AM

#1

hello, i have been tinkering with a old yamaha 1969 enduro 250. Is this also called a dt250? how can i tell if this uses premix, or is oil injected? what is the normal sparkplug size? i have heard that i should replace the crank case seals>.what jetting should i be running for 6000ft? how about carb setting? can anyone point me to some sites related


-Thanks
Chris

  • 05dr650

Posted 18 May 2007 - 02:22 PM

#2

Does it run?
I would leave it alone for now if it runs. The bike should have a oil tank, if oil injected. But some times on those old buggers, people have taken the tank of and pre mix (I do).
As for spark plug I have no idea. You could ask the jetting experts on this site, what he would run. I have before, and he is very good.
Best of luck, and enjoy the old DT:thumbsup:

  • pantera

Posted 18 May 2007 - 08:22 PM

#3

http://www.yamahaenduro.com

The best site there is for early Yamaha enduros :)

  • OLD TIME BIKER

Posted 18 May 2007 - 08:56 PM

#4

The 1969 DT-1B 250 Yamaha was the second year of production for the DT-1which had a four year run before it was significantly changed and re- designated the DT-2 in 1972. On the left side of the engine, there is a small cover at the front of the larger clutch cover that houses the oil pump. If the pump is still there and connected to the throttle with a cable AND there is an oil tank with a line running to the pump AND there is a small line running from the pump to the lower back of the cylinder, your oil injection is still intact. If not, run a 32 to 1 premix and make sure the hole the pump was in is covered with a metal cover with a gasket, and the hole on the bottom of your cylinder is plugged with a bolt and gasket. An NGK B7E or B8E (or equivilent) would be the correct plug and the gap should be .20. Replacing the crank seals would be a good idea, but not necessary if the engine passes a leak down test. Get your self a Clymers manual that covers this bike and you will have all the info you need. These were virtually bulletproof bikes that were stone reliable (mine still is) but they handled terribly. Lowering the frame and modifying the swing arm were "must do " mods that made the bike handle much better especially for Scrambles, short track and motocross. But if all you intend to do is ride the bike for fun, the stock frame will be OK, it will definately make you a better rider and you'll be amazed when you get on a better handling bike.

  • chrismyers67

Posted 19 May 2007 - 01:33 AM

#5

thanks for all the help. i ended up finding out that my dads old yamaha mechanic had all the info i needed, and is going to help me along. it is actually a 1970 dt1 mx 250. got her running like a champion today. first kick..... quick other question, does anyone have a cross reference for a rear tail light bulb? finding a 6v bulb is quite tricky, is their a auto bulb that works?

  • OLD TIME BIKER

Posted 19 May 2007 - 12:48 PM

#6

The standard 1157 tail lamp will work, although because it's 12 volt it will be a little dim. Most auto parts stores will be able to get you a 6 volt bulb in a few days. Ask them to order you a couple of spares and you'll have them handy if you need them.

  • pantera

Posted 19 May 2007 - 03:39 PM

#7

thanks for all the help. i ended up finding out that my dads old yamaha mechanic had all the info i needed, and is going to help me along. it is actually a 1970 dt1 mx 250. got her running like a champion today. first kick..... quick other question, does anyone have a cross reference for a rear tail light bulb? finding a 6v bulb is quite tricky, is their a auto bulb that works?



If it has lights on it then it isn't an MX. (Motocross Bike)

You can check the VIN on the frame; the 1970 DT1 MX's started at frame # DT1-95101 and ended with frame # DT1-97268. (2,167 of them built)

The regular DT1's for 1970 started at frame#DT1-50101 and ended with frame# DT1-66389 (16,288 of them built)

  • Ithumpwheniwalk

Posted 19 May 2007 - 08:34 PM

#8

If it has lights on it then it isn't an MX. (Motocross Bike)

You can check the VIN on the frame; the 1970 DT1 MX's started at frame # DT1-095101 and ended with frame # DT1-097268. (2,167 of them built)

The regular DT1's for 1970 started at frame#DT1-050101 and ended with frame# DT1-066389 (16,288 of them built)



Where on the frame would you find this #? I've searched my entire bike and never found it.. just one on the side of the engine itself.. :)

  • pantera

Posted 19 May 2007 - 09:36 PM

#9

The numbers are stamped into the steering head of the frame, on the right side if you were sitting on the bike. If you still have the metallic decal/sticker on the steering head it's on there too.

What is the number you found on the engine?

  • Dwight_Rudder

Posted 19 May 2007 - 11:27 PM

#10

hello, i have been tinkering with a old yamaha 1969 enduro 250. Is this also called a dt250? how can i tell if this uses premix, or is oil injected? what is the normal sparkplug size? i have heard that i should replace the crank case seals>.what jetting should i be running for 6000ft? how about carb setting? can anyone point me to some sites related


-Thanks
Chris


Probably a good Idea to replace the main bearings and crank seals on any old Yamaha. They call this bike a DT-1 250 Enduro. It normally has oil injection unless someone has removed the oil pump and plugged the oil injection hole in the intake flange. Make sure the oil is injection type and that the oil pump is bled of all air bubbles. There is a screw on the side of the oil pump for this.
Normal spark plug is a B8ES.
Dwight

  • lanz

Posted 22 May 2007 - 05:55 AM

#11

1969 was a gold tank, 1970 was dark red tank. I had a 69 back then. MX back then I remember meant you put a MX kit on it which was a different top end and expansion chamber exhaust.

  • pantera

Posted 23 May 2007 - 08:10 AM

#12

1969 was a gold tank, 1970 was dark red tank. I had a 69 back then. MX back then I remember meant you put a MX kit on it which was a different top end and expansion chamber exhaust.


Actually I think you are talking about a GYT kit (Genuine Yamaha Technology), which was a factory hop up kit that consisted of a cylinder, head and pipe.

These were very popular to put on a regular DT1's of the time, but it doesn't make them a true factory DT1 MX. In the good old days folks would take standard DT1's, strip off all the lights, bolt on a few parts, throw on some knobbies, & go racing!

The first factory DT1 MX came out in 1970, it was officially called the DT1C-MX. It put out 30HP (vs 23 for a regular DT1), a close ratio transmission, no lights of course, and had a 21" front wheel.

Posted Image

This is my 1971 DT1 which is painted the 1970 Red color.
Posted Image

  • 73DT250

Posted 19 July 2007 - 03:36 PM

#13

sorry to thread jack but i have a bike just like that one ^^ but is is green. what year would that be?

  • motoxvet

Posted 19 July 2007 - 06:44 PM

#14

Regarding removing the oil pump and going to pre-mix, wouldn't the jetting need to be changed? I have a DT-250D and I'm considering this change.
Thanks.

  • pantera

Posted 21 July 2007 - 07:18 PM

#15

sorry to thread jack but i have a bike just like that one ^^ but is is green. what year would that be?


If it has the emblems in the tank like mine and it's green it's a 1970 CT1B 175.
Posted Image

If it resembles my bike but has white decals on the tank that spell out the individual letters "Yamaha" and it's also a 250 it would be a 1973 DT3 250.
Posted Image




 
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