1975 YAMAHA DT125 ENDURO

SHAD · Posted: Fri Mar 05, 2010 8:43 am Post subject: 1975 YAMAHA DT125 ENDURO

HELLO, I HAVE JUST AQUIRED A NICE OLD GEM. I WAS AMAZED TO SEE THAT AFTER A LONG TRUCK RIDE FROM THE FARM, AND FROM SITTING OUTSIDE UNCOVERED FOR WHO KNOW HOW MANY YEARS, THIS LITTLE PUPPY FIRED RIGHT UP WITH JUST A FRESH BATTERY!!
BUT IT IS IN NO WAY IN "GOOD RIDING ORDER"
IM GONNA START TEARING IT DOWN WHEN THE SNOW MELTS BUT I WAS WONDERING... I GOT ME A CLYMER MAG. AND I WAS LOOKING AT THE CARBS
(THIS BIKE BLEEDS GAS OUT THE BANJO BOLT AND THE BOTTOM OF THE BOWL)
AND IN THE MAG. IT SHOWS THE BANJO BOLT WITH ANOTHER BOLT SCREWING INSIDE IT AND THIS BOLT IS CALLED UP AS THE MAIN JET?!?!?!
BUT THATS NOT THE MAIN JET??? REALLY CONFUSED HERE IN THE EXPLODED DIAGRAM THERE ARE 2 MAIN JETS??!!
ANY FEEDBACK WOULD BE GREAT TO HELP ME UNDERSTAND WHATS GOING ON HERE THANKS! Rolling Eyes

zjeppe · Posted: Sat Mar 06, 2010 1:25 am Post subject:

Welcome Shad, but...why shout(capitals are considered shouting at forums Idea

) sorry can't help you with your prob but I'm shure the guys around here 'll point you in the right directions Wink

drew0512 · Posted: Sat Mar 06, 2010 8:56 am Post subject:

does this help?

http://images.cmsnl.com/img/partslists/carburetor-dt125a-19741975_bigyau1078b-5_7521.gif

drew0512 · Posted: Sat Mar 06, 2010 9:00 am Post subject:

this one is better;

http://www.babbittsonline.com/pages/parts/viewbybrand/2/Yamaha.aspx

tcanough · Posted: Sat Mar 06, 2010 9:04 am Post subject: 75 dt125

Welcome Shad ; Is the weather starting to break in your part of Canada ? I currently own a 75 dt125 and have had my trials with it and expenses as well . Just got it running again , passed emissions , registered , insured and the same day [ 3.5miles later seized the motor ] had to order everything for the bottom end build as I already had the top end parts from a previous miss diagnosis . This bike looks like it came from the showroom , original condition ,and 4,500 miles . You just can't erase 35 years of sitting . Check the engine out completely before running it too much . And save yourself allot of time and expense " DO NOT PRESSURE WASH THIS BIKE " I can tell you this from $400.00 worth of engine rebuild experience !
Now for your original question , I do believe that the Clymers and others call that particular jet a main jet [ I'm holding the exact carb in my hand and had to disassemble it to see what you were referring to ] . This is not what you or I would think of as the "MAIN JET " Located in the top portion of the carb . It is a jet and it's function is unknown by me . Oh Ya , the reason I'm holding the carb in my hand is that it is part of what I took out with the pressure washer , along with the oil pump , the points the points cam and probably contributed to taking out the oil seals causing the crankcase to loose vacuum and seizing . The last point is a guess as I've not disassembled the engine yet . I'm leaving that to a professional of which I'm not . Good luck to you with the little Yamaha . I love mine when it's running .

drew0512 · Posted: Sat Mar 06, 2010 9:11 am Post subject:

or try this;

http://www.wgcarbs.com/

Bikegeezer · Posted: Tue Mar 09, 2010 7:05 am Post subject: Re: 1975 YAMAHA DT125 ENDURO

Steve Searles · Posted: Tue Mar 09, 2010 7:52 am Post subject:

In that particular carburetor the "main" jet is indeed in the "banjo" bolt in the carb bowl. The other jet "pilot " is in the main body of the carb. Just make sure both are clear and you can see light thru them and continue on. Don't let terminology get in the way of a good easy carb cleaning. Take out air idle mixture screw after documenting how many turns out it is set at. (Usually 1 1/2 turns out). Blow out all passages, clean bowl and reassemble. Check needle and seat as well. It should be just fine. New plug, file, clean points, etc.

SHAD · Posted: Fri Mar 12, 2010 9:51 am Post subject: NEW PARTS BIKE!!!

Hey all thanks for the quick response, i cant wait for all the snow to melt so i can get started on this bike (i dont have a garage Crying or Very sad

BUT just lastnight i found a 1972 AT2 125....I think it matches the pic on google.
but i was aondering if anyone know of these bikes and if it is a good parts bike candidate for my 75'.....
one thing i noticed right away on the 72' is (2) spark plugs?? what that about its 2 stroke... in the google pics i found 1 that was complete resto and it had (2) plugs but w/ the cable going to only (1) ??
so plz let me know if this motor is totaly different or a good candidate..
if not it not that bad it got lots of parts (body related) that are worth well over the $50 i paid for it : Surprised

Hoss · Posted: Wed Mar 17, 2010 9:16 am Post subject:

I believe the second spark plug is a spare. I could be wrong.

jayel · Posted: Wed Mar 17, 2010 9:59 am Post subject:

it's a compession release port originally just a block-off plug in that hole but you could use the compression release (better than brakes on dirt, acts like engine braking on a four stroke) or a extra plug

pd · Posted: Wed Mar 17, 2010 10:53 am Post subject:

For conversation , my '58 Simplex has a double spark plug and both fire at the same time from the same coil . It's a two stroke .

jayel · Posted: Wed Mar 17, 2010 11:21 am Post subject:

Bikegeezer · Posted: Fri Mar 19, 2010 5:24 am Post subject:

About that second plug in the hole intended for a compression release, a lot of guys think it's a swell idea to put a hotter plug in that hole. The thinking seems to be that if the cooler plug fouls, you can just swap the wire to the hotter plug. That may be true, but one should beware of how hot a plug goes in that hole. The plug doesn't create heat, it removes heat. And it does that whether there's a spark going across it or not. If it's too hot a plug, it'll hole the piston - wire connected or not. Best to keep spare plugs under the seat, and fill that second hole with a factory type blanking plug or a compression release. Sometimes, both holes are spaced equally from the center. But if one hole is centered and the other is off to the side, the hole at the center of the head is the one that should have a spark plug in it.

Stu