1979 YZ 250 - need your help

If its race ready its worth it.

If you got a junker for 800-1000 you dont think you could drop 1100 in time and parts no problem? The most important thing is that it didn't live a hard life. You dont want something that has been pounded into the ground and fixed up to look nice again. Like any one of the Kardashians.
And whats 2100 .00 in todays world? 2K and you have more fun than any vacation you can take.
If you can spare 2k from life then just go buy the bike. Make him an offer. Needs tires.

That was a very good bike back in the day.

Paw Paw

My favorite bike from that era. I used this one up. If it was running, I was riding or racing it.

I have the big brother to that bike a YZ 400. Solid platform to work with. For that price the motor should be fresh so check it as much as you can. A compression test and pull the stator cover to look for crank play.

I rode one back in the day and bought another one when I started riding vintage.
Looks like a bike that wasn't beat up......I mean it still has the stock pipe and silencer, kick stand, stock bars plus it looks like the original tires.
Great bikes, very reliable, lots of power, parts are plentiful and with a little suspension work you'll enjoy riding it.
Those '79's were very well received by the test articles in magazines.

Go for it you're saving your self a bunch of hassle and you can ride it same weekend !
Bring it to Ormstown and race it in August ! Try and get the title for it, makes a HUGE difference if you ride in Qc. You'll need a plate to haul out in the open, otherwise closed trailer ( cops want a plate or impound )

......so did ya buy it ?????

1979 was a one off year. I'd check availability of Pistons, bearings, clutches and other high wear engine parts. 1978 and earlier used DT motor parts and those are plentiful.

Umm not for the 250. 77-79 all similar. Parts are easy to get for the 250. My 400 on the other hand is a one year wonder.

Yes part a plenty, interchange with IT of same years, VERY reliable bikes. Not as sexy as G or H but well set-up get job done. Did you get the title /papers Ron ?

....and while you're at it, better go ahead and grab this on the bay.
great test review from team Yamaha Mike Bell.

http://www.ebay.com/itm/December-1978-Cycle-Magazine-/190520752182

also notice that the forks on your bike are pulled down in the triples. I would definetly correct that issue as it will affect the handling.
Bring the forks up in the triples, I'm guessing about 2 inches higher than it is now, and you would be closer to stock specifications.
Look at the pic on magazine cover as guide.

78-79 are like designs. They both used the shrunken down cases that debuted on the 250 in 78 on the E model. The 77 YZ250D still used the larger, older style cases. E-F engine parts all interchange.

77 D 250 parts will not. In 79 , the 400F got the case shrink treatment as well.

Overall, the 250E was a faster , mid to top engine. The F had the low to mid power enhanced over the E.

I had a mix and match of three different engines (E-F) for my Champion 250 short track bike. For the larger tracks, 1/3 mile and up, I used the E (2K7) cylinder. Just flat out faster on top. The F (2X4) cylinder was better on short tracks 1/4 or less.

The best engine combo I had was a 2X4 (79) bottom end, Falicon prepared /balanced crank and top end assembly, 87 YZ80T ignition system (external flywheel with 14oz of weight added & and balanced), Jemco pipe, and a 39mm D slide Keihin carb.

Had three engines ,run ready that I alternated between. Two F cylindered, one E.

Stock porting on all cylinders, with only squish chamber reworked by BPM.

That bike / engine was more than a match for the water coolers up to 1995, when I raced it for the final time.

Took me to the win in the Southeast regional 250 class championship in Daytona ,'95.

It's the blue and orange bike in the picture.




Holeshotting the 250 final at '94 SE Regionals on one of two dry barrels to make the main.

87 YZ80T ignition I used on the E-F engines. Taper is the same as the 250's. This will not work on the 250 D ,as they still used the large nosed crank in '77, in the old style cases.

Only a small centering ring, cover spacer, and new slot milled in the cases for the wire lead exit point was required. It worked great. I believe the 80 system had a bit higher rev limit, as the engines sure would twist tight.

Probably a bit past the safety limits of the design / construction of the 250 engine. Only had one main bearing failure in over 5 years of racing these engines. I attribute that to maybe a bit of extra weight from the flywheel, but more so ,the cheap OEM Yamaha bearings with the plastic ball separator cages.

The ignition side bearing broke a cage one night. She back fired hard after a full throttle blast on a small 1/8 mile track, as the throttle was shut off going into a turn. The cage broke, all the balls rolled together, and it basically lost crank / ignition timing.

The bearings only had about 10 races on them when it occurred.

Bought some real, C3 bearings, and never had any more troubles. Ran the dog crap out of those engines.

And that white bike in the picture, one of the biggest turds Yamaha ever made. The bike, another Champion, was great. The 74 MX 360 engine in it was slow, and not super reliable. Even had a bit of port / head work from a name short track tuner, but out classed by good running Bultaco Astro 360's, XL350 Honda's.

It would seize on occasion, especially on 1/2 miles, where the heat build up seemed uncontrollable. In talking with others who raced (or tried) these engines hard, I learned it was just part of the MX360 life style.

Had an old MXA magazine, where they tested a new 74 MX360. Their bike seized within the first three hours of the test.

cool shizz there PRacer.
Here in Houston, Daryl Hurst has one of his old champion framed flat trackers with the "wet" barrel YZ250.
Back in the early '70's, Houston hosted the "Yamaha Gold Cup" series which was held in the Astrodome.
Hurst won the short track event one year but of course was a air cooled engine back in those days.
As a kid back then, the flat track races were always a treat to attend.

Project Racer, are you calling air cooled engines dry barrels? I have always wanted to try racing in a circle. Hard flat corners arent my strong point. I think it would help me alot. I see those ovals and I cant imagine just flying in a throwing it sideways. I know I can because I did on the road avoiding Mr Magoo driving a Chevy Caprice and a trip to the ER, but on the track Im way more comfortable with a berm for my tires to ride against.

MaxP, yes ,air cooled. Dirt track is fun. More fun if there is a bit of moisture / grip in the surface. When it's dry slick, with a layer of dust that keeps getting blown across the groove, much more unforgiving, especially on a zingy two stroke.

The amateur / regional scene during Bike Week in Daytona used to be fun in the early to later 90's. Could run 5-6 events in a weeks time, riding two classes at most events. If you had a vintage bike also, throw in a couple of more, if you could keep your crap running all week.

These days, lucky if there are three good amateur events scheduled for the week. No vintage national either.

Sorry to hijack the thread. Just remembering how good the old 250 E-F Champion ran. Had so much engine spares for those bikes at one time. All my DT stuff is gone.








This was a nice half mile at Holiday Downs ,Georgia. Only place that was loose enough to run a Pirelli on the rear in the south east.

Cool neat stuff ! Post up some more pics Ron. Are you going to Ormstown in august ?