Just bought a 1985 YZ250


43 replies to this topic
  • patpatpat

Posted August 14, 2006 - 08:34 PM

#1

Whats up Fellas

I just got myself a yz250, pretty excited. I just learned about the gas/oil mixture today. Haha, I was running 100% gas earlier today, no wonder why it didnt idle and ran like crap. I put in a New Uni air filter, the old was falling into pieces. I cleaned out the carbs with cleaner. Lubed the chain. I used JB weld to seal a exhaust leak also. Hopefully it fixes the leak after it drys. 3rd Gear is a "netural" gear, it doesnt grab anything. Hard fix? Fuel filter is changed. I have not changed the oil or spark plug yet, they look ok. Where is the oil filter? and how do I check the oil leve, is this one of those fill plug type? No dipstick or sight window
:thumbsup:

It would be nice to hear any comments or tips :ride:

Also, new to the dirt biking world.

Pat

  • DLHamblin

Posted August 15, 2006 - 03:48 AM

#2

Whats up Fellas

I just got myself a yz250, pretty excited. I just learned about the gas/oil mixture today. Haha, I was running 100% gas earlier today, no wonder why it didnt idle and ran like crap. I put in a New Uni air filter, the old was falling into pieces. I cleaned out the carbs with cleaner. Lubed the chain. I used JB weld to seal a exhaust leak also. Hopefully it fixes the leak after it drys. 3rd Gear is a "netural" gear, it doesnt grab anything. Hard fix? Fuel filter is changed. I have not changed the oil or spark plug yet, they look ok. Where is the oil filter? and how do I check the oil leve, is this one of those fill plug type? No dipstick or sight window
:thumbsup:

It would be nice to hear any comments or tips :applause:

Also, new to the dirt biking world.

Pat


Well, if you did run staright gas you likely need to pull the top end off and see how bad its hurt. :ride: There is no oil filter. A shop manual is also needed and will answer most all your questions. Not sure if Yamaha still carries them but you might be able to get a Clymer https://www.buyprism...l.asp?PRDID=403 . Replacing 3rd gear is a engine teardown; you will need a manual for that.

  • UpAllNight

Posted August 15, 2006 - 04:14 AM

#3

I once owned a 83 YZ250... pretty much the same engine as the 85.

Mine had 1st and 3rd gear out (like your 3rd). I had to split the cases to fix it. That was the first Motocycle engine I completely tore apart so it was a leaning experience. But I was also a experienced auto mechanic (hobbiest) so I already had that going for me.

You might be able to fix it but you will need a manual and be good at doing things the first time... otherwise you might want to find a shop with decent prices.

Oil level, there is no dip stick. It goes strictly by the amount you pure in. If you look at the engine you will see something like 900ml or 900cc or 950ml or whatever... thats the amount of oil you are to add in after an oil change. Any engine oil will do. That oil only lubes the gear box and does not lube the piston or crank. Piston and crank are lubed by the oil premix you put in the oil (thats why its not a good idea to run with no oil in the gas). Usually they dont run any longer than 10 minutes without major damage with no oil in the gas.

By the way, If you are using weed-eater oil go to a motorcycle shop and buy some real motorcycle 2-cycle oil. They are different.

Where was the pipe leaking from?

That bike has a rotating drum for a powervalve... I am sure it is stuck and dirty because they stick so easy in them years. Again, a manual will walk you through cleaning and inspecting the powervalve. After its done the bike will have more power everywere!

You best friend is going to be Ebay! If you are not a Ebayer yet, you better become one because it will save your hundreds and thousands of $$$ on parts and other things to make your new ride nice.

Its your first dirtbike. There is alot to learn, alot of mistakes to make, alot of money to be invested in fixing mistakes and alot of fun to be had.

I feel for you because I was in your very shoes years ago.. feel free to ask any questions in this forum, there are alot of knowledgeable people here that will help.

  • glasseye

Posted August 15, 2006 - 04:29 AM

#4

Also, new to the dirt biking world.
Pat


Obvious. I'd say! Hope you got this for free 'cause you'll be dumping alot of cash into it to make it right.I advise professional help.......... with the repairs, that is.

  • patpatpat

Posted August 15, 2006 - 09:05 AM

#5

Thanks for the tips!

I will definitely put oil into my gas from now on. Seems like 32:1 is the MOST recommended. I will go ahead and change the oil while I am at it. I ran with straight gas for less than 2mins.

The exhaust leak was near the block.

Suspension wise, I notice there is a dial i can turn. It is located somewhere near the center of the bike. I guess that adjusts the damping? Clockwise means less or more damping?

3rd gear, I am gonna wait a bit before I tackle that.

And what PSI do you guys run on your tires? I know there are specs on the tires, but just want to know what you guys have.



Pat

  • UpAllNight

Posted August 15, 2006 - 09:44 AM

#6

10 to 15 PSI for the tires.... Most people put them at 12 PSI on average.

That little round thing you turn on the shock, is it on the bottom of the shock or the top?

Did the pipe have a crack or hole or was it just leaking where it meets the cylinder? If it was leaking where it meets the cylinder, I you have to do is remove the pipe, put some Hi-temp RTV around the flange and slide it back on. That seals them up nicely.

  • patpatpat

Posted August 15, 2006 - 09:54 AM

#7

It is at the bottom of the shock.

I used JB weld. I will find out if it did the job or not later on today.

  • UpAllNight

Posted August 15, 2006 - 10:13 AM

#8

That shock only had one adjuster if I remember correctly... It was for comp/rebound. Kinda did both that the same time. Cant remember which way did what though.

If you used JB weld on the part of the pipe where it meets the cylinder, you ant ever gonna get that pipe back off. Thats whats nice about using RTM, it comes back off when you need it too.

On motocross bikes, you will find yourself removing the pipe pretty often.

  • patpatpat

Posted August 15, 2006 - 12:11 PM

#9

Sounds like I screwed up already. If you dont mind me asking, why would I find myself removing the pipe all the time?

Are you talking about the gasket sealant thats toothpaste like?

  • UpAllNight

Posted August 15, 2006 - 12:46 PM

#10

Yes the red gasket sealent in a tube. Just put a thin layer on the cylinder side of the flange and slide on the pipe.

On two strokes the pipe has to come off to reach alot of the parts like the powervalve and such. My pipe comes off at least once every other month for one reason or another.

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  • gulley04

Posted August 15, 2006 - 02:25 PM

#11

Sounds like a project, Nice! :thumbsup:

  • patpatpat

Posted August 15, 2006 - 08:59 PM

#12

Sup fellas

I check the exhaust leak today. No more leak! I changed the oil, there was less than a quart in there! My gearbox said it needs .9 quarts. And the old oil was just nasty. So I am gonna do frequent oil change to get all the crap out. Then finish it with some nice synthetic stuff. I also got some Rock Oil to mix with my gas, the dude at the counter said thats the best!

I took it for a spin. Man, did it pull! Power! It was smoking quite a bit at the exhaust pipe tho. My friend said it smells like it is running rich. The smoke was white, lots of smoke :thumbsup:

Once again, any tips/comments/suggestions are welcome!

Dirt Bike rules!

Pat

  • UpAllNight

Posted August 15, 2006 - 10:51 PM

#13

No need for synthetic... especially because your clutches are working in that oil. Just good ol dino oil will work. I personally use Shell Rotella 15-40.

The heavy smoke could be a normal "Clean out" that will clear up after the bike is warmed up or it could be from a stuck powervalve, or you could be mixxing you oil thick.

32:1 is basicly only 4 onces of oil per gallon of gas.

  • Modmotoman

Posted August 16, 2006 - 06:12 AM

#14

JB weld wont seal that head pipe for very long. that stuff cracks at very high temps.

  • DirtDawg

Posted August 16, 2006 - 06:26 AM

#15

On the rear shock, there is compression and rebound adj. .

The compression is on the top - clockwise (or "in") will make it stiffer, counter-clockwise (or "out") is softer.

The rebound adj. is the black knob on the bottom of the shock shaft, below the spring pre-load adj. nuts. For more rebound turn it clockwise (to the right), for less turn it counter-clockwise (to the left).

1985 YZ's also had the funky B.A.S.S. system, suppose to reduce compression damping during braking (cable connected from shock to rear brake pedal). There is an adjustment for this also that affects compression damping. Standard setting is 4 turns out. Minimum is 1/2 turn out, Max. is 4 turns out.

Hope this helps, Good luck.

  • DirtDawg

Posted August 16, 2006 - 06:30 AM

#16

Forgot to mention, look for a product called Chamber Seal. Its a putty like stuff made to seal headpipes. Pretty good stuff, no drying time needed like silicon sealer.

  • 06yz

Posted August 16, 2006 - 06:48 AM

#17

Sup fellas

It was smoking quite a bit at the exhaust pipe tho. My friend said it smells like it is running rich. The smoke was white, lots of smoke :thumbsup:

Once again, any tips/comments/suggestions are welcome!

Dirt Bike rules!

Pat


I don't know sh*t about bike mechanics. I know newer bikes have packing in the silencer, I would think yours does too. If it does you should change your packing.
Just curious, how much did you get the bike for?
Have fun with it.

  • patpatpat

Posted August 16, 2006 - 02:00 PM

#18

I got it for $200.

Thanks for the tips guys!

I will let the bike have 1 bottle of synthetic and then dino after that!

  • gulley04

Posted August 16, 2006 - 02:21 PM

#19

mine only holds 700mL, that white smoke could be coolant :thumbsup:

  • BRM

Posted August 16, 2006 - 02:21 PM

#20

Keep an eye on your transmission oil if your bike continues to smoke a lot. When you change the tranny oil just measure it to make sure its about the same volume you put in. If it is greatly reduced you may have a worn main bearing seal thats letting gear oil into the crank cases and causing it to smoke out the exhaust.
A quick check is to pull the spark plug out and sniff it, if it is a real pungent odour you are burning tranny oil.





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