Yamaha dt250 - strange battery ?

[jordan325ic]

Hello everyone. I just finished my MSF course last week and am currently on the hunt for my first bike.

I've got a friend who has a barely-running 1976 Yamaha DT250, which he offered to let me ride in the meantime if I can get it going. The battery was dead, so I tried to jump start it. However, once I lifted up the seat I did not find a battery I recognized.

The battery I saw looked like this:


BUT it had no terminals and no threaded holes. The only thing it had was a red wire going in, black wire going out and those little yellow knobs. There was not any visible metal at the battery or anywhere down the wire to attach the jumper cables.

How do you jump a battery with no terminals?

Also, quick bonus question: The air filter is in very poor shape (disintegrating). I have (with some difficulty) tracked down an OEM air filter, but I'm wondering if I should go with an aftermarket K&N filter which can be cleaned/re-used? What does adv think?

[gvthnks]

That's a 6v battery. Don't jump it. The DT250 will run without the battery but you shouldn't.

I'd use a foam type stock filter.

[dan-c]

Originally Posted by gvthnks

That's a 6v battery. Don't jump it. The DT250 will run without the battery but you shouldn't.

I'd use a foam type stock filter.

It won't hurt a yammie enduro to run without the battery. The battery basically supplements the lighting, i.e. blinkers are better, tail light lights without the engine, stuff like that.

Better batteries are the sealed agm ones that are used for back-up power for home alarm systems. Just take the battery to your local Batteries Plus store or the like and get one. No worrying about acid eating up the seat and battery box and the damn drains that never seem to get routed correctly.

I use a UNI filter on my yamaha's they come with the cage and sleeve that are just like stock except better.

[jordan325ic]

So the battery will not effect the bike's ability to start?

I guess I'll start looking elsewhere for the reason why it won't start. I tried kick-starting it many times, tried to pop the clutch with the bike rolling. It sounded like it wanted to start but never did catch and actually run. I guess I'll replace the air filter and go from there. This is my first time working on anything with a carb, so it will be a learning experience.

[dan-c]

Originally Posted by jordan325ic

So the battery will not effect the bike's ability to start?

I guess I'll start looking elsewhere for the reason why it won't start. I tried kick-starting it many times, tried to pop the clutch with the bike rolling. It sounded like it wanted to start but never did catch and actually run. I guess I'll replace the air filter and go from there. This is my first time working on anything with a carb, so it will be a learning experience.

No it get's all the power from the magneto (and coil).

If it's been sitting pull the plug, ground it to the head and see if you are getting spark (should be a decent fat spark, not weak looking), never hurts to change the plug while you're at it.
If you have spark, you may want to pull the carb and rebuild it. It is pretty easy to do.

[capeklr]

Check that you are getting fuel through the fuel tap and into the carb. there must be fuel in the carb bowl or float chamber.
Remember also to check that there is 2 stroke oil in the bottle and that the pump works or it won't run for long.

[Inane Cathode]

New plug right now. Take the carb off, clean it out, put a filter on the fuel line, rinse the tank out with fresh gas, give it a spritz of ether in the intake it should fire up.

[baloneyskin daddy]

Ether eats the hell out of 2stoke crank seals.

[Inane Cathode]

Not any more than they already are, and just a spritz you're not plumbing the stuff into the carb. If it wont fire on ether it wont fire on anything and it indicates a major problem.

[Beezer]

JC Whitney has all those batteries. an ya, pour some gas in the sparkplug hole it should kick off if you have spark.

[jordan325ic]

Hmm. It just dawned on me that he may not even realize his bike is a two stroke. He told me the oil filter is probably clogged, but that it's OK if you put some oil in the gas tank. Now I have never had any experience with 2-strokes, but a few minutes of googling indicates that 2 strokes don't have oil filters and there is a pretty specific ratio of gas to oil that needs to be upheld.

Anyway, I recall the bike being pretty smokey when it last ran. I think he may be putting the wrong amount of oil. What ratio of gas to oil do ya'll use?

And what could be damaged by running the wrong ratio of gas to oil?

[CoolioRZ]

The bike should have an "oil filter" screen at the bottom of the injector reservoir. Maybe your friend was referring to that?

As far as a pre-mix ration goes, 32:1 will suffice.
Damage from the wrong ratio could be as simple as fouled plugs and too much smoke. Running too rich will also quickly carbonize your top end.
Running to leaning will quickly wear out rings, seize your top end and maybe the bottom end.
If you go the pre-mix route, I'd definitely recommend using a ratio-rite.

Excess smoke can also be a symptom of a bad clutch side crank seal.

What year is your DT? Is it a reed valve model?

[jordan325ic]

Well, I found out the problem. He was mixing in 4 stroke oil instead of 2 stroke, so the plug was fouled. Replaced the plug, cleaned the carb, replaced the air filter, put new gas in, and she started right up.

Got to ride her around, and she is fast! Now there's either a throttle issue or an idle issue, because when I'm not in gear (clutch in or in neutral) she revs very high. Tach is broken, but it's way wrong. He thinks it's the throttle sticking. Also, that headlight SUCKS. Need to upgrade that if I'm every going to ride at night again.

[RodT]

The throttle issue might be an air leak. If the bike sat for a long time, and just because of age, the main seals could be bad. The seal under the mag, might be sucking air. That can cause an eratic throttle. If it is an air leak, do not run it, it will seize the piston. If the other side is leaking, it can suck oil out of the trans. and cause it to smoke really bad. You can do a pressure test to see if the seals are bad. Rod

[jordan325ic]

Originally Posted by RodT

The throttle issue might be an air leak. If the bike sat for a long time, and just because of age, the main seals could be bad. The seal under the mag, might be sucking air. That can cause an eratic throttle. If it is an air leak, do not run it, it will seize the piston. If the other side is leaking, it can suck oil out of the trans. and cause it to smoke really bad. You can do a pressure test to see if the seals are bad. Rod

I'm sorry, I'm new. What's a mag? Where are the "main" seals and what do they seal?