electrical help needed

[guggi102]

Ok so I bought a 250r and knew it had no spark. I test the kill switch, stator,coil.... All within given specs in Beerocks thread. No headlight on the bike or anything either. I am replacing the CDI next, is this the right step? I also checked all wiring due to past people cutting and splicing and everything is connect properly and I cleaned it up and redid some poor connections. Only other thing that threw me a bit was when I tested the coil. The primary came up at .4 instead of .1-.3 and the secondary only got a OHM reading not a KOHM reading like the thread said. I ran this past my father (certified tech) said the primary should be ok like that, not sure why the sec. came up as it did. Any help is great, I already got a CDI so hopefully I just get lucky. Bike sat for 3 years before I bought it, due to not having spark.

[Aceman]

Sounds like your moving in the right direction. Checking all the connections, make sure you engine is well grounded, and ohming out the electrical components. However, I've been burned more times by assuming something will still work when out of spec(like your coil). A CDI is the last resort after everything else checks out, I don't believe there's a way to check it without swapping it for a known good one. If the CDI doesn't make a difference, I'd be looking at a new coil.

[wilkin250r]

If you don't get a proper reading on the coil, that is my first suspect.

It's not just an improper reading, but even more important, the TYPE of improper reading. Like your father said, I'm not too worried about the primary reading, it's the secondary that has me worried.

The coil's job is to boost voltage. It trades one type of power for another. It transforms low-voltage/high-amp into high-voltage/low-amp. (When it's broken down into mathematics, it's exactly like gears, transforming torque into speed).

To do this, the ignition coil is made up of two different coils of wire. The primary has a low number of turns, and the secondary has LOTS of turns, literally over a thousand feet of wire. This is why the secondary measures 7-11k ohm (7000-11,000 ohm). Long wire, lots of resistance.

If you are only measuring a few ohms on the secondary, it means the coil is shorted somewhere. If it's shorted, then the secondary isn't developing the full voltage it's supposed to. Instead of several thousand volts, you only get several volts (not nearly enough to spark). Double and triple-check it to make sure, but it sounds like the coil is your problem.

By the way, I'm an electrical engineer, I used to design stuff very similar to ignition coils.

[guggi102]

I realize the coil being off seems like the first suspect but after doing some research and finding out that a honda 250ex coil falls in the exact same specs and trying that and getting the same numbers on the meter threw me. The 250ex coil should fall exactly where the 250r coil does. In fact I was told that any honda coil is almost identical numbers wise (resistance). Both came up on the meter exactly the same. Second I also even tried the EX coil on the R just to give it a go, same results. After leaving my house(live on campus) I reread how to test the sec. for like the 5th time and stupid me realizes I didnt take the plug cap off. Could this be the difference in reading there? If the 250ex coil came up differently I would have purchased a coil, but the fact its the exact same and its off a running atv I am not sure what to think.

[C-LEIGH RACING]

The plug boot has a resistor in it & can throw off the reading.
Check the wiring harness as well & all those connectors, the black wire with the white stripe is you main ignition wire & one which gives the most trouble.
Neil

[wilkin250r]

Originally posted by guggi102
the secondary only got a OHM reading not a KOHM reading like the thread said.

But THIS is the part I'm worried about, the secondary. Did you get a reading of 7 ohms, or 7k ohms? There's a big difference.

[guggi102]

I realize the difference in the OHM reading but wouldnt the 250ex coil from a running quad come up with the right numbers since its identical? Am I testing the secondary wrong that both came up like this? The meter is on auto but should have a small K next to the reading if I am not mistaken. I bought a cdi already cause it was cheap. I was told that the 250r will run on any honda coil someone tell me if this is true because if so I know the 250ex coil is good and have tried that on the R with no luck. Thanks for the help so far... next part to buy is the coil... unless i figure something else out. All connecters have been checked by the way as stated in original post.