No spark after a bump

Went riding the Yamoto 150 tonight with the little guy and we were on our usual 10 mile loop. We were on a sandy trail about 2 miles into the ride when I hit a small jump/large mound. I might have got a couple inches off the ground as we were not trying to jump. Upon landing it dieseled for about 30 feet because of the speed, but was not really running. As soon as my brain realised something beyond bumping the kill switch happened, I hit then and braked hard to stop asap.

My last experience like this was with a CR250 smoker so I had visions of a pitted piston and head.

We looked for a rope someone left in a junk pile so he could slowly tow me out, but no such luck. So I ended up pushing it 2 miles through sand to get home.:worthy:

I got home and checked the plug, it was still as new as it was when I put it in last week-but no spark. So I tried a new plug...still no spark.

I got the volt meter out, the kill switch functions properly, voltage spikes when on if you kick it over. At the same time though, the wires to the coil don't show any voltage when you turn the engine over, but the coil to the plug cap does show a lot of resistance in ohms...which I believe to be good.

This leads me to believe that the problem is that black plastic and epoxy square thing with two connections going to it. First, I don't know *** it is, and second, where the hell am I going to find a replacement for that?

Is it some sort of computer thing?

Keep in mind, whatever went wrong happened as soon as I hit a bump, so something was jarred loose...but I don't know what.

Please don't mind my rambling, pushing 2 miles through sand will make anyone pissed...:thumbsup:

I hope someone might have an idea, my first ever non obvious electrical problem.

The key is, that this happened after hitting the bump. More than likely, if you're getting no spark, it's a connection issue. The little black epoxied thing with 2 wires sounds like the coil. It should have a pulsing 12vdc supply.

The key is, that this happened after hitting the bump. More than likely, if you're getting no spark, it's a connection issue. The little black epoxied thing with 2 wires sounds like the coil. It should have a pulsing 12vdc supply.

Not the coil, I found that ok, but I have no idea what it could be.

Mind you when I bought the bike last year, I gutted all the heavy stock crap that was on it and made it into a real dirtbike. It has no key, no electric start (or starter), no batter and no lights. It looks great, and has a very simple electric system. I would have blamed it on something I did then, but that was a year ago, so it seems highly unlikely that I did this myself.

Basically, wires go from the bottom of the engine (magneto I presume) up to this mystery box, then from that to the coil then to the plug. The mystery box has two connections to it, with 6 wires, (4 on one connection and 2 on the other) I can't trace these wires back because they all merge together into one black taped up mess (not my doing)

The 4 pin connection is running to the box, then the 2 pin connection runs from it to the coil. I can't find voltage either entering this box or leaving it, but I really don't know why more than two wires would go to it from the engine. Unless it was some sort of security thing.

I don't know much about electric systems, but shouldn't you be able to pass the pulse of power from the magneto directly to the coil without passing through the mystery box?

Ahh ok. the Mystery Box sounds like the CDI. It's more or less the electronic control module for the spark. Sounds like it may have bit the big one. It should have a common/ground, 12vdc, kill switch, flywheel sensor connections at least.

This bike uses a lot of Honda parts for replacement, what are the odds that a CRF150 CDI would work? I'm just doubtful I'll ever find the stock one, the guy I bought it from is long out of business.:thumbsup:

Might want to hit up chinariders.net. Lots of resources there.

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