I have had this 300ex for a couple of years, and it has never let me down, until last week. We were riding all day, and I pulled it straight up and it fell on the left side into sand. The bike stalled. I put it back down, started it went about 50 ft, and then killed the bike w/ the kill switch. After this I could not restart it. (7 miles from the truck too)

In the field we assumed it was the kill switch because of the fall. We disassembled the swithc and manually jumpered the wires to repliate what the switch says. Still no luck. We pulled spark plug out, and we are not getting any visual spark at all. We then towed it back with a strap the 7 or so miles and called it a day.

Yesterday I dug into this thing some more. I pulled the coil off of my 400 and hooked it up to see if the coil was at fault, It did not work. I rigged up the 300 coil to my 400 and it works fine. So coil is not the isssue. I have +12 on the black w/ white wire going to the CDI. After the CDI I do not have a peak voltage tester to see what is coming out. On my 400 When I hook up my cheapo digital volt meter I get something like 18 volts going to the coil. When on the 300 I get 0 untill I stop pressing the switch, and it jumps to around 6v or so for 1/4 of a second or so.

I tried my cdi from the 400 in the 300, but I am not sure if the wiring is the same. (They are physically different sizes, and the 300 has one more wire) It did not work. 300cdi in the 400 did not work either.

Does anyone know how to test the cdi? or what else should I look for? I have a fairly good understanding of electroncs and know how to use my meter.

 

does it turn over at all? my 300 doesn't even turn over.. i've only ridden it for like 5 hours in the past two years because it has been acting the same way as yours.. my local honda shops are baffled at what the problem is.. they get it running, but then it runs for like 30 minutes and when i shut it off or if i stall it it wont start back up.. its weird..
the easiest way to check the cdi is to find another 300ex and swap them out.. its the easiest and cheapest.. you can take it to a honda dealer but they will charge you like 55 just to run the diagnostics on it..

 

The Bike Turns over at standard speed. Battery voltage while not cranking is 12.4v. To my understanding that means it is mostly carged. and runs (at least did) run great. I guess I need to find someone else with a CDI. Does anyone know of the likelyhood of this actually failing, or is Is it worth a 20 dollar gamble on e-bay?

 

i was told by the honda shops that it is a rare occurance... but it happens ya know.. thats what i got out of the story.. i'd go ahead and say hold off on purchasing one .. try and get ahold of someone that has one if you can.. i'd say if you were going to spend the 20 to gamble with the cdi.. i'd just take it to a honda shop and let them run the diagnostics on it.. like i said its around 55.. i think it would be worth it just to go ahead and cut right to the chase instead of searching endlessly like i have..

 

Gambled with the CDI, and the gable paid off. The bike now works just as good as it had before. Thx for the help

 

in order to get your topic back on top just type "bump" then submit reply, im gunna bump this one up, this is your second topic of the same thing, no prob just trying to help.....