My boys atv got ran through a water puddle a couple thousand times and now wont start. got fuel and spark and only sputters a little bit when I crank it over. Thinking its got to be the timing. My question is what controls the timing? Is it the cdi? Please help?

 

I looked all over the forum and I' pretty sure it might be the cdi. Its a 5 pin cdi. Was looking to figure out how to test it ut maybe I will just try and buy a new one. I have no idea where to buy one but I will try.

Thanks

 

http://forums.atvconnection.com/chin...ml#post3139024

Read through that topic. I just dealt with the CDI issue and it ended up being one of the kill switches. In the topic it explains read outs, etc.

 

I read that post and itdoes not really tell me about timing. I have good spark but when it fires it seems like its out of time. I ordered a new cdi. I will see if that fixes the problem. Thanks for the help

 

Was just providing what you asked for

 

How are you determining that the spark is out of time? Are you guessing? Are you using a timing light? If so what are you getting as a result when you shine the timing light down on the flywheel?

Ignition timing is not adjustable like on an old car. It is fixed by the position of a raised bump on the flywheel to a fixed position of the trigger pick up coil outside the flywheel. The flywheel is of course fixed in position to the crankshaft via a woodruff key.

Ignition timing advance is handled inside the CDI by measuring the amplitude (peak voltage) of the pickup coil signal - which increases proportional to engine speed.

On an AC powered CDI (like yours) the spark is weakest at cranking speeds. SO if you have spark at all at cranking speeds that points away from the CDI since if the engine catches even once that raises the engine RPM, raises the power to the spark, and off it goes. At idle the trigger voltage and the AC ignition power voltage is about three times higher than at cranking speeds.

Two caveats to the above scenario:

1) The spark plug is bad. It takes a higer voltage to fire a plug under compression inside the cylinder. It is possible for a plug to fire at cranking speeds outside the engine, but fail to fire inside the engine. CHange the plug. It so cheap that should be a first item to try - even it a bad plug is rare.

2) Sometimes CDIs will fire randomly on their own without waiting for a trigger signal. That would cause erratic ignition timing. The solution is to change the CDI, but this problem is very, very rare. I have one of these CDIs, and figuring this out - even for someone who knows what they are doing and has some good test equipment - is tough to say the least. My bad CDI starts up and idles fine, but won't accelerate past idle without bogging down - mimicking the classic symptoms of a dirty carburetor.

But you have spark while cranking. With rare exceptions this points to something else other than ignition problems. I think you might be barking up the wrong tree...

Your boys ran through mud puddles a "thousand times". Did this problem gradually appear, or suddenly? Was there a time lapse between when it started, and when it didn't? HAve you measured compression? Is this a four stroke? WHat size engine? If it is a four stroke, when was the last time you adjusted the valves?

 

Thanks for all the help guys. Lets see if I can clear the air a little bit with some more info. Before the water puddle we've never had any problems with it starting and always ran good. The atv is a 90cc falcon( i thought it was a redcat when I created the thread). Its a four stroke also. The atv died suddenly and would then not start which led me to believe something got wet. I pulled the plug and checked for spark and to see if anything was in the cylinder. Had spark and what seems like good compression holding my hand outside of the spark plug hole. Let it sit for a few days to see if it would dry out and it never would start. I have never adjusted the valves and was reading some of the other posts and thought I might try this if the cdi does not work. Again, it dieing abruptly led me to think electrical. When cranking it over it will pop out of the carb a little bit like its trying to fire but just don't seem right. If I pump the throttle it will flood out or I can smell gas ( i have the air cleaner off since I wanted to make sure it had air and I also pulled the carb to give it a cleaning). Oh and I also tried a new plug whick looked like it had more spark but I did not realize when in the motor under compression the spark may be weaker, good to know. I have also sprayed a little starting fluid down the carb with the gas flow shut off and carb drained to see if it was getting to much gas but will only sputter a couple times then just cranks over. Once again thanks for the help and if there is any more info I can provide let me know.

 

Oh and I have never adjusted the valves, once again it dieing so sudden figured it had to be electrical.

 

OK so I got the new cdi and it does not help. I keep checking the plug when I start to smell gas but it does not look wet, I think I jumped ahead and thought I was getting gas because I could smell it. I did spray some starting fluid in the cylinder and re-installed the plug but it did not fire. I know I am getting spark for sure. Maybe I will look on the forum and figure out what the specs are for the valve adjustment. Any thoughts?

Thanks

 

Water in a cylinder can easily bend a rod or even break it. Might be un-likely but i have done it to a go cart and my dodge truck. Bent rods will cause firing issues. If you are going to pull it apart to check valve clearance, etc, check the rod and piston while you are in there. It is not hard to inspect.