Honda TRX 450R banner

1 - 9 of 9 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
Hello, this post might be a little long, so bare with me. I tried searching the forums first but couldn't find anything. I'm working on an '04 450R and it lost spark and quit while riding. I went ahead and replaced the ignition coil and sparkplug and still no spark. I used a test light to check for power at the connector coming from the stator (exciter coils) and it had power, lit up the test light, both the high and low coils. So, then I unplugged the CDI and used the test light to make sure the power was getting to the CDI and it was. Plugged the CDI back in and got no power on the black/yellow wire that plugs into the ignition coil, so I assumed the CDI was the problem. I bought a new CDI and still no spark. So, after reading on the internet that the stator going bad was a fairly common problem with the '04 450R, I went ahead and bought a new stator and replaced it. It was a little hard to start, but it started and idled. When I started to push the thumb throttle, the engine quit. I didn't really even push it any.........just barely touched the thumb throttle and it quit. So, it started back up and I thought I would let it idle and warm up a minute before I tried again. It sit and idled perfectly for about 5-6 minutes and then it just shut off like someone turned it off. Again, it was hard to start, but as soon as it started, it would shut back off just as if you had turned the key off or hit the kill switch. So, I thought, the carb probably needs cleaned because it had sit for about three months since it had quit. I went ahead and pulled the carb and took it all apart and gave it a thorough cleaning. It appeared to be perfectly clean, but I cleaned it anyway. Put the carb back on and still the same problem......it would start and quit as soon as it started. So, I pulled the sparkplug and hooked it to the coil wire and grounded it to the side of the head and it would mostly fire blue, but sometimes it would be orange looking. I pulled the stator cover back off and rechecked the stator to make sure I put it in right and I did.....couldn't see anything wrong. So, I bought another new sparkplug and with the new plug, it had a good strong spark (blue) with every kick. I put the plug back in and it started up and quit as soon as it started just like before. I got tired of messing with it, so I let it set for a few days.

Today, I tried to start it again and it started and quit. This time, it wouldn't start back. I took the plug out and now it's not sparking at all. I used the test light again and I'm getting power from the stator coils to the CDI, but no power is leaving the CDI to the ignition coil. I put the old CDI back in and the same thing. I'm getting power to the CDI, but not out of the CDI to the ignition coil. It's almost like something is grounding out the ignition system, so I unplugged the wiring connector that goes to the kill switch and I unplugged the wiring connector that goes to the key switch and it still won't fire at all. I'm out of ideas. Is there anything else that could be shutting off the ignition.........like the TPS or something. But from what I've read, I don't think the TPS can shut the ignition off and cause it not to spark or can it? If anyone has any ideas, it would be greatly appreciated.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
Yeah, it sit for a while, and I did change the gas and clean the carb, but there's no spark at the plug now. Something is keeping it from firing the plug.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #4
I tested the throttle position sensor and it's bad, but from what I've read on the internet, that's not supposed to keep it from running. From what I've read, everybody says it just sends a signal to the CDI at wide open throttle or near wide open throttle and the CDI adjusts the ignition timing to make it run better. Anyone know for sure if this is the case or not? I read where someone said they even unplugged theirs and couldn't tell any difference in how it ran.
 

·
Fairly fast foreigner!
Joined
·
3,583 Posts
The TPS is pretty much along those lines, it adjusts the timing depending om the slide position. Yes you can unplug it and it will not adversely affect anything. You sure you got a good stator?
 

·
Registered
Joined
·
4 Posts
Discussion Starter #6
The TPS is pretty much along those lines, it adjusts the timing depending om the slide position. Yes you can unplug it and it will not adversely affect anything. You sure you got a good stator?
I'm not 100% positive the stator is good, but it lights a test light for both, the high and low coils. I tested the wires as they enter the CDI and it lights the test light with every kick, but when I check the black/yellow wire that leaves the CDI and goes to the ignition coil, it doesn't light up the test light. I've tried two different CDIs and get the same results.
 

·
Fairly fast foreigner!
Joined
·
3,583 Posts
Don't forget the stator will constantly generate a current when the fly wheel is turning but the ICM pulses for the coil (the duration of that pulse probably won't be seen with a test light or dvm).
 

·
Registered
Joined
·
49 Posts
so is the TPS the plug at the back of the carb, just unplug it? or is there a bypass?

isn't there also some sort of WOT safety aswell? I'd like to eliminate the simple stuff first, before I start chasing other potential issues.

i'm reading too many "no start" threads, and too many stator issues for quads that are less than 10 years old.
 

·
Registered
Joined
·
4 Posts
My 07 rancher lost spark and I moved the tps connector and got fire again. Still trying to figure out why it won’t run though
 
1 - 9 of 9 Posts
Top