Very Challenging Diagnosis

[xc450_thumper]

I have a 2008 450r Kicker.

My last race was a mud race, it downpoured during the start on top of all the rain before that too so it was nasty. I had my light come on a couple of times. I pulled off and let it cool then went again. I kept a keen eye on it at all times.

Anyways, third gear pinned wide open, click, turned off. Thought I hit the off switch or kill switched jerked. Both were good. Kick and kick and kick....and kick. Wouldn't start. After I got it home, I got it started on the second kick. I think I may have lost some compression but I don't think that would factor into my issues.

Anyways, next week after that. I am at the motocross track. I had been tearing it up for 4 1/2 hours when all of a sudden. It bogged down fast, then it revved right back up for like six seconds to normal. Then it died. It took way more kicks than normal to get it started and I brought it home.

The NEXT week after that. It took me 15 kicks to get it started. I got it half way around the track. It was going great, when it bogged down really fast and just quit. Me and some passerby took turns kicking it. About fifty eight kicks in it started. I got back to the trailer fine. I let it sit there. It has ALWAYS ALWAYS idled amazing. Well after six minutes of idling it turned off. Another seventeen kicks later I got it going and loaded it. Now I sit staring at it pondering what is going on?

Another piece of information, that last ride, after it was warm, hot start would not get it started. After it is warm, I've always got it started with hot start, one kick, sitting down even. This time I had the choke on, and then it went. It was really wierd.

Those two wires going into the throttle have been disconnected for a long time and it never affected anything, I plugged them back in to be safe, although I am not sure I plugged each one in the right slot.

I wouldn't be surprised if mud got in through the air intake, as my k&n vibrated off AGAIN for the tenth time. I am about to pop rivet that thing in there. Also, when I refueled at the mud race, mud might have got in. I am going to do a complete cleaning of the carb, but this has intermittent electrical issue written all over it.

[Sjorge450R]

you got yourself a basket case here.


I would defintellty go through, clean filter (switch to a uni..save yourself the questioning of whether or not the K&N is working) then clean the carb, gas tank. Also CHECK THE VAVLES! These hondas love to eat valves. Make sure they are in check. Engine at TDC, intake are supposed to be at .006 +- .001 and the exhaust are .011 +- .001.

[WilRideAnything]

I would check the valve clearance.

[hendershot106]

check your stator.... seems to be dying when it warms up.... stators do that at first... then they completely burn up and produce no spark...

[4ABURN]

coil or dirt in carb would be my first try.

[JAKE YATES]

not 100% but sounds like a valve problem to me.

[fastredrider44]

Valves, Coil, and maybe stator later. But valve adjust/grind if necessary would be my first route. And x2 on getting an UNI.

[pro-rider46]

sounds like when i blow a crank, the rod bearings start to go, and then it starts to seize the crank through that bearing. then frees up, them seizes again, eventually snap the bottom of the rod. or maybe your piston is scraping. one of those two if you ask me.

[xc450_thumper]

I am doubtfull on the valves being the issue. I mean, if it was the valves it would run like crap all the time wouldn't it? I can get on and go like 100 yards full throttle perfect perfect perfect, then quits.

The stator idea sounds the best. How exactly do you test a coil, stator, pickup, etc...

Definitley heat related I am thinking. I will check the valves some time this week when I clean the carb and throw on a different spark plug.

The fact that it will start back up after sitting for like twenty five minutes adds to the idea that it is heat.

[Tommy Warren]

I think there is a fuel filter in these things somewhere you might want to check that. it would explain your bogging, revving and bogging again.

[fastredrider44]

Stator I'm not sure about, but you can ohm out the coil. I'm not sure what it's suppossed to be though. Maybe someone with a service manual can look that up.

[hendershot106]

Originally posted by xc450_thumper
I am doubtfull on the valves being the issue. I mean, if it was the valves it would run like crap all the time wouldn't it? I can get on and go like 100 yards full throttle perfect perfect perfect, then quits.

The stator idea sounds the best. How exactly do you test a coil, stator, pickup, etc...

Definitley heat related I am thinking. I will check the valves some time this week when I clean the carb and throw on a different spark plug.

The fact that it will start back up after sitting for like twenty five minutes adds to the idea that it is heat.

the best way is to switch out the stator with a new/ used one off a good running bike... if you have a buddy that has one.. just pull of his stator cover and install it, cover and all on yours... its a cheap diagnosis trick that will only cost you the price of the gasket and a quart of oil... instead of $150+ wasted just incase it isnt the stator....another way to check this is- when you initially start it and it runs... you know you have spark.... when it quits after it is good and warm; then pull the spark plug cap off, put an old plug in it and hold it against the engine to check for spark... if your not getting spark then.... its 95% likely its the stator...

[xc450_thumper]

Not to kick an old thread, but I feel an update is in store.

I was to busy to mess with it for a while there so it just sat. I checked the valves, the ones under the cam, intake I believe had a .000 gap. I set them properly and it fired on first kick. I took it to the track and started tearing it up.

Three laps in it cut out for a second and then came right back, never shut off but definitley cut out. No problems next ten or so laps. Cut out once more some time after that but never shut off.

Then after about hour and a half of good hard riding it did it. It cut out and died. Fourteen kicks later it started up and I took it back to trailer. I thought hey I might be on reserve. Added EXACTLY one gallon of gas and it filled it right up to the cap. Let it idle for a minute or two then hit the track again. Like 50 yards in it cut out and died. I trailered it, and now its sitting in the shop again.

It sucks I have to ride it really hard for a long time before I can really get it to show. I changed the spark plug too, just to be safe. As much as I want it to be the stator, I can't see a stator failing on such a new low hour machine. Not even 20 hours on the clock. My pro design kill switch the wire is soldiered so I wouldn't think that to be it.

Next time I'm getting a yamaha :grr:

[HondaRaceReady]

I have the exact same model as you. When my clutch cable was adjusted wrong it would take 50 or more kicks to get it started and it stalled very easily. Its probably not your problem, but worth checking. Mine also shuts off for no reason sometimes, but its rare and time for some maintenence anyway.

[xc450_thumper]

Would have been a possibility but I have a rekluse z-start pro clutch. Forgot to mention that.

[mc_racer]

I had a intermitent spark issue that turned out to be a bad stator ground. It would just die whenever it felt like it and was really inconsistent on what it wanted to restart. It started after I overheated it really bad. I finally found the problem by running a jumper wire front one of the stator cover bolts to the motor mount bolt.
Ended up pulling the cover off, cleaned the bolts, alignment dowels, and holes. Soo far, so good.

[duke416ex]

Have you checked to make sure your vent on the gas cap isn't stopped up? I have seen several act this way when that vent was stopped causing no air to go into the tank and then not allowing gas to flow to the carb.

Also, my bro had trouble with his that turned out to be a broke wire going to the cdi at the connector.

[BERT306]

Originally posted by duke416ex
Have you checked to make sure your vent on the gas cap isn't stopped up? I have seen several act this way when that vent was stopped causing no air to go into the tank and then not allowing gas to flow to the carb.

Also, my bro had trouble with his that turned out to be a broke wire going to the cdi at the connector.

+1 on the vent. I'd also clean out your fuel petcock. dirt could be clogging it up and starving your carb of fuel at certain times and then bouncing around and giving more/less fuel. What thought was a heat/electrical issue could possibly be fuel? worth a shot IMO

[CNC_guy]

Originally posted by duke416ex
Have you checked to make sure your vent on the gas cap isn't stopped up? I have seen several act this way when that vent was stopped causing no air to go into the tank and then not allowing gas to flow to the carb.

Also, my bro had trouble with his that turned out to be a broke wire going to the cdi at the connector.

I had this happen on the Rancher one time. The quad only had about 30hrs on it. I finally gave up and took it to the dealer and they couldn't find out what was wrong either. I found out that it was kinked one day by accident....I've never felt so relieved yet so stupid at the same time before.

[xc450_thumper]

This weekend I am going to tear the carb apart and blow all the needles out with the air compressor. Where exactly is the fuel filter and how do you get it out, is that inside the petcock?

As for the gas vent hose, I have a tusk racing cap with the little short 3 inch snorkel. Popped the cap off the top just to be sure and there was no dirt in there.

[duke416ex]

You may not be able to tell if it is clogged without removing the vent hose or loosening the lid when it dies. I would just check it before I tear into the carb.

Other option may be the stator.