Then it stopped......

[lukey_muffler]

Hello all. I have a 99 wr400f that is not playing the game! Story goes about 3 years ago it was my commuter, took it off the road and raced it in a few enduros, so removed all the lights, regulator etc. It ran great for about a year, then it stopped. To start with I thought it was a fuel problem, so pulled out the carby and gave it a good clean. Put it back in the bike and I was back in business, took it for a ride and it was going great, then it stopped. Next idea was an electrical problem, pulled out the manual and followed all the test proceedures on testing the stator, magnito, ignition coil, etc. All tests out fine. I have plenty of spark and I'm sure the issue isn't with the carby. When I kick it, it sounds like it wants to start and when it dies it does it suddenly at any rev range. Usually in the hardest place to get it out from.

I would love it if anyone can offer me some advice or suggestions. I love this bike and it's saddens me to see it in a million pieces in my shed!

Thanks!!

[MANIAC998]

How's your valve clearances?

Maniac

[lukey_muffler]

I checked them 3 stoppages ago and they where fine, if they where out I thought I wouldn't get any life out of it?? It's just strange that it goes so well then dies...

[jraffety]

Running fine then just shutting off at any rev sounds electrical. If its intermittent everything can check out fine in the shop then stop working on the trail. Not sure if 99 400 is same ignition as newer 450s but intermittent failure of pickup coil, CDI or ignition coil could cause it. Even a short in the shut off switch. It can be hard to find intermittent electrical issues, sometimes just have to replace parts that seem to be ok.

[lukey_muffler]

I was kinda scared that that was going to be the response, I was also leaning toward an electrical problem. The only thing that was putting me off is the amount of spark I have. Suppose I just start with one at a time and see how I go. Thanks!

[Taxgod4u]

always start with the least expensive variable, and only chang eone variable at a time. check all electrical connections, unplug inspect for crud an corrosion and reconnect. Confirm ignition switch/button are not faulty and bypass the kill switch. A corroded connection can act flaky by limiting current, signal, or just breaking the circuit. next is the spark at the correct time? could something have slipped/moved?

[MANIAC998]

I seem to remember someone on here recently that had some of the same symptoms as you. In his case, it was his rotor. The magnets on the backside were all shattered. With a flywheel puller, this would be an easy check.

Maniac

[lukey_muffler]

Thanks for all the ideas, I think i need to set up in the shed with a few beers and alot of patience and go through my whole loom and triple check everything. The kill switch suggestion makes me feel kinda dumb, I haven't checked that yet! And Maniac, I have pulled the flywheel (got a bit creative making a puller) and it was grotty, but in good nick after I cleaned it up. I thought I had it when I saw all the crap on the flywheel!

I'll have a go at it tomorrow night and let you all know, thanks again!!

[SPLATT]

Could be your gas cap vent is either fully or partially plugged and causing a vapor lock as well.

[MANIAC998]

Like SPLATT said. Check, actually, remove the stupid one way valve in the gas cap breather hose. I've had times where the engine heats up so much, that the gas swells up inside the tank and can't vent properly due to that gas cap valve, and instead, the pressure has to go somewhere, so it over-powers the floats in the carb and floods the engine out. Just remove the damn thing!!! Thanks Splatt, for reminding me about that damn thing!!!

Maniac