06x ran for a day after valves and carb work- wont start

I done up a friends bike with kibble white intakes ,re cut the exhausts and opened up the intake and did carb mods 08 ap stuff and ncvs needle. long story short it ran great around the yard for short bits running the dog occasionally and continued to work good for the owner for about 50 miles or a days riding- first outing.

now its back to me and wont start after many kicks not even a fart. its valves are in specs, timing is on and the float bowl holds lots of fuel- the bowl plug didn't look to have water or crud in it. the spark plug came out dry and the spark looked kind of yellow to blue and week- it might have been better if I wasn't chicken to hold it grounded better , certainly not what I would call a hot blue spark. I put in a new plug and the bike still would not fire and I did knock an eight inch off the plug wire on the boot end.

So I'm fishing for ideas?

bump start it?

dump a spot of gas down the plug hole and see if she fires

dis connect the kill switch

clean up the ground

clean up the coil contact areas check the coil

wiring looks connected and un damaged

So after 40 kicks with the fuel on and the choke pulled shouldn't the plug come out wet?

who has logical ideas? maybe i'll start today with putting the bike in the dark shop and properly grounding the plug and watching for a strong blue spark then a spot of gas down the plug hole and see if she fires then if not try going down the hill and poping it in to second?

1. Check the hot start...make sure it's not hung up.  Also closely inspect the nut.  It's plastic and may have cracked.


2. Make sure the vent lines on the carb are clear and not pinched.   You also may want to crack the gas cap open a bit while testing.


3. Remove the air filter, put a mirror in the box and see if when you whack the throttle open you get a good strong flow of gas...does it bump now?


4. Try a light spray of starting fluid does it bump now?


  beyond that, it's hard to say without knowing more....ie. how did it run before it quit?   Was it just a failure to start?


  Given the recent work, I would suspect something with that and check the decompression system.  I think I'd also check for a good strong flow of gas at the carb from the tank.  Could be an odd coincidence that it happened now, but the filter in the tank may be plugged/collapsed or the line itself.



Edited by Jim Dettman

Is it easy to kick over...like no compression?  Did you adjust the Decomp lever?  I am guessing that since you did the Accelorator Pump mods that the bike is a 2007 or older.  These years of X need to have the decomp adjusted AFTER the exhaust is verfied/adjusted to be in spec.  Was the bike hard to get dialed in on jetting after the air box mod or did you leave the jetting as it was?  Did you happen to record the jetting since you were in the carb already?  I would try to bump start it just to see if you can get it to fire.  Sorry for all the questions...just trying to get some info flowing to spark ideas and rule things out.

still didn't get out to the shop yet but I have some answers

the hotstart lever feels fine and it was serviced when mods done-I did not check the nut yet

did not check vent lines yet- leand bike over and fuel was flowing on the ground- droped float bowl cap and loots of fuel

i'll check the squirt

did not get to bumping it yet

didn't try fluid- thanks jim

warhammer... comp relese is at 14 thou int and ex specs are good and its got compression and the bike ran great but just got harder to start and wouldn't start eventualy

I forget exactly on the jetting but it ran great I had put the 55 leak jet and 42 pilot and maybe 165 main and a ncvs 2nd or 3rd also a new throttle plate seal and the acc pump upgrade kit  serviced the carb end to end krannie style- hot start and choke out and passages cleaned new pilot and pilot passage behind the jet clear good a pump squirt just missing the slide

the bike was easy to get dialed in after the build and ran strong- this was probably the 10th 450x I have done in the past couple years.

no sighns of the bike being swamped or leaking and the owner said no odd noises or smoking and great power.

thanks guys

bike didn't cool down then get hard to start it got hard starting after stoping for a smoke- 5 minits

The spark is never a "hot blue spark"...it's normally quite faint.

Stupid question...the slide is in correctly???

slide is right side up hole at bottom facing the head

rolling it down the hill and bumping it to second it spit's a couple times but not even close to running i'll try again with new gas after draining the tank and carb

Kill switch, take it apart and make sure the circlip is not grounding out. Had this happen to a friend before. Maybe a loose connection.

It's gotta be electrical if your fuel and mechanical stuff all check out. Happen to have a spare cdi that you could swap out and/or stator. I'm still a bit new to the X motors but have seen a lot of trx450,s have bad cdi and stators ,myself including.

You don't think your flywheel came loose by chance or sheared the key? The gas is turned on, right? I mean if it ran until you stopped it, it makes me wonder if something went out of whack such as ignition or valve timing. I've heard of shim slipping before too leading to valve not opening. I mean it almost sounds like something this weird and considering you were just fiddling with all of this...I always suspect whatever I messed with first.


RZ Rob

I spent some time dumping the gas and in with new fresh fuel, confirming timing at the crank gear cam gear and rotor - all the valves were in spec and the comp relese  . cleaned up the contact points of the coil and frame connecting points, separated and re hooked all the conections that I could and just touched the starter button and bang she's running and running good.

I think I would feel better if I knew exactly what it was

My guess would be fuel.  After a 50 mile ride, had to be getting to the bottom of the tank.



jim it had a third of a tank in it, when I pulled the float bowl plug I was care full not to dump it before I got a look,i didn't see crud or any water

Check to see if your timing chain has jumped. You will have fuel and spark but still not be able to run.

condor read 4 posts up^ - it says I confirmed the timing at the crank gear cam gear and rotor, I could allways be wrong but if the chain skiped or the key on the rotor sheared then all 3 points would not line up at the same time ? thanks for your thoughts.

Does kind of feel like an electrical issue.


You can also maybe try to use some starting fluid while cranking it, if you want to get around the fuel deal.

Sorry I missed that post where you checked that and got it to run. Sounds like you tracked it down to a bad connection somewhere. Wish we could have pin printed it better.

at this point the owner has it back and its running well.

I hope it really was only a faulty conection or bad ground but time will tell after a bit of riding .

It sounds to me like it was just low on gas and wasn't picking up. The petcock will only pickup fuel if it's higher than say 1 1/2" - 2" in the tank. Below that it will only pickup fuel on the reserve setting.

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