z400 backfires/won't start

[bigwake]

i recently got an 04 ltz400..it rus great but after riding for a few hours it won't start...when it finally does start (after pop starting) it backfires badly..once the engine is totally cold after i get home it will fire right up and run fine..any ideas?

[TRX450R_Racer]

Sounds like a valves need to be adjusted or it is a timing issue.

[bigwake]

i was thinking timing as well..its just odd that it only happens after a couple hours of riding..like when the bike is realy hot

[01ZX12R]

next time you go riding turn the gas off when you turn the quad off. The float may be sticking causing it to flood out.

[bigwake]

i always turn the gas off..and i burn most of it out

[johnyfz450]

sounds like the valve specs are off.Real easy to check.Check the float level first thats a good place to start.Or it could be because you didn't buy a yamaha j/k not really

[bigwake]

if the valves were out of spec that would make the motor not start and backfire when its been run all day?

[rider]

actually if the valves were out of wack..it wuld start it wuld just be hard starting..pop open your valve cover and get a feeler gauge and check your clearences ..that is a really good thing to do before it gets to late

[bigwake]

the motor was completely rebuilt 6 months ago..the previous owner road it around his block..i dont think its valves..more of a timing issue

[greenmachine]

usually when an engine gets hot & starts popping & shuts down then wont restart until it is cooled off, then does the same again.
It is the coil going bad. It also could be the gas cap not venting.

[bigwake]

that sounds like a possiblilty as well..thanx!