06 backfires no start

I have an 06 YZ450 that it will no longer start it only back fires. where should i start? timing has been checked, valve clearances adjusted,carb gone through. it just back fires through the exhaust. any input??

When you checked the timing, did you verify that the marks on the flywheel were aligned with TDC?

Silly questions;

How long since you rode it last?

What's the sparkplug look like?

How old's the gas?

Was this a progressive problem? i.e. Was your bike having hard starting problems that got progressively worse, to the point of not starting at all?

A little history of the problem will help a lot.

When you checked the timing, did you verify that the marks on the flywheel were aligned with TDC?

timing was verified with the marks on the flywheel and also with the piston.

Silly questions;

How long since you rode it last?

probably last time it ran long enought to ride it was september. I have been fighting this problem since then.

What's the sparkplug look like?

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How old's the gas?

gas is fresh. just put it in this morning.

Was this a progressive problem? i.e. Was your bike having hard starting problems that got progressively worse, to the point of not starting at all?

it was getting progressivly harder to start. and then it got to the point that all it would do is back fire, and here i am today asking for some help :bonk:

A little history of the problem will help a lot.

also, the bike has a vortex ignition, I do not have a stock ignition to swap out to test though.

replace that plug with a new one

Are you getting a consistant spark at the plug with it stuck in the coil and grounded on the engine?

Are you getting a consistant spark at the plug with it stuck in the coil and grounded on the engine?

I would not say its consistent, it seems very weak truthfully.

I would not say its consistent, it seems very weak truthfully.

Hmmm..... without being able to swap in the stock CDI you'll have to throw the dice and buy a CDI. If you pin check the coil and stator and they spec-ok you really don't have a choice.

Do try replacing the plug first though, if you haven't already done that.

Hmmm..... without being able to swap in the stock CDI you'll have to throw the dice and buy a CDI. If you pin check the coil and stator and they spec-ok you really don't have a choice.

Do try replacing the plug first though, if you haven't already done that.

I'm picking up a new plug tomorrow, I'm trying to locate a cheap cdi also.

I'm picking up a new plug tomorrow, I'm trying to locate a cheap cdi also.

You have oter options other than a stock or Vortex CDI. Dyna makes a programable CDI (not quite as cool as the Vortex) for about $350 (retail). A little shopping you should be able to get one for under $300.

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