Backfire and won't rev cold 04 fe450

Buffalo Bill · Apr 12, 2012

This problem developed on my 04 fe450.

When starting cold, the engine will kick back starting and runs very rough after it starts for about 10 minutes.
More time that the choke is needed.

Then it is like a switch is flipped and the engine will run perfect and the bike will start smoothly.

If you leave the engine off for more than 15 minutes. The engine will kick back and won,t rev . for less time than starting cold. Then the engine will run perfect and can ride many miles.

The problem feels like the timing is off and then changes to correct timing.

I have checked and cleaned the carb and jets for problems. Also checked for water in gas.

I have adjusted and checked the valve adjustment.

Taffy · Apr 13, 2012

are you pulling on the red or the black button?

check for a broken valve spring

cam chain adjustment. take the unit out and measure what you have left? maybe that your chain has had it.

finally tappets, double check them.

regards

Taffy

OldNewbie · Apr 13, 2012

I had to go very rich on the pilot jet before my bike would behave.

Buffalo Bill · Apr 16, 2012

I looked into your suggestions.

The choke the black button, can be pushed in right after engine starts. The red is hot start.

I have owned the bike since new in 04 and this problem is something different.
The bike always starts and runs smoothly. Just initial tuning at purchase.

I have removed the cam cover.
No broken valve springs, cam or tappet problems.
There are 2 clicks left on timing chain tensioner.
Checked valve adjustment again before removing cover. good.

About 2 years ago I replaced the timing chain, cam and rockers due to roller failure.
Alot of miles on engine and everything else is untouched.

When the engine runs for a while and switches to the good running condition.
The engine runs,revs and starts smoothly.
When starting in the bad condition the kick starter kicks back and feels like timing is off. Feels advanced.
Running in bad condition misses and backfires.
I have rode about 20 times with this condition and repeats good and bad condition every time.
Scary to start in bad condition with how bad it kicks back.

The service manual under engine won't rev- electronic advance defective

Is this the CDI?

Any suggestions on what to check next?

Thank you
Bill

Taffy · Apr 16, 2012

just check that the plate is still on the face of the carb slide? I think that there's a little on it on the doc under carburation keihin?

regards

Taffy

Buffalo Bill · Apr 17, 2012

I looked at the carb slide and I think everything is ok.

The round hole is recessed on one side and no crack marks on other side.
Have not removed slide from carb (removing screw in shaft turned into a challenge)

Slide does rattle at idle. I will have to look into o-ring.

The problem seems like something changes.

Idle engine in bad condition engine missing and wonder if will stay running.
Then just let it sit idle and it will switch then instantly run smooth. Then I can ride many hours.
The condition is not like the engine warming up and running better. It is like a switch is flipped.

I have rode many times hoping something will fail to find the problem. Just getting harder to start in bad condition.

Bill

OldNewbie · Apr 17, 2012

The good news is that you have no trouble reproducing the bad condition.

Something is shifting, it's either fuel or ignition, and it sounds like you've ruled out the carb and valves. Also, if it were mechanical, it would be more likely to go good and bad as it vibrated in and out of position.

Time to look at CDI and stator?

Backfire and won't rev cold 04 fe450

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