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2003 Burgman AN400
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155 Posts
Discussion Starter · #5 ·
what was the last thing touched? looks like the timing is just a bit off. not supposed to have fire in the intake manifold...just sayin' :whistle:
Well JRoss... That is a broad question you are asking here. Timing is controlled by the ECU. If I have no sensor error codes on the dash. I am assuming they are all within range. What else could make the timing be off? This is a real head scratcher for me....
 

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So I have no codes on the dash. I don't know what the problem is with this bike. I'm back to square one.
Back in August you showed us that it was running fine - no sound on that video though, unfortunately.

So what have you done between then and now?
Checked valve clearances? (and on correct stroke when so doing?)
What else?

ECU controls SPARK timing, not valves.
 

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based on my personal experience and long years of wrenchin, (swmbo told me) IT"S BROKE! Yer innie and outie seems to have got mixed up. I'd be lookin at 2 things , valves and fire insurance, and both outside the garage. The ecu is great but it don't check EVERYTHING ,. It's time for a refreshin beverage and then dive back in to the fuel / air/ fire (spark) flow mix system, half your problem is done, fuel going IN is ok, up to the point of the injectors for fuel , air is a different thing, and spark, the ecu thinks , welp the piston is in the right place, so lets throw a match innit, whatever tells the ecu the piston is in the right place is LYIN and yer fire is gettin in the open intake part, orrrr the outey part is messed up and lettin fire get in to the inny part .
Sorry about all the technical language .
 
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2014 Burgman 400
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The bigger question is how you got to this condition, did it progressively occur/worsen or sudden failure :unsure:, what did you messed with or not, etc. Check the mechanical part first, make sure your cams are in correct timing and valves are properly adjusted, etc., like mentioned above. It kinda looks like a timing issue, bent/burn valve or possible misfire from a leaking fuel injector.
 

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2003 Burgman AN400
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155 Posts
Discussion Starter · #9 ·
Back in August you showed us that it was running fine - no sound on that video though, unfortunately.

So what have you done between then and now?
Checked valve clearances? (and on correct stroke when so doing?)
What else?

ECU controls SPARK timing, not valves.
The only thing I have done is resolve the issue with the connector to the fuel pump. I had a faulty connector. And replace the injector. Maybe I will put back the old injector and give it a shot again. But I replaced it because this issue started after I figured out the connector problem.
 

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To get fire out of the throttle there is a timing issue, not a fuel pump connector or injector issue. One of the two are wrong, Ignition timing or Camshaft/Valve timing.

Just for giggles, did you mistakenly swap the connectors on the Secondary Throttle Valve? The Black and Grey connectors are the same shape and will reach to the wrong port.
 

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2008 AN400
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326 Posts
I'm also in the timing-is-off camp, and agree that replacing an injector or connector won't mess with the timing - I like Dave_J's idea above.

It seems something affecting the synch between fuel and spark.

Are you sure you didn't do any other work, even not directly touching the timing? For instance, I read that if you rotate the variator in reverse (while removing it, not just for fun ;) it will mess up the timing.

It'll be something simple, just a question of finding it, and it will miraculously run perfectly 8)
 

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There is no secondary throttle valve in 03-06 Burgman 400, not saying is certain :unsure: but a leaking injector "Could" cause the flashback thru throttle body, ignition is a "Wasted Spark", it fires every time piston is up, it will spark at exhaust/intake valve overlap, in any case you have to have fuel to create fire you can see in the video. Of course, there's the possibly that other mechanical issues and or "Human Factors", as motorcycles don't normally "jump" out of timing :unsure:
 

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2003 Burgman AN400
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155 Posts
Discussion Starter · #13 ·
To get fire out of the throttle there is a timing issue, not a fuel pump connector or injector issue. One of the two are wrong, Ignition timing or Camshaft/Valve timing.

Just for giggles, did you mistakenly swap the connectors on the Secondary Throttle Valve? The Black and Grey connectors are the same shape and will reach to the wrong port.
I will double check the connectors. I also want to mention is the fire in the throttle body is when I attempt to give it gas. If I open it all the way it just dies.
 

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2003 Burgman AN400
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Discussion Starter · #14 ·
I'm also in the timing-is-off camp, and agree that replacing an injector or connector won't mess with the timing - I like Dave_J's idea above.

It seems something affecting the synch between fuel and spark.

Are you sure you didn't do any other work, even not directly touching the timing? For instance, I read that if you rotate the variator in reverse (while removing it, not just for fun ;) it will mess up the timing.

It'll be something simple, just a question of finding it, and it will miraculously run perfectly 8)
The replaced the spark plug, but I have not touched any other components of the ignition system. I'm gonna check to make sure the spark plug is seated all the way.
 

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2008 AN400
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It's quite a puzzle, but I'm sure you'll find it.

To see the fuel mixture ignite through the air intake, it means the valve on the intake side wasn't closed as it's supposed to be.

So the cycle is off.

Piston moves down, intake valve opens, injector sprays fuel in, intake valve closes, piston moves up, spark plug sparks - boom! ignition! That's the correct sequence, kind of :)

What we're seeing in your video is the fuel igniting when the valve is still open. Otherwise we wouldn't see the flame through the air intake.

It can happen when you don't get the piston at TDC when setting the valves or timing chain - but that's still old school, mechanical, so I think Dave_J may have hit the nail on the head with the swopped connectors (but related to EFI, not quite secondary throttle, but worth a check) and the leaky injector idea by zrx212 is also a very good possiiblity, since you replaced the injector recently, though you'd still need the spark at the wrong time.

Two good BUSA leads to follow! :) Gluck!
 

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It's quite a puzzle, but I'm sure you'll find it.

To see the fuel mixture ignite through the air intake, it means the valve on the intake side wasn't closed as it's supposed to be.

So the cycle is off.

Piston moves down, intake valve opens, injector sprays fuel in, intake valve closes, piston moves up, spark plug sparks - boom! ignition! That's the correct sequence, kind of :)

What we're seeing in your video is the fuel igniting when the valve is still open. Otherwise we wouldn't see the flame through the air intake.

It can happen when you don't get the piston at TDC when setting the valves or timing chain - but that's still old school, mechanical, so I think Dave_J may have hit the nail on the head with the swopped connectors (but related to EFI, not quite secondary throttle, but worth a check) and the leaky injector idea by zrx212 is also a very good possiiblity, since you replaced the injector recently, though you'd still need the spark at the wrong time.

Two good BUSA leads to follow! :) Gluck!
I like the leaky injector best
 

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I will double check the connectors. I also want to mention is the fire in the throttle body is when I attempt to give it gas. If I open it all the way it just dies.
That's reads more like a clogged or intermittent operating injector, a lean condition will cause a misfire ! Make sure you match correct wires at fuel pump connector and fuel gauge is operating correctly, etc Usually same 12V + source powers fuel pump and injector thru the fuel pump relay. The fuel gauge circuit is completely separate on 03-06.

We still lacking details , but this sticks out 🤔, you fixed one thing and other issue started, time to recheck your fix 🤞
Maybe I will put back the old injector and give it a shot again. But I replaced it because this issue started after I figured out the connector problem
 

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I watched the video at .75 speed. I still say timing has slipped. Ether the ignition timing or the chain slipped and the valve timing is off.

One other thing is maybe the intake valve is bent or burnt.

I had a intake valve on a Chrysler 2.2 get burnt when the Charcoal Canister popped and some charcoal lodged the valve open. It too popped fire out of the Carb.
I did a compression test and I had 185+ PSI in 3 cylinders but only 75 PSI in the burnt valve one. When I took the head off there was still a huge chunk of charcoal lodged in the intake port. It should have been granular charcoal but something had clumped it together. It broke apart with my fingers.
 

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2003 Burgman AN400
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155 Posts
Discussion Starter · #19 ·
That's reads more like a clogged or intermittent operating injector, a lean condition will cause a misfire ! Make sure you match correct wires at fuel pump connector and fuel gauge is operating correctly, etc Usually same 12V + source powers fuel pump and injector thru the fuel pump relay. The fuel gauge circuit is completely separate on 03-06.

We still lacking details , but this sticks out 🤔, you fixed one thing and other issue started, time to recheck your fix 🤞
I put the old injector back in. I do not see fire in the throttle body when I twist the throttle. It's not running as bad as with the new injector. But it still doesn't want to idle for more than a minute.
Maybe the injector I got off ebay was bad. I think I may try and order another one. Anybody has a source for a good injector vendor?
I also think the idle adjustment screw is off. How is the idle adjusted?
 

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2003 Burgman AN400
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155 Posts
Discussion Starter · #20 ·
I watched the video at .75 speed. I still say timing has slipped. Ether the ignition timing or the chain slipped and the valve timing is off.

One other thing is maybe the intake valve is bent or burnt.

I had a intake valve on a Chrysler 2.2 get burnt when the Charcoal Canister popped and some charcoal lodged the valve open. It too popped fire out of the Carb.
I did a compression test and I had 185+ PSI in 3 cylinders but only 75 PSI in the burnt valve one. When I took the head off there was still a huge chunk of charcoal lodged in the intake port. It should have been granular charcoal but something had clumped it together. It broke apart with my fingers.
I'm gonna check this last. Going for the easy stuff first. i think the previous owner may have dropped it once. Could that cause the chain to slip?
 
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