Posts
1878
Joined
7/25/2009
Location
Emerson, NJ
US
Edited Date/Time
10/1/2015 6:12am
I am looking to see if anyone as found any good tricks for reducing flame-out which is a pain in the ass on 2009-2012 CRF450's. I am looking for engine tricks that adress the actual cause rather than bandaids like a heavier flywheel or lower gearing.
By flame-out, I think I need to clarify what I am talking about as many beleive it it referes to different situations. I dont mean stalling at low speeds or when closing the throttle or when locking up the rear wheel or backfiring out the exhaust.
By flame-out, I mean when the engine quits when you crack open the throttle... it happens when you grab a handefull of throttle when the engine is at low rpm and the throttle plate is initially almost fully closed. From what I heard is that at low rpms with the throttle plate almost fully closed, the fuel gets to the spark a split second before the fuel, as well as the fuel being pulled i by the low pressure along the walls of the throttle body from the almost fully closed throttle plate, and the fuel blows ou the spark before the air can get there. It totally sucks when you are about to jump a big obstacle coming out of a slow tight turn and she just dies and leaves you there kicking the enginee over in a race.
The bike already had Tokyo Mods fuel and ignition mapping (did nothing to help this particular problem), FMF 4.1 slip-on, the HRC fuel injector trick, and one more tooth on the rear sprocket. I run the idle at 2000+ rpm.
This is what I have done so far to get more air to the combustion chamber faster;
1. removed the airfilter backfire screen
2. did the Dave Simon choke mod
3. rerouted the valve cover vent line from the airfilter box to an external filter so the engine only breathes fresh air
4. added a Moto Tassinari Air4orce air boot with the long velocity stack which should improve air speed at low rpm according to my discussion with the manufacturer
I heard a hotter spark plug would help, but a cant find a hotter one, only a cooler plug that fits the CRF450.
There is a few feet of snow on the ground so cant see how these mods improved the problem, but I wanted to see if any of you guys found any good solutions for this really annoying problem with this engine.
thanks,
mike
By flame-out, I think I need to clarify what I am talking about as many beleive it it referes to different situations. I dont mean stalling at low speeds or when closing the throttle or when locking up the rear wheel or backfiring out the exhaust.
By flame-out, I mean when the engine quits when you crack open the throttle... it happens when you grab a handefull of throttle when the engine is at low rpm and the throttle plate is initially almost fully closed. From what I heard is that at low rpms with the throttle plate almost fully closed, the fuel gets to the spark a split second before the fuel, as well as the fuel being pulled i by the low pressure along the walls of the throttle body from the almost fully closed throttle plate, and the fuel blows ou the spark before the air can get there. It totally sucks when you are about to jump a big obstacle coming out of a slow tight turn and she just dies and leaves you there kicking the enginee over in a race.
The bike already had Tokyo Mods fuel and ignition mapping (did nothing to help this particular problem), FMF 4.1 slip-on, the HRC fuel injector trick, and one more tooth on the rear sprocket. I run the idle at 2000+ rpm.
This is what I have done so far to get more air to the combustion chamber faster;
1. removed the airfilter backfire screen
2. did the Dave Simon choke mod
3. rerouted the valve cover vent line from the airfilter box to an external filter so the engine only breathes fresh air
4. added a Moto Tassinari Air4orce air boot with the long velocity stack which should improve air speed at low rpm according to my discussion with the manufacturer
I heard a hotter spark plug would help, but a cant find a hotter one, only a cooler plug that fits the CRF450.
There is a few feet of snow on the ground so cant see how these mods improved the problem, but I wanted to see if any of you guys found any good solutions for this really annoying problem with this engine.
thanks,
mike
Been thinking about a Recluse but dont see how it would help the problem I mentioned. I tried to clarify I am not talking about stalling poking around at slow speed or when braking. I am talking about when I crack open the throttle which happens in gear as well as when sitting at the starting gate in neutral. Not sure how a rekluse woul help that.
I will say that the flame out when cracking the throttle definitely seems more prevalent when the bike is not completely warmed up. Probably due to the sensors/ECM adjusting the mixture richer. I have mine remapped by Sisneros and the flame out seems pretty minimized. Rarely ever happens. Getting your throttle hand to be more sensitive, combined with careful mapping, is probably is the best cure.
The Shop
http://www.youtube.com/watch?v=92Yg8egAMlM&sns=em
My buddy did the fuel injector mod to his CRF and said he noticed a difference right away... Have you heard about it?
http://www.thumpertalk.com/topic/999566-some-of-you-may-have-known-this-but-most-probably-did-not/
Honda revised the injector position on the 2013 and 2014's based on what they learned from the race team on the 09-12's. The new position provides a straighter shot into the intake port.
http://www.sisnerosspeedworks.com/
mike
mike
The cam cure shown above can also do the same thing.
There is also another youtube video of another cure for the flame out as well.
Chris' mod is also a good reason to throw in a Hot Cams cam.
mike
Pit Row
mike
Remove assembly, start bike (push start if you're worried about the kick shaft). If the flame out is gone, then you know what caused it. Reassemble with a modified decomp and you should be good to go.
Just kidding. That sucked.
Paw Paw
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