my 426 yzf back firing alot


8 replies to this topic
  • yzf426rider2000

Posted March 08, 2008 - 07:08 AM

#1

hey guys i was wondering if anyone could help me with my bike. i just bought a 426 yzf and i can't start it for starts and the one time that i did start it the damn thing just back fired let crazy and the pipe got really red and i don't under stand what the red nob and the black nob on the carbs are i know one of them is a choke.

  • dirtysouth

Posted March 08, 2008 - 08:25 AM

#2

hey guys i was wondering if anyone could help me with my bike. i just bought a 426 yzf and i can't start it for starts and the one time that i did start it the damn thing just back fired let crazy and the pipe got really red and i don't under stand what the red nob and the black nob on the carbs are i know one of them is a choke.


Red Knob is a hot start knob..Where did you buy the bike from? Was it bought from someone at really high elevations relative to your area...if so it may be jetted really lean. If you do not know much about jetting then do a search on the things that you are questioning and also check the sticky threads at the top of the forum board here. They will clue you in to a bunch of things you will want to know about.

  • yzf426rider2000

Posted March 08, 2008 - 04:25 PM

#3

well the the elevations are the same he just live down the road. people are tell me the timing chain slipped and other people tell me to clean and jet the carb

  • yz250fmx

Posted March 08, 2008 - 04:33 PM

#4

yea you should clean and jet the carb because what you describe it sounds like its running to lean. use the black knob (the choke) when you try to start it. the choke make more fuel to go through the carb into the engine, see if the symptoms get better

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  • yzf426rider2000

Posted March 08, 2008 - 04:45 PM

#5

so u think a good carb cleaning and new jets will do it

  • yz250fmx

Posted March 08, 2008 - 05:53 PM

#6

so u think a good carb cleaning and new jets will do it


well if it has sat in one place for a long time with gas in the carb it could gunk up the inside of the carb causing it to not work as well. and a red header (though they all glow red to some extent) usually means its running to lean. check the spark plug, if it has a white-like area where it sparks, its running to lean. it should be a tan or brownish color (not dark).

  • dirtysouth

Posted March 09, 2008 - 04:42 PM

#7

hey guys i was wondering if anyone could help me with my bike. i just bought a 426 yzf and i can't start it for starts and the one time that i did start it the damn thing just back fired let crazy and the pipe got really red and i don't under stand what the red nob and the black nob on the carbs are i know one of them is a choke.


Like I said...do a few searches (try the advanced searches option) and read all that you can stand reading regarding the issue that you are having. I suspect the gas is no good and the carburetor is dirty but that does not eliminate the possibility of timing issues. Thing is, cleaning the carb is probably easier than timing if you are not so experienced with the wrenches. Do some searches and then some reading though. There are many different things that could be the cause of your problems. You just need to understand the possibilities before making adjustments based on some abstract individual's (like me) opinion. There is a TON of info here man.:thumbsup:

  • matt4x4

Posted March 10, 2008 - 05:40 AM

#8

Ok, so you're located in Ontario, and it's -10 right now, the last time the bike was probably running, it was likely +20, so there are a couple of things at play here.
Bad gas unless it was removed prior to winter.
Gummed up carb - from the old gas
Currently running really lean because of the temps here - rejet unless it's not going to get ridden.

I would remove the carb, take it apart (but DO NOT remove the TPS!)
Clean it with carb cleaner and a toothbrush.
If you're planning on riding it, you'll need to rejet for hte current temps, however, if you just want to make it run for spring, leave the jetting alone.
Remove the gas in the tank, replace.
Start the bike with Hotstart (red) in and choke (black) out using the starting procedure you can find here.
let it idle for about 5 minutes in these temps before riding it, it will likely pop on decelleration with the summer jetting.

  • Dano426

Posted March 10, 2008 - 11:23 AM

#9

Ok, so you're located in Ontario, and it's -10 right now, the last time the bike was probably running, it was likely +20, so there are a couple of things at play here.


Bingo


You need to rejet your bike every 20 to 25 degrees. If you want to ride in the winter you will need to jet for that and change the jets back for summer riding.




 
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