Huge backfire then stall and no restart


16 replies to this topic
  • zippor25

Posted May 09, 2009 - 06:59 PM

#1

So I have read a ton of posts about backfiring and hotstart lever issues but I really need help. I was out riding today and for the 1st hour or so, no problems. Bike ran great smooth and powerful. Then it started running rough and missing so I thought maybe it was a dirty air filter. I changed the filter and bike started right up. After about 2 minutes it started hesitating again and running really rough. Then all of a sudden it felt like the bike flooded or something and when I turned the throttle ther was no response, then there was a HUGE backfire like 2 or 3:foul: times and the bike died. I kicked it 20 or 30 time and nothing. I know for a fact there is a big exhaust leak between the mid pipe and silencer, I just havent fixed it but could this cause the bike to die like that and not restart? I never use the hotstart lever but when I rejetted the bike a couple weeks ago I had a really hard time getting the cable back in the carb. could that be the issue? Please help. I cant afford to take it to the dealership right now. Thanks

  • BLUEDUDE

Posted May 09, 2009 - 07:14 PM

#2

sounds like exactly what happened to my 426 the other day. Try changing the spark plug and see if that fixes it.

  • BC3

Posted May 09, 2009 - 10:23 PM

#3

Kinda hard to trouble shoot this deal without actually being there but here goes:
1. remove the plug as mentioned and look at it and see if it looks black and shiny... Replace plug and check for spark make sure the plug wire fits tight on spark plug.

2. check kill wire to see if it is pinched or grounding out on frame or
handle bar.

3. Place a clean rag under the float bowl and drain the bowl, taking notice of any water or dirt laying on clothe...or main jet...Remove float bowl and replace jet

4 start bike and see if your problem still exists.

If you still have the problem check all your elec.connections under the tank
but I think you are going to find that it is a fouled plug......as far as the
hot start cable if it idles smooth and has a little free play at the lever you have it installed correctly........


Good luck let us know if you fix it....

  • BC3

Posted May 09, 2009 - 10:26 PM

#4

I read your post again to make sure I had all the info and noticed you said you re-jetted the bike......What jet sequence did you use?(Main jet ,Pilot jet..)
and what year is your bike?

  • grayracer513

Posted May 10, 2009 - 07:01 AM

#5

In cases like this where the bike quits suddenly and backfires like that, it's always worthwhile checking for 3 things:

  • Check for spark
  • Check to see if the flywheel key has sheared by finding TDC with a screwdriver in the spark plug hole and seeing if the mark on the flywheel agrees.
  • Check the cam timing


  • fastlane42

Posted May 10, 2009 - 07:10 AM

#6

One way to check your hot start lever is to pull it while bike is idleing. If RPMs increase it is working properly.

  • TIG88

Posted May 10, 2009 - 07:59 AM

#7

My guess would be that you jumped time. Fairly common.

  • zippor25

Posted May 10, 2009 - 05:23 PM

#8

jet sequence is 168 and 45. needle pin is 4 from top. Bike is 2007. I went in today and checked spark plug(clean), checked TDC and it was dead on, then I checked spark and noticed that it was getting spark but not very bright (if that makes sense). Could it be getting a WEAK?? spark? My buddy said I should go buy a new coil. Not really sure how to check cam timing. any advice?

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  • zippor25

Posted May 12, 2009 - 07:28 PM

#9

Well its been 3 days and after kicking the bike about 100 times, I still have nothing. I guess Im gonna have to take it to the shop. There goes all the extra money I had for mods.

  • XRYoda

Posted May 12, 2009 - 07:34 PM

#10

i'd find a buddy with a similar year bike and try swapping the ecu and the coil.

  • gdbarr1976

Posted May 13, 2009 - 08:00 AM

#11

jet sequence is 168 and 45. needle pin is 4 from top. Bike is 2007. I went in today and checked spark plug(clean), checked TDC and it was dead on, then I checked spark and noticed that it was getting spark but not very bright (if that makes sense). Could it be getting a WEAK?? spark? My buddy said I should go buy a new coil. Not really sure how to check cam timing. any advice?


Replace the plug. You can sometimes see a spark but when it is under comprsession it is not powerfull enough to ignite the gas. Worth a try before heading to the dealer. Also if you cleaned the air filter and did not let it dry before cranking you could have sucked stuff into the little jets were the air box boot attaches(leak jets)? Anyway, pull the carb boot off and spray some carb cleaner into those jets and then some compressed air if you have it. Remove the drain plug from the bottom of the float bowl to let it drain. What you are describing happened to me and this cured it.

  • grayracer513

Posted May 13, 2009 - 08:13 AM

#12

... if you cleaned the air filter and did not let it dry before cranking you could have sucked stuff into the little jets were the air box boot attaches(leak jets)?

Air jets.

  • zippor25

Posted May 14, 2009 - 06:21 AM

#13

I talked to the guy I bought it from and he said after he bought the bike new(like 2 weeks) he had to replace the stator. His description of the problem was exactly what happened to me. Is it possible to have 2 bad stators in 2 years? I dont ride hard, only trails and no big jumps?!?!?! How do I test the stator with a multimeter?

  • grayracer513

Posted May 14, 2009 - 08:26 AM

#14

How do I test the stator with a multimeter?

The test is on page 6-6 of the manual.

If you don't have the manual, get one:

http://www.yamaha-mo...ice/manuals.jsp

  • zippor25

Posted May 14, 2009 - 09:15 AM

#15

thanks gray I just downloaded one. Looks a lot easier than I thought it would be. Well we shall see. Thanks for the info, your a huge help always!!!

  • zippor25

Posted May 16, 2009 - 08:02 AM

#16

anyone ever heard of OVER OILING an air filter?!?!? Well I used a multimeter and checked everything electrical and no problems so I called a friend and he told me about the over oiled filter issue so I removed the filter and bingo!!! Started after 2 kicks and ran for 10 or 15 minutes no problems. wooohooo. GONNA GO RIDE TODAY!!!!!!!! I used an oil that was very sticky and it was not the same brand as the filter and he said sometimes they get clogged up so I went out and picked up a no toil filter with no toil cleaner and no toil oil. Lets pray!

  • zippor25

Posted May 16, 2009 - 05:38 PM

#17

:doh: :snore: Back to the drawing board. Ran great for about 2 minutes and thats it. Idled great at startup but once i got on it and took off, popping started, misfiring, bogging down then stall and that was it no more go. Must be in the carb. maybe when I rejetted it I screwed something up. I dont know?!??!





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