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08 XR backfired, now will not start :(

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I just got a '08 XR650L, 1000 miles, rode it around the yard a few times.  Then put in a dyno-jet kit in the carb and an FMF pipe.  It cranked and ran about a minute, running a little rough or just cold, backfired and quit. Now won't start.  Put in new spark plug, and it seems to spark too often and kind of weak, but I don't have anything to compare.  Sounds normal turning over.  Tried a little starting fluid, but no fire, no putt at all.
This has got me puzzled.  Apparently, there are common CDI problems among this model, but I'm not sure what the problem is.  Any ideas out there?
 

Edited by MartMX

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Brian is far and away the expert with this issue but if I've learned anything about them it is to first try to smack the back of the CDI a few times with a screwdriver handle and then see if it fires up.  If it does then you've got the CDI problem.  The backfiring was a tell tale for my CDI problem.  There are a couple options for solving that issue.  

If it doesn't you may have a corroded kill switch (run/stop) problem.  Cleaning usually does the trick for it.

Check it out and let us know what you find...

Edited by Hollerhead

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my bike backfired a few times and wouldn`t start on my last ride,,then I found out I was out of gas,,,:devil:  it backfired bad a few times,,scared the crap out of me...:lol:

 

CDI can do it,,,really lean condition from lack of fuel,,,,,,,and also tight valve adjustment..

 

B

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Any chance you can blame the DynoJet kit?

I know that a few people around here love them, but others have had problems with them and even Dave, of "Dave's Mod" fame couldn't get a bike to run right with one.  I'll only use Keihin jets.

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I have no experience with the XR's, but I did have a nearly identical problem with a TT-R125.  It ran fine when my daughter rode it around the yard on Saturday.  She went back out on Sunday to start it.  It cranked normally except for one, single, faint, metallic "ting" sound and a backfire.  After that it would not fire, at all.

1. It blew the carburetor out of the intake boot.

2. It bent the exhaust valve so it no longer had any compression.

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Yea, the Dyno-Jet / carb could be suspect since that is what I just worked on, but I think I did a good install of the kit along with cleaning out the bowl and jets.   If it were a carb/fuel problem, I would think the starting fluid should fire it up for a moment, but it does nothing.

When it backfired and quit, it made a kind-of strange sound like coming from the head.  I don't know if that was from the backfire, or what it was - just a clue.  I took one plug out of the head and saw the valve moving when cranking.  Like I said, it sounds normal when trying to start, and I tried starting with the kickstand up and down.

I did take out the CDI box and bang on the back of it, but still not starting. I ordered 1 new one anyway.  That's where it is now.  If it helps, you can hear a short clip of it trying to start here - first showing the old spark plug, then the spark plug in the engine connected:  

 

Edited by MartMX

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I forgot to turn on the fuel ON on my 650L. Started a ride, backfired through the carb and pushed the carb off the intake boot. Took awhile to find that one. It would fire for nothing. 

 

As for the too many sparks on the plug... I don't know this for fact on the L, but on the XR4 I got rid of, it fired at tdc on every rotation, not every other rotation. The L may be the same way. 

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You're getting a strong spark, so it isn't the CDI.  You won't get a spark when that is bad.

Running for a minute would be what I would expect if it used up the fuel in the float bowl and there wasn't any more coming into it.  Although I'm guessing that if you changed jets in the carburetor the float bowl would have been empty when you installed the carburetor, so there must have been fuel flowing into it to get it to start the first time.

For some reason, these sorts of things usually happen to people who are new to the bike and rarely happen after you've put a few thousand miles on it.  Some sort of operator error can cause some of the problems.

But you're getting spark, so most of the electrical issues should be ruled out.  Good luck figuring it out.  It's frustrating when they don't want to start.

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Open the bowl drain screw and see if fuel comes out. If not , you put the float in upside down.

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Good news: IT'S RUNNING.  Like CORider and boogie_4wheel suggested, it blew the carb off the boot to the head.  I looked at it closer with a flashlight and saw it sitting off the boot.  Then, I managed to get it all the way on and tightened.

Bad news: Running rough, bogging down when I give it just a little gas, have to run with the choke on.  This is sort of the way it was running before and I thought the new gas, jet kit, and new spark plug would fix the problem.  Maybe I didn't do something right or the clip fell off the needle in the carb - not sure.  I'll have to check into it later, and maybe get some hands-on help.  

Thanks for all the help here.  I do appreciate it from all you experienced XR gurus.

MartMX

Edited by MartMX
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Did you hear it run or ride it at all or did the problems begin with the first start after you brought it home?  An '08 with 1000 miles I'm guessing there was plenty of time sitting and there is likely some standard issue clogs in the carb.  Probably clogs in more than one circuit.  Old dried fuel is stubborn and it can be tough to clean.

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Originally, I did ride it around the yard and it seemed to be running at about 80% of normal - just sounded a bit lean and throttle response was kind of slow.

So, I put the Dyno jet kit following these instructions:  http://www.dynojet.com/pdf/1148.pdf.   Selected the DJ165 main jet and the 3rd clip position on the needle.  While apart, I cleaned out the small holes in the mixing tube because it did have some green junk clogging up the holes.  With it back together, it basically runs very lean.  Requires full choke to idle and giving it any throttle bogs it out and quits.

So, then I took the carb back off and apart (see pics below).  I don't see anything wrong. The bowl was full of gas. The needle is in place and moving fine. The jets are clear.  But, there must be something wrong that makes it barely run and run so lean.  The carburetor boot to the engine seems ok and it was definitely on tight when I ran it this last time.

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Just to follow up on this: It's RUNNING FINE now.  HollerHead pointed out to me that if the smog pump has been removed (it was), then vacuum line from it to the carb should be removed and closed at the T.  I did that and it is running fine.  Rode around this weekend with a couple of other guys.  First time riding a 'dirt bike' on the highway.  Went to the river, trails, roads, fields, back home - I'm loving this dual sporting.

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