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Fellas, About a week ago I rode my 2001 DRZ-400S, everyting was perfect and it ran very well. Yesterday I tried to go for another ride, it started and idled fine but when I started to give it throttle, it sputted and backfired like there was no tomorrow. I pulled tank off, checked pitcock and filter, pulled sparkplug, cleaned and gaped it, put everything back together and same thing, sever backfiring and no power. What could have gone wrong. I have put over 17,000 miles on this bike, with no problems expecially backfiring. Can someone give me some advice and what is happening and maybe a fix.. Thank you very much The Spudman:confused:
 

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Has the motorcycle been stored with untreated fuel in it for any length of time?

What color was the spark plug electrode when you pulled it out?

Did you replace the fuel with new or reuse the fuel that was already there?
 

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The plug looked between brown and black, fuel was new and I use premium. Kind of stumped because the old gal has just ran fine and like I said on my original post, just rode it a week before and now severe backfiring. thanks The Spudman:confused:
 

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When were the valves last adjusted?


Backfiring through the exhaust means raw fuel is not getting completely burned and igniting down the pipe. It could happen from an incorrect fuel mixture, a bad or mistimed valve, or the spark firing at the wrong time.

With electronic ignition, the spark timing issues are rare. If the computer gets fried, it usually won't spark at all. The possibility is remote.

A compression test will detect a leaky valve.
 

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I don't know if it is of any benefit, but my big single will not even fire on the gas in the carb after a week. Did you drain the carburetor float bowl? If not, try it.

Another thing I can think of is if your DRz made a lot of cam drive racket, if so, it is possible the tensioner failed and allowed the cam chain to jump a tooth. Some people ignore the clatter when told all of them make that noise. I know it is an issue with some DRz400s and a whole lot of Kawasakis. I know, because I make the replacement manual units. If yours didn't make noise from the cam drive, that isn't the issue.

One other possibility is if for some reason there is an exhaust valve stuck slightly open or the clearance has closed down to nothing, causing misfiring through the exhaust or intake, whichever it is misfiring through.

If you pull the cam cover you can check the cam timing and also the valve clearance.
 

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Went out for a ride the other day on my DRZ400e 2015, got 500meters from home and the bitch started popping, backfiring and farting, then the S.O.B wouldn't start.

Pushed it home and checked for all the usual things, is there a spark, yes- nice and big and bright blue, is fuel getting through carb, yes- smelled like a lot of unburnt fuel from rear, no blockages in air-box, so there's the trifecta of how a motor works.

Rang the local Suzuki mechanic, said it could be primary coil, secondary coil- stator, or spark plug. Well I'm pretty sure that spark is big enough to drop a meth head so I replaced the 2 month old Iridium plug with original plug and bingo! She runs like a dream once again, thank f*%k.

Apparently plugs can go faulty and break down when loaded, even expensive Iridium plugs.

Moral of this story, carry a second 'known' good plug not necessarily a new plug, because money doesn't always buy reliability!

Happy riding
 

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In my experience, the spendier the plug, the more likely an unexplained failure. Learned this the hard way on our ice racer 35 yrs.ago. - thought we were being "trick" by installing the then new, all-the-rage platinum plugs. After the second one developed a misfire we threw them over the left shoulder and never had a problem with the stone age ones. Since then god knows how many generations of plugs have been tried each gen. featuring a newer and always more expensive metal. Nothing better than "plain ole" if you can get one that fits.
 

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Plugs will also magically start firing again. Had a VTX 1300 where the rear would randomly just stop firing and magically start again if I did nothing but just keep riding as best I could. Threw new plugs in and problem vanished.
 
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