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Engine Stutter

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Hi everyone.  

 

I bought a used 2009 DRZ400SM late last season from the local dealer and I'm having some engine stutter.  I test drove it for a few KMs before purchasing it and it seemed to run well.  I never rode enduros or dirt bike so I didn't exactly know what to expect.  Dealer wasn't aware of any modifications apart from headlights.  

 

Anyway, after some highway riding, I started noticing small backfires and difficulty holding a constant speed.  It seems as if it stutters, then surges, then stutters, etc.  It also doesn't like being at high RPMs, it starts stuttering when fairly high.  

 

A little bit of research and I found the bike was previously for sale on Kijiji.  I wrote to the former owner and found out it was rejetted for a yoshimura exhaust but exhaust was then removed when sold to the dealer.

 

What should I do to try and remedy this?  Purchase and install stock jetting?

 

Thanks

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They really shouldn't have had to change the jetting much for just the pipe. Look and see what jets are in it. This would be a good time to do the 3X3 mod. Guaranteed Horsepower and will take care of the jetting problem.

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You need to confirm the carb settings...Needle setting and main jet..Is it the stock needle installed?....The stock needle has no multi clip adjustment...

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Hi everyone.  

 

I bought a used 2009 DRZ400SM late last season from the local dealer and I'm having some engine stutter.  I test drove it for a few KMs before purchasing it and it seemed to run well.  I never rode enduros or dirt bike so I didn't exactly know what to expect.  Dealer wasn't aware of any modifications apart from headlights.  

 

Anyway, after some highway riding, I started noticing small backfires and difficulty holding a constant speed.  It seems as if it stutters, then surges, then stutters, etc.  It also doesn't like being at high RPMs, it starts stuttering when fairly high.  

 

A little bit of research and I found the bike was previously for sale on Kijiji.  I wrote to the former owner and found out it was rejetted for a yoshimura exhaust but exhaust was then removed when sold to the dealer.

 

What should I do to try and remedy this?  Purchase and install stock jetting?

 

Thanks

 

 

a stutter sounds more like an electrical short. wiggle the key while it's idling and see if it does it. as the key switch wears, it will cut out at higher rpm's. 

 

then test the stator, given the 'deep fried stator' tests on thumpertalk. 

 

if the bike is too richly jetted now, it should run better with the airbox cover removed. a few short test rides should confirm this with better ridability. 

 

if there is a vacuum leak it will manifest as surging idle and misses at higher rpm's also. 

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Thanks, this gives me a couple things to try out.  There's still 4 feet of snow on the ground so I won't be able to ride for at least a couple weeks but at least I can check the bike out.  Is there a tutorial on checking the needles and carb settings?  As far as the current jets, I was told they're not stock.

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Thanks, this gives me a couple things to try out.  There's still 4 feet of snow on the ground so I won't be able to ride for at least a couple weeks but at least I can check the bike out.  Is there a tutorial on checking the needles and carb settings?  As far as the current jets, I was told they're not stock.

Start here, http://www.thumpertalk.com/topic/339955-every-thing-you-need-to-know-about-carbs/

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look at what jets you have, make sure they arnt clogged, and check to see if youre getting fuel to the carb

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Just an update. After snowblowing a good hour, I made it to my garage. The battery was dead in the DRZ so I took some pieces off and found that the 3x3 mod has been done to the airbox. Would covering the hole backup fix my issue if I don't change the exhaust? If so, what should I use?

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Just an update. After snowblowing a good hour, I made it to my garage. The battery was dead in the DRZ so I took some pieces off and found that the 3x3 mod has been done to the airbox. Would covering the hole backup fix my issue if I don't change the exhaust? If so, what should I use?

 

Partly covering the air intake would help if your lean....

If the PO correctly jetted for open pipe, when the stock exhaust is fitted ,it should now be rich.....reducing the air opening will add to a theoretical rich condition...

If you run it with the airbox door removed,and it is better, the theoretical rich condition can be confirmed...

You really need to look at the current needle setting and main jet to know what we are dealing with....

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