Uncorked 2006 sputtering problem


11 replies to this topic
  • Maroast

Posted August 09, 2006 - 07:45 PM

#1

I'm having trouble finding any threads dealing with this problem...any help would be great.

Bikes in texas...pretty warm here now.
68S, 175 main jet, new needle clip in 3rd position
all plastic riped out of intake and new maniforld gasket.
End of stock tip drilled out.
Did all this two days ago.

This thing pulls like a muther now! but I'm havig some trouble with the throttle...If I crack it open too fast it sputters..then kicks in and runs through the RPM pretty smooth and fast. I cant even wheelie or cut through cars on the highway because of the unpredictability of this sputtering. Is this just how this carb is becauses its a slider? My KLR had a CV and the throttle was ALWAYS smooth, rich or lean. Any help would be great. Thanks

T-bone :thumbsup:

  • snaggleXR650

Posted August 10, 2006 - 03:45 AM

#2

It's hard telling. I ran those settings on my 650R here in NW Flordia, and my bike was a bit rich.

Install a UNI filter, and gank 3 of the 4 screens out of the backfire screen.
Try going back to the 65s pilot and retune the pilot screw.
Experiment with the needle in the 2nd position.

You can loosen the boots on the carb and simply rotate it sideways (top of the carb points out the right side). Then you can get access to the bowl and the pilot/main jets on the left and to the needle from the top on the right side. No need to totally remove the carb from the bike...

Finally, learn to roll on the the throttle, don't snap it.

If all else fails, ~$400 for a Mikuni TM-40 pumper or Edlebrock Quicksilver pumper will ease your pains.

In the end, the big XR needs to breathe. More open exhaust pipes really help alot too.

  • Maroast

Posted August 10, 2006 - 07:44 AM

#3

Finally, learn to roll on the the throttle, don't snap it.

:thumbsup:

Yeah, I've done some reading and I'm thinking its too rich... I'll try going down on the main and moving the clip on the needle down a bit. Thanks

  • sl33py

Posted August 10, 2006 - 09:36 AM

#4

hey guys - complete carb noob so be gentle.

just desnorkled and put full FMF system on. A lot better power/torque but a bit of a hesitation just like Maroast. And popping / backfire on the decel...

completely stock carb... help?!?

thanks!

rob

  • snaggleXR650

Posted August 10, 2006 - 10:22 AM

#5

Maroast,
NOT the main jet. The main jet only affects 3/4 - full throttle. Your problem is at lower throttle positions IE. your pilot jet and/or needle. Still more than likely, the rich jetting isn't the problem. What air filter do you use? Is the stock backfire screen still intact (it's restrictive)? Etc... No mater how your carb is jetted, if you can't move enough air, the bike will bog...


Sleepy,
What bike do you have? Did you change the jetting when you installed the new pipe? More information please!

  • Maroast

Posted August 10, 2006 - 01:55 PM

#6

GOT IT!!!!!!!!!!!!!!

Went to the pigpen and followed the jetting guide better (I tried to fudge it at first)

down to 65S, 170main and 2nd clip on the needle...also turned the pilot screw down a bit to lean it out....

HOLY SHIT THIS THING RIPS!!!!!!!!!!!!

No nore hesitation at the low end and with the TWO there is no surging in the upper rpm range (6500+). :thumbsup: :applause: :ride:

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  • sl33py

Posted August 10, 2006 - 02:05 PM

#7

snaggle - 97 650L. completely stock carb. just desnorkeled and put FMF system on. only thing non stock - K&N filter.

Maroast - nice!

  • snaggleXR650

Posted August 10, 2006 - 03:47 PM

#8

Maroast, good deal, glad you got it sorted.

Sleepy,
Lucky for you, I just got through helping my buddy with a 650L. You need to do "Daves Mods." To start out, you need a 55 or 58 pilot jet, and slip a ~.030" washer under your needle. I think a #4 washer from the hardware store will be just about perfect. Then you need to install a bigger main jet. More then likely you will need to go with a 162 or 165 main jet. You aren't done yet though. Your piston slide in your carb has 3 holes in it. One is right in the center, where your needle comes through, the other two are off to one side. Drill the two of to the side out with a 5/32" drill bit for better throttle response.

Your fuel mixture screw, (pilot screw) has a block on it from the factory. You need to grind this off so that you can have full adjustment of your low speed fuel mixture. You will want to start out at ~2.5 turns out from fully closed (righty tighty). However, depending on the pilot jet you end up with, you will have to tune your bike for the highest idle with the fuel screw, so you may end up anywhere between 2 - 3 turns out.

You NEED to do this stuff ASAP, and quit riding your bike until you get it done. Your bike is undoubtedly running way to lean with your airbox and exhaust mods.

Call this place http://www.carbparts.com/ and order the pilot and main jets.

Read up here for "Daves Mods"

http://www.4strokes....?TOPIC_ID=11416
http://www.4strokes....xr650lcarbmods/

I'm really serious, you need to do this stuff. Running your bike lean like it is is NOT GOOD.

  • motopsycho650

Posted August 10, 2006 - 07:01 PM

#9

Just put the needle jet to the fourth spot and play with the pilot adjustment a little, and it should wake right up. Some of these guys get way too complicated.

Cheap Air Filter Mod:
Get a TwinAir Original replacement filter, (or 2 or 3). Cost 15 bucks ea.
Get a XR's Only High flow backfire screen (around 20 bucks w/ shipping).
http://www.xrsonly.c...emart&Itemid=77

Then cut out the screen, like so. The X's & the line represent where the side plate presses against the filter. http://www.geocities...ireScreen02.jpg

  • snaggleXR650

Posted August 11, 2006 - 03:35 AM

#10

Motopsycho,
You are helping the wrong guy with the wrong bike. This thread has two bikes in it, an R and an L. The R was easily sorted already. The L needs alot of carb work. Complicated as it may sound, it's necesary and widely proven to greatly improve the performance of the stock L carb. Thanks for your input though, that's good info for the R guys.

  • sl33py

Posted August 11, 2006 - 03:46 PM

#11

Maroast, good deal, glad you got it sorted.

Sleepy,
Lucky for you, I just got through helping my buddy with a 650L. You need to do "Daves Mods." To start out, you need a 55 or 58 pilot jet, and slip a ~.030" washer under your needle. I think a #4 washer from the hardware store will be just about perfect. Then you need to install a bigger main jet. More then likely you will need to go with a 162 or 165 main jet. You aren't done yet though. Your piston slide in your carb has 3 holes in it. One is right in the center, where your needle comes through, the other two are off to one side. Drill the two of to the side out with a 5/32" drill bit for better throttle response.

Your fuel mixture screw, (pilot screw) has a block on it from the factory. You need to grind this off so that you can have full adjustment of your low speed fuel mixture. You will want to start out at ~2.5 turns out from fully closed (righty tighty). However, depending on the pilot jet you end up with, you will have to tune your bike for the highest idle with the fuel screw, so you may end up anywhere between 2 - 3 turns out.

You NEED to do this stuff ASAP, and quit riding your bike until you get it done. Your bike is undoubtedly running way to lean with your airbox and exhaust mods.

Call this place http://www.carbparts.com/ and order the pilot and main jets.

Read up here for "Daves Mods"

http://www.4strokes....?TOPIC_ID=11416
http://www.4strokes....xr650lcarbmods/

I'm really serious, you need to do this stuff. Running your bike lean like it is is NOT GOOD.


crap - it figures. Lean and it pops and backfires? figured that would be from being too rich...

I have Zero time this weekend and don't want to mess up my bike, but it's all i have right now for transpo. I will start reading now and order needles.

thanks Snaggle!!!

rob

  • motopsycho650

Posted August 12, 2006 - 04:54 AM

#12

Motopsycho,
You are helping the wrong guy with the wrong bike. This thread has two bikes in it, an R and an L. The R was easily sorted already. The L needs alot of carb work. Complicated as it may sound, it's necesary and widely proven to greatly improve the performance of the stock L carb. Thanks for your input though, that's good info for the R guys.


Oh, oops. I guess that's what I get for skimming all the replies. hehe





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