Mid range miss?


13 replies to this topic
  • bigdrtrdr

Posted April 13, 2006 - 12:46 PM

#1

I have an 01 WR 426, I have noticed a miss while Im cruising at about 50-55 mph on pavement. Its like a stutter in the power delivery with no real rhythm to it. It did it with both the FCR and the current Edelbrock carb. "TPS is disconnected"
Off road I don't notice it and the power is great. It also doesn't miss under heavy exceloration.
Just while cruising at a steady speed on roads.
I just had the valves checked.
Any Ideas?

Thanks,
Eric

  • dbailey223

Posted April 13, 2006 - 01:02 PM

#2

How wide open is your throttle when it happens?

  • bigdrtrdr

Posted April 13, 2006 - 04:19 PM

#3

Probly about 1/4

  • Farmer Hank

Posted April 13, 2006 - 04:57 PM

#4

Try raising the needle and see if it gets better (or worse!). I found that the accelerator pump covers up for a lean midrange. At steady throttle (no extra squirt of fuel from the accelerator pump) the engine runs lean. Off road, with constant acceleration and deceleration, the problem is masked. I ended up with a fairly rich needle setting (compared to the jetting database) and a slightly smaller main.

  • freestyle250

Posted April 13, 2006 - 04:58 PM

#5

Pilot Jet?

  • creeky

Posted April 13, 2006 - 05:25 PM

#6

My Edelbrocked WR400 will do the same thing if I have the carb just a little lean. Try going 1-2 clicks richer on the adjuster and see if that helps.

  • bigdrtrdr

Posted April 14, 2006 - 05:56 AM

#7

Thanks guys,
I think Im all in on the Edelbrock needle so I'll go to the next larger.

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  • GCannon

Posted April 14, 2006 - 09:08 AM

#8

Mine does that same thing constant throttle 1/4 to 1/2 steady throttle. it sounds like a ping or lean hesitation only on pavement. my question is raise the needle one or two slots? other than that jetting is good ( 168 main Canadian needle, BK mod )

  • byggd

Posted April 14, 2006 - 11:32 AM

#9

I had the exact same condition with my 02 wr426 (a miss while cruising at about 50-55 mph on pavement). According to James Dean a constant RPM miss is NOT jet related. He suggested disconnecting the TPS and when I did sure enough the miss went away. However, I like the way it runs with it connected better for the dirt.

  • GCannon

Posted April 14, 2006 - 02:01 PM

#10

So maybee it is a ping (detonation) and not a lean fuel mixture issue. Maybee the ignition map is advanced too far at constant throttle Hi load from the pavement?what do you think and what did you do to fix it?

  • bigdrtrdr

Posted April 14, 2006 - 05:32 PM

#11

So maybee it is a ping (detonation) and not a lean fuel mixture issue. Maybee the ignition map is advanced too far at constant throttle Hi load from the pavement?what do you think and what did you do to fix it?


Its definitly not Pre ignition (detonation) I can actually feel the power cut out if just for a split second.
As I said Its not the TPS as Im running an Edelbrock carb.
Its not the Pilot jet. See above.
Im putting the larger needle in the Edelbrock this weekend and see what happens.
The weird thing is, the bike ripps offroad. it just feels like its not gonna make it to the destination on the Hywy. ... .. . ... . .......... . .. ..... . ....... ..?
I'll let you all know
Thanks for the input
Eric

  • bigdrtrdr

Posted April 17, 2006 - 08:27 AM

#12

Changed to the K8 Edelbrock needle, Problem solved.

It was just lean in the middle, Its amazing how much more power it makes.

  • jsaffordwr426

Posted April 17, 2006 - 09:49 AM

#13

I had the same problem on my 01 wr 426, for me it was at 55-60 ( Its geared higher) i found that by removing the drain plug on the bottom of the air box took care of the problem, the extra air helped the bike run better and eliminated the "miss." however this can cause a problem off road with dust being sucked into the air box. two solutions for this: only remove the plug when your riding on road, or they make air box filter plugs, you can simply drill a hole and insert a plug that allows air through but has a built in filter.

  • bigdrtrdr

Posted April 17, 2006 - 10:18 AM

#14

I had the same problem on my 01 wr 426, for me it was at 55-60 ( Its geared higher) i found that by removing the drain plug on the bottom of the air box took care of the problem, the extra air helped the bike run better and eliminated the "miss." however this can cause a problem off road with dust being sucked into the air box. two solutions for this: only remove the plug when your riding on road, or they make air box filter plugs, you can simply drill a hole and insert a plug that allows air through but has a built in filter.


I dont think that would make much diferance as I threw away the airbox lid and snorkle the day I bought the bike :thumbsup:

Anyway its fixed,

Eric




 
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