Persnickity WR 400



8 replies to this topic
  • Rob_in_Madison_WI

Posted October 23, 2000 - 04:45 PM

#1

Hi folks,
Glad I discovered this forum. May keep me from going KTM. Here is my issue: I've had my '98 WR 400 for a few years now and have always seemed to have starting problems. Lately it seems to be fouling spark plugs right and left. I've got a WB E series pipe with a tapered head pipe, 8 discs, stock air filter, no baffle. My cam timing is set to YZ spec. My spark plugs were always wet and black. I've now gone to a 162 main jet and my mixture screw set at 1 3/4 turns and it seems to run better. I try to keep the air filter with minimum oil coating. Question: Why does this thing run so rich? Sure wish I could solve this issue cause starting it has been a nightmere on anything but a fresh plug. And we know how much fun that can be every ride!

Any help would be most appreciated. Thank you very much.

Rob

  • Moto-Mike

Posted October 23, 2000 - 05:30 PM

#2

Rob-
Did you make it to the Springfield Corners enduro yesterday? That was a fun enduro and beautiful weather...
How did you arrive at the 162 main that sounds rather lean. I'm using a 175 and alot of wr riders are going richer then that. What is your pilot jet is it stock or something different. Another area to check would be your clip setting on the needle...raise the clip to lean the midrange jetting.
Check out the jetting area in the technical section of this site for some baseline jetting specs. Good luck

  • Boit

Posted October 23, 2000 - 05:50 PM

#3

Rob: Does the engine ever smoke? I can't imagine how your particular jetting could be rich. What comes to my mind is oil fouling. If your engine is smoking blue, the rings could have blow-by from wear, or your valve stem seals are worn and allowing oil into the combustion chamber. As a last thought, make sure your engine's vent hose is not plugged with mud causing an over pressurization of the crankcase.

  • James_Dean

Posted October 23, 2000 - 06:11 PM

#4

Rob,
We shouldn't give direction without knowing what pilot jet, needle, clip position, etc.

Probably:
-your needle clip is too rich
-or you need to turn in your pilot screw
-or you need a leaner needle
-or your float level is too high
-or your accel pump is set too early
-or the pilot jet is too big
-or the pilot air is clogged
-or the air filter... no not that

Oh, I really just don't have any clue except it is NOT your main jet, that is too small... :) ( really)

James Dean

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  • Rob_in_Madison_WI

Posted October 24, 2000 - 06:23 PM

#5

Originally posted by Moto-Mike:
Rob-
Did you make it to the Springfield Corners enduro yesterday? That was a fun enduro and beautiful weather...
How did you arrive at the 162 main that sounds rather lean. I'm using a 175 and alot of wr riders are going richer then that. What is your pilot jet is it stock or something different. Another area to check would be your clip setting on the needle...raise the clip to lean the midrange jetting.
Check out the jetting area in the technical section of this site for some baseline jetting specs. Good luck


Mike, thanks for your advice. I'll look into the clip setting. I have not changed that from stock. I agree my 162 sounds lean compared to other settings I've read about here but the bike ran the best it ever has last weekend. No, I didn't make it to the Madison enduro as I promised a friend I would take his son riding on his KDX 80. He wanted to give the enduro a try but I talked him out of it as he is new to riding and I thought it would be a bit much for him. Anyway, I'll try the clip change. Thanks,

Rob

  • Rob_in_Madison_WI

Posted October 24, 2000 - 06:28 PM

#6

Originally posted by Boit:
Rob: Does the engine ever smoke? I can't imagine how your particular jetting could be rich. What comes to my mind is oil fouling. If your engine is smoking blue, the rings could have blow-by from wear, or your valve stem seals are worn and allowing oil into the combustion chamber. As a last thought, make sure your engine's vent hose is not plugged with mud causing an over pressurization of the crankcase.


Boit,
No, I have not seen any smoke except when I first start it. Then it smokes a bit when the choke is on. In this case the smoke is black from running on choke. Also, I am not using any oil to speak of...a good thing since there is not much to lose! I think I'll go back to the stock 168 main and try changing the clip position to the next leaner setting. Thanks! Rob

  • Rob_in_Madison_WI

Posted October 24, 2000 - 06:37 PM

#7

Originally posted by James Dean:
Rob,
We shouldn't give direction without knowing what pilot jet, needle, clip position, etc.

Probably:
-your needle clip is too rich
-or you need to turn in your pilot screw
-or you need a leaner needle
-or your float level is too high
-or your accel pump is set too early
-or the pilot jet is too big
-or the pilot air is clogged
-or the air filter... no not that

Oh, I really just don't have any clue except it is NOT your main jet, that is too small... :) ( really)

James Dean


James,
Thanks for all of your suggestions. I have owned the bike since new and am sure everything in the carb is stock except for the main jet change and I have changed the mixture screw (bottom of carb next to main -- not sure of exact name) setting from 2 1/2 turns out to 1 3/4 turns. I'll look at the plug to see how it looks and make the clip change. Hey, at least the thing runs without fouling plugs. My right knee and bottom of my right foot are much happier!

Rob

  • James_Dean

Posted October 24, 2000 - 06:52 PM

#8

Rob,
Maybe the pilot screw is all that you needed to change. However, the standard clip setting for the newer '99WR is #3. If you are in #4 then #3 will probably help.

Other thoughts:

The stock DTM is a pretty rich needle on the straight diameter portion of the needle. This affects fuel at 0-1/4 throttle along with pilot jet settings. As the bike gets more hours it may well need a leaner clip for wear on the brass nozzle (needle jet) or a leaner needle such as DVP. This is what Clark has listed in the technical section of ThumperTalk.

The other thing about your hard starting is that a little faster idle seems to help a little.

James

  • hart

Posted October 26, 2000 - 10:26 AM

#9

When does your plug foul?? right when you start it? Mine fouls a plug once in a while when I start it and if i hold the throttle on for a few seconds and let it idle high, it won't fowl. It seems like a gas foul and when you start it there is not enough heat to burn off extra gas.(obviously it's rich the choke is on) If I don't let it get enough air, its over!!

Good luck


Originally posted by Rob in Madison WI:
Hi folks,
Glad I discovered this forum. May keep me from going KTM. Here is my issue: I've had my '98 WR 400 for a few years now and have always seemed to have starting problems. Lately it seems to be fouling spark plugs right and left. I've got a WB E series pipe with a tapered head pipe, 8 discs, stock air filter, no baffle. My cam timing is set to YZ spec. My spark plugs were always wet and black. I've now gone to a 162 main jet and my mixture screw set at 1 3/4 turns and it seems to run better. I try to keep the air filter with minimum oil coating. Question: Why does this thing run so rich? Sure wish I could solve this issue cause starting it has been a nightmere on anything but a fresh plug. And we know how much fun that can be every ride!

Any help would be most appreciated. Thank you very much.

Rob






 
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