01' 426 fouling plugs.



13 replies to this topic
  • Fastline

Posted February 11, 2002 - 11:42 AM

#1

I recently bought an 01' 426 in San Antonio Texas after ridding an CR for many years. During the parade lap of a local hair scramble a freind said my bike was popping excessively when I let off the gas. Before the race, we replaced the 162 main jet with a 165 jet. Now the bike fouls plugs after every ride. Additionally when I removed the carb for inspection and installation of the 162 jet I observed an oil residue near the top of the carb. Finally the end of my exhaust pipe is black w/ sute. Does any know where this oil is coming from

  • sirthumpalot

Posted February 11, 2002 - 12:14 PM

#2

The oil in the carb may be from the air filter (sucked through). I'm not sure how else it would get in there as all crank case vents are vented to the outside on the YZF. The extra soot on the pipe is probably from the extra gas not burning (it's not smoking blue smoke is it?).

If it's popping when you back off of the gas then the main jet is not what you want to play with. You should be adjusting the fuel screw. Hopefully you will have enough adjustment in the fuel screw to fix the popping without having to change anything else. If you only changed the main jet to cure the popping then put the 162 back in and adjust the fuel screw to stop the popping. IMHO anyway..

  • Fastline

Posted February 11, 2002 - 12:21 PM

#3

Originally posted by sirthumpalot:
The oil in the carb may be from the air filter (sucked through). I'm not sure how else it would get in there as all crank case vents are vented to the outside on the YZF. The extra soot on the pipe is probably from the extra gas not burning (it's not smoking blue smoke is it?).

If it's popping when you back off of the gas then the main jet is not what you want to play with. You should be adjusting the fuel screw. Hopefully you will have enough adjustment in the fuel screw to fix the popping without having to change anything else. If you only changed the main jet to cure the popping then put the 162 back in and adjust the fuel screw to stop the popping. IMHO anyway..



  • Boit

Posted February 12, 2002 - 03:51 PM

#4

Where was the oily residue? On the outside front and top area of the carb? Did you inspect the valve cover for seepage? If it is leaking a little from around the valve cover, air moving around the engine as your ride will blow it on everything behind the cylinder. Oil should be totally contained on a 4-stroke and should not be found one the outside of the engine, especially around the carb or cylinder unless the crankcase vent was re-routed from the bottom of the frame member. If the vent hose has been re-routed, you could get a slight oil residue from the vapor/mist and sometimes oily drip the comes out of this hose.

  • Norman

Posted February 12, 2002 - 04:09 PM

#5

Funny, I had the same problem today. I bought a new 01 a month ago, went through proper break in and it was doing fine. I thought it was running lean at quarter to half throttle so I lowered the clip on the needle one position. At our last harescramble I went to start my bike and it wouldnt start, put in a new plug and it fired right up, ran fine and started fine the entire race. I went riding today and it wouldnt start, cleaned my old plug and it kept gas fouling the plugs, finally I cleaned one, poured a little gas on it and lit it with a lighter, put it in and if cranked. It ran like crap all day. I had a 2000 and once jetted it ran great. I have done some searches and really havent found any info that applied to me. I have a stock pipe with the promoto billet spark arrestor, im at sea level and the temp is between 50 and 65 right now. Does anyone have any suggestions?

Norman
Beaumont TX

  • Norman

Posted February 12, 2002 - 04:17 PM

#6

Funny, I had the same problem today. I bought a new 01 a month ago, went through proper break in and it was doing fine. I thought it was running lean at quarter to half throttle so I lowered the clip on the needle one position. At our last harescramble I went to start my bike and it wouldnt start, put in a new plug and it fired right up, ran fine and started fine the entire race. I went riding today and it wouldnt start, cleaned my old plug and it kept gas fouling the plugs, finally I cleaned one, poured a little gas on it and lit it with a lighter, put it in and if cranked. It ran like crap all day. I had a 2000 and once jetted it ran great. I have done some searches and really havent found any info that applied to me. I have a stock pipe with the promoto billet spark arrestor, im at sea level and the temp is between 50 and 65 right now. Does anyone have any suggestions?

Norman
Beaumont TX

[ February 13, 2002: Message edited by: Norman ]

  • Merfman

Posted February 13, 2002 - 04:40 AM

#7

All,

Many of us here in Colorado, with '01 426's have had this problem. Search for "Fouled plug = foul mouth" for more info.

The short answer is that many of us have solved (?) the problem by running race gas during the winter. We're forced to run Oxy fuels here during the winter. Even though they should make the bike run leaner, we've fouled lots of plugs. None fouled with the race gas. Just something to try...

Merf

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • txthumper

Posted February 13, 2002 - 01:16 PM

#8

well ihope yall figure it out, cause my 01 is doing the same thing...went riding sunday..got unloaded, dressed..all that..bike wouldnt start, changed plug..fired right up...it has done this several times..and nope..i keep my hand on my handguard when starting...couple friends have wr 400's...they dont have this problem...i talked to Thumper racing today..Gary seems to think maybe float leval to high...im gonna check mine this week..if yall figure something out let me know..im about to go back to a 2 smoker!!!!

  • SkinSF

Posted February 18, 2002 - 06:15 PM

#9

Guys, are your bikes sputtering and popping when you hold the throttle a quarter to half open? Mine started this after I washed it at the car wash. It would not start. I changed the plug and it ran good for about 10 min. The engine started backfiring on deceleration. Then the popping and backfiring started happening at mid range. Finally the bike started dieing when I would come off the gas. Not good when your trying to do a double or triple! I tested the electronics and found the Secondary Coil to be a 20 ohms instead of the book recommended 9 to 14 ohms. I did not mess with the jetting because the bike was running fine all year. The problem started after I took my bike to a high pressure wash (first and last time). Have an of you looked at the ignition yet? Please let me know if anyone has a good fix. I have finally gotten up to speed and want to ride.
Thanks

  • Fastest1

Posted February 18, 2002 - 07:06 PM

#10

Though I have a 2000 with the BK mod I also had this problem before I went to race gas. I also as a precaution always turn the fuel off when I am riding back to the pits ( 100 yds or so). Then I start it without turning the gas on. Works like a champ. I am in Houston with a 170 main jet,OBEKR needle 4th groove from top, 48 pilot jet, approx 1&1/2 turns out on the fuel screw and it rocks. The Bk mod has my spray to .3 of a second. Kill anyone who comes near your throttle! Good Luck I have never seen such a sensitive 4 stroke. But when they run it is hard to hold on!!!!!!!!!! Cya :)

  • therapture

Posted February 18, 2002 - 07:31 PM

#11

Originally posted by Fastest1:
Though I have a 2000 with the BK mod I also had this problem before I went to race gas. I also as a precaution always turn the fuel off when I am riding back to the pits ( 100 yds or so). Then I start it without turning the gas on. Works like a champ. I am in Houston with a 170 main jet,OBEKR needle 4th groove from top, 48 pilot jet, approx 1&1/2 turns out on the fuel screw and it rocks. The Bk mod has my spray to .3 of a second. Kill anyone who comes near your throttle! Good Luck I have never seen such a sensitive 4 stroke. But when they run it is hard to hold on!!!!!!!!!! Cya :)


With my 2000 model, I also had some plug fouling issues, ALWAYS in cooler weather, first start of the morning...it would catch and then die 2-3 times, then nothing, dead. After changing the plug, it would lite off fine and be great the rest of the day. I did 2 things that mostly solved the problem...
1) turn OFF the gas at the end of the day, it seems some "seep" gas into the motor via the petcock/carb, resulting in an overly rich (see:flooded) condition the next time you start it
2) ran 103 octane VP race gas, forget higher ratings, not needed unless you run a higher compression piston.
And the final thing that TOTALY solved my fouling and hard starting problem? The BK mod with proper jetting...the single, most effective, and worthwhile gain you can do to a stocker...even BK himself says Ferry's practice bike, with nothing but a DSP exhaust and the mod, RIPS...

  • urla

Posted February 19, 2002 - 11:35 AM

#12

Believe therapture's point 1 is the key to the fouling problem.
When you transport the bike gas is splashing around in the float bowl and due
to an internal leakage the carb gets flooded.
If you have fouling problems, try turn off the gas at end of the day and let
the motor run until it dies or drain the carb.
I also used to foul plugs when getting on the gas after hard braking in bumps.
My internal leakage problem was:
The tread for one of the outer screws holding the
middle portion of the lower section to the upper section of the carb was drilled and threaded in to the float house.
After putting some epoxy in to that hole, I haven't fouled a plug.

And don´t blip the gas when starting a 2001, guess most 1998-2000 is ok to "blip".

[ February 19, 2002: Message edited by: urla ]

[ February 19, 2002: Message edited by: urla ]

  • Hokie

Posted February 19, 2002 - 12:46 PM

#13

Originally posted by txthumper:
well ihope yall figure it out, cause my 01 is doing the same thing...went riding sunday..got unloaded, dressed..all that..bike wouldnt start, changed plug..fired right up...it has done this several times..and nope..i keep my hand on my handguard when starting...couple friends have wr 400's...they dont have this problem...i talked to Thumper racing today..Gary seems to think maybe float leval to high...im gonna check mine this week..if yall figure something out let me know..im about to go back to a 2 smoker!!!!


My 01 426 float level was off when I got it. It was also jetted really crazy. I think the jetting was screwy due to the float bowl being out of spec and the oxy gas we get around here.

I jetted to CO specs and fixed the float bowl and have not had any problems since late summer.

Oh yeah, you can get non Oxy gas in CO at the intersection of HWY 52 and I25. Doesn't help the CO Springs folks much though!

[ February 19, 2002: Message edited by: Hokie ]

  • mikeolichney

Posted February 22, 2002 - 11:33 AM

#14

Hokie, how did the HS go? Sorry I couldn't talk, my 3 yr old was running away through the crowd.





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