Fouled plugs = foul mouth!



111 replies to this topic
  • Guest_Guest_*

Posted January 06, 2001 - 01:35 PM

#61

I can remember having intermintent ignition problems with a Yamaha XT600. The bike would sometimes pop and spudder when throttle was applied. It would stall and not start back up. After a while it would fire back up. The plugs were wet (no spark). The tech at the local Yamaha dealer recomended spraying electronic coolant spray (picked it up at the local Radio Shack) on the CDI. If it started up, then this would determine that CDI electronics were bad. I was told this was a problem with other mid 80's XT600's. It might work for your yz426 to help determine if you need to replace electronic ignition.

  • blbainb

Posted January 07, 2001 - 07:52 PM

#62

Ok! I swapped out the CDI from my '00 426 and put it into the '01. Weather: clear/42F at 5000'. 91 Octane premium unleaded. Bike started using choke/2 throttle hits and 1 kick. Warmed up normally, sounded fine.

This time (a first, really) I didn't notice ANY 'twilight zone' period of poor running/poor idle at any time, even after taking a break. However, I'm not ready to make a conclusion until I ride it a few more times. mikeolichney thought that a carb swap had cured the problem only to have it recur a few days later. Last Friday, for example, I rode under the warmest conditions yet (54F) and noticed only a very short/slight period of poor running. So, we'll see. I'll be riding again later this week (Thurs/Fri)and keep you posted. Anyway, the jury's still out but it looks promising.

  • Boit

Posted January 07, 2001 - 11:30 PM

#63

4-strokes should NOT foul plugs! This is the main difference that sets us apart from those pesky gnats! This is so bizarre. Yamaha has a problem and should investigate....but don't hold your breath.

  • Moto-Mike

Posted January 08, 2001 - 09:11 AM

#64

Another indication would be if it still has that black sooty plug, hopefully not! To bad it's such a pain to do a simple plug check...oh well if Yamaha would not have produced faulty bikes we would'nt be so concerned about getting to the plug all the time. Sounds promising on what you've seen so far...I'll keep my fingers crossed. Keep us posted...Thanks

  • mikeolichney

Posted January 10, 2001 - 09:28 AM

#65

My bike has been running great in the warm weather we have been having-even got a tan plug with a 158 main! The dealer swapped out my CDI and we will see what happens when it gets colder. Thanks to all for your comments and suggestions. The 426 is soooo much fun when it runs good!

  • Moto-Mike

Posted January 12, 2001 - 04:21 PM

#66

Blbainb - Have you had another chance to ride since the CDI swap?
Mikeolichney keep us posted on how your bikes running after the swap.
Has anyone tested their CDI's per the service manual. I was discussing ignition testing with a mechanic who said that testing is not always reliable. Good can test bad and bad can test good. He recomended swapping componets when possible!I plan on ordering a new CDI within the next week...hopefully tearing into the carb on a weekly basis will become a thing of the past. :)

  • blbainb

Posted January 12, 2001 - 08:14 PM

#67

I've ridden twice with the '00 CDI in my '01 and both times it's been perfect. The only hesitation I have about declaring it the solution is that the weather has been a bit warmer (~50F) and the '01 seemed to run better under warmer conditions anyway (although not as well as with the '00 cdi).

Tomorrow, if the snow isn't too heavy, I plan to take a morning ride (short one -brrrr!) to see if there is any problem at lower temps - it should be only ~30F. Then I'll pull the plug and check.

I've run complete (as possible, anyway) checks on the ignition system and according to the manual everything is fine. The primary coil resistance is a little high (0.7 ohms instead of 0.2-0.3) but I don't think it's a real problem as such a low resistance is hard to measure anyway.

If the bike runs fine tomorrow then I'll swap the old one back and see if the problem returns as a double check. Right now the CDI seems to be the answer. It's nice to see that Mike Olichney has also had success so maybe the solution is in sight.

  • Guest_Guest_*

Posted January 12, 2001 - 08:52 PM

#68

geez........this is my first time on here and was just browsing....I have a 99400 and was getting ready to sell and buy brand new this spring but you guys have changed my mind! thanks
I race hare n' hound and hare scrambles .
I have used this bike for two full seasons of rippin' thru the desert at 80mph and thru the mtn trees and winter riding 16dgrs last wk and summer racing at 96dgrs and only replaced the stock plug when i bought the bike because i am very anal about things like that. I probly have 20 races on this plug of 60-106 miles and uncountable miles of dunes and practicing in snow and dust. sorry for eeveryones probs and i will talk to my mech friend and see if he knows anything new from Yamaha........G4

Originally posted by blbainb:
I've ridden twice with the '00 CDI in my '01 and both times it's been perfect. The only hesitation I have about declaring it the solution is that the weather has been a bit warmer (~50F) and the '01 seemed to run better under warmer conditions anyway (although not as well as with the '00 cdi).

Tomorrow, if the snow isn't too heavy, I plan to take a morning ride (short one -brrrr!) to see if there is any problem at lower temps - it should be only ~30F. Then I'll pull the plug and check.

I've run complete (as possible, anyway) checks on the ignition system and according to the manual everything is fine. The primary coil resistance is a little high (0.7 ohms instead of 0.2-0.3) but I don't think it's a real problem as such a low resistance is hard to measure anyway.

If the bike runs fine tomorrow then I'll swap the old one back and see if the problem returns as a double check. Right now the CDI seems to be the answer. It's nice to see that Mike Olichney has also had success so maybe the solution is in sight.




------------------
ride BLUE

  • Taffy

Posted January 14, 2001 - 02:54 PM

#69

can i justt ask here for a straw pole. my jetting isn't absolutely standard. i presume nobody else's is. if you have absolutely standard untouched jetting & have the problem, would you tell us here please. taffy has a hunch!!!

Taffy

  • blbainb

Posted January 14, 2001 - 07:37 PM

#70

Ok, here's the current status. Today, conditions were ~40F (I waited until noon) and clear/dry. My '01 had the '00 CDI as well as a 45 pilot/needle at 4/7 and main at 162. Bike started and ran great all day with no rich running condition and not odd 'twilight zone' period (~10 minute period of popping/backfiring/ and dying idle).

I pulled the plug and surprisingly it was black and sooty. Now it's possible that I need to lean it out some but I've tried this with the '01 CDI and it didn't seem to make any difference. Still, it ran great all day and never missed a beat.

I've replaced the '01 CDI back into the bike and will see later this week if the problem returns. I was disappointed to see the plug condition but the bike is still running much better than before. Go figure. The shop has notified me that the replacement accel pump diaphram is in but I've let them know about the results of the CDI swap and will hold off on doing anymore carb work for the moment.

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  • luvmythumper

Posted January 15, 2001 - 07:40 AM

#71

Taffy,

I have not had to touch my jetting at all. I have an 01 426. I recieved it in the crate. When I got it all my two smoke buddies came over. Once we prepped it I spent 40 minutes trying to start until. Finally, one of my buddies pulled me behind his truck with everyone laughing at my new thumper. It fired up. Next day we went to the track. It fired up first kick(it also did twice the day before after I got it started) It was idling and then died. Would not start. I put a new plug in(old plug was extremely black and sooty) Since then I have ridden on the same plug for 20+ hrs. The plug is black, but not sooty. I am pretty sure I flooded the bike the first time I tried to ride it.

The jetting is fine(I am in southern calif. - warm and sea level) I raced at Gorman(3000 ft) and experienced some problems during the first few warm-up laps.(mild backfiring when decelerating) Some stutter. Was going to re-jet but then started running much better. Still did not run as good as at sea level, but given what I had red, I didn't want to play with the jetting on race morning so I just ran with it. Hope this helps with taffy's hunch.

  • Hick

Posted January 15, 2001 - 07:51 AM

#72

blbainb,

Thanks for the update. I think it has to be your CDI. Maybe you could post a pic of your used plug. I don’t pay much attention but I’m willing to wager that your plugs don’t look any blacker or sootier than mine (currently 162/45/1.75 EKP #4 at 4,000 ft., ’00 YZF).

Maybe I’ll get off my rear and post a few pics of mine and start a new thread. Anybody else have the inclination to go through this hassle?

Letting them give you the diaphragm to try certainly won’t hurt anything, I know of at least two guys who would be interested in the difference this makes on your bike. I’ve been trying to get the std. ’01 diaphragm but it isn’t available yet.

  • mikeolichney

Posted January 15, 2001 - 09:12 AM

#73

Ok, heres an update on my situation. My bike has a new carb, 158/3/42/1/5 turns jetting, an CR8EVX plug, and now has a new CDI. It was running well before the swap, something I attribute to the warm weather at the time. Yesterday the weather turned cold again, and I had another 2 1/2 hr HS. It was below freezing. If the problem was still there, I was convinced it would show up. IT RAN PERFECTLY! I even got a dark brown and black plug, no soot on it! I was most interested in getting the bike running, so multiple things were changed. I also ran 1/2 trick 114 race gas, 1/2 91 Octane pump gas. Next time I practice I will run pump only. I think it was the CDI, but I had to swap, so I don't have the old one for debugging.

On another note for CO riders, I really have to recommend the dealer Twin Peaks who took care of me on the carb and CDI swap. I had been going to Colorado Powersports (who I had bought several bikes from before), but they did not go out of their way for me like Twin Peaks did with the swaps. I bought my 426 mail order, so my leverage was not as good with either dealer, yet Twin Peaks came through. I am going to buy WR250F from Twin Peaks, you can count on those guys!

  • ACS

Posted January 15, 2001 - 06:00 PM

#74

My $$$ wort is that it is a CDI problem. In late 70's Suzuki PE's had bad CDI's and coils and they did the same, cough a lot foul plugs, then die. New coils in lower end fixed the problem each time. Honda XR250 around 84 did the same but that was the plug connections between the coils and the CDI. Bit of water and they would play up and foul plugs and then die. Clean the terminals and it would run. I solved that problem with silicone grease (electrical grease) to waterproof the connections. Recently two friends bikes were doing similar things. Loose CDI connection on a 99 Honda CR80 and Kawasiki KX125 was the same, fouled plugs then no spark, new plug it would run then die later.

Hint to me was the low ohm reading off one of the coils, a dirty connection or water in poor insulation can knock a CDI out. In USA i gather its cold and wet, here in Australia its hot and dry. 2001 YZ426's are running well.

I'd put money on poor insulation / insulation breakdown somewhere in the wiring.

  • Taffy

Posted January 16, 2001 - 10:33 PM

#75

my hunch was that we had all mucked with the jetting but obviously it happens with standard bikes as well. why do we all fit a larger pilot jet? i was having no problems except that it took three or four kicks to start. so why didn't i look at the STARTER JET. the book says the pilot jet works at 1/8 throttle!!

my bike only tried to start when i swapped CDI's. it now runs on my standard one again. it first played up on a bitterly cold day...

could it be a connector when we all jet wash the bikes?

i've also mentioned the chance of a low coil output before. if you have a low voltage output the spark can't jump the gap. it gives a sooty reading. you can jet down but then the bike runs like s*** for a different reason.

do NGK make tthe gold palladium plugs to suit this model?

Taffy

  • blbainb

Posted January 16, 2001 - 06:48 PM

#76

I've replaced the '01 cdi back into the '01 426 and it does seem to run richer for a few minutes after I start riding. So I think the CDI does contribute to the problem. Everything else was the same so certainly the cdi is a major contributor. It could be that some other component is acting in concert with the cdi to aggravate the situation but trying to tie down 2 components would be tough. I did check all the electrical aspects of the bike and everything is fine except for 2 minor details: the primary coil resistance is 0.7 ohms instead of 0.2 to 0.3 and the TPS resistance is a bit higher than it should be. Both are probably not problems and the first could be due to the difficulty of measuring low resistance values. The TPS resistance at idle is supposed to be 1k to 2k ohms and mine was a bit higher than 1k but then the manual goes on to state that if the tps is replaced then the idle should be adjusted to 624 to 720 ohms. Again, probably not a big deal. Voltage input to the TPS was exactly 5.00 volts, as specified.

In looking over the carb specs and comparing them to the '00 carb, everything is identicle except for the needle. The '01 needle is 2 steps richer than the '00. Why? Except for the Ti valves and accel diaphram the top ends are essentially the same. Why put more gas into the motor in the mid range? I think it is related to the stumble that occurred in the '00 bikes when rapidly opening the throttle but I can't say with certainty. Also, I've noticed that the bike seems to use much more gas than the '00.
What I will do now is move the clip up two notches to 2/7 and order the next 2 leaner needles. If we have black plugs now, in winter conditions, what will happen when temps reach 95F? I see a mountain of fouled plugs in my future. I don't think a main jet change will do it as my plugs show a white insulator after performing a full throttle run/shut off.
At this point I think it's a combination of a borderline CDI and a too-rich needle. Yeah, and this thread is getting a bit long - time for a new one (to reduce load times).

  • James_Dean

Posted January 16, 2001 - 10:29 PM

#77

blbainb,

I aggree with you on the overly rich needle for the '01. The way Yamaha went richer on BOTH the clip and the diameter was a surprise. Probably clip #3 would be better for most '01 YZ426's.

  • Taffy

Posted January 17, 2001 - 02:00 AM

#78

JD

i've still got my EKP from last summer. but my bike runs well on the DXM (clip 4/5) how do i get to the EKP. they are hardly on the same chart at quarter throttle?

Taffy

agree about the new post

  • James_Dean

Posted January 17, 2001 - 09:11 AM

#79

Taffy,

Suggest you try:
EKP#4
#45 pilot
1 1/2 turns out on pilot screw
#100 pilot air
#165 main

(Similar to Hick's jetting above)

I also use a #48 and 1 turn out.
------

You had mentioned something that concerns me though. At one point were you running a #45 with the pilot screw bottomed?? There had to be something wrong if this was the case.

When you tried the EKP before there was some hesitation to the response. During the summer I had recommended EKP clip #3, being cautious not to cause plug fouling in my Thumpertalk friends' bikes. Leaner jetting for warm temps. (UNLIKE YAMAHA THAT CHOSE TO USE 1 1/2 CLIPS RICHER - EJP#4 :D )

The EKP clip #4 recommended now will be less likely to hesitate but richer. This will be close to DXM#5 and will crossover from leaner to richer at 1/4 throttle.

----------------

There is a limited range of clip position that will work best. Production tolerances should err on the side of lean, not rich. After testing many combinations last summer, my conclusion was EKP#5 and EJP#4 are just too rich to gamble with the risk of plug fouling. :) Better stay with EKR#4, EKP#4 or EJP#3. The comments above reaffirm this.

James

  • blbainb

Posted January 17, 2001 - 08:33 PM

#80

It looks like no needles will be availabe for the '01 until April so I have to hold off on trying leaner needles. However, the district Yamaha rep has suggested trying a different diaphram for the accel pump (which turns out to be one for the '00 model). So I've returned the stock needle to 4/7 (162 main, 45 pilot) and have installed the supposedly leaner diaphram in the accel pump housing.

Comparing the two side-by-side it appears that the metal post in the center of the diaphram is shorter on the replacement. This could mean that either the plunger doesn't contact the post until further in the stroke (which would mean less fuel until the throttle is rotated further) or that the diaphram can deflect further before bottoming out (which would mean more fuel). I assume the former but who knows?

Anyway, I'll try it out on Friday and see what happens. Nightmare on Elm Street XV.





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