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Plusdome

YZ426 frustration, Dirty carb??

26 posts in this topic

I'd like to think I'm pretty proficient with the search option but I couldn't find anything quite like this. So a little background I just picked up a 2000 yz426 it looks like a 2000 leftover no scratches on the cases no paint off the frame and chalk marks on the tires the bike had been stored for around four years after being ridden "5 times" the gas in the tank was drained for storage but fuel was left in the carb the guy says he cleaned out the carb and when i removed the bowl there was no trash or residue. The bike has hinson clutch components a white bros head pipe and e series exhaust.

Now the problem, I meet the seller get on the bike and use the standard starting technique recommended by yamaha /most posts I had read here to my suprise it started on the first kick. I pay the guy get the bike home and warm it up run it up and down the alley behind my house it ran great. The next morning i was going to go riding I try to start it and nothing so after working up a sweat i decide the plug is probably fouled. I go get another plug pull the old one (it was sooted up) I'd been kicking/pulling the plug for almost a day with nothing more than a 2 second idle before cutting off. A good friend of mine shows up and kicks it once it fires and runs!! he hits the engine stop button and says"so whats your problem" well he soon learned as we have not been able to get it running again even after replacing the plug. The only thing i have changed is the idle setting after reading posts about the idle affecting starting but I've tried starting at many idle positions and i would think that it would still start as long as the idle is somewhere close. I've checked the spark and its there and its getting fuel.

I love the bike its the cleanest 2000 I think I've ever seen but I'd rather be getting it dirty instead of looking at it sitting on a stand......any suggestions??? :)

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Make sure you hand is off the throttle so you dont twist it at all while kicking.

Check your fuel screw position, it should be at about 1 1/2 turns out from lightly seated.

Try clearing it out, hold the throttle wide open, with the compersion reliese in, and kick it about 20 times. Then go back to the normal satrting procedure.

Kick it all the way through the stroke , speed is not the key, but a good strong kick all the way through is, Get it to top dead center, and kick it good.

If your gettin spark, gettin fuel, gettin air, she should fire.

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I would say welcome to the club man. Mine would run but I had to keep it running and it was popping alot. My FMF system and air tract was all really free flowing but the jets in it were all stock. I got to learn alot about how to jet the thing (02 wr426) and I got alot of the help from FMF before finding out about this site. Now I'm dealing with the accellerator pump for just off idle issues but otherwise it rips.

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Thanks a lot for the prompt answers I just saw that it has a p-38 which I'm not real familiar with could that have anything to do with it?? As for the throttle while starting I began putting my hand on the brake reservoir just to be safe, the throttle open clearing you suggest sounds promising I have the day off tommorrow and i plan on getting this bastard running by sundown I had planned on riding but o well. Its looks so weird torn down in my apartment kitchen/garage its so clean that even under all the plastic there's no mud/dirt on the frame anywhere just collected dust, what a waste. I wonder if gasoline is good for hardwood floors??? :)

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After you have turned the idle screw to 1 1/2 turns out try this -

1.Pull out the hotstart.

2.Pull and hold the decomp in.

3.Hold killswitch in.

4.No throttle, kick through 20 or so times.

5.Release decomp and killswitch, push hotstart back in.

6.Pull choke out.

7.Kick through to TDC.

8.Pull decomp and kick one inch past TDC.

9.Release decomp and kick all the way through.

If it doesn't fire within four kicks (ie steps 7-9), push the choke back in and repeat 7-9 without choke.

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Thanks bucky, I just got a PM about checking the valves the guy said if the valves are tight it would be a hard start no matter what. But how would the valves tighten in like 20 mins while not running?? I'm not saying that they aren't off but is it possible for valves to cause on again off again problems if so I've never seen it happen. Either way they probably need to be adjusted as this bike has barely been broken in and I would estimate it has under 50 miles on it. Thanks everybody for the replys, earlier today I was ready to commit a murder suicide involving the bike and myself:mad: If I can work up the courage to try my first valve check/job on a "modern" 4-stroke tomorrow I'll let everyone know what I find out. I work at a shop so I may offer some beer to a tech to babysit me while I do it who knows maybe I'll learn something. I've adjusted valves on xr's and raptors before but never on an engine like this to be honest I'm a little scared......

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Valve clearances should not cause on/off type problems, but, they will need adjusting after the break in period. Once the valves have seated themselves, then adjustments will not be required so regularly. However, I'd be surprised if the clearances are so far out to be causing you severe starting problems.

Checking the clearances is a simple job.

Pull off the tank, the cam cover and the flywheel cover. Turn the flywheel with a socket until you see the 'I' through the viewing hole. Stick feeler guages under the cam lobes and measure the gaps. Too easy.

They will tighten. From memory, exhaust should be 0.25-0.3mm and intake 0.15-0.20.

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Checking valves will not solve your problem, it is a blue bike and does not need any low hour valve adjustments.

When being careful not to touch the throttle while kicking it, did you give any throttle blips at all before kicks? Sounds to me it does not get fuel and therefore won't run. When I had my 426 I was a master to get it running and often had to help out others.

Engine hot, give it air (hotstart) and no gas. You may need to ventilate it as yzfmxer described.

Engine cold, tip over the bike till you see fuel dripping from carb hoses, then give 2-3 blips, choke on, hand off the throttle, max. 5 good kicks, if not starting then choke off and hotstart on, kick again several times before you go back to choke and perhaps one more blip. Remember, when you pull the decomp lever at TDC, all you need to get the piston past it is one millimeter to change the piston direction. Let off the decomp and bring the kickstart back up and give a solid kick-thru.

You will find the way to fire it up. When you get familiar with it and after some good riding it suddenly won't start and gives only pops, time to throw in a new spark plug again. Good luck. :)

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I'd been kicking/pulling the plug for almost a day with nothing more than a 2 second idle before cutting off. A good friend of mine shows up and kicks it once it fires and runs!! he hits the engine stop button and says"so whats your problem" QUOTE]

Your friend just accidentally gave it a blip precisely at right time when kicking.

Believe me, you're not giving it gas it needs to fire up!

:)

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Try putting in a auto decompression cam in it and a power now That will fix the pain in the ass starting no more trix just kick and go riding :) that's one kick :)

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I pulled the carb today and the idle jet was clogged. I removed all the jets and accelerator cover and doused it with carb cleaner blew it all off. I then looked at the fuel screw it was 2 1/2 turns out!! I changed it to 1 1/4 turns out and put everything back together.

I then proceeded to kick till my face was blue changed the plug and tried again thinking I was going to kill myself I sat down and took a break reading the manual preparing for a valve check/shim. Getting my wits about me I pulled the decomp lever pumped through like 20 times, boom a blue flame shoots out of the pipe. I find TDC kick it like I mean it and viola instant start I had forgotten how bad ass it sounds I took some high speed spins across the parking lot(the first I had been able to do) and it was all worth it. THIS THING IS A HOSS it pulls like crazy and I can tell once we get to know each other we'll get along just great. To anyone with a "new to them" 426 be patient and learn what the bike wants with the cleaned out carb the starting procedure yzfmxr and bucky suggested :)IS SPOT ON:) . Having just come of xr's and older 2-strokes I feel like I'm going to do a backflip everytime I blip the throttle and I'm smiling from ear to ear

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I did the BK mod on my 426 and it helped out ALOT!!

I would use the P38 and the BK mod.

DO a serch for the BK mod, you will find everything you need to know about it and how to do it. :)

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Cool, let us know how it goes for the next few rides. Interested to hear if you have any more troubles.

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I've already got the P-38.....and for all I know it works great because from the test runs I did today there is no stumble down low. It's a shame its not somewhere else on the bike as it is a nice little piece of billet :)

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Bucky I took the bike out today for about two hours I stalled it twice and it started first kick with hotstart out both times, and it started on the second kick when cold. I must say that the initial frustration I felt with the bike dissappeared within seconds of the start of my ride, it has power everywhere kind of like a two stroke powerband at all RPM's. I would pick the wrong gear and it would still pull I don't care how finicky the bike is when shes running right I have to :) BOW DOWN :)

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Well I know I'm coming in after the fact, but I empathize with you because I had the exact same problem with my 2000 426 just after I bought it. I cleaned the carb and found that the idle choke clogged. Once that was cleaned out, she now starts so easily everytime! I love it. She sounds tough and she pulls like mad.

Just drain the float bowl after each ride and I doubt you'll have any problems in the future. They're bullet proof!

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My buddy is riding a 2000 wr400 at the moment. I've started it a few times and that has taken me a few more kicks than my 426. Maybe it's because I'm not used to the bike. The 426 takes a good long kick, but the 400 seems to have a shorter stroke. I also live in a mild climate, so that probably helps me out - no jetting troubles.

Great to hear you got it going quickly, plusdome. Sounds like you had a good day. I went out too. Rode trails for about 4 hours, going fairly hard...well, fast enough for me. All sorts of terrain and it only used 2/3 of a tank. Not bad I reckon - we probably covered 70kms.

Had two big get offs. Went over the bars going slowly down a ledge and the bloody big thing landed on top of me - pinned me face down in the ground! Luckily, had a pack on with a two litre water bottle in it which saved my back. Went over the bars again in third or fourth gear. Too quickly over rocks, wrong line, ouch. Mild concussion I think. All good though!!

Get into it. Keep ontop of the oil changes and hopefully she'll serve you well.

:)

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All good answer

I will add a few items to the list

The Dril Learn it, love it, Sleep with it and most of all kill anyone who twists that GRIP :)

The GBmod GBmod Explained Thanks Garrett

2001 Clutch Fix 2001 Clutch Fix for 2000 426

And last but not least the EPJ needle fromt he 2001 426 5JG-14916-JP-00 .NEEDLE (#EJP) STD(5JG5) this will help lean the mid out and give you a bigger hit in mid when the bike hits the cam :)

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