WR400 hard starting


27 replies to this topic
  • Skidad

Posted October 01, 2007 - 05:47 AM

#1

I think the wr400 is a 2000 model it's not mine it's my brothers
he told me it's very hard to start . bike is like new and stock.
he would like to sell,but we need to get running.Is it a carb
problem like jet ,needle ?

  • matt4x4

Posted October 01, 2007 - 06:04 AM

#2

That's rather strange - usually, starting is never an issue if you have it figured out right.
What's your/his starting procedure?
NEVER touch the throttle - matter of fact, place your right hand on the tank, don't bother with the choke unless it's below 10C out, decompression lever through the comp stroke, release and kick it like you mean it - should fire right up.

  • Skidad

Posted October 01, 2007 - 06:44 AM

#3

Bike has not been started in a few years so will the carb need to come apart and be cleaned? Obviously drain bowl and use very fresh gas. TOTALLY stock bike and like new. Were there any needed jetting changes necessary to make them run better?

Bike has always been hard to start. What is the best starting pocedure for firing it up?

Thanks,

Skidad

  • matt4x4

Posted October 01, 2007 - 07:09 AM

#4

How was it stored?
If it was stored w/o gas in it, everything drained, then it should be good to go, however, if bad gas is in it, you'll need to drain it all out remove the varnish buildup in the carb - might want to dissaseemble the carb B/C if it sat very long, it could have some serious buildup. Carb cleaner works well for breaking up the varnish.

Since it hasn't been fired in a year plus, you may want to make sure your valves aren't stuck open, to test for that, kick it over without the decomp lever, if it kicks over without any real resistance, your valves are likely stuck open, remove sparkplug, pour 1 capfull of oil down the hole into the cylinder, put the plug back in and repeatedly kick it over, the oil should work the valves loose pretty quick and you'll get compression back.

Starting procedure I wrote up top is probably the best for a WR400, at least it works fine for my needs. - here's a more detailed version
I haven't had to use the choke on my bike yet (warmer temps), my way is:

I put bike in Neutral, turn on fuel, perch myself on the footpegs, place right hand on tank, (NO THROTTLE) pull about 1/3 down on decomp lever, keeping clutch pulled in, kick it over slowly, to feel compression stroke, once I'm TDC, I release the kick start, release the decomp lever, then kick it thru real hard - one smooth motion - follow all the way through til you bottom on the footpeg and it should fire.
If you can't get it through because of hitting the comp stroke again, another way that'll work is to keep a little pressure on the decomp lever, (less than 1/3 pull) and at the end of your kick, release the decomp lever and it'll catch - my kid does it that way because he doesn't have the strength to do it without using the decomp lever, but he's only 8 so I give him kudos for even getting it started.
Of course all he ever wants to do it ride it after starting it, I just point to his kx65.....he argues that if he can start it he should get to ride it.....

  • Renas

Posted October 02, 2007 - 04:25 AM

#5

Hi guys,

as the topic is similar to mine, I will not be starting new thread, ok Skidad? I have 2001 WR400F. I have been searching the forum for two days and haven't managed to find the proper answer to my problem.

So I have the same problem it's very hard to start it cold. Good thing though that it's uber-easy to start when it's hot:) Half kick and she runs like a dream.

I have cleaned air filter and checked spark plug. The problem is that I have to kick it 10-20 minutes, then it starts... but only with hot start plug pulled and only if I mange to catch and open throttle after a split of second it shows sign of starting. It's quite hard to explain, but procedure goes like:
- 5-8 kicks, no choke out, no hot start plug out. No sign of engine is going to start
- red button (hot start) button out
- 3-4 kicks, something blurbs, seams like it wanted to start
- gasoline starts to smell
- few more kicks, it "grabs" but no start
- again a few kicks and when it grabs quick throttle opening and if I'm lucky engine is on.
- works but not evenly, strong gasoline smell from exhaust

As I mentioned, hot start is a dream, half kick and engine is on. When riding, throttle is sharp, no lag, no dips, everything is smooth and steady.

I'm sure that something wrong with the mixture, as I'm using hot start plug which leans it up. Tried to screw in pilot screw - not much difference.

Can anyone explain what happening? Was it common problem (too rich mixture when cold) for 2001 WR400F model? Any advice? Is it fuel pump related?

Thanks for any help!

  • matt4x4

Posted October 02, 2007 - 08:23 AM

#6

Hi Renas,
First - what would your ambient temperatures be in Lithuania? - I just checked the weather there, with 12 celcius I'd be using the choke.....
I noticed you don't use the choke at all - have you tried with the choke?
I also noticed a bit of a conflict in what you're doing, first you seem to need to use the hot start to help lean it out, however, you're smelling gas, meaning it's flooding and probably really rick, and you're in need of grabbing the throttle adding even more gas, so I'm just wondering at why the need for the hot start button?
I've noticed one thing common on these bikes, even the smallest movement of the throttle while kicking it makes it harder to start the bike - by smallest - I mean even if you think your hand didn't move, so have you tried starting it with placing your right hand on the gas tank?
Also - your decomp lever - how are you working it during your starting procedure? If you're pulling it while kicking the bike, it'll probably never start, maybe your finger is fatiguing towards the end of your starting procedure to the point where it finally gets enough compression to fire.
You've cleaned the plug, but do you know how old it is? Have you tried replacing it?
Once you do get it started, how is the idle?
It just seems that if your bike runs good and strong outside of starting and there are no noticeable problems with acceleration or any excessive bogging, that your carb is likely adjusted correctly and the problem is in your starting procedure.

  • ccoates445

Posted October 02, 2007 - 04:25 PM

#7

If it's truely a stuck valve problem, the capfull of oil trick won't do squat for you. But it does help coat the rings and bring back enough compression to start the beast. In the future, if you store the bike for long periods of time, make sure the piston is at TDC as that will keep the valve springs from being collapsed for too long. Also, drain the fuel as that can be the culprit washing the cylinder oil coating down and thus dropping compression.

  • 1rkcooper

Posted October 02, 2007 - 05:02 PM

#8

Try starting different ways on different days. Eventually you will find what works the best for how the bike is set up. If my 400 hasn't been started today, I give it two twists of the throttle, pull the choke out and it fires on the first kick every time. It also fires usually first kick but always within three kicks when warm, two kicks and if it hasn't started I pull the hot start and away it goes.
Do you have stock cams in still or have you done the auto decompression mod? Here is a link to starting with stock cams, there is no system with the mod done, just kick like a two stroke.

Part 1: (Cold Start) http://www.yamaha-mo....roke_vid_a.mpg

Part 2: (Hot Start) http://www.yamaha-mo....roke_vid_b.mpg

  • C-P

Posted October 02, 2007 - 07:44 PM

#9

:confused: linkies no worky...

These old 400's should start no prob. I 2nd that you twist the throttle 2-3X prior to kicking to squirt a little gas in the carb.

Lately, when cold I kick the thing over a couple times with decomp lever in to get some oil moving. Then, as described a bajillion times around here:

kick to the point that it's really HARD to push. THEN, squeeze decomp lever and move kick lever just just a hair (about 10 degrees?) to get past comp stroke. Then, no decomp lever, just a good full kick from top to bottom. Try with no choke first, add choke if not works. My '98 is usually a one kick start hot or cold with the piston in the right place. I can start the thing in my bunny slippers, too.

On that bike that hasn't run in years...a new plug wouldn't hurt? Or just sell it here cheap. We'll take it from there.

  • Renas

Posted October 02, 2007 - 11:17 PM

#10

Hi Renas,
First - what would your ambient temperatures be in Lithuania? - I just checked the weather there, with 12 celcius I'd be using the choke.....
I noticed you don't use the choke at all - have you tried with the choke?
I also noticed a bit of a conflict in what you're doing, first you seem to need to use the hot start to help lean it out, however, you're smelling gas, meaning it's flooding and probably really rick, and you're in need of grabbing the throttle adding even more gas, so I'm just wondering at why the need for the hot start button?
I've noticed one thing common on these bikes, even the smallest movement of the throttle while kicking it makes it harder to start the bike - by smallest - I mean even if you think your hand didn't move, so have you tried starting it with placing your right hand on the gas tank?
Also - your decomp lever - how are you working it during your starting procedure? If you're pulling it while kicking the bike, it'll probably never start, maybe your finger is fatiguing towards the end of your starting procedure to the point where it finally gets enough compression to fire.
You've cleaned the plug, but do you know how old it is? Have you tried replacing it?
Once you do get it started, how is the idle?
It just seems that if your bike runs good and strong outside of starting and there are no noticeable problems with acceleration or any excessive bogging, that your carb is likely adjusted correctly and the problem is in your starting procedure.


Hi matt4x4,

Thanks for the answer! Yes, temperature is around 10-12 C at the moment:) Answering other your questions:

I noticed you don't use the choke at all - have you tried with the choke?

- I don't use choke as it's not possible to start engine at all with it pulled out. Gasoline smells even worse, no signs/sounds of engine is even going to start. Just dead kick and that's it. Pulling red knob and kicking a few times and it starts to sound like it's going to start. You can hear a few turns, but it's never like "don't touch the throttle it will idle". Never.

I also noticed a bit of a conflict in what you're doing, first you seem to need to use the hot start to help lean it out, however, you're smelling gas, meaning it's flooding and probably really rich, and you're in need of grabbing the throttle adding even more gas, so I'm just wondering at why the need for the hot start button?

- As far as I understand when throttle is opened more mixture goes to the engine, though it's not related with rich or lean, mixture is predefined and leaned by red knob. I just raise revs and give more mixture to start it. Otherwise engine dies after few turns if throttle is not opened.

I've noticed one thing common on these bikes, even the smallest movement of the throttle while kicking it makes it harder to start the bike - by smallest - I mean even if you think your hand didn't move, so have you tried starting it with placing your right hand on the gas tank?

- No, I haven't, but I don't believe that it's a cause of the problem :confused:

Also - your decomp lever - how are you working it during your starting procedure? If you're pulling it while kicking the bike, it'll probably never start, maybe your finger is fatiguing towards the end of your starting procedure to the point where it finally gets enough compression to fire.

- No, just standard procedure from the manual. Some kicks till i find TDC, decomp lever, pas through TDC, release kick, full kick. As I mentioned it's possible to start the beast when it's hot even kicking half way! :confused:

You've cleaned the plug, but do you know how old it is? Have you tried replacing it?

- No, and this is the first thing I will do. I haven't checked it and haven't changed it since I bought the bike. (1000 km off-road, not that much riding this year...)

Once you do get it started, how is the idle?

- When hot, runs even as a clock. When cold need to throttle it for 30-40 sec. As it tries to stall, gas smell, uneven on low revs.

Thanks for helping me out! :confused:

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  • matt4x4

Posted October 03, 2007 - 03:38 AM

#11

Well, with 10-12 degrees, i really would recommend using the choke...
it also sounds like your engine wants the choke - dying out unless you give it some throttle for 30-40 seconds definitely tells me it'll at least run without throttle if the choke were pulled.
I'd try what Rabbitracer suggests, with the choke out, because I think you're running into a dilemma with the no gas to start but needs gas to keep running thing here, I can see it being really hard to use NO gas to get it fired, then jump on the gas as soon as you hear one fire - kinda hard to do, the choke shouls alleviate that issue by keeping it running as soon as it fires.

Oh, BTW - here's something else I found - believe it or not (this is kinda funny actually), when I got my bike and was still working through finding the best starting procedure, I'd be all geared up, kicking and kicking, I'd get hot, rip the helmet off, set it aside, get back on, kick it ONCE and it'd run (EVERY TIME :confused: ) so now, I don't put my helmet on until it's running and it only ever takes 1 or 2 kicks.

............So maybe it's just that you're wearing a helmet while kicking it!

  • 1rkcooper

Posted October 03, 2007 - 04:42 PM

#12

Try starting different ways on different days. Eventually you will find what works the best for how the bike is set up. If my 400 hasn't been started today, I give it two twists of the throttle, pull the choke out and it fires on the first kick every time. It also fires usually first kick but always within three kicks when warm, two kicks and if it hasn't started I pull the hot start and away it goes.
Do you have stock cams in still or have you done the auto decompression mod? Here is a link to starting with stock cams, there is no system with the mod done, just kick like a two stroke.

Part 1: (Cold Start) http://www.yamaha-mo....roke_vid_a.mpg

Part 2: (Hot Start) http://www.yamaha-mo....roke_vid_b.mpg



Interesting that these don't work from my post.
Go to the yz forum and at the top of the page is a sticky with common threads, open this and go to the bottom of the page and there they are, and they work, I checked.

  • Dan_from_HB

Posted October 04, 2007 - 02:21 PM

#13

Starting was an issue with some people. Here in Socal, with my own 2000 WR400F, starting was never a problem stone stock between 0 feet and 3500 feet elevation. It became a problem when I jetted it to run better, until I got it right. Runs like a striped ape when its jetted right for altitude and temperature, with needle changes and jet changes per JD specifications and spreadsheet. While you are working out jetting changes, it can be a bear. The JD kit will help tremendously.

I suspect your problem, if it's truly stone stock, is that the carb needs cleaning. You might also check the bare areas on the frame where the coil grounds to the chassis. If they become sufficiently rusty, you can have an ignition problem. Also, make sure your carb slide is all the way down to a low idle position, else it's just like opening the throttle. It won't start and could kick back and damage some kickstart components under the side cover. Pay particular attention to the idle jet and fuel screw position when you clean the carb. Be prepared for an hour-long project, at least. The subframe and airbox boot usually need to come mostly off the bike. Also, check both throttle cables while it's apart. The return cable sometimes frays. Put in a new plug, and it should fire quickly.

  • SDBSKI

Posted October 04, 2007 - 07:11 PM

#14

Check the pilot screw setting. You can adjust to the factory setting initially but it has to be fine tuned while running after you get it started and warmed up. It's the small screw at the bottom middle of the carb in the small hole. You will need a very small screwdriver to adjust it. Turn your idle down to minimum just above engine stalling. This way it is easier to hear the engine speed changes and adjust the pilot screw in and out until you get the highest RPM from the engine. This will be your correct idle mixture setting and will ease starting.
The engine should need the choke to cold start and no air valve. The idle setting should be high enough so it will come up to a high idle on it's own without having to open the throttle until after it starts and stabilizes.

  • rally2210

Posted October 07, 2007 - 04:02 AM

#15

I have a 99 400 which i buoght as a basket case, it had been sitting in a shed for nearly two years, gave it a restoration an now am having the exact same symtoms as described by Renas however i live in Western Australia a cold day here is 20 degrees celcius, i have a new ngk iridium plug code CR8EIX 4814. Actually checked it today after reading some threads in the tech section on jetting and it was quite sooty followed some advice posted changed the pilot screw and still only starts with the hot start lever pulled out. Is this damageing provided i push it back in quickly once the bike is running? Does it matter how it starts as long as it starts? Any way will keep trying different things and will keep yall posted on any results

  • Renas

Posted November 05, 2007 - 01:31 AM

#16

Hi guys,

Tried lot's of things, changed spark plug (plug was wet and black after some trying to start it). Still no luck starting it with choke out. In fact was not able to start anyway yesterday (after one month of no operation). Intense gas smell, even backfired a few times...

It looks like I should clean the carb. It would be great to find a step by step guide with photos. Anyone could help?

Thanks!

  • creeky

Posted November 05, 2007 - 06:36 AM

#17

I bought a pristine '00 WR400 from a buddy a few years ago, had starting & jetting problems. The cure was an Edelbrock carburetor, easy starting, no jetting hassles, better fuel economy, great power delivery. Not cheap, but very effective.

  • Rich_in_Orlando

Posted November 05, 2007 - 09:49 AM

#18

You gotta get in there and clean the carbs fully. Every nook and cranny. Then start it correctly using "the drill".

  • DanyR1

Posted November 05, 2007 - 02:45 PM

#19

Same probleme whit my 98 WR400 hard to start cold but half kick when it hot for start it. I have find a solution to my probleme I have put an EDELBROOKE carb and now cold start is 2 ou max 3 kicks....hot start half kick.
Best mod on my bike....now I love my bike.

  • Aion

Posted December 19, 2007 - 04:58 PM

#20

Renas,

Not sure if you have tackled your problem yet, but just in case want to share my experience with the bike which had exactly the same symptoms as yours of not wanting to start unless you pull out the hot start knob.

I have a 2000 WR400F which I have been riding for two seasons (from April till November). It is stock, no mods (apart from de-baffled muffler). It has never caused any problems to me as I serviced it regularly (usual stuff as per the manual). This month I disassembled part of the bike including the carb which apparently needed to be cleaned and checked. After putting the whole thing together the bike did not want to start either with choke on or off and only showed the signs of life if the hot start knob would be pulled out. This is in my garage where it is always hot due to the fact that the house heating equipment is there.

Anyways to cut the long story short, I tried all and everything to figure out what was causing the problem with no success, though. Finally, (having messed with the carb for a couple of weekends) I looked at all jets after I took the carb apart again and noticed that both main air jet and starter jet were almost of same size and had identical thread. The difference between the two, though, was that main air jet, as you can easily tell, has a much bigger hole in it (for air flow), whereas the starter jet has a tiny one (for fuel flow). I was stupid enough to misplace these two buggers and that had resulted in very rich mixture (less air intake and excess fuel). I swapped them aroud and, bingo, it runs sweet and steady again after you kick it just once.

I am not sure if you had disassembled your carb like I did, so maybe this is not your case.

Hope you have your bike alive again. Cheers.




 
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