yz426F wont start, Help!!


30 replies to this topic
  • yeti stever

Posted October 06, 2007 - 10:27 PM

#1

i have a 2000 yz426F that wont start its my firts four stroke dirt bike so im a lil un shure, its got sparki cleand the carb and it had nothing viibly wrong with it and every thing but just backfires and it will only back fire if i crank the throttlel up a few times and get gas in with accelorator pump it has me totaly lost so please help me out thanks:cry:

  • Yamaha4lyfe

Posted October 06, 2007 - 10:32 PM

#2

check the valves!

if they are very very tight, it will run bad. and will be close to imposible to start

umm check your jetting, you said its got spark?

  • yeti stever

Posted October 06, 2007 - 10:43 PM

#3

ya its got spark hot the greatist but still way better than my kx and you say check if teh valves are tight? what do you mean buy this im new to the four stoke dirt bikes i had the valve cover off and the timing chain seemd prity tight but was not shure of corect tension for it but il chek the valve gap withe a feeler gauge and see if its corect to the specks, thanks

  • 1rkcooper

Posted October 07, 2007 - 05:55 AM

#4

At the top of the YZ forum is a sticky with common thread in it. At the bottom of that page is a couple of links to starting procedures. If you don't have a manual there is also a link in there for manuals. Check all the info in the sticky.
Where in BC are you?

  • grayracer513

Posted October 07, 2007 - 07:34 AM

#5

First, put a fresh plug in it. Then watch the videos at the link cooper mentioned before you try it again.

  • yeti stever

Posted October 07, 2007 - 10:35 AM

#6

okay i tryd the links and i have bine finding the compresion stroke then using the decomp lever and folowing procedure evin instald a new plug still dose the same thing geting nothing out of it but back fires when i crank the acelorator pump and i have not got it to fire in the chamber once yet or do any thing that turns the motor, it back fires out the exhast and some time s the carb and the valves all apear to be working when i hade the valve cover off, and 1rkcooper i live in langley BC, thanks for the help

  • shawnspawn

Posted October 07, 2007 - 04:11 PM

#7

Rule #1 really make sure you are following the start-up procedure exactly.
Rule #2 don't touch the throttle, ever...
Rule #3 If nothing is working, I hold in the decomp lever and kick it 5 or more times just to clear the engine out and then try again.

also, I always choke when first starting. I rarely use the hot start, unless I drop it or flood it.

I just got my 02 426 this summer and can start it 1st or second kick now. But before I knew what to do there were some times where I could not start it at all. I can usually start my bike faster than my Bro-in-law's 03 450 but I think I would like his auto decomp cam just for the bump starting.

  • maxx2200

Posted October 08, 2007 - 08:45 AM

#8

This may be a stupid question but here it goes... You mentioned this bike was new to you, has it ever ran? Have you ever gotten it started? If so, follow the recommendations from the other posts. Watch the starting procedire video. Make sure you have fuel flow.

  • 1rkcooper

Posted October 08, 2007 - 05:42 PM

#9

Yeti Stever
I would check the timing and make sure it is correct. Also check the valve clearances to ensure they are correct. If they are correct, you have fuel and spark, you follow the starting procedure the bike should start.
Langley is too far away, I'm in the Okanagan.


Shawnspawn
Spend the $$$ and get the YZ450 cam and install it, It is by far the absolute best mod you can do. I finally put it in my WR400 this spring and there are far more advantages besides it starting like a 2 stroke and bump starting, the bike is far more forgiving than it was before. It is simple to do, just do it.

  • yeti stever

Posted October 08, 2007 - 07:03 PM

#10

ther was oil in the fly wheel cover that was mixed with gas how could this have happend it did spend a winter out side in penticton with the gas valve posibly open and the gas in side smelld relay bad but i clenad the carb i have no history on the biek cause it was reposesd in some police thing, think the gass may have run though the rings and washd out all the oil coting the cylender and that my be my problem woudl that be possible ? peace thanks
ya i just got the bike and want t to get it going befor i put parts on it and see if i evin like it over my 97 kx,

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  • yeti stever

Posted October 08, 2007 - 07:07 PM

#11

ther is not sopsosed to be oil in the stator area is thier? and what do you mean buy the valve clearances? its runig straight off the cams with no ajusters that i can see or are the vave clearances difrent than the valve gap ? peace thanks

  • grayracer513

Posted October 08, 2007 - 08:40 PM

#12

ther is not sopsosed to be oil in the stator area is thier? and what do you mean buy the valve clearances? its runig straight off the cams with no ajusters that i can see or are the vave clearances difrent than the valve gap ? peace thanks

Yes, oil belongs there. Gas gets in it when people leave the gas on for long periods.

Read:

http://motoman393.th...ech/valves.html

http://www.thumperfaq.com/valves.htm

http://www.yamahaown...ook.com.au/?r=0

  • yeti stever

Posted October 09, 2007 - 02:41 PM

#13

okay thanks alot il go do that

  • 1rkcooper

Posted October 09, 2007 - 07:45 PM

#14

At the top of the Yz forum is a stickyfor common threads. Find this and look through this page. There is a ton of useful info for you in there. Grayracer is a wealth of info and help, be sure to check everything he directs you to.

  • yeti stever

Posted October 09, 2007 - 09:28 PM

#15

okay i checkd the valve clearences and they wher all fine and iv done every thing els i inc an think of and used the correct starting prosess and still have not got any thing out of the bike so guss il have to get it taken to the shop and have em fix it, but thanks for all the help peace

  • gsk1968

Posted October 16, 2007 - 06:43 PM

#16

I first got my 01 426 and thought i had made the biggest mistake in my moto life. I kicked the crap out of it. It looks like you have tried alot and forgive me if I mention repeats. Try to back the idle screw out watching your throttle,when the trottle stops, then turn it back in aprox 3 turns. only twist the thottle one time before kicking and dont touch it, put your hand on the brake resevor. Try pulling the choke and the hot start at the same time.
If you have new jets, new gas, new plug, and good spark, she should fire.
Slowly kick til it stops, pull the decomp, and only kick 1" more (1" not 2")
let out the decomp, let kick starter back to top, then kick it all the way through. oh yea, don't touch the thottle. Thanks to good TT info, I am starting 1 or 2 kicks now. If flooded, pull hot start & hold in decompress for 10quick full kicks as mentioned earlier.

  • yeti stever

Posted October 16, 2007 - 09:48 PM

#17

okay il try the idel ajust and see if that works and try that starting proceder again , thanks for all the help with this thing hope i get it working cause i was hoping it would be easyer than my kx but it being a bit of a pain , it is a good idea to replace all the jets on the carb ? peace thanks.

  • chadta

Posted October 17, 2007 - 09:00 AM

#18

ther was oil in the fly wheel cover that was mixed with gas how could this have happend it did spend a winter out side in penticton with the gas valve posibly open and the gas in side smelld relay bad but i clenad the carb i have no history on the biek cause it was reposesd in some police thing, think the gass may have run though the rings and washd out all the oil coting the cylender and that my be my problem woudl that be possible ? peace thanks
ya i just got the bike and want t to get it going befor i put parts on it and see if i evin like it over my 97 kx,


did you drain the gas and put new stuff in ? if its sat long enough for gas to drain into the motor your gas is probally stale.

and as everybody else says, find the hard spot , hit the decomp, move 1 inch, back to the top and kick right through, i stand on the curb and do mine cuz ya have to make sure to get full kick, and as mentioned many many times do not touch the gas. I use choke and get it 1st or 2nd kick all the time now.

  • todds924

Posted October 17, 2007 - 03:18 PM

#19

okay i checkd the valve clearences and they wher all fine and iv done every thing els i inc an think of and used the correct starting prosess and still have not got any thing out of the bike so guss il have to get it taken to the shop and have em fix it, but thanks for all the help peace


My guess is that you only THINK you cleaned the carburtetor. With the bad gas now- adays it doesn't take long for a pilot jet to get plugged up, also the leak jet. Remember, these are very very small holes. If your pilot jet is plugged up the thing will probably never start. I would do a thourough carb cleaning the PROPER way and if like you say, the valves have the proper clearance, the thing should run.

  • shawnspawn

Posted October 20, 2007 - 10:55 PM

#20

Yeti is that your add in craigslist? giving up on the 426?

Oh well, btw there are some nice bikes to be had at International Motorsports. I just looked at their add yesturday and there was quite a few 250f and 450f bikes to be had at nice prices...

and no I don't work there I just thought you would like to know.





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