Hey guys just bought a 426 was running gud. started 2nd kick almost every time.they guy i got it off said never been serviced in long time so i changed oil pug and filter..the bike was perfect put it back in the garage for a week got it out ..wont fire at all...it has a gud spark and fuel is gettin to the plug...any ideas ??

Sounds like the person who tried to repair it did not know what he was doing. I would take it to a person who has experience in these things.

same voltage as the batteries in series connection ( 12 volt batteries connected positive to negative is series and would be 24 volts
batteries connected positive to positive will be 12 volts

Hi, Anonymous you may have transmission-clutch-valve issues for this situation I would call my local dealer or reputable shop's service/parts department and inquire about any possible quick fix, answers, or parts inquiry. If necessary, transport your bike to the dealer or shop and have a professional technician take it for a test drive, if it is in running condition, and give you a written estimate of repairs and answer any specific questions you may have about your problem. For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
Yamaha YZ426F Owner Service Manual
OEM parts for Yamaha
Yamaha YZ450F Owner Manual Page 3
What are the top 5 mods to get for yz426f YZ 400 426 450
Yamaha YZ 426 FN 01

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

The setting of the ignition is too ADVANCED and so there is PREIGNITION. Perhaps this is done to have the engine respond well into higer RPM and so if there was backfiring only when the start was missed , I would suggest that you try out to start and if not you must get the bike tuned once again for fuel settings and ignition setttings including timing.

You can find PUK code from your service operator, just call them and find the PUK no. PUK no is genrally Coming up with SIM card at the time of purchasing. It is 16 digit no and you can find out through your service operator.

Gud luck

For a cold start, turn fuel on at fuel tap. Pull out the choke knob. slowly kick the kickstarter until you feel it become harder(more resistance). push past this resistance then release the kickstarter. What you have done is put the piston in the position just after top dead centre of the compression stroke.Now give it a big kick whilst opening the throttle slightly. There is a real techneque to it so don't think your the only one who has problems! Otherwise, ask your local Yammy dealer for a look at the owners manual. It has a description on how to both hot & cold start your bike. They may let you photocopy it. Good luck.
If it just isn't happening try removing the sparkplug,put it back in the plug cap,rest the plugs metal body on the cylinder head (don't hold it there or you could get a nasty shock) Now kick the kickstarter while watching the sparkplug gap. Did it spark? If it didn't theres a problem. No spark means it wont run! Then you'll need to find out why theres no spark. Hope this helps to get you started Otherwise let us know and i'll se what else I can suggest.

G'day TJP..OK...Lets concertrate on starting procedure.Bring the piston up on the compression stroke , you will feel the kickstarter offering resistance.Pull in the decomp lever and bring slight pressure on your kicking leg,you only want to move the kickstart lever 10-20 mm.Close the decomp and kick her in the guts...show her who's BOSS...Be a MAN.Dont forget the choke,fully out when cold,but no more after a few kicks. Keep on try'in, you'll get it.I've seen guys kickin and kickin till the cows come home only to find that they have sooted up the plug and need a hip replacement.Once you do master it you'll have every man,woman and child wanting YOU to start their 4 stroker for them.I think there is something about starting procedure in the service manual...check it out. failing that you may have to clean the carby,IE, air ways,pilot jet etc Good luck...TJP98611.Please leave feedback if i've helped.

is the spark nice and blue? if orange, coil is weak and needs to be replaced.

pull trigger press crank down till it stops let it go all the way back to the top pull trigger push crank just one click then kick it down hard also keep hand off throttle hold brake cylender instead choke once then repeat unchoke should start right up

hold the decompression lever in and kick it slow then let go of the decompression lever and give it a good kick without using the decompression lever.