Bike will not start and stay on cold start

Sounds like a choke issue. but I am no expert on Bikes.

follow the cable from the start to finish it might have been bent or damaged. then have a look at the carbs they might have been damaged in the two accidents if the mix is wrong or they are letting in air

minha yz426f quando vou de terceira marcha devagar mas quando eu acelero a fundo ela engasga , mas ? so de terceira marcha de rewsto nao faz isso

Well - usually something like this would make me suspect the compression and timing first then the jetting in the carb. You might want to do a quick compression check although I do not know what the pressure should be for your bike. I would suspect at least 165PSI. You could have bought a bike that was run without an air filter or something like that.

I would also check the simple stuff - clean the air filter, drain the float bowl and tank and replace with fresh fuel (especially if your fuel is diluted with Ethenol !) and maybe even replace the spark plug.

If all this checks out OK and you still have the same thing going on, you might need to alter the low speed jetting (pilot jet).

Scott

You should be able to adjust the choke to where it will stay in without holding it by turning the rubber piece behind the choke clockwise towards you until the choke stays out on its own. You can adjust this so the choke automatically adjust as the bike warms.
Hope this helps..
Jeff

The choke should only be used when starting cold. After the bike is warmed up you can turn the choke off. If it keeps shutting off after being warmed up for a few minutes, then check your gas/air ratio for the idle air mixture knob. Loosen it up 1/4 turn to allow more gas to flow.

hi nl friday,

here is a trick i learned from a friend who is a great fan of V twins.

on cold starts he usually opens the drain plug to let the carb balancer / floater set. once a few drops comes out, open the choke then start the engine. right after pushing the choke back, twist the throttle to force the jet to spray out.

hope this will work for you.

regards,

voodoo

HI

It is clearly that you have poor mixture.
Every engine needs more fuel in starting, thats the reason for the choke circuit.
But yours doesnt work as you said
Fix your choke circuit in your carbs and every thing will be OK
If you had problem with your fuel pump your bike never run ok cold or hot it dies in any throtlle response

Have the carburators cleaned. this is the first step to ensure there isnt any dirt in the carb.
2nd. Jets should be standar.
3rd. The Fuel/Air screw or knob should be properly set. This is usually 2.5 turns outward from full close. Check for the manual for the proper opening.
4th. Idle knob maybe set too low.

no doubt this bike is running very lean at idle. Thats the way the EPA wants it. Im a harley mechanic and i used to work in a US dealer. all carb bikes at set up time had the carbs "readjusted". We drilled out the EPA plug and turned the idle air screw out and drilled out the pilot jet too. The bikes worked much better. we were at sea level too so the bikes were very lean from the factory. I can imagine that after the new legislation that came into force they are even leaner and require a full warm up to run properly. Warmed up means you put your hand on the motors head and its hot enought to have to jerk it away. this could take more than a couple minutes. and yes our "readjustment" was illegal. i advice you to do the same.