Hay all been awhile hope every 1s new years r going well. I've got a new toy today a yz 400 4 stroke Its not for starting. There's excellent compression the decomp works fine there's fuel getting to the plug. The fella I got it off has been using it in Spain but now moved back to the UK near the sunny sea of Cleethorpes ha not its freezing which makes me think the air fuel MUX could need altering. Does any 1 know what the setting should be ??.

P.s also does any 1 know the correct way to kick her over thanks as always in advance

Hi dsb" it be a YZf if shes a 4stroker then :eusa_shifty:/ is she fuel injection / or carb, av seen a few of these in mates shop, pigs to kick .

Yeah mate sorry its a yz400f. Its gotta carb on

1. Place a large boot on your right foot .

2. Push down the kickstarter until you feel the compression build toward top dead centre .

3. Use the decompressor to get the piston just past TDC .

4. Kick the Bejesus out of it !

If it doesn't start go back to 2 and try again . You will get the hang of it . If you think the YZF is hard to start have a try with an XR650 . You'll be glad to get back on the YZF , lol .

I start my XT500 with no decompression cable as its knackered (takes all my 95kg of weight to get it past compression). Always use a motocross boot on the right foot for cold start (don`t need broken ankles at my age).

Thanks guys always appreciate your responses

Not so much ankles , its the bruised sole if poor footwear is worn

you didnt mention if you are getting a spark?

Yeah I've got spark mate

Hey all well today I got her running.I've took her out and basically she cuts out whilst riding then she's a nightmare to start litraley I've kicked a hundred times and nothing.

Please help lol

Ok if she starts, and runs then cuts out,,,its either fuel starvation or coil break-up, pull fuel pipe run it into a jug, see the flow

if this is ok , its maybe float valve [ in carb] sticking or crap in it,,,

do this fisrt then ,if it still dies change coil , or spark plug too,

Thanks for your help again mate. I will try a tommorow. She back fires after a few good kicks aswell could this be likebubsay a weak spark and the coil/plug is weak or no wotking. I'm gonna reset every thing back to stock on the carb but how far after I have turned it right in do u turn it out ???

Thanks again I appreciate your help

Make sure the vent in the fuel cap is not plugged with dirt .

and cut the last 4mm or so of the spark plug lead and refit the cap. sometimes the end of it gets dirty/frayed/burnt and dosent make a great connection.

"how far do I turn it back out " [Quote]

I take it its the airscrew your on about ? 1 &1/2 turns , Unless manual says different,

Had a 2007 KTM250SXF with the extreme reluctance to start once stalled out on the trails. Turns out the fault was my kick technique. The spanner man at the dealership just kicked it into life while sitting on it saying they're designed for a particular kick-thru speed and my stand up and/or on the pegs karate leg chop with subsequent beetroot facial complexion was just too much OTT! With lesson learned, I adjusted my kick thru speed, it fired up reliably and the wife recognised me once more. Lol!

Had a 2007 KTM250SXF with the extreme reluctance to start once stalled out on the trails. Turns out the fault was my kick technique. The spanner man at the dealership just kicked it into life while sitting on it saying they're designed for a particular kick-thru speed and my stand up and/or on the pegs karate leg chop with subsequent beetroot facial complexion was just too much OTT! With lesson learned, I adjusted my kick thru speed, it fired up reliably and the wife recognised me once more. Lol!

Hey all again thanks for your input. I've been away do sorry for the long wait. I have had the carb off today ultrasonic cleaned and back on she took a few good kicks and started with the choke on soon as I took it off she died. I've tried my best to start her again she fire a bit then dies and other times just back fires. Any help would be appreciated guys I'm always gratful

sounds a bit like what my diversion was doing . clean the tank inside and whip the carb of again and blow it out. it may have been clean but if there was dirt in the tank/filter it will have blocked the pilot system in your carb.

and to help the engine when you go to start it again give it a spray of easy start. i know some say engines get addicted to it and that may be true but for the first start it will help. cant do any harm cause an engine that wont go isnt any use no matter what its addicted to..

Hi mate thanks for your time. Do u think it could be as simple as that ??? I was wondering if the valve shims bmay be worn