[henrik940]

Hi. I've just got my '06 CRF450R dirtbike.

To day and other days, when i start the bike cold, it usually start up quick.

But if i stall the bike, within' 1-2 minuts after starting, the bike wont start AT ALL.

What could be wrong? Valves? Main jet? Spark plug?

Cheers!

[JimDirt]

When you say it wont start at all , do you mean that when kicking it without touching the throttle , or after the choke is off and using the Hot Start , but as long as the choke is used it starts right up ?? , or once it dies then it wont start no matter what is done until it cools off or sits for a long time ?

If it starts any time you use the choke weather cold or hot , then it is lean , and could be caused by a stuck hot start , which is on the carb right above the choke on the intake side , or a clogged jet , or a loose muffler seal at the header or muffler joint , to start off with

Usually a lean condition is accompanied by popping on deceleration , which can also be a sign of tight intake valves , if when running you rev the engine even slightly and upon letting off the throttle especially if you snap the throttle it pops out the muffler like crazy or even shoots flames out the muffler along with the popping then its either lean or the intakes have tightened up

If you recently purchased the bike and it sat for a while (longer than 1 month) and the gas has gone bad , which is fairly common , you will be lucky if it starts , or if it does it will pop like crazy and most likely the pilot jet will be clogged from the varnish from the gas going bad , these bikes need higher octane gas , usually Premium that is FRESH , if the gas is old it may run fine in your car or lawn mower , but you will be lucky if your bike will even start with it

Also if the bike was used at a completely different elevation then it is now , for example if you live at 2000 ft above sea level and the bike came from or was mainly used at 500 ft above sea level , you will be lucky if it runs at all and will need to be rejetted for your elevation

Hope this gives you some ideas where to look,,also , very important , buy a Factory Service Manual for your bike if you plan on keeping it , they are between $40-$60 and worth every cent ,(they sell them here) and will tell you everything you need to know when it comes to maintenance or servicing your bike

[henrik940]

Thank you for answer. I apologize for my english, i'm from Norway...

After a few kicks i usually starts, but if i stall it, or stop it in like 1 minute after start-up, no chance in hell that it will fire up after.

I will drain the carburetor, fuel tank, change spark plug and check valve clearance next weekend.

Regarding the hot start, the lever is broken, so you thoughts about the hot start is absolutely not a bad thought.

If I understand the hot start; Then the lever is pulled, it stops the fuel injection? Make it leaner?

Thanks for tips.

[JimDirt]

The Hot Start adds more AIR into the system , and leans it out , it does not change fuel flow

But yes with a broken lever i would question the Hot Start assembly , you should be able to pull on the cable end easily and it should snap back closed again , if it is hard to move or does not move at all , i would think it is your issue

And no worry about the language , most of us here butcher the English language ourselves , lol !

[henrik940]

Well, I'm back.

I've changed the spark plug, cleaned the air intake.
The valves was within specs, and hot start OK.

I did drain the fuel, and refilled it with brand new sexy fuel.

Now it starts like a dream, and i think the main problem before was that I did not use the hot start.

[JimDirt]

Glad its starting ok now , when the bike is hot/warmed up , dont use throttle when starting its easy to flood , that is the purpose of the Hot Start , although , make sure you have the correct jetting for your elevation , this will make starting even easier , if its jetted right and its been running and is off for a few minutes , it should start without the Hot Start , the Hot Start should only be needed for instances like when you stall it and try to start it right away , but if it has sat for a couple minutes it should start up without it

Also if the bike sits for more than a month , its best to dump the gas (including what is in the carb) , then put fresh in when your ready to ride , if it only sits for a few weeks at most then its not a issue , you can use the removed gas in your car or lawn mower , these bikes need 91 octane or better , so when the gas breaks down it makes the bike harder to start