CRF50F problem...

[DRTLuvr]

My son's 2005 CRF50f has been running great up until this point, and I've heard that they are virtually indestructible.
However, when trying to start it now, with the choke open, it runs for a couple seconds like it is at half throttle, then it dies. It will not start at all with the choke off. Clogged jet maybe? I took the carb off and cleaned it out, could not see any clogged holes. Maybe I'm not looking in the right place. I'm sure someone has had this problem before. HELP!

 

[DBforlife]

ok i am not tottally sure but i have this problem with my ttr. and i was told that the needle in the carb could be worn out and this is the result. one of my buddies told me this but it doesnt really make sense to me. please help us both out. also i am sorry if i am wrong. i guess it supposdly has something to do with the gas flow. I have the same symptoms with my ttr. but i start it with the gas off and then once it stays running ii turn the gas on.

SOMEONE PLEASE CORRECT ME IF I AM WRONG.
DB

 

[Patman]

First I have never heard of a carburator needle getting worn out. It should only ever be in contact with air and fuel which should not cause any wear.

Is the air filter clean? Is the gas fresh? You would be amazed at how often one of these is part of the problem.

As far as fixing the problem... It's a little engine with a little carb that has itty bitty jets with tiny little holes. So any kind of contamination or buildup can really screw you up. Properly cleaning the carb is a bit more involved than removing it and squirting some cleaner through it which is what many people thinks it involves. If you are even moderatly comfortable with a screwdriver it is no big deal to totally dismantle the carb down to it's most basic pieces and carefully clean each one. Check to see bright light through each jet, use a good quality cleaner such as Berryman's or CRC and just put it together in reverse order. Look at the exploded diagrams in your shop manual or on line at one of the parts sites to help. Setting the float height will be something you need to get from a shop manual as far as the proper method and dimension for your carburator.

 

[DBforlife]

Sorry if im wrong again but there is a needle hanging off the float, is there not? Float needle maybe?

sorry DB

 

[Patman]

Again it's not a real high wear item. The rubber tip can tend to get hard on the needle valve and sort of "wear" but I'd be looking for blocked passages, jets and assuring the float height is set correctly. If the tip was not sealing then the overflow tube should have gas running out of it as it meters the flow of raw fuel to the float bowl but nothing else. On something like the CRF50 because they really are pretty rock solid reliable given just a tiny bit of maintenance most of the issues are REALLY simple.

 

[DBforlife]

Thanks for correcting me Pat
DB

 

[Patman]

I think it's more explaining than correcting. Look up a parts diagram some time and it's all pretty easy to see how it is supposed to work. Picking up a factory service manual for your specific bike is also a great way to learn not only the specifics of your bike but how everything works in general on other bikes and engines in general. Eric Gorr's performance books are also and exceptional resource and make things a lot eaier to understand than the manuals.

 

[DRTLuvr]

thanks for all the help guys!