XR50 will not rev up...... Frustrated!! Bummed out 8yr old

[MikeT]

History: This is a 2000 XR50 that my son sank in a very deep puddle earlier this year. I pulled off the air box and cleaned it out and installed a new UNI filter. I also cleared out the exhaust and pulled the ignition cover off and dried it out with wire dryer. It ran after that however now about 2 months later (we just haven't had a chance to ride) it will not rev up. It seems to only want to run with the choke partially on. If I take the choke off, it dies. Put the choke back on and it runs.

This week I put in a new spark plug, took the carb all apart and did find some debris in the bowl. I cleaned all that out and took the entire carb apart. I was able to use carb cleaner and spray it into every hole with it flowing cleanly through and coming out other orifices in the carb (nothing seems clogged). I also removed the intake manifold and made sure there weren't any dead fish in there but it still won't rev up.

The spark seems very blue and pretty snappy to me, I am just Frustrated that it will not rev up. With the choke all the way off it just dies when I give it throttle. The air mixture screw is on 1 1/2 turns out from snug. Please help!!

 

[Pushin50]

Try new jets. Just because you blow cab cleaner through them does not mean they are clear.

 

[MikeT]

I guess, like a new main jet? From what I could see, the main jet was the only one that I believe could be changed on this bike.... I think the others are all just screws. Not really sure though as this is my only 4-stroke bike.

 

[tepco]

Pilot hole is tiny and is usually the culprit if it doesn't pull off the bottom.

 

[Ol'89r]

Pilot hole is tiny and is usually the culprit if it doesn't pull off the bottom.

+1. Remove all of the jets and make sure you can see daylight thru the orifices. Then blow compressed air in the holes the jets came out of to make sure they are clear.

 

[MikeT]

Pilot hole is tiny and is usually the culprit if it doesn't pull off the bottom.

I need to figure out which one is the pilot hole..... How do I identify it?

 

[pesky nz]

Remove the air screw and dribble carb cleaner into it and some will come out the pilot jet inside the fuel bowl
the pilot jet has a screw slot in it and can be removed but the hole is very small, too small for 1 strand of wire brush so I use one strand of old throttle cable and only push in and pull out by hand ( more than 10 pulls will change the jet size).
As old89r said compressed air is good and you can feel where it comes out

 

[MikeT]

OK, I took the carb apart again and put a piece of wire in the hole and then squirted some more cleaner into the air screw hole. I then blew air into the air screw hole and then put the whole thing back together. It now runs and pulls fairly well. I messed some more with the air screw setting and got it to run better. I think because it is so hot outside that it probably needs a main jet change to be perfect, but that is not what this bike is for. Currently it is for a 8yr old girl to ride and she will be happy with the way it is right now.

Thanks for all your help. I think this is a successful repair. :)

 

[BSWIFT]

I think because it is so hot outside that it probably needs a main jet change to be perfect, but that is not what this bike is for. :)

Record heat here again today, 110 at my house. I rejetted the heat pump in December and I really happy with the performance!:)

 

[pesky nz]

glad to have been a help
RECORD LIGHTNING at my latitude (about 38.3 degrease south) and I just saw one flash about 250 yards above ground and paralell to the ground from cloud to cloud about 3miles long so no kite flying for me

 

[tepco]

Glad you got it running Mike, anytime! Now get her riding and come on by.