[Davered00ss]

I just picked up a used 05 CRF 50 for my son. When I got it home, it starts onthe first kick, but would idel and stall as soon as you gave it gas. It would run with the choke open, but not idel.

I cleaned the carb. Did not remove the 2 idel screws. I did not want to screw up the settings.

Now it is a little better, but still needs the choke cracked to run. Now it also sputters a bit. I did drain the old gas and replaced it with shell 93 octane.

Any advice?

Thanks,
Dave

[CRF916]

When you cleaned the carb did you remove the jets and clean them? I think your jets are clogged. idle jet clogged maybe.

[Davered00ss]

I don't think I removed the jets. Do you mean the 2 screws on the side? I removed the screw that led to something that looked like a spray bar and cleaned in there and the bar itself.

[CRF916]

No. you need to remove the carb, pull off the float bowl. Then unscrew the jets pictured below. Clean all the passage ways (little holes). You probally don't have jet cleaners thats ok. I just cut 6 inches of electrical wire and split the strands so its as fine as hair almost and use that to clean the jets. I also use carb cleaner and compressed air.

Pilot jet



Main jet



This is a picture of a crf450 yours will be differnt, I just want you to get an idea of what your looking for.

[gal8x]

I did drain the old gas and replaced it with shell 93 octane.

Any advice?

Thanks,
Dave

High octane only works with high compression.

[Davered00ss]

I though the CRF50 was a 10.1 compression. I know on a car that would be considered high. Is it different on a bike?

[Asmith]

I though the CRF50 was a 10.1 compression. I know on a car that would be considered high. Is it different on a bike?

It is 10:1 and that's not high compression.

You don't have to worry about pinging and such until it gets above 13.5:1 - 14:1.

[Davered00ss]

Still not running well. It needs the choke to run & will not idel for long, so I'm going to have to take the carb apart and try cleaning it again. I may have missed something.

I also think I may have put the long tube jet in backwards?

I pulled the plug and replaced it today. The old one was black with carbon. Running rich?

[Davered00ss]

Did not put the jet in wrong. It can only go one way. I did pull the carb again and clean. Will put it back in tomorro and test it. I think I may need to adjust it with the set screws on the side.

I guess one is the idel set and the other the Air/Fuel mix? I would guess the A/F one needs adjusting?

[gal8x]

Start and warm the motor.
Adjust the idle a little so you can hear the changes in rpm easier.
Adjust the F/A screw and note the start of the sweet spot.
Continue adjusting until the rpm start to drop.
Turn the screw back to the center of the high rpm window.

[Davered00ss]

I give up. Dropping it off at the dealership tomorrow.

[ScottX]

The crf50 with stock jets will only run with the stock air filter if someone put an after market filter on it will need to have bigger jets

If it will run with the choke on or partially on it's not getting enough gas check for pinched gas line a clogged tank vent line, clogged jets, clogged needle/seat or clogged petcock/screen

[Davered00ss]

Interesting. I replaced the air filter with a "Twin Air" filter, that they sold me when I asked for a new air filter. Looks nothing like the stocker I took out.

The dealership did get it running right by adjusting the idel. charged me $20.

Well worth it.

[ScottX]

Good to hear it's running now.

If the filter is for the stock housing it will work fine, When you remove the stock housing and replace it with a pod style filter you need to rejet

[Davered00ss]

Good to know. I was planning on an aftermarket unit like the K&N and an Exhaust once he gets use to the bike.

I know a lot about Modding and tunning LS1 engines (vettes/camaro/firebird/gto's) But nothing about the carbs or bikes.