Yamaha TTR 225 no power under load

[BusyBeaver]

If it's like my '07, it has a vacuum operated, diaphragm slide throttle. Check that the diaphragm is intact and drill out the hole that sends the vacuum signal up top.
Also be sure to gut the muffler out as suggested. Then get your jets sorted out. The pilot jet screw is EPA non adjustable similar to a chainsaw's jets. You have to drill off the jet access cover to expose the slotted screw and then adjust the screw out to richen it up. Stock is 1 1/4 out, set it at 2.5 -3 turns out. Makes all the difference in the world.
BB

 

[happysaws]

How's the bike coming along?

Steve

Running good, but it starts hard and idles rough when cold.

 

[happysaws]

Where is this jet access cover?

If it's like my '07, it has a vacuum operated, diaphragm slide throttle. Check that the diaphragm is intact and drill out the hole that sends the vacuum signal up top.
Also be sure to gut the muffler out as suggested. Then get your jets sorted out. The pilot jet screw is EPA non adjustable similar to a chainsaw's jets. You have to drill off the jet access cover to expose the slotted screw and then adjust the screw out to richen it up. Stock is 1 1/4 out, set it at 2.5 -3 turns out. Makes all the difference in the world.
BB

 

[s sidewall]

Should be cut out around the float bowl, will be a hole with a plug in it, it's covers the mixture screw.

Steve

 

[sb47]

As said before check for any in line filters or screens. DI box may be going out or the stater is going out. If the stater is not putting out enough currant it will bog at high RPM's

 

[s sidewall]

Lot easier to work on if looking at it.

Steve

 

[s sidewall]

Get that bike going?

Steve

 

[happysaws]

Get that bike going?

Steve

Ya, starts really well now, and runs well without the air filter. The float height was incorrect, it was letting too much fuel into the carb, causing it to constantly run rich and foul the plug.

 

[s sidewall]

Glad to hear that.

Steve