2005 cr125 feels like 4 stroke bouncing off rev limiter when I get on it

I just put new piston,crank bearings, cylinder replayed. Went through carb set float level with a guage to 7.5mm, 400main, 55 pilot. Did leak down test and doesn't seem to be leaking. Gas flows freely from peacock. It feels like its starving for fuel. I bought the bike seized up so don't know how it ran before. I'm at my wits end. Any ideas?

change the spark plug? piston in the correct direction? jetting stock?

Has a new plug I'm sure piston is in correctly. Jetting is per manual for my elevation 6,500ft

Exhaust not plugged up?

Check on the above advice.  Check to make sure your powervalve is opening correctly.  Did you replace crank seals on your build?  Make sure they are installed correctly.  Leaking seals can fool the engine into thinking you have rich and lean conditions causing your motor to not run properly.  Also, make sure your stator is operating correctly and all the grounds are good on your wiring harness.

Edited by frdbtr

Make sure the Carb Float is set properly...............

I set the float level using a guage. I've wondered about the exhaust valve. I have a manual and put it together like it said. Does anyone know how to check the function? The manual does not specify.

6 hours ago, 870 said:

I set the float level using a guage. I've wondered about the exhaust valve. I have a manual and put it together like it said. Does anyone know how to check the function? The manual does not specify.

Take the cover off and rev the bike, make sure the valve is rotating when the engine revs.

On 8/10/2017 at 0:50 PM, 870 said:

I set the float level using a guage. I've wondered about the exhaust valve. I have a manual and put it together like it said. Does anyone know how to check the function? The manual does not specify.

But have you checked your silencer to make sure it's not plugged? I have seen this many, many times. People chase the problem thinking all sorts of other things and it's nothing more than the packing has clogged up or the baffle has broken closing off the exhaust.

Check the intake boot for a tear.

4 hours ago, SS109 said:

But have you checked your silencer to make sure it's not plugged? I have seen this many, many times. People chase the problem thinking all sorts of other things and it's nothing more than the packing has clogged up or the baffle has broken closing off the exhaust.

I have not I have to leave town but I'll check that when I get back. I would be surprised if it has ever been repacked. I will also try to post a video when I get back

Often when a 2-stroke 'cuts out' and feels like it's hitting a rev limiter, it's running too rich on the needle circuit.

 

Too rich on the main jet will kill top end & overev,

too rich on the pilot the engine won't idle & run well at lower rpms and be prone to fouling

but either won't 'cut out' under acceleration.

 

Easy test would be to lower the needle / raise the clip one position.

A worn out needle (smaller diameter than specs) may also richen that circuit.

 

Your float height may be set but are the fuel inlet needle's tip and seat worn or damaged?

If so that may make the actual fuel level higher and richen each metering circuit.

Edited by mlatour

Well said ^
Double check that your main jet isn't plugged. I have had that issue before.

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