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yz250 no top end power/ rusty crank pics

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M

M0102

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Location
georgetown tx
I repacked my silencer about a month ago and haven't really ridden my bike since. I went out and started it just because I try to run it every it other week and it has no top end power I rode it around my neighborhood not really doing anything crazy but enough to know it falls flat on its face. I didn't think I would have to rejet the bike just from the silencer repacking and was wondering if it might be a powervalve problem. I'll try and up load a video of it idling now since it sounds terrible if i can figure out how. I did a compression test after the bike was warmed up in about 68 degree weather. got around 205
IMG_2934_zpsf60lnqck.jpg
If previous owner did top end when he said 12 hours should be on this top end.
 
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Re: yz250 no top end power

it sounds terrible at idle? how is low end power?

check the air box for a critter nest, they like air box's and can stop one up fast.
 
Re: yz250 no top end power

focus frenzy said:
it sounds terrible at idle? how is low end power?

check the air box for a critter nest, they like air box's and can stop one up fast.
Click to expand...

The air box and filter are fine. I'm going to try taking it for a little ride tomrrow with the silencer off. I found a thread where someone had similar problems on thumpertalk and something was blocking the flow to the silencer after repacking
 
Re: yz250 no top end power

I would check your reeds for sure. I have seen a small crack make the bike act like there was a hole in the piston. Let us know what you find.
 
Re: yz250 no top end power

Main jet came loose and laying in the float bowl? Seen it before.
 
Re: yz250 no top end power

I just rode it without the silencer and its still the same. I'm going to tear into the carb and check the reeds no since my compression is ok. Hopefully it is the main jet laying in the float bowl from how hard I shake my bikes to mix the fuel after its been sitting a little. I can probably get up to maybe 20mph if I short shift the **** out of it.
 
Re: yz250 no top end power

I found some sand in the bottom of my carb bowl
IMG_2941_zpstahwab2x.jpg


my main jet looks white. doesn't that mean its super lean???Main jet is 178. also I have no idea how to get the bolts out to look at the reeds the manual says they are torque to 7.2 lbs but I have no idea how to make these move. I might just do a top end and reeds
 
Re: yz250 no top end power

The main jet was super clogged. I'm sure it will be fine now....well except for the sand part. This thing will probably seize sooner rather than later after seeing that. I still can't get those Allen bolts to get to the reeds
 
Re: yz250 no top end power

The reeds are just under the four bolts in the front air boot the carb goes in. Nothing is "easy". But taking the reed cage out once the carb is off is well right there.
 
Re: yz250 no top end power

You might want to check your tank to see if there's sand in it going into the carb. Also, the vent hose will sometimes suck sand into the bowl. You can run a cheap in-line fuel filter between your tank and the carb. If you use a clear one, you can see if there's stuff coming from the tank.
 
I'm going to dump all the gas and start fresh and soak the entire air box in some simple green to get off all the pj1 spray and grit out. I might just sell this bike for cheap once it runs decent. I spent a lot more on it than I wanted just to hopefully avoid things like this. I think there was very little maintenance done on this bike for only having 75 hours when I got it.
 
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