YZ250 Sound

[WhiteRice]

I’m getting concerned my bike is in need of a rebuild. I was already planning to do it this winter, but have one more ride planned for the year. Do you guys think it sounds ok? Or should I hold off on the ride and go ahead and rebuild? I’m not sure how noisy these bikes usually are. It’s just a slight ticking or buzzing noise. 

 

Thanks guys 

 

https://m.youtube.com/watch?v=3aCwHySIAkM

It may be nothing and sound like its suppose to. I’m new to this bike and don’t want to blow it up.

[WhiteRice]

Just a side note, I haven’t noticed any loss in compression, bike start first or second kick (choke on) and I have not noticed any loss of power.

[shrubitup]

sounds fine to me. couple things to check if you're concerned:

1. remove exhaust pipe, shine bright LED light into cylinder looking for burnt oil below rings. That's blow by and indicates that the rings are done.

2. remove ignition cover, grab ahold of flywheel. If it moves up/down then left crank seal is done. If it moves in/out then right crank seal is done.

 

[WhiteRice]

51 minutes ago, shrubitup said:

sounds fine to me. couple things to check if you're concerned:

1. remove exhaust pipe, shine bright LED light into cylinder looking for burnt oil below rings. That's blow by and indicates that the rings are done.

2. remove ignition cover, grab ahold of flywheel. If it moves up/down then left crank seal is done. If it moves in/out then right crank seal is done.

 

I can look into that. You think it’s ok for one more 8-10 hour before putting up and rebuilding?

[shrubitup]

4 minutes ago, Tdhooker1 said:

I can look into that. You think it’s ok for one more 8-10 hour before putting up and rebuilding?

I didn't hear anything out of the ordinary. Pulling the pipe would take 20 minutes...

[Smoking 2's]

If grabbing fly wheel and anything is moving up/down your main bearings are done

[WhiteRice]

Do I need to remove fly wheel nut in order to wiggle it?

[Smoking 2's]

1 hour ago, Tdhooker1 said:

Do I need to remove fly wheel nut in order to wiggle it?

Nope

[WhiteRice]

4 hours ago, Smoking 2's said:

Nope

I assume remove the oil? Was planning an oil change anyway. And will the gasket need to be replaced? Lastly, I mix my gas 50:50 with 93 pump and 110 unleaded. With a 32:1 yamalube oil. Does any of this possibly explain the louder engine noise? I don’t know exactly what detonation sounds like, and if that’s what it is doing. 

 

[Shooter88]

20 minutes ago, Tdhooker1 said:

I assume remove the oil? Was planning an oil change anyway. And will the gasket need to be replaced? Lastly, I mix my gas 50:50 with 93 pump and 110 unleaded. With a 32:1 yamalube oil. Does any of this possibly explain the louder engine noise? I don’t know exactly what detonation sounds like, and if that’s what it is doing. 

 

You dont need to drain the oil. The oil is contained in the transmission and none will come out by pulling the left engine cover. Literally all you have to do is pull the cover, grab the flywheel and try moving it in the ways described above. Easy peasy lemon squeezy. 

I cant watch your video right now but I highly doubt you're detonating with mixing it the way you describe. In fact, I just run 93 pump and have never had detonation issues. As long your jetted not too lean and you dont have any mods that raise the compression higher than stock, your bike should run just fine on pump alone. 

[WhiteRice]

12 minutes ago, Shooter88 said:

You dont need to drain the oil. The oil is contained in the transmission and none will come out by pulling the left engine cover. Literally all you have to do is pull the cover, grab the flywheel and try moving it in the ways described above. Easy peasy lemon squeezy. 

I cant watch your video right now but I highly doubt you're detonating with mixing it the way you describe. In fact, I just run 93 pump and have never had detonation issues. As long your jetted not too lean and you dont have any mods that raise the compression higher than stock, your bike should run just fine on pump alone. 

Kinda what i thought. Thank you. I’ll check as soon as I get a chance 

[shrubitup]

1 hour ago, Tdhooker1 said:

I assume remove the oil? Was planning an oil change anyway. And will the gasket need to be replaced? Lastly, I mix my gas 50:50 with 93 pump and 110 unleaded. With a 32:1 yamalube oil. Does any of this possibly explain the louder engine noise? I don’t know exactly what detonation sounds like, and if that’s what it is doing. 

 

To me, the motor sounds healthy. I don't hear detonation. No gasket replacement as long as you don't tear it off. No oil to worry about either as already noted. Stock motor only needs 91 octane. Yamalube at 32:1 is a great oil.

[WhiteRice]

55 minutes ago, shrubitup said:

To me, the motor sounds healthy. I don't hear detonation. No gasket replacement as long as you don't tear it off. No oil to worry about either as already noted. Stock motor only needs 91 octane. Yamalube at 32:1 is a great oil.

Thanks. I’ll probably stop running the 110 then after I use it up.

[cmstbcchamp07]

On 9/28/2019 at 3:25 PM, Tdhooker1 said:

Just a side note, I haven’t noticed any loss in compression, bike start first or second kick (choke on) and I have not noticed any loss of power.

It sounds normal to me bro. I'd just do what the other guys said check compression with a gauge. Pull the tune pipe off and have a look for any scooring or blow by on the rings or cylinder ways. Also pull the staitor side cover off(the left side when You are sitting on the bike) and try to wiggle it up and down. Nice bike too btw