250 The 1999 YZ250

Mihylo33 · Dec 27, 2016

Are you using yamalube?

Trfsrfr · Dec 27, 2016

Mihylo33:
Are you using yamalube?

Yessir, 2R.

Mihylo33 · Dec 28, 2016

Trfsrfr:
Yessir, 2R.

Good oil but ashy and what I call a dirty oil. Nothing wrong with and it it's an excellent oil it but it gives false readings. IMO it's still lean. Did the carb issue get better when you had the 178 jet in there? What number plug are you running in her?
I also agree with Andy on the top end. I think it's time to install a new top end for good measure along with some new reeds.

PALMER84ONE · Dec 28, 2016

There goes the plug for Mikesoil. :poke:

Mihylo33 · Dec 28, 2016

PALMER84ONE:
There goes the plug for Mikesoil.

Oh no.... I'm a firm believer in run most any premix oil unless you are racing. I am a finicky little prick though.

Trfsrfr · Dec 28, 2016

Mihylo33:
Did the carb issue get better when you had the 178 jet in there?

I'm not sure really. When it hit the power it went, but still sputtered a bit getting up to it, but then it did that before too.

Mihylo33:
What number plug are you running in her?

Plug is an NGK BR8ES.

What do you suppose it that silvery stuff on the plug?
Is that the top of my piston?
Makes me nervous to run it again. Makes me wonder about the timing too. I dont have a dial indicator to check it though. Maybe I'll see if Harbor Freight has one...

Mihylo33 · Dec 28, 2016

Trfsrfr:
I'm not sure really. When it hit the power it went, but still sputtered a bit getting up to it, but then it did that before too.

Plug is an NGK BR8ES.

What do you suppose it that silvery stuff on the plug?
Is that the top of my piston?
Makes me nervous to run it again. Makes me wonder about the timing too. I dont have a dial indicator to check it though. Maybe I'll see if Harbor Freight has one...

By the pic on my phone it looks like ash but if the bike is lean it could be flaking.
Take that with a grain of salt though. If one of us were there This would be a different story and we could see and hear what is actually happening.

ossagp · Dec 28, 2016

when you have to drop 4 sizes to get one to start cleaning up there is a reason. you need to find that.

Trfsrfr · Dec 28, 2016

ossagp:
when you have to drop 4 sizes to get one to start cleaning up there is a reason. you need to find that.

Any thoughts on what could be going on?

ossagp · Dec 28, 2016

hard to guess when i am not there. i would look to the float needle and a sacked spring on the needle in particular. does it smoke when it is burbling getting up to rpm?

Trfsrfr · Dec 28, 2016

I didn't notice any unusual smoke. I did notice a lack of smoke and an unusual scent from the pipe after my rip around the neighborhood yesterday,
So if it was running rich and I had to drop 4 jet sizes, that would mean that there is some extra air getting in somewhere, yes?

Mihylo33 · Dec 28, 2016

It's at this point where I would stop. Pull the pipe and have a peek inside the exhaust port at the piston.
I would actually pull the head and look myself but the pipe is good.

2Wheels · Dec 28, 2016

Unusual scent is probably cooking residual oil in the pipe. running hot

Trfsrfr · Dec 28, 2016

Mihylo33:
Pull the pipe and have a peek inside the exhaust port at the piston.

That is a great idea. I'll do that tonight, and get a photo of it.
I gotta new front tire I need to put on it as well.

It did smell hot.

Mihylo33 · Dec 28, 2016

Trfsrfr:
That is a great idea. I'll do that tonight, and get a photo of it.
I gotta new front tire I need to put on it as well.

It did smell hot.

If you are just riding around the hood mid throttle and it's got that hot oily snatch smell then it's lean. If you spent all day riding at top speed and on the pipe (the peak power curve aka powerband) and it smelled a little like that then that's normal.