Since i got my radiators sent out to be repaired i figured id pull the head to check the topend, i never seen this before on any of my other bikes, i think it might of been burning a little coolant? also how does the cylinder look? just run a hone thru it? and the plug is fairly new maybe 3 tanks of gas looks rich but not sure if it will look different do to if its burning coolant.... sorry for huge pics haha

I dont think its burning antifreeze. Generally when you burn antifreeze it leaves a yellowish tint on the piston and head, not to mention the exhaust is usually white. If your o-ring is leaking it will usually leave a discoloration on the aluminum part of the cylinder where its going into the cylinder. It looks like your fairly rich. It looks to me that your fuel charge is washing the piston clean. As far as the cylinder goes, it looks like there is some minor scuffing but you can also still see some crosshatch in it. Can you feel it with your fingernail? If its still fairly smooth I would just hone it and throw a new piston in it.

cant feel any scratches in it just very glazy, def gonna do a topend in it, as far as jetting the plug is light tan on one side and black on the other.

highmark00700, on 01 May 2012 - 05:22 PM, said:

You sure about this? Can't say that I've seen it in motorbikes, but I've seen it several times in cars and all it does is clean the heck out of everything.

ahahaah that engine loves u looke the black marking in a heart!!!!!!!

Was it pushing any coolant out of the rads? It does look like something was washing the the top of piston...or did you wipe off the piston and plug before taking the pictures?

Edited by Blackwoodz, 01 May 2012 - 06:31 PM.

plug was wet and black same with parts of the head, i wiped them off but the piston was like that. I thought when it burns coolant it cleans everything since its like steam cleaning which it looks to me . i checked the radiators before each time i ride and the coolant is right at the fins, so i filled it up til the bottom of the cap neck and after the my rides its back down to the top of the fins everytime? maybe its over flowing or maybe burning it

Edited by Evil_CR, 01 May 2012 - 07:16 PM.

That does not sound like a head gasket leaking then. It's probably ok.

corndog, on 01 May 2012 - 05:52 PM, said:

Yup I have seen it several times in sleds. I might even still have a piston that I pulled out after an o-ring failure. If I do I will post some pics. Usually if its a small leak from flat o-rings or a warped head is when you see the yellowish tint. If you are getting enough to wash everything completely clean you will usually see antifreeze in the exhaust, thick white smoke while its running. Usually very easy to tell.

So you guys think Im running a little rich, I just cleaned the carb I didn't check jet sizes all I I know is the pilot is stock 50 that's all I remember seeing when I had it apart. But def new top end for sure?

This was in a sled with a bad o-ring. all carbon was washed away with a residue left on the piston from burning antifreeze.

Edited by highmark00700, 02 May 2012 - 08:48 AM.

Looks a bit rich, shouldn't have that much wash, and the plug is pretty dark. But on the plus side your port flows look really evenly matched.  Also note, it's VERY hard to determine jetting the way I just pretended to. You could have a big fat pilot jet and a main that's 5 sizes down from stock, but if you lug all day it'll look like the plug and piston are rich, when in reality you are one WOT blast away from engine destruction.

I would also say it's not burning coolant. My bike will only keep coolant to abou the top of the fins. Since there's not overflow catch it just burps any extra out when hot, then as things cool and contract ar fills that void back in. Plenty of posts here too claiming the same - top of the fins.

Edited by adam728, 02 May 2012 - 08:54 AM.

Here is a pic of piston wash. From rich to lean:




Burning Antifreeze:

When I had the carb off I checked the reeds and one had a slight gap doesn't that make it have a richer a/f mixture? And thank you for all your Guys help and pics !!!

Davis538, on 01 May 2012 - 05:54 PM, said:

hahahaha yeah man his bike loves him !

two stroke love!

Your piston crown looks just like my 2006 YZ250 when it was running close to stock jetting.
Setup was as follows:
Hours: 8
Gas: 93 octane, 70:1 Amsoil Saber
Stock jetting except slightly leaner 2007 needle
PC R304 silencer
Track: 300' elevation, prepped mx
Rider: Intermediate
At that time, I was having some detonation during roll-on. As I recall, I found my stock timing to be advanced by a couple of degrees over standard.

The same topend is now at 25 hours.

I currently run stock timing, one step leaner pilot (48) and the same leaner needle and I blend in 25% 110 Sunoco gas with my 93 Octane. I am currently using Kal-gard Pro Comp 2 at 50:1 w no detonation.
Will post a pic next time I lift the hea and/or change the piston and rings.
No spooge and the silencer is just slightly greyed from black.

Edited by Swappa, 26 October 2012 - 10:54 PM.

Swappa, on 26 October 2012 - 10:53 PM, said:

Point of clarification, the 2007 needle (N3EW) is slightly RICHER than the 2006 needle (N3EJ).

Your running way to lean. Go 40:1 instead of 70:1or at least 50:1.

Woops, my bad guys read the wrong comment.

Edited by Peterrides, 28 January 2013 - 10:33 AM.

Peterrides, on 28 January 2013 - 05:55 AM, said:

How do you figure he's lean? And how did you figure his oil mix ratio? Your diagnosis is quite a bit different from the rest of us...