oil leaking from cylinderhead nut

[JohnBeton]

One of my 250r's was leaking oil through the base cylinder gasket and from one the headnuts.
So last night I took of the head and cylinder, cleaned everything up, degreased everything. I also checked if anything was warped but it wasn't.

I installed new gaskets and fired it up today, The basegasket is now OK, but it is still leaking oil from one of the headnuts.

I know if the gasket is bad or something is warped it would leak coolant, but I never had oil leaking from a headnut.

I was thinking of trying copper washers in between the head and the nuts, but that would solve the underlying problem of where the oil can get to the stud ???

[wilkin250r]

How on God's green earth are you getting oil leaking from the head nuts?

The only possible solution I can see is the head is warped and you're getting compression loss in that area, or the threads are stripping down below on the stud (and it can't hold tightly) and thus you're getting compression loss in that area.

[DnB_racing]

Originally posted by wilkin250r
How on God's green earth are you getting oil leaking from the head nuts?

The only possible solution I can see is the head is warped and you're getting compression loss in that area, or the threads are stripping down below on the stud (and it can't hold tightly) and thus you're getting compression loss in that area. even if thats the case I would still think that you would see coolant, either leaking out or into the cylinder,

[C-LEIGH RACING]

Now aint it a little late for April fools jokes.

On another note, might be something going on we dont know about, kinda like when I drove trucks & had to duck out in the hammer lane to keep from running over a car & then come to find out was no car there to start with.
Neil

[JohnBeton]

guys, I'm not fooling around here , I know it's a weird problem, it's not pure oil, more like black unburned fuel.
The exhaust leaks a little, but I checked and it's not spitting that far :huh

[JohnBeton]

i had some time again today to check this problem on this 250r, after a good inspection I noticed the oil was actually coming out of the sparkplug hole.
The more I opened the throttle, the more gas would spit between the head and sparkplug.

I tried several new sparkplugs, torqued them to the right specs, but didn't help.
I guess the threads are bad and/or the head is warped a little bit where the sparkplug meets.

I had another head in stock, so I changed the head.
Hopefully I can test it tomorrow and everything is ok :)

[sdyme1995]

Is this a stock head you put on, what type of head did you take off? if they are both stock heads have they or the cylinder been cut, decked? If it is aftermarket what size domes? What is static compression? Squish if you know it?

Or this head change fixed the prob, then just disregard all that garbage above.

[ridehonda400ex]

On the 300ex i rebuilt for my sister, there was oil shooting out of the spark plug hole(burned oil real bad) and it was because they hadnt tightened the spark plug up good enough and it also didnt have the right plug. But i re-built it and put the right plug in. Doesnt burn any oil or shoot any out anywhere. So maybe your using the wrong plug?

Good luck tho

[JohnBeton]

thanks guys, it's running good now.
the old and new head are both stock heads. I always use b8es or br8es sparkplugs for my 250r's.

The old head seemed to be warped a little but and I think the threads of the sparkplug hole weren't 100% anymore.

I changed the head and it ran, but after half a mile i failed the plug. It was way too rich.

I have played with the jetting this afternoon, put a fresh sparkplug in and it ran great.

I took it for a small ride and it ran good, not 100% yet, have to tune the jetting a little bit.
But I'm glad this problem is solved.