pit marks in dome of cylinder head

[Huffa]

Can this be wet sanded smooth again (pits are pretty deep) or should I just look (probably?) for a good head that isn't pitted at all ?

This is off a MX bike but the question I'm sure would pertain to any 2 stroke head dome.

What exactly does this effect when running a machine like this ?

My theory is they created hot spots which in turn make the bike run leaner then it should be, am I way off in my thinking, does it do otherwise ?

[Dirtcrasher]

I wouldn't worry about running it myself. But, if it bugs ya I'd just get it machined, cleaned up and resurfaced.

Not sure if yamahondaman is still around, he never answered my PM's.

[WIkid500]

Sand it down and run it. Had a zr500 that ate 3 pistons and the rings beat the head up bad. Bought a new head the first time. Second time we sanded the dome down and ran it. Sold that hunk of junk lemon of a snowmobile. I wouldn't be afraid of using it is you sand it down.

[300rman]

the pits wont hurt anything.
sanding the pits down will make the dome larger, and could cause a substantial drop in compression.

put it together and run it.

[tri-Z ripper]

use a dremel and you can polish them out carefully not taking away to much material to make it smooth again! and of course check to see if its flat on a peice of glass or something of that nature!

[Huffa]

the pits wont hurt anything.
sanding the pits down will make the dome larger, and could cause a substantial drop in compression.

put it together and run it.\\

1st you say it may cause a substaintial drop in compression (I knew that is a possibility), which if it does, I'm certainly not going to put it together and run it.

You make no sense ?

[Dirtcrasher]

Using a dremel is not the best idea, one slip and you damage the sealing area. Run it or machine it is the best advice I can give ya :D

You would have to sand or grind the HELL out of it to lose compression.

[Huffa]

use a dremel and you can polish them out carefully not taking away to much material to make it smooth again! and of course check to see if its flat on a peice of glass or something of that nature!

That's an idea! I will ask my engine builder guy too though, see what he says about all these comments.

[Huffa]

Using a dremel is not the best idea, one slip and you damage the sealing area. Run it or machine it is the best advice I can give ya :D

You would have to sand or grind the HELL out of it to lose compression.

The dome area can just be machined ? What type of machine does it?

[Bryan Raffa]

:lol: :lol: :lol: :lol: :lol: :lol: a milling machine,,,make shure you show him this..:naughty:

[Bryan Raffa]

or this:naughty: :twisted:

[300rman]

\\

1st you say it may cause a substaintial drop in compression (I knew that is a possibility), which if it does, I'm certainly not going to put it together and run it.

You make no sense ?

how dont i make sense?

i said the pits wont hurt anything.
i said sanding them out could cause a substantial drop in compression.
i said you would be fine to put it together and run it with the pits.



what didnt make sense?

[RedRider_AK]

I've seen heads like that all the time, rebuilding snowmobile engines here in Nome. There's a theory that rough surfaces on the head help turbulate the fuel-air mixture and result in a cleaner, more complete burn. :lol: I don't know if it's true but I've never noticed a large drop in performance running a used head like that.

[Twilight]

if its a two stroke, its fine and a lil normal. run it, a machined head wont do any better...if lil at all.

[Huffa]

how dont i make sense?

i said the pits wont hurt anything.
i said sanding them out could cause a substantial drop in compression.
i said you would be fine to put it together and run it with the pits.



what didnt make sense?

NO, you didn't say it in that order ......

" the pits wont hurt anything.
sanding the pits down will make the dome larger, and could cause a substantial drop in compression.
put it together and run it. "

The way you phrase it above, it's to be taken as put it together and run it even though I could have a sustantial drop in compression. The " put it together and run it " should have been in the same sentence with " the pits wont hurt anything."

[Huffa]

or this:naughty: :twisted:

OOOOo, ahhhh, how much would mine cost to have that done since we are on the subject?

Too bad no one sees it, ya know, looks so nice !


If my engine guy agrees with most of you guys and says it won't make much difference, won't hurt anything, then yea guys, I will just run it like that.

[300rman]

NO, you didn't say it in that order ......

" the pits wont hurt anything.
sanding the pits down will make the dome larger, and could cause a substantial drop in compression.
put it together and run it. "

The way you phrase it above, it's to be taken as put it together and run it even though I could have a sustantial drop in compression. The " put it together and run it " should have been in the same sentence with " the pits wont hurt anything."

notice the periods in the end of the sentences? the lat sentence "put it together and run it" was supposed to be separate from the other 2 exclamations.

im done arguing, i really dont care, im just irritated i cant ride my damn toy for more than 5 minutes before it breaks.

[Huffa]

i really dont care, im just irritated i cant ride my damn toy for more than 5 minutes before it breaks.

:lol: Who's fault is that, the trikes or the mechanic ? :D

.......and no one explained to me what those pits come from, can they be from dirt getting though carb also, because my airboot from airbox to carb had a fair amount in. Dirt in gas too I suppose ?

This is really the pits ! :D

[Dirtcrasher]

Those pits come from anything that gets past the air and the fuel filter. When you lose the connecting rod big end bearing, it gets ALLOT worse than what you see there.....

[cr480r]

I would fix it... It obviously bothers you... and it would bother me too... Even though it will probably run just fine as is... Just use and old spark plug to chuck it in a lathe, then set the compound at the same angle as the squish band and cut out the marks... then cut down the sealing surface to restore the step cut of the chamber... CC the chamber volume before and after so that you dont unintentionally alter the compression..

[300rman]

:lol: Who's fault is that, the trikes or the mechanic ? :D



its something different every time. everything ive fixed works fine.

[Nick_R_23]

.......and no one explained to me what those pits come from, can they be from dirt getting though carb also, because my airboot from airbox to carb had a fair amount in. Dirt in gas too I suppose ?

Every time Ive seen pits in the heads like that, something usually gernaded before, most likely a piston, rings, or reeds broke off. I use a soft stone dremel and lightly grind off the burrs or raised areas that are around the pits, and run it. Never had a problem yet.

-Nick :TrikesOwn

[brapp]

huffa send it up here i'll chuck it up in my buddys lathe and take a verry little bit of material of fand deck the head to keep the same cpmpression if you leave it liek that it coudl couse detonation due to hot spots( the superheated points) and it could cause diseling or detonation witch is bad for a motor. take the time and take it to a machine shop and hev them knock the high spots an djust brake the glaze small divits are fine but the high spots is what is goign to kill it for ya. have a machien shop chuck it in a lathe and take .020 of fthe dome are and then .025 or .028 of fthe gasket surface for a lil mor epower and a slight bit more compresson should help with a nice crisp throttle responce if jetted properly. and what kind of bike i s it? i may have a head if its a older cr250 or 125