milling head

chrisdoc0608 · Jul 7, 2007

i have a stock head on my sj, it has already been milled and is sitting at 175-180psi i believe. right now i think the head is warped bc i overheated the motor a while back and i now see exhaust gas come out of the pissers when i start it out of the water. it comes out more when i rev it, so i am pretty sure it isnt sealing properly. i also have seen a little milky (water) substance on my plugs two times since it happened. i want to take the head to a machine shop and get it milled so it is perfectly flat so it will seal right, how do i figure out how much i need to tell them to shave off? i dont want to raise compression any more than i have to though.

Mouthfulloflake · Jul 7, 2007

then see if they can cut it just enough to be flat, without cutting enough to raise compression?

the trick, wil be knowing roughly how much removed from the deck surface will increase compression.

It is likely, if its already cut, it wont be able to be made flat without removing too much.

maybe with a thicker head gasket?

Rickster · Jul 7, 2007

Mouthfulloflake said:
maybe with a thicker head gasket?

:haha:

If you ask, I bet someone on here would send you a stock head for free.... I think I have a 650 head you can have for free, if you want it. You pay shipping... :biggthumpup:

chrisdoc0608 · Jul 7, 2007

i would, but my stock head has a modified cooling system, it has multiple taps in it, i guess group k did that when it was sent off for modification. if i just took it to a shop and asked them to see if it was warped is there a way they can tell?

Mouthfulloflake · Jul 7, 2007

why is that so funny?

the thickness of the headgasket or the milled surface around the domes is the only thing he is talking about messing with isnt it? I have a bag full of different thickness head gaskets for kawasaki engines, and I know there are at least a couple of thickness yamaha gaskets available too.

maybe your point is that a $40 head gasket is worth more than a stock head?
I guess so, if you dont figure in the mill work, I dont think it would be hard to ad the additional cooling tap though, simply drill and tap the hole for an NPT nipple.

any (good) shop that is capable of milling a head, should be able to check it for flatness.

Rickster said:
:haha:

If you ask, I bet someone on here would send you a stock head for free.... I think I have a 650 head you can have for free, if you want it. You pay shipping... :biggthumpup:

Rickster · Jul 8, 2007

Mouthfulloflake said:
why is that so funny?

the thickness of the headgasket or the milled surface around the domes is the only thing he is talking about messing with isnt it? I have a bag full of different thickness head gaskets for kawasaki engines, and I know there are at least a couple of thickness yamaha gaskets available too.

maybe your point is that a $40 head gasket is worth more than a stock head?
I guess so, if you dont figure in the mill work, I dont think it would be hard to ad the additional cooling tap though, simply drill and tap the hole for an NPT nipple.

any (good) shop that is capable of milling a head, should be able to check it for flatness.

Mouth, I'm definitely not laughing at you...

I was chuckling at the cost of a thicker gasket and getting the old head milled again (trued), versus just getting another stock head.

Mouthfulloflake · Jul 8, 2007

I gotcha

just going back to a stock head for cheap is going to loose him about 40 psi per hole though too.

so...

yeah, cheap = slower.

:biggthumpup:

Rickster said:
Mouth, I'm definitely not laughing at you...

I was chuckling at the cost of a thicker gasket and getting the old head milled again (trued), versus just getting another stock head.

chrisdoc0608 · Jul 9, 2007

well my fear was just verified. i just did a compression check again results not good lol. i guess it could be much worse, but the front cylinder pumps up to abt 177 then slowly loses psi. the rear cylinder pumps up to abt 177 then holds well, so my front cylinder is not sealing right. the gasket on there is new ( couple weeks old) i put it on when i over heated the motor, so what should i do?

Mouthfulloflake · Jul 9, 2007

check the head for flat ( on a peice of glass with feeler guages, it should probably be flat to within 1 or 2 thousandths of an inch)

glue FINE sandpaper to the glass and "lap" the head to remove any high spots.

check frequently, use a thicker base gasket, or simply stick some silicone goop on the gasket and ride on.

chrisdoc0608 · Jul 9, 2007

hmm i will try that. thanks, ill update with my results.

chrisdoc0608 · Jul 9, 2007

so here are my findings... :bigeyes:

cylinders and piston tops look extremly good :biggthumpup: (sorry for the foggy look, its really humid)

but the 3 week old head gasket looks like this :banghead:

so why is that gasket like that? it hasnt overheated since my first incident....

i took the head and lightly moved it accross a board with a sheat of light grit sandpaper also

chrisdoc0608 · Jul 10, 2007

Mouthfulloflake · Jul 10, 2007

permatex copper sealant in a tube, HI TEMP

smear it all over that gasket, thin layer, bolt it up and go ride.

It should hold, we redid mine in GA at SFF and ive ridden it many times since then on that TEMPORARY fix.

chrisdoc0608 · Jul 10, 2007

nice thats what i had planned on doing, i had bought some high temp copper sealant earlier, and it has held really well on my headpipe. so i will give it a try this afternoon, its too damn hot to do anything right now lol

chrisdoc0608 · Jul 10, 2007

what causes the gasket to get like that though?

chrisdoc0608 · Jul 10, 2007

:banghead::banghead::banghead: @#*$@#!!!! i cant believe this sh*t!!! i just went out and decided to go ahead and put the head back on.... after putting the copper stuff on and torqueing the bolts to 11ftlbs then going back to troque to 22ftlbs the #2 bolt to torque would not torque to 22, it would to 20, so i said ok... what ever then went to the #4 bolt and it just Fn stripped on me, i didnt even apply much pressure at all. its not the torque wrench, i just bought it last night....:banghead::banghead::banghead: is there anything i can do to save this cylinder?

Mouthfulloflake · Jul 10, 2007

dont do anything else, UNTIL.

you go buy a metric tap and die set ( anout $30 at local parts store normally)

figure out what size/pitch it is in a GOOD hole.

re-tap that hole, and use a vacum to get the chips out.

I did this last time I did one, I noticed it was slipping and cleaned the threads before really going to town on it.

Id clean the threads, put some goop on that gasket, and torque it 20 if thats all it will hold.

long term fix is time cert or heli coil in that hole.

chrisdoc0608 · Jul 10, 2007

i just went to nappa and got a M8 * 1.25 helicoil kit, im gonna put one in the hole that will not torque at all and in the one that only torqued to 20

Mark44 · Jul 10, 2007

y

chrisdoc0608 said:
i just went to nappa and got a M8 * 1.25 helicoil kit, im gonna put one in the hole that will not torque at all and in the one that only torqued to 20

Fix them all you will be glad you did in the future and get a new head gasket!!!!

Mark44

chrisdoc0608 · Jul 10, 2007

damnit, another head gasket? i just replaced that one 3-4 weeks ago. why would it get like that? i dont want to keep throwing gaskets at it and not solve the real issue.

milling head

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