Frankfort MB's
Well-Known Member
If you do mill the head down then it will actually make more compression (more power!)
Blown Head Gasket
- Thread starter Timbone
- Start date
45u
Active Member
You would have to mill it quite a bit to make much difference. At least .005 to .010 which would take a while by lapping it on a piece of glass. Stock compression on these bikes is lower then my 1942 or 1946 Harley flat heads I owned. LOL. This is because China made motors will not take much. In reality they are REAL LOW compression at around 6 to 1. If they where high quality at 6 to 1 they would run forever.
45u
Active Member
With out making my own components I would never want to go over about 7 to 1. They all ready have problems at 6 to 1 messing up wrist pin bearings.
HeadSmess
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when using teflon, LESS is better.
its ALL i use, other than on water cooled stuff, cus they are simply impossible to use it on. too many lil water passages.
if you got a slant plug head...thats why it isnt working for you. i bet your plug faces the same way the leak is occurring.
ive ran 10:1 satic CR without any issues... factor in a tuned pipe and you can get up to 14:1 when its hitting powerband.
its ALL i use, other than on water cooled stuff, cus they are simply impossible to use it on. too many lil water passages.
if you got a slant plug head...thats why it isnt working for you. i bet your plug faces the same way the leak is occurring.
ive ran 10:1 satic CR without any issues... factor in a tuned pipe and you can get up to 14:1 when its hitting powerband.
Timbone
Well-Known Member
The Teflon tape did work: one small section folded into double then wound into string. It got me home! My attempts at thicker strings (more is better, right?) were absolute failures..
And you are absolutely right: it is a slant plug head and that's where the leak/ fail is occurring.
In the next week, I am going to very slowly and carefully grind down the head to absolutely flat and smooth. I should be able to make this head work and yield more compression.
And you are absolutely right: it is a slant plug head and that's where the leak/ fail is occurring.
In the next week, I am going to very slowly and carefully grind down the head to absolutely flat and smooth. I should be able to make this head work and yield more compression.
Timbone
Well-Known Member
I think I get it now. I gave my cylinder head a good look and, though it doesn't come through on the pics I've taken, the head is clearly warped. That flat standoff part that has the compression ring on it has an obvious v-like bend. I made a straight gauge to check for level and there was a significant gap on the rear part of the head (main leak) and a very small deviation in the front.
My plan is to smooth and flatten the compression ring on the head. I'll just have to do it slowly, making sure to take the metal off of the places where it's needed. That's not so easy for me because it's kinda hard to figure out where to start and where to finish.
My plan is to smooth and flatten the compression ring on the head. I'll just have to do it slowly, making sure to take the metal off of the places where it's needed. That's not so easy for me because it's kinda hard to figure out where to start and where to finish.
HeadSmess
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yup, get new head. it will never get better, you get the warp out, it will come back.
i much prefer the central plug heads, they dont tend to warp as they have more metal, a bridging piece between the two studs. this bridge is missing under the plug in the slant heads. though i have seen one that had the bridge...
less metal= more warping. keep that in mind when milling heads.
less teflon tape= better sealing. yes you do need the two surfaces to be flat. its useless if anythings seriously warped, it doesnt work as a washer but rather more like a liquid sealant. it oozes into the tiny little crevices.
i much prefer the central plug heads, they dont tend to warp as they have more metal, a bridging piece between the two studs. this bridge is missing under the plug in the slant heads. though i have seen one that had the bridge...
less metal= more warping. keep that in mind when milling heads.
less teflon tape= better sealing. yes you do need the two surfaces to be flat. its useless if anythings seriously warped, it doesnt work as a washer but rather more like a liquid sealant. it oozes into the tiny little crevices.
