Birdoprey
Well-Known Member
What is the typical piston-to-valve clearance on a stk V-max? How much can safely be milled off the head?
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Not sure on the head but you can take .040 off the block.
Sean
Sean
mymax04
Well-Known Member
did we ever find the answer to this question cause i was thinkin bout what i wanna do this winter & head work comes to mind like port, polish, mill? has neone done this and seen worthwhile gains?
RagingMain
Well-Known Member
Sean wouldnt taking some off the head be easier?:confused2:
Guess what I am asking is why the block and not the head, seems like it would be the same either way:confused2:
namyzzo
Well-Known Member
How much - guesstimate, would this raise compression?..etc..
I have been sitting on some goodies for awhile now and getting closer to using them... I have a 1996 crank/rods..1986 Cams/heads/block(cases)....New Yamaha Pistons/Rings (0.50MM O/S)..A seal/Gasket kit - from the internet (not sure of the cylinder/head gasket dimensions..etc..)
No blower intentions...nitrous would be interesting
...Anyways, would it be a good idea for me to deck the block/cylinders, with different head gaskets - would that maybe get my compression back up OR ??....
Whats best ?? n should I worry about decking the block over whats needed to make it true/flat...
:ummm:
Thevmaxrider
Well-Known Member
I know that PCW decks the block and takes JG flat top pistons and cuts valve reliefs into them custom to fit. Makes me think that the clearances may be a wee bit close, especially if you start tinkering with valve timing etc.
Milling the head does not tighten up your squish band. It does decrease combustion chamber vol, raising compression. By milling the block you get a tighter piston to head clearance arround the outside of the combustion chamber. This causes turbulence in the chamber helping in a better burn of the mixture. It also reduces the chance of pre ignition. You can only go so tight on this clearance also.
Jim
Jim
I will note that if you change either by much the exhaust will be much harder to install. I do not suggest to take much off of either. Get custom pistons that sit higher in the bore.
Sean
Sean
snowprophet1
Active Member
Another point to make, is that you could take the same amount off either the head (easier) or block, (harder) but you would raise the compression more by taking it off the block (or smaller head gaskets) because you would be raising the compression by the area of the bore diameter and thickness (block or gasket change) whereas the removal of head material would be the thickness removed and the area of the dome in the head (less). Also by removing it from the head not only would it be less of a compression ratio change, but the valves would be closer to the piston WITHOUT the benefit of the squish clearance changing. As the plug fires and starts buring the mixture, the piston goes down. Whatever is shrouded in the squish area does not get burnt until "x" amount of degrees crank rotation (I forget the approximate degrees) and even though it gets burned up, does not bring any hp to the table at that time. If squish clearance is tightened up, it brings the more turbulance, etc as mentioned already, and there is more mixture available to be used as power.unk:Win-win!
unk:Win-win!
mymax04
Well-Known Member
all right so this kinda thing is new to me. It sounded good as a thought, but what i get from what has been said ...... no on milling the head, how about port and polish? is this something i can do with a small amount of direction? or is it even worth the time?......ive read & believe and it is obvious the japs were ahead of the game on most things when they built this thing so I guess im just thinking out-loud:ummm:
I have a similar question. Does any one know if the thickness size of the head gasket matters with ross racing pistons. I don't have the heads or block milled.
The reason I ask is the one I got from cometic is .030" and the one I took off the motor was approximately .080" (also cometic).
Just worried about valve piston clearance with the ross racing pistons (even though there is valve impressions in the ross pistons). Will the .030" head gasket work? Hopefully this all makes sense.
The reason I ask is the one I got from cometic is .030" and the one I took off the motor was approximately .080" (also cometic).
Just worried about valve piston clearance with the ross racing pistons (even though there is valve impressions in the ross pistons). Will the .030" head gasket work? Hopefully this all makes sense.
