Head milling Suggestions?

[Et2rnal Smoker]

Hey there fellas, I am a lifelong dirtbike guy who has recently decided to branch off into a quad, originally mostly for my daughters' benefit as they needed something they were comfortable riding and I am always happy to spend money on new toys. I picked up an 04 Blaster pretty reasonable and after spending a bit of saddle time on it myself I naturally want to massage a lil' more ummpphhh out of it soon. Not planning anything too fancy..just a new top end, DMC exhaust and jetting specs and am also wanting to have the head milled and reworked by reputable and experienced Blaster aftermarket shop to raise the compression some and create a more efficient combustion chamber. I know there is some more juice in that motor as it is in a pretty mild state of tune from Yamaha. Seeing as the Blaster motor is nothing more than an ol' IT 200 powerplant, I know they can have a bit more coaxed out of them rather easily. Any suggestions on the headwork would be greatly appreciated.
Thanks a bunch in advance.

 

[sicivicdude]

There is a lot that can be done with a blaster head. They're VERY mild in their stock format and luckily, there's a lot of meat in them for tuning purposes.

Before and after on a +4mm stroker crank head mod for a high rev pipe:

Stock stroke head rechambering for a "mid pipe":

 

[xKroniK13x]

There's lot of mechanics on here that you could look into. Each have their favorites.
Ken Oconnor Racing and Flotek will probably be your most recommended on here. You should call them both and talk to them and make a choice based on that. Very effective mod for a relatively cheap price I:I

 

[Triplecrown421]

there are many people that Know lots about makin powa with a rechambered head. The factory head squish and quench are very Mild, I think it was like over 1mm gap and you want that closed up to around 0.040. For any application its hard to beat the good old fashion Hemi head. When i started my first head i set out to copy the dt200, pretty darn good place to start yamaha themselves.

 

[dksix]

I think it was like over 1mm gap and you want that closed up to around 0.040.

:-/:-/:-/:-/:-/:-/:-/ Isn't .040" more than 1mm? :

 

[Triplecrown421]

Isn't .040" more than 1mm?

Yes Just Abit :-[

Lol that was weak of me, im off on numbers abit but i mean well. The gap between the head and piston on a stock is to much!!

 

[dksix]

Yes Just Abit :-[

Lol that was weak of me, im off on numbers abit but i mean well. The gap between the head and piston on a stock is to much!!

Just busting you balls, brother.....I know you know what you're talking about (even if no one else has a clue)

 

[best]

You are amongst friends here.
I am a dirtbike guy myself, swung over to the dark side by the light weight and simplicity of the Blaster.

Dang! SIcivicDude just let the whole secret to Blaster power out with this picture:

The 50%area hemi chamber, with a flattened 11 degree squish, 0.030-0.060" from the piston (squish distance) and about a 18-22cc head volume is the biggest power bump you can gain. The stock squish (for my numerically challenged kin!) is about 0.120" or about 3mm. Ideal is about 0.040" or 1mm.

Closer squish tends to rob power from excess compression and risks mechanical damage. Lower cc volumes help mid range torque but pump more heat into the piston.

I forget the name right now, but there was a builder on here that will cut a good head for you...

 

[Myblasterisblue]

Ken oconnor does great work. I recommend him for top end work

 

[dksix]

If I get my suspension and brakes done this week, I'm going to try doing a head or 2 next week. Can I measure the piston while the head is off to get a starting point for how deep to start the squish band in the head? How many thicknesses of head gaskets are on the market? I thought if I had the various thicknesses of head gaskets on hand, I could adjust the squish for testing. Since I have a leak free engine now and don't want to alter port timing during comparing, I'd rather not pull the cylinder or change base gaskets.

 

[joeak47]

Here's just a few I've done. The power increase is very noticeable. EVERYTHING WORKS BETTER! It takes the somewhat lazy "rev" of the stock engine,and makes it "rev up" much quicker and snappier. We're talking dirt bike rev! It will also pull sixth gear much better. Idle is also much crisper and pronounced. You won't need a timing advance with a properly rechambered head,because the head does all that for you with the much faster,more efficient burn.

If you couple a re-chambered head to a properly ported "Aggresive Trail ported" cylinder,you will be looking for 7th gear,because it will now pull 6th gear like 5th gear. You will be double the stock power output. A very fun ride!

Here's just a few of mine....

Here is a 19 CC "Hemi chamber" with an 11 degree 50% squish band. This is what I'm currently running.

Here is a 19.5 CC "Toroidal chamber" (donut shaped) with an 11 degree 50% squish band. This is what KTM runs on many of they're engines. I have not tested it yet. This was cut for a beta tester that will be testing it very soon.

Here they are side by side... Both of these are going to the same person for comparison tests between the hemi and the toroidal chamber shapes. That why the chamber sizes are very,very close.

Here is another. This one is cut to DT200 spects. It is 22CC "Hemi" chamber with a 11 degree squish and 40% band. It works awesome too,but focuses on the "Top end Rev" a bit more than the 50% band heads which focus the power more in the mid range.

Here is the same head cut to "DT 200 specifications" that I did a "step cut" to the sealing surface,so I could close up the squish distance.

Here's another shot showing the "step cut"...

All of the above heads that I've cut along with many others I've done give BIG power increases but with the ability to still run premium pump gas with NO DETONATION!
Thats icing on the cake!
Don't get sucked into the belief that you can just "shave" a bit off a stock head,get a power increase,and not get detonation. A "shaved" stock head will and does DETONATE once you take off around .030 thousands,and gives very little in the way of power.

If your feeling "experimental",perhaps you would like to try cutting your own?
They can be time consuming at first,but VERY rewarding. I can now cut a head in less than an hour including CC'ing the chamber size. Thats start to finish including the polishing of the band and chamber. I encourage people to try this modification! I:I

With the simplicity of the blaster,its as easy as 6 nuts,6 washers,and 20lb/ft of torque to swap things over and...back again if you desire.

 

[sicivicdude]

If I get my suspension and brakes done this week, I'm going to try doing a head or 2 next week. Can I measure the piston while the head is off to get a starting point for how deep to start the squish band in the head? How many thicknesses of head gaskets are on the market? I thought if I had the various thicknesses of head gaskets on hand, I could adjust the squish for testing. Since I have a leak free engine now and don't want to alter port timing during comparing, I'd rather not pull the cylinder or change base gaskets.

Stock head gaskets are .8mm or ~.032". I believe Vito's sells one thinner steel gasket (instead of the stock copper) but I'm awful leary of bolting together two pieces of aluminum around a chunk of steel instead of soft copper....

Joe, "percentage" of the squish area relative to the bore size is a function of the ability of the head to clear the old charge out at high speed and the distance that the piston has to push the charge. That's a build decision based on pipe and carburetor choice and is not an absolute rule. Trick is, the wider the squish area (the more of a percentage of the bore the squish area is) the more squish thickness you need! The piston, as it rises, is pushing the charge along the surface of the head. The farther that charge has to be pushed the more energy (heat) the piston is imparting on that charge. The "no detonation" claim at 40% bore area with a squish thickness of .040" might be true. However, increase that bore area percentage to 55% at .040" and it'll knock worse than a 1978 Oldsmobile diesel...

 

[best]

If I get my suspension and brakes done this week, I'm going to try doing a head or 2 next week. Can I measure the piston while the head is off to get a starting point for how deep to start the squish band in the head? How many thicknesses of head gaskets are on the market? I thought if I had the various thicknesses of head gaskets on hand, I could adjust the squish for testing. Since I have a leak free engine now and don't want to alter port timing during comparing, I'd rather not pull the cylinder or change base gaskets.

Short answer, yes, with a qualifier...
I am used to flat top pistons that are easier to measure to.
With them I find it pretty easy to measure up the various distances to get the finished squish exactly right.
Not so much with domed pistons. I find I have to do a mock up and solder test to get a good measurement.

As for headgasket and shimming the head, all the copper gaskets we have are the same thickness but I thought I saw a thinner one for sale somewhere. Hand cut gasket paper and aluminum shim gaskets can be used for trials because no coolant is involved. The reality is that unless you know exactly what you want, there is a wide range of clearances that will work, and if you are cutting your own you can easily go back in for a second cut.

This is a simple thing. If you are cutting a new chamber and squish band it only gets a little bit more complicated with the new cut shape.
If you are just trying to get the squish right, do a solder test to get the measurement and then cut the head if you have an exact measurement in mind.

Steve

Somehow I posted this before seeing Joe and James answers. They are both totally right in my experience.
I liked SICivicDude's explanation of squish width/clearance/and energy. That is why more band and
less clearance are not always better. There is an optimum point.

 

[sicivicdude]

There is an optimum point.

For a particular, exact setup. That's what I refer to as a "widow's peak" configuration.

There is also a decent "round figure" point for a lot of different setups that is also nearly completely optimized. That's how the round figure of .050" squish came to be. In my experience, .040" squish is too little for a high rev pipe with an aircooled head after it gets a little carbon on it.

The extra .010" isn't a huge drop in velocity of the charge or cranking compression (the chamber size can be reduced to compensate) but it does allow a little extra "fudge factor".

I think I'm going to do a write-up on overall head design theory and actual practice. I think for those who do not have a lathe a how-to isn't practical but even for those who are purchasing their headmods, it would be nice to understand the principles involved. Look for a twin to the "squish, mystery or not?" thread.

 

[Et2rnal Smoker]

Thanks alot for all your info... I've read quite a bit of good about Ken O Conner racing on here and I beleive I will give 'em a call. Any suggestions on the best piston for the Blaster? More specifically I'm wondering about the Wiseco "Superlite" as well as the Vito's equivelent and the claims of 5hp increase as well as the potential strength and reliability of a piston with that much cutaway built into it. Anyone have any experience with them?

 

[scotj77]

most of us run weisco pistons round these parts. the people who call them junk and say they blew up the first day they ran it probably had massive airleaks that caused the piston to seize. weisco is a forged piston and it won't disentagrate with overheating it will swell and seize in the cylinder. a cast piston is more likely to disentagrate slowly and keep running giving the false impression of it being better but all those small particles coming from the piston wind up in your crank bearings. as for the vitos.... never ran one so i can't really say. the moral of the story is to make a leak free engine and do proper maitnance and inspections on it

 

[tommysaxboy]

joe(joeak47) do you work on other ppl's blaster heads? send me a pm please.

 

[Awk08]

@ tommysaxboy.........

i forwarded that post/info to JoeAk for ya !!!
and deleted your personal info from the worlds eyes

 

[wwholden]

You are amongst friends here.
I am a dirtbike guy myself, swung over to the dark side by the light weight and simplicity of the Blaster.

Dang! SIcivicDude just let the whole secret to Blaster power out with this picture:

The 50%area hemi chamber, with a flattened 11 degree squish, 0.030-0.060" from the piston (squish distance) and about a 18-22cc head volume is the biggest power bump you can gain. The stock squish (for my numerically challenged kin!) is about 0.120" or about 3mm. Ideal is about 0.040" or 1mm.

Closer squish tends to rob power from excess compression and risks mechanical damage. Lower cc volumes help mid range torque but pump more heat into the piston.

I forget the name right now, but there was a builder on here that will cut a good head for you...

Maybe you were thinking about me? Haha

Im still turning heads and experimenting. If the OP is interested check out the link in my signature.

 

[joeak47]

Motocrossguy17..."The Hemi head raffle winner"
You should have your head this week I believe...

Before...

After...

Now I can say that I officially have one of my heads in Scotland!!! I:I