Head Milling and what it does to you...

[Outlawed Genetics]

would more pics help you guys know for sure what was done? i've got a very good camera capable of very close up shots as long as i can avoid glare from the flash

(canon 40d/30d with canon 60mm macro lens and canon mr-14 macro ring flash)

 

[lasxgames]

good post !!!!!!!!!!!!!!!!!!!!!

 

[2smoker85]

they fuct ur sh*t up outlaw, send it to someone to fix it, otherwise you will more than likely have low compression and the possibility of detonation, because that is garbage, but you could be fine on the other hand, if you feel you want to test it, put comp tester on it before you run the head on there.

 

[blasterman87]

the center part is just cleaned with a wire brush/wheel, the squish band is not modified, only the head shaved.. it is safe, its just a shaved head nothing else is modified(squish band) they could have cleaned the carbon off it better but that wont effect proformance at all, bolt it up and do a compression test, before and after, let us know what it is but either way, its fine

 

[jrt1470]

Great post!! I just was wondering if you have a good machine shop to recommend, then i could ship my 2001 head to them. Thanks

 

[waltermmckown]

are the heads the same for all years? mine is an 06'. you know, grab a decent used one and send it out?

 

[yfz450bence]

are the heads the same for all years? mine is an 06'. you know, grab a decent used one and send it out?

yup you can do that, threres over 30 of them on ebay, choose your weapon of choice

 

[specialized7]

send her to flotek, kennedy , or wildcard

 

[waltermmckown]

thank you! this site actually works! ask a question and people answer. been on other sites and its an eternal flame war.

 

[ClimbAnyHill]

And keep elevation in mind when deciding on how much to deck out!
I'm at sea level so I get the most bang for the buck with a head mill.

 

[Little-J]

So wait a minute.. Ive gotten lost in this post. Are we agreed that the stock compression ratio is about 6.6:1? Thats what I found in a Yamaha service manual i downloaded..

I dont think my heads been shaved, but my exhaust port has been raised, so this gives me abilty to shave a bit more than normal off my head since more of the fuel charge gets blown out of the exhaust port?

I was thinkin of getting a few heads n see how high i can get the compression ratio before i get detonation issues.. I may modify my stator plate to drop the ignition timing back 1 or 2 degrees..

 

[Little-J]

So, are we all in agreement that the stack compression ratio of a blaster is about 6.6:1? thats what I found in a yamaha service manual with extensions for all years..

Also, I can get away with shaving more than average off my head because the exhaust port has been raised n therefore more of the fuel air charge will escape?
Anythoughts on high compression n dropping the spark advance back 1 or 2 degrees?

 

[racecar]

Just Shaving the head is a NO NO!
This process will put the spark plug closer to the Piston, This will cause the Piston dome to over heat and cave in? What ever you cut off the head you will have to machine that much out of the spark plug threds in the dome of the head and use a spark plug spacer on the plug. Many of the motors that have come to me have had a failure do to this process, It is very time consuning to machine a head to raise the compression ratio, and still maintain a maintance free engine. when you shave a head the squish band WIDTH and the Angle of the squish becomes critical for performance and duribility.

 

[Paulie B]

Just Shaving the head is a NO NO!
This process will put the spark plug closer to the Piston, This will cause the Piston dome to over heat and cave in? What ever you cut off the head you will have to machine that much out of the spark plug threds in the dome of the head and use a spark plug spacer on the plug. Many of the motors that have come to me have had a failure do to this process, It is very time consuning to machine a head to raise the compression ratio, and still maintain a maintance free engine. when you shave a head the squish band WIDTH and the Angle of the squish becomes critical for performance and duribility.

I've been running one for years and have not noticed any of what your saying.

 

[Little-J]

Just Shaving the head is a NO NO!
This process will put the spark plug closer to the Piston, This will cause the Piston dome to over heat and cave in? What ever you cut off the head you will have to machine that much out of the spark plug threds in the dome of the head and use a spark plug spacer on the plug. Many of the motors that have come to me have had a failure do to this process, It is very time consuning to machine a head to raise the compression ratio, and still maintain a maintance free engine. when you shave a head the squish band WIDTH and the Angle of the squish becomes critical for performance and duribility.

Yes, ok, but this is of course subject to the heat range of the plug and the thickness of the piston crown. There are mass manufactured "high compression" gasket kits that bring the crown closer to the plug electrodes and they have good reviews. im not talking about changing the combustion chamber geometry, just taking off about 0.5 to 0.75 mm off the head gasket seat. I can always pull the head off after a few hours and check for a hot spot on the piston crown..

 

[blasterbogger]

is it good if i run 40:1

 

[underwaterboy82]

if you are askin about the oil mixture then no, run 32:1 if you are mixing your own gas.

my question is if the head in nicked up pretty bad how much would i have to mill it or would i have to buy a new head. if pics are needed i can add them later

 

[*Quad*King*1986]

Keep in mind that differents cranks will affect your compression ratio as well. If you truly need to understand and know where your compression ratio is here is the formula....

CR=(D + PV + DC + G + CC) / (PV + DC + G + CC)

CR = Compression Ratio

D = Displacement

PV = Piston Volume

DC = Deck Clearance Volume

G = Gasket Volume

CC = Combustion Chamber Volume

Hope that helps clear things up a bit...

I wish I paid better attention in math class! Lol, that actually confused me more

 

[best]

Just Shaving the head is a NO NO!
This process will put the spark plug closer to the Piston, This will cause the Piston dome to over heat and cave in? What ever you cut off the head you will have to machine that much out of the spark plug threds in the dome of the head and use a spark plug spacer on the plug. Many of the motors that have come to me have had a failure do to this process, It is very time consuning to machine a head to raise the compression ratio, and still maintain a maintance free engine. when you shave a head the squish band WIDTH and the Angle of the squish becomes critical for performance and duribility.

I'll betcha this guy doesn't know the Blaster sparkplug is 0.850" (or 21.6mm) from the piston. Shave it all you want, you are going to have a hard time getting it within 1/2" (0.500" or 12.5mm) which is where I'd really like to see it.

With the stock head you can experiment by removing the base gasket and sealing it up with Yamabond sealer or hand cut paper gaskets (0.006" = 0.15mm) to drop the cylinder the amount you plan to skim off the head. The proper gasket is 0.030" so leaving it out will tell you what a 0.030" cut will do. We also measured the squish distance on the stock head, came out to 0.110", a bit large. We ran the cylinder 0.020" low for 0.090" squish and got spark knock on the stock engine and only slight performance increase in the mid-range. It did spark knock in our engine at max speed and power.

No good.

So experiment #2, we opened up the chamber on the head. Hemispherical bowl of about 1.900" diameter as opposed to the Blaster 1.300" chamber.
Awesome difference even with still big squish gap of 0.070" and messed up squish angle. Chamber shape is critical for power in these Blasters. Head skimming is a waste of your time until it is rechambered by an expert.

Experiment #3 raised the exhaust port and skimmed the rechambered head another 0.010". WOW! This machine is running strong, engine screams like a motorcrosser and yet still lots of low end. Skimming the head an additional 0.010" made no big diference. Here is the head shape:

That is the state of tune in this vid: