Decking the head and port tips?

Tashka · 08-25-2018, 01:42 PM

My head gasket is leaking oil, so I think thst the problem is that the bolts holding the head on are loose. since I would be pulling the rocker assembly and tank to be able to tighten, I thought I might aswell do some port work and to deck the head while I'm at it.

What did yall guys use to deck the head? Did yall take it to a machine shop and have it done, or did you use a miter saw or something?

Also any tips for porting? I know to go slow, more is less,
cover the valve seats with duct tape. Any areas in particular that might need some cheerfulness and special touch?

I've never ported or decked a head before. I am sufficient in the use of power tools though. I'm On the quest to hotrod my hawk, lol

**JerryHawk250** · 08-25-2018, 03:04 PM

I ported and decked the head myself. Click on the link in my signature for more info. As far as decking I used sand paper taped to a thick piece of glass or you could use flat steel plate as long as it is good and flat. There are YouTube videos on this process. I removed 1mm which will put you at 10:1 compression ratio. I've got a good bit of experience in this technic from years of building performance outboard engines. Check Megadan and Silva' s threads as they have done porting and decking too. Porting will be a big improvement as the exhaust side is very restrictive.

Azhule · 08-25-2018, 08:00 PM

For the intake porting, I like to "think outside the box"

Chinabike · 08-26-2018, 02:20 AM

stupid question? But what is Decking the head and port

slowroller · 08-26-2018, 06:28 AM

Carry to machine shop decking and multiangle valve job. Graphite gasket may seal on homebrew job but not on a steel shim like im using. Most porting will help more on exhaust side if stock head. Porting with a single cut valve seat will not be as effective as could be. First inch from valve seat most important. Decking cylinder will help to my piston .030 in hole + .041 for head gasket = alot. Anything done on exhaust side will help dont cut into spring pocket.

Tashka · 08-26-2018, 11:18 AM

So I only want to shave about a mm off, if even, from the ports?

I have lots of glass availablw at my job that my boss wouldn't mind me taking. what grit of sand paper did you use? Do you think 10.5:1 or 11:1 would be too much for the engine? should I jsut stick with 10?

Any issues with clearance when decking? i was planning to get a brisk spark plug and I've heard itd a little longer thsn stock or ngk. should it still clear with no worries?

Tashka · 08-26-2018, 11:19 AM

Also about how long did it take decking thr head with sand paper and glass?

ben2go · 08-26-2018, 12:13 PM

Quote:

Originally Posted by Chinabike

stupid question? But what is Decking the head and port

Decking is machine the head surface down where it mates to the cylinder block to get a higher compression. Porting is enlarging the intake and exhaust runners in the head to make them larger and be able to flow more fuel and air into the engine and push more exhaust gasses out. If these are done properly, more HP and torque can be made.

**JerryHawk250** · 08-26-2018, 05:11 PM

Quote:

Originally Posted by Tashka

Also about how long did it take decking thr head with sand paper and glass?

It took me about half an hour and lots of elbow grease. Lol. I started with 100 grit and finished it up with 220.
I used the depth gauge on my caliper and a good straight edge to measure my starting depth. Pick a point for reference and use that same point every time you take a measurement. With the 100 grit sand paper taped to a thick piece of glass, I placed the head flat. Using only the weight of the head I start moving the head back and forth rotating the head every 4th or 5th stroke to remove material evenly. Take measurement often as it doesn't take long to remove 1mm of aluminum. When you get close to the depth you want finish it up with the 220 grit. These heads are small and don't take long to mill them down with this method. If you don't feel comfortable doing it them bring it to a machine shop.

Tashka · 08-26-2018, 09:30 PM

I'll do it myself lol. Save that money, it doesn't sound too hard to do at all.

I don't have a caliper, but I was thinking that I could lay the head on the glass, take my feeler gauge set and put the bottom 2 together that make about 1.06 mm (might be alittle different, cant remember exactly. and take a pencil and mark it around the head with the feeler gauge being the measurement. That sound like it would be good?

would it be good to grind the intake manifold to make it a little larger diameter?

In your opinion what would be the and compression ratio you think would be safe for the engine? i might play it safe and aim for 10:1 but if I can squeeze more power out i will.

**JerryHawk250** · 08-27-2018, 08:37 AM

Quote:

Originally Posted by Tashka

I'll do it myself lol. Save that money, it doesn't sound too hard to do at all.

I don't have a caliper, but I was thinking that I could lay the head on the glass, take my feeler gauge set and put the bottom 2 together that make about 1.06 mm (might be alittle different, cant remember exactly. and take a pencil and mark it around the head with the feeler gauge being the measurement. That sound like it would be good?

would it be good to grind the intake manifold to make it a little larger diameter?

In your opinion what would be the and compression ratio you think would be safe for the engine? i might play it safe and aim for 10:1 but if I can squeeze more power out i will.

Don't know how accurate that method would be. Invest in a cheap HF caliper or use a ruler to take the measurements.

You can port match the intake and intake side of the head if you plan on porting the head. The intake should flow more than the stock PZ30 carb as it is.

Anything above 10:1 you will start to run into issues with the engine running hot. Adding an oil cooler will help on cooling oil and engine.

MDStroup · 08-28-2018, 04:45 PM

What kind of performance increase did you gain on the hawk after decking and porting the head?

**JerryHawk250** · 08-28-2018, 05:34 PM

Quote:

Originally Posted by MDStroup

What kind of performance increase did you gain on the hawk after decking and porting the head?

Big improvement in power from mid to high rpm range. Throttle response is almost instant when you blip the throttle. Can cruise 60-65 without having to wring the throttle all the way. Just feels stronger all around. Definitely worth the effort.

Gh426 · 08-28-2018, 05:58 PM

Rrunning a thinner head gasket, perhaps with some spray on copper sauce, will increase compression on the cheap and EZ, If you mill and go thin gasket I've seen folks reassemble with a lump of play DOH! on the piston, (sans gas or spark) to check for valve interference.

If you increase the Compression alot you will need 93 octane and/or alky or ? to compensate, yes oil cooler good idea for longevity and overall performance / insurance.

I've seen folks do the old jewelers rouge, ie fine grit stuff to polish both valve and seat, the poor mans 3 angle. I personally would NOT hook up a power drill in this procedure tho...

I would think just SMOOTHING of bowls, runners, intake?, pipe? would yield HUGE torq/hp/ seat o pants POW-R!! removing as much as 1 mm may get a bit dicey, ie a warped head down the road 1000 miles or more.

blue painters tape to protect seats etc duct tape maybe a tad too thick? dunoo

Whatever your result PLEASE post pics, info for US ALL to bench race etc with.

Good luck
GH

Tashka · 08-30-2018, 03:43 AM

Quote:

Originally Posted by JerryHawk250

Don't know how accurate that method would be. Invest in a cheap HF caliper or use a ruler to take the measurements.

You can port match the intake and intake side of the head if you plan on porting the head. The intake should flow more than the stock PZ30 carb as it is.

Anything above 10:1 you will start to run into issues with the engine running hot. Adding an oil cooler will help on cooling oil and engine.

Do you think i will have any issues with overheating if I increase the compression and don't add oil coolers.

08-25-2018, 01:42 PM	#1
Tashka Join Date: Aug 2018 Posts: 158	Decking the head and port tips? My head gasket is leaking oil, so I think thst the problem is that the bolts holding the head on are loose. since I would be pulling the rocker assembly and tank to be able to tighten, I thought I might aswell do some port work and to deck the head while I'm at it. What did yall guys use to deck the head? Did yall take it to a machine shop and have it done, or did you use a miter saw or something? Also any tips for porting? I know to go slow, more is less, cover the valve seats with duct tape. Any areas in particular that might need some cheerfulness and special touch? I've never ported or decked a head before. I am sufficient in the use of power tools though. I'm On the quest to hotrod my hawk, lol
	0

08-25-2018, 03:04 PM	#2
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,561	I ported and decked the head myself. Click on the link in my signature for more info. As far as decking I used sand paper taped to a thick piece of glass or you could use flat steel plate as long as it is good and flat. There are YouTube videos on this process. I removed 1mm which will put you at 10:1 compression ratio. I've got a good bit of experience in this technic from years of building performance outboard engines. Check Megadan and Silva' s threads as they have done porting and decking too. Porting will be a big improvement as the exhaust side is very restrictive. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	0

08-25-2018, 08:00 PM	#3
Azhule Join Date: Dec 2015 Location: CO Posts: 1,525	For the intake porting, I like to "think outside the box" __________________ "Think as you like... but this self proclaimed Professor is always right" - Buckshot "You never know what someone is hiding beneath their smile..." - NinjaTom - R.I.P.
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08-28-2018, 05:58 PM	#14
Gh426 Join Date: Feb 2018 Location: LA Posts: 74	idea's Rrunning a thinner head gasket, perhaps with some spray on copper sauce, will increase compression on the cheap and EZ, If you mill and go thin gasket I've seen folks reassemble with a lump of play DOH! on the piston, (sans gas or spark) to check for valve interference. If you increase the Compression alot you will need 93 octane and/or alky or ? to compensate, yes oil cooler good idea for longevity and overall performance / insurance. I've seen folks do the old jewelers rouge, ie fine grit stuff to polish both valve and seat, the poor mans 3 angle. I personally would NOT hook up a power drill in this procedure tho... I would think just SMOOTHING of bowls, runners, intake?, pipe? would yield HUGE torq/hp/ seat o pants POW-R!! removing as much as 1 mm may get a bit dicey, ie a warped head down the road 1000 miles or more. blue painters tape to protect seats etc duct tape maybe a tad too thick? dunoo Whatever your result PLEASE post pics, info for US ALL to bench race etc with. Good luck GH
	2

08-26-2018, 02:20 AM	#4
Chinabike Join Date: Jan 2018 Posts: 361	stupid question? But what is Decking the head and port
	0

08-26-2018, 06:28 AM	#5
slowroller Join Date: May 2018 Posts: 77	Carry to machine shop decking and multiangle valve job. Graphite gasket may seal on homebrew job but not on a steel shim like im using. Most porting will help more on exhaust side if stock head. Porting with a single cut valve seat will not be as effective as could be. First inch from valve seat most important. Decking cylinder will help to my piston .030 in hole + .041 for head gasket = alot. Anything done on exhaust side will help dont cut into spring pocket.
	0

08-26-2018, 11:18 AM	#6
Tashka Join Date: Aug 2018 Posts: 158	So I only want to shave about a mm off, if even, from the ports? I have lots of glass availablw at my job that my boss wouldn't mind me taking. what grit of sand paper did you use? Do you think 10.5:1 or 11:1 would be too much for the engine? should I jsut stick with 10? Any issues with clearance when decking? i was planning to get a brisk spark plug and I've heard itd a little longer thsn stock or ngk. should it still clear with no worries?
	0

08-26-2018, 11:19 AM	#7
Tashka Join Date: Aug 2018 Posts: 158	Also about how long did it take decking thr head with sand paper and glass?
	0

08-26-2018, 09:30 PM	#10
Tashka Join Date: Aug 2018 Posts: 158	I'll do it myself lol. Save that money, it doesn't sound too hard to do at all. I don't have a caliper, but I was thinking that I could lay the head on the glass, take my feeler gauge set and put the bottom 2 together that make about 1.06 mm (might be alittle different, cant remember exactly. and take a pencil and mark it around the head with the feeler gauge being the measurement. That sound like it would be good? would it be good to grind the intake manifold to make it a little larger diameter? In your opinion what would be the and compression ratio you think would be safe for the engine? i might play it safe and aim for 10:1 but if I can squeeze more power out i will.
	0

08-28-2018, 04:45 PM	#12
MDStroup Join Date: Apr 2016 Location: Chesapeake, VA Posts: 207	What kind of performance increase did you gain on the hawk after decking and porting the head?
	0