Cylinder head porting?

Need advice on which oil to use or which tyre best suits you? Share your topic and get help here.
User avatar
Varastorm
Posts: 1088
Joined: Mon Apr 07, 2014 10:48 pm
Location: Isle of Anglesey

Cylinder head porting?

Post by Varastorm » Fri Jun 27, 2014 11:25 pm

Hi,

Just purchased a set of VTR heads and will be overhauling them over the next month or so.

Has anyone any top tips on porting the VTR heads? What have you done & has it worked?

I am not looking for mega gains, only a little port cleaning. Any pictures of jobs people have done etc, might help.

I have done some porting years ago on a Austin MG Midget, A series & I used a David Vizard book (excellent read) as a guide.

Also Honda XL engine, which were easy due to no matching of the ports, until I cut into the inlet valve spring seat...... Happy days...

All I have is a compressor, die grinder, tungsten bits & patience.

No flow bench!

As usual, any help greatfully recived.

Regards.

User avatar
8541Hawk
Posts: 1639
Joined: Sat Jul 21, 2012 4:21 am
Location: Bosque Farms, NM

Re: Cylinder head porting?

Post by 8541Hawk » Fri Jun 27, 2014 11:39 pm

Clean the flash out and if you are real adventurous flatten the floor of the bowl just a touch and that is about all you need. :thumbup:
They call me "Mr. Flat Earther"

NZSpokes
Posts: 643
Joined: Sat May 31, 2014 9:50 am
Location: Auckland, New Zealand

Re: Cylinder head porting?

Post by NZSpokes » Sat Jun 28, 2014 3:39 am

8541Hawk wrote:Clean the flash out and if you are real adventurous flatten the floor of the bowl just a touch and that is about all you need. :thumbup:
What kind of gains would you expert from this? would you do exhausts as well?

User avatar
Stephan
Posts: 935
Joined: Sun Apr 15, 2012 5:58 pm
Location: Prague, Czech

Re: Cylinder head porting?

Post by Stephan » Sat Jun 28, 2014 5:08 am

8541Hawk wrote:Clean the flash out and if you are real adventurous flatten the floor of the bowl just a touch and that is about all you need. :thumbup:
can you write it up a bit more? To be honest, in this case I don´t understand what you say :-)

Roger Ditchfield
Posts: 144
Joined: Tue Apr 26, 2011 5:55 pm

Re: Cylinder head porting?

Post by Roger Ditchfield » Sat Jun 28, 2014 11:13 am

Be very careful when porting fully other than cleaning up the rough edges/surfaces. To do a full porting job, which should vary depending on the camshafts you install and the exhaust you are using, I suggest you take expert advice or send the heads to an experienced company used to dealing with "V" twins. A full porting job involves a slight difference between the front and rear heads. If you "overport", which is often done by firms using "flow benches" but with little experience of "V" twins the gas speed in practice drops too low with disappointing consequences that are difficult to reliable rectify. Take care and Good Luck

NZSpokes
Posts: 643
Joined: Sat May 31, 2014 9:50 am
Location: Auckland, New Zealand

Re: Cylinder head porting?

Post by NZSpokes » Sat Jun 28, 2014 8:47 pm

Another question on this line then, when a head is off is there a benefit in skimming it to raise compression?

User avatar
8541Hawk
Posts: 1639
Joined: Sat Jul 21, 2012 4:21 am
Location: Bosque Farms, NM

Re: Cylinder head porting?

Post by 8541Hawk » Sat Jun 28, 2014 10:04 pm

NZSpokes wrote:Another question on this line then, when a head is off is there a benefit in skimming it to raise compression?
Micky did it to his with what seemed like good results.

As for my comments on porting, it is pretty much the same as what Roger has said.
I was given my info from the Mori boys but it followed the same lines.
Just clean up any flash (or rough spots) in the ports but don't reshape them.
Then there is a little to be gained by a minor bit of work the the floor of the bowl, though it is very easy to take too much and cause yourself problems and end up making less power so it really isn't worth the time or effort.
For the street that is about all you will ever need.

On a race engine, yeah you can go to over-sized valves, if you can find or afford them.
That will give you an extra 1mm on the intake and .5mm on the exhaust.
You should also try to set the valves as far to the outside as you can.
Then porting to match the cams and other mods but you end up with a "race" bike.
IMHO those really are not much fun to ride on the street.

To sum things up, porting will not get you much by itself and with a stock or fairly stock engine.
In fact IMHO it is not really worth the time and cost to pull the heads to do it.

On the other hand it is pretty easy to do and if the heads are already off..... well it doesn't hurt either, unless you go wild in there.
They call me "Mr. Flat Earther"

NZSpokes
Posts: 643
Joined: Sat May 31, 2014 9:50 am
Location: Auckland, New Zealand

Re: Cylinder head porting?

Post by NZSpokes » Sun Jun 29, 2014 2:46 am

8541Hawk wrote:
NZSpokes wrote:Another question on this line then, when a head is off is there a benefit in skimming it to raise compression?
Micky did it to his with what seemed like good results.

As for my comments on porting, it is pretty much the same as what Roger has said.
I was given my info from the Mori boys but it followed the same lines.
Just clean up any flash (or rough spots) in the ports but don't reshape them.
Then there is a little to be gained by a minor bit of work the the floor of the bowl, though it is very easy to take too much and cause yourself problems and end up making less power so it really isn't worth the time or effort.
For the street that is about all you will ever need.

On a race engine, yeah you can go to over-sized valves, if you can find or afford them.
That will give you an extra 1mm on the intake and .5mm on the exhaust.
You should also try to set the valves as far to the outside as you can.
Then porting to match the cams and other mods but you end up with a "race" bike.
IMHO those really are not much fun to ride on the street.

To sum things up, porting will not get you much by itself and with a stock or fairly stock engine.
In fact IMHO it is not really worth the time and cost to pull the heads to do it.

On the other hand it is pretty easy to do and if the heads are already off..... well it doesn't hurt either, unless you go wild in there.
I would only do it if there was another reason to go there. I need the bike ride-able to work in traffic everyday.

Which leads me to the next question, would it be better to fit the JE pistons or to skim the head?

So do the JE piston create a better squish area or are significantly lighter?

From what i have read there is a very small gain to be had with running 2 exhaust valves but is the a cam profile I can get ground that creates more power with out killing ride-ability down low?

User avatar
Stephan
Posts: 935
Joined: Sun Apr 15, 2012 5:58 pm
Location: Prague, Czech

Re: Cylinder head porting?

Post by Stephan » Sun Jun 29, 2014 5:32 am

8541Hawk: thanks for info :)

Roger Ditchfield
Posts: 144
Joined: Tue Apr 26, 2011 5:55 pm

Re: Cylinder head porting?

Post by Roger Ditchfield » Sun Jun 29, 2014 6:17 pm

In theory the maximum amount to skim off VTR heads with Moriwaki Hi-comp 10.6:1 pistons is 1mm or 40 thou. In practice I used 38 thou to be safe and used the same with JE Hi-comp 11.1 : 1 pistons

tony.mon
Posts: 13675
Joined: Wed Jul 25, 2007 9:46 pm
Location: Norf Kent

Re: Cylinder head porting?

Post by tony.mon » Sun Jun 29, 2014 7:27 pm

Roger Ditchfield wrote:In theory the maximum amount to skim off VTR heads with Moriwaki Hi-comp 10.6:1 pistons is 1mm or 40 thou. In practice I used 38 thou to be safe and used the same with JE Hi-comp 11.1 : 1 pistons
Roger; that wouldn't apply with oversize inlet valves as well, would it?

I'll be adding those after the obligatory dyno runs between each mod.
It's not falling off, it's an upgrade opportunity.

User avatar
Varastorm
Posts: 1088
Joined: Mon Apr 07, 2014 10:48 pm
Location: Isle of Anglesey

Re: Cylinder head porting?

Post by Varastorm » Sun Jun 29, 2014 7:42 pm

Hi,

Thanks for all the help & information guys, really appreciate it.

I have also been reading the "porting" threads on "The unofficial SuperHawk" forum, trying to gain as much info an I can before I plunge the burr into anything!

As I have not got the heads at the moment, I have used some picture's from the above forum for reference only. I hope it's ok?

INLET

http://www.superhawkforum.com/forums/at ... 09-003-jpg

EXHAUST

http://www.superhawkforum.com/forums/at ... 09-009-jpg

I was also going to blend the casting around the valve guides also? Not the severe porting as this picture below, only around the valve guide area!

http://www.superhawkforum.com/forums/at ... g_0709-jpg

I was reading about the various tools used for porting work & saw some awesome porting work with a 90 degree die grinder with an extended mandrel.( http://i40.tinypic.com/2ztengh.jpg ) Looks like the tools for the job to me.

http://i44.tinypic.com/s43mlx.jpg

http://i39.tinypic.com/104rkgy.jpg

On the i39 picture, is that the "flattening" of the inlet you are talking about 8541Hawk? Also is there a need to open the inlet tract that wide? The last time I went down that road I broke into a valve seat........

I also came across this seller on ebay (headportingsupplies) who had porting tools for sale.

http://headportingsupplies.co.uk/index. ... ation_id=4

Are these the tools for the job?

Mega thanks again guys, for all your help.

Regards.

Roger Ditchfield
Posts: 144
Joined: Tue Apr 26, 2011 5:55 pm

Re: Cylinder head porting?

Post by Roger Ditchfield » Sun Jun 29, 2014 8:54 pm

tony.mon wrote:
Roger Ditchfield wrote:In theory the maximum amount to skim off VTR heads with Moriwaki Hi-comp 10.6:1 pistons is 1mm or 40 thou. In practice I used 38 thou to be safe and used the same with JE Hi-comp 11.1 : 1 pistons
Roger; that wouldn't apply with oversize inlet valves as well, would it?

I'll be adding those after the obligatory dyno runs between each mod.
YES - THIS WAS WITH O/SIZE VALVES

User avatar
Bleh
Posts: 153
Joined: Sat Nov 02, 2013 11:11 am
Location: Sunny Swansea, South Wales

Re: Cylinder head porting?

Post by Bleh » Mon Jun 30, 2014 9:09 am

Obviously, an experienced tuner is going to be the best person to advise you accordingly, but...

If I can put a theoretical spin on it. In the last 6 months, as part of one of my degree modules, I spent quite a bit of time with a flow bench and doing LOTS of calculations for the flow of gases into an engine and methods of increasing an engines performance through just its inlet system.

Porting is without doubt one of the most important improvements you can make on your engine but it can also have the reverse effect if it's overdone - excessive mixture can cause the undesirable detonation effect (when part of the mixture remains temporarily unburnt) and/ or loss of performance/ power.

If road riding/ commuting is your main intention for riding, polishing the ports (as previously suggested if I recall) would be all you need with the right combination of velocity stacks to compliment it. A good job here will significantly reduce any frictional resistance of gases/ mixture on the port walls and ensure a very good and improved introduction of fuel/ air mix into the combustion chamber.
Once you're happy with your improvements and have ridden around for a while and one day decide you want a bit more (again), a selection of good cams would be (personally) the next thing. Altering the valve (open) duration would again introduce more mixture into the engine to aid your performance enhancements accordingly.
Finally, increasing the valve sizes at any point WOULDN'T benefit you in any way if you intend on only using the bike on the road - it would likely have the reverse effect and make the bike so lumpy and uncomfortable to ride on the road you'd have to sell it as a track bike project with the engine mostly already done!

If we can just look at it logically for a second;
1) Polished ports = increased intake area (overall) = more fuel mix in
2) Upgraded cams = adjusted valve duration = more fuel mix in
3) Larger valves = larger area for entry = more fuel mix in

So 1+2 = good stuff... Pushing to the point of maximum 'enjoyable' potential for the bike on the road.
And 1+2+3 = racing stuff... No good for the road. To much mixture low down the bike won't be at all enjoyable, especially in traffic (previously mentioned?), but if you want to tank it on 'ye ol' bypass', the benefits of all that extra available power during max power rev range would bring nothing but a big grin to your face.

Personally, I would stick with 1 & 2... Actually, I intend on doing it myself upon having an appropriate budget to pay an artist to polish the heads to perfection and purchase the relevant number of cams.

p.s. Head skimming is a MUST (IMO) on any engine where the heads have been removed and replaced. A basic skim shouldn't adjust your CR significantly. CR is very simple to calculate accurately by taking simple measurements with the aid of a vernier, WD40 (or equivalent) and a pippet.
Should you want simple guidance on how to do this (assuming you may not already know), I'll happily put a easy to follow guide here for you.

;)
I'm not death to power tools... If it breaks, it's obviously NOT a power tool!!!

User avatar
Varastorm
Posts: 1088
Joined: Mon Apr 07, 2014 10:48 pm
Location: Isle of Anglesey

Re: Cylinder head porting?

Post by Varastorm » Tue Jul 01, 2014 1:09 am

Hi,

Thanks for that Bleh.

I have been hunting for the right tools for the porting job & I think I have found them, they are called "cartridge rolls".

Here is the info & cheapest place I've found to get them:-

York Cartridge Roll Kit

Spirally wound aluminium oxide cloth roll that wears in use, constantly exposing new abrasive. Used for weld flash removal, deburring, blending and polishing applications.

https://www.cromwell.co.uk/index.php?q= ... ddtobasket

They seem to be quite common on the American market, but not so much in the UK!

It took me ages to find out what the product was called, rather than "head porting kit"

So there you have it, (http://www.ebay.co.uk) "head porting kit" for 59 quid.
Or a (http://www.cromwell.co.uk) "York Cartridge Roll Kit" for 36 quid (41 quid delivered).

I was thinking, that the money saved could go towards a new cylinder head after I screw up the first one...........

Regards.

Post Reply