Finger porting

[Varastorm]

I am still keen on porting & fitting my own heads, but I was reluctant to remove the heads just to clean the flash off the castings. Also after reading many write ups on not needing to go nuts with a die grinder, I decided to have a go at cleaning the ports & flattening the port floors in situ, with my FINGER

Here goes, I did this a few months back but was reluctant to mention it just in case it was a bad decision & caused me running issues. Now done, I can report no ill effects what so ever & have since covered around 400 miles on the engine.

Firstly I made sure the pistons were at tdc & the intake valves were closed then tightly packed around the valves with bog tissue, imagine loading an old musket. Making sure there was no way of touching the valve stem with sand paper.

It took me quite a few sheets of (coarsest I had) 180 grit 6" sticky da sander discs folded & torn into 3/4" strips & hours per head fingering the ports till I couldn't feel my finger

Once I was happy I pulled out the tissue using a bent welding rod as a hook, then blasted it clean with an air line

Here is what they used to look like.



This is how they are now.





I have to buy a straight die grinder to knife edge the divider, as the 90°one will not reach with the short cartridge roll mandrel I have.

Not sure if there are any gains to be had by doing this & because so many changes have been done over the last few months its hard to tell what's improved what.

I know they still look a little rough around the most important part, the neck under the valve seat. But hey, the main chambers are as smooth as silk & with no running issues at all

[NZSpokes]

You didnt do the exhausts?

[tony.mon]

For the cost of two head gaskets, you might as well have done the whole job. If you strip out the valves you can blend in the guides.

Bet you got sore fingers and bruised knuckles, I always do...

[darkember]

Just a quick question on this subject. I can understand the idea of getting more fuel/air faster into the firing chamber but doesn't the roughness disrupt the air/fuel mixture creating a better combustible mass??

[tony.mon]

You're talking about boundary layers and laminar flow, golf ball dimples theory stuff.

The castings av=re very rough, as factory finished, and the difference between that a a mirror polish is huge.
Somewhere between the two seems to be about right.

To get the boundary layer effect you need to use rotary motions to end up with the tiny scratches 90 degrees to the flow, rather than in and out.
A die grinder with a flex shaft is the tool for the job.

Others may well disagree

[Varastorm]

You didnt do the exhausts?

How long do you think my finger is?

No I didn't NZSpokes, It was only done out of boredom to be honest, I had just snapped a pilot jet at the time. The carbs were off so I took my frustration out on the ports & gave them a good fingering. They have just always looked too rough for their own good TBH.

For the cost of two head gaskets, you might as well have done the whole job. If you strip out the valves you can blend in the guides.

Bet you got sore fingers and bruised knuckles, I always do...

That's the plan Tony, I also just wanted to see if the 180 finish would upset the slow running of the bike. I am going to put another set of heads on in the future, they have already been bought & are sitting in a box in the shed waiting to get cut.

Sorry Tony, I fingered the ports, not fisted them

Out of interest, does anyone know it the difference between Varadero Head gaskets & VTR ones? Different thickness? Hence the different part numbers & compression ratio? Just an idea.

[tony.mon]

A bit of a polish just makes it seems a little livelier, no negatives really apart from the cost of the head gaskets. It's a small difference in itself but the cumulative effect of all the little things makes quite a difference in the end.

[Varastorm]

A bit of a polish just makes it seems a little livelier, no negatives really apart from the cost of the head gaskets. It's a small difference in itself but the cumulative effect of all the little things makes quite a difference in the end.

You've summed it up spot on with that Tony

I noticed a big difference firstly with the carbs, then the Ducati stack mod, then the lightened flywheel, then the camshafts & finally the finger polish.

It is a totally different beast now, so aggressive on the throttle. Just listening to it when I blip the throttle it's unbelievable how responsive it's become. Quite frightening TBH.

I would definitely mark it down as a must do mod. It costs next to nothing to do, also you'll find it very hard to remove too much metal because your finger will give out first

[VTRDark]

Did you use plenty of lube.

(:-})

[flak monkey]

Not really sure it'll mean anything, but having done a lot of headwork over the years on a number of different engines here's my take...

When I do heads I aim for the following finishes on ports and chambers:
Inlet ports - 120 grit finish at 90deg to flow. Nothing finer than that.
Exhaust ports - mirror finish
Chamber - mirror finish

I doubt you'll see much improvement from what you have done - the biggest improvement in head flow will come from the bowl area under the valve and around the valve seat itself, and you'd be looking at removing a reasonable amount of material with cartridge rolls on a die grinder to get any noticeable difference on the dyno. Sure the excessive roughness in the inlet port will have some negative impact, but I expect it'll be barely measurable on the dyno, 0.5hp maybe. To do it properly the heads have to come off and be stripped down.

[Varastorm]

I doubt you'll see much improvement from what you have done - the biggest improvement in head flow will come from the bowl area under the valve and around the valve seat itself, and you'd be looking at removing a reasonable amount of material with cartridge rolls on a die grinder to get any noticeable difference on the dyno. Sure the excessive roughness in the inlet port will have some negative impact, but I expect it'll be barely measurable on the dyno, 0.5hp maybe. To do it properly the heads have to come off and be stripped down.

I recon your about right on the 0.5hp Flak monkey, It does feel & sound a lot livelier though

Like Tony mentioned before.

It's a small difference in itself but the cumulative effect of all the little things makes quite a difference in the end.

I have a set of heads in the shed I need to port, polish & skim for the next stage & I really fancy some of those JE hi comp pistons also

Will this addiction ever stop

[lloydie]

Simply put no .
I enjoyed doing my heads myself, took ages tho to get them right ,
They only down side I found was if you were sat in traffic on idle for a while it'll bog down when you tried to pull away as all the fuel stuck to the walls of the inlet track making it run very rich [CRYING CAT FACE].

[tony.mon]

Simply put no .
I enjoyed doing my heads myself, took ages tho to get them right ,
They only down side I found was if you were sat in traffic on idle for a while it'll bog down when you tried to pull away as all the fuel stuck to the walls of the inlet track making it run very rich [CRYING CAT FACE].

Don't buy sticky fuel.
The thinner the better, but not thinners, that's different.
[HAPPY CAT FACE, SAT ON BY FEMALE CAT].[/quotemehappy]