porting

[steve speed]

is there a do it yourself way ?? or did everyone who had it done go to TTS is it a reshape or a smooth finish ??

[slow codger]

Aren't the inlets supposed to be slightly rough to allow the fuel mixture to better mix, and the exhaust smooth to get rid of the exhaust ASAP? Must be a reshape if you want higher performance as the standard ports allow for better all round performance at lower power levels.
Bucket of fuel and an airline, mix it, squash it to a 20th of its size, set fire to it and get rid of the smoke as quick as you can then do it again as quick as you are able.
Got a book in the loft for tuning BSA singles somewhere, goes into porting and also high lift cams, high comp pistons, bigger carbs, and better exhaust systems. Havent got a BSA single though!

Dave E

[trixynut]

The most important thing to remember about Porting is ........... always pass it to the left !

[HansJ]

Depends on Your goal, there's work that You can do, and there's work where it turns in to a combination of science and religion...

First stage porting would be smoothing out 'errors' from the casting process, and adjusting the carbs, inlet and rubbers to the head. This is about as far as I'd go, as a layman. If You want to go further, You have to have an idea what You want to acchieve, and maybe a couple of heads and a Dyno...

It's not all about removing material, in some areas You might even to add material, depending on the goals. And the closer to the valve seats You get, the shape gets more important (i.e. errors have also greater impact...), and valve seat cutting is almost an art form which needs expensive equipment...

So, have I put You off? There's still potential for a DIY action, but don't get too greedy unless You know what to do...

And yes, inlets shouldn't be too smooth (laminar flow), but exhausts should be like a mirror (reflecting the heat)

[phuk72]

Best bet is to pay someone who knows what they are doing to doing the porting / gas flowing in one go.

I didn't use TTS but I understand they know what they are doing

[cheesie]

there can be very little in a scrap head and a good un so leave it into someone who knows what they are doing

[Quan-Time]

Porting heads many people think is some black art.. Its pure science and physics..
A lot of older guys will tell you its art and technique that yield the best heads.. Fluid dynamics wasnt really perfected until the mid 80s.. They were porting heads in the late 60s.. Probably why they say that.

Many people "port match" or "gasket match" which is universally the BIGGEST mistake you can make (in my books). The TRX head can have improvements via a few ways. Cams, Valves, port shapes.

The exhaust port can benefit quite a bit, but as a stock unit, the inlet is actually quite good for what it is. Sure you can improve it, but its fairly reasonable for a cast item.

It really depends what you want out of the head / engine.. More top end, mid, free flowing curve, flatter, but higher torque line, economy, more rev, less rev, etc.. Theres a bucket load of things to account for.
And to clear up the more / less rpm incase you are wondering.. Going from idle to 6000rpm (max power) rather than idle to 9000rpm will obviously be quicker, so you can get on your power faster, and not stress the engine doing so. Many NASCAR teams have spent the past 4 - 5years trying to LOWER their peak RPM while maintaining the same power level.. Sure you get more power from more rpm, but they want to drive out of corners faster, more over take options, etc.. And dont believe the tacho's you see. They are deliberatly false. Mainly to stop other teams seeing their development. Its sometimes 10% over what it really is, or it could be out by 1000rpm over the whole range.. Really depends on the team.

For a road use only bike, id personally suggest mid range and more torque rather than rpm and HP. Its all personal.. But how often do you stay at 75%+ of your RPM range ? you spend most time about the middle third. Which is where you want to develop your torque curve (for more pull, and the ability to climb from 3000 to 5000rpm faster) which very usable for day to day riding.

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SUMMARY
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If you do it yourself, you might get a touch more power in one part of your rev range according to the bum-dyno, but in 99% of cases, you sacrifice power in another area, or put a dip in your torque curve. Get a pro to do it properly. Its like trying to paint a master piece with a paintball gun and a blind fold. Right tools for the job help give good results. But you first need to learn how to use the tool.