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Discussion Starter #1
Anybody tried it?

The intake port floors seem really low. It's almost like the head came from the factory with a crap porting job. That forces a really sharp turn on the short side just above the valve seats. I took off the edge, but radiusing it any further would effectively flatten the floor even further, so that's a no-go, even though my gut tells me it's still way too sharp.

This is the first Triumph twin I've tried to port, and I know that they're supposed to be a little quirky in terms of porting. Were this any other engine, I'd fill the port floors, smooth the short side radius, enlarge the pocket, and call it a day. I may well just go ahead and do it, but thought I'd check first to see whether anyone with more experience with these engines had tried it or had any thoughts on it.
 

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I had the head flowed and my guy had to fill because the floor was too low,he also said
the head was overexhausted and we had to put in 33mm intake valves, 2mm larger
than stock.
The stock head flowed 218 CFM and when he had finished it flowed 282CFM.
When finished with thunderbike cams,39fcrs,904kit,staintune revese cones it ran 86rwhp
62ftlb.
He also said it should have run better but the narrow headers ot the bonnie was the limiting factor.
 

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Discussion Starter #4
Well, I jumped the gun. After looking at the ports a couple more times this afternoon, I decided that it would be hard to do worse than the stock setup, so I traded sanding rolls for carbide burrs and went to work. Enlarged and re-contoured the pockets and filled the floors. I also took the roofs up just a touch to smooth the transition into the choke point. No sense in putting a high velocity venturi right at the end of a low velocity intake tract.

Unfortunately, I have neither a flowbench nor a baseline dyno run to see what effect it has, so I'm just going for "seems right" based on past experience. That means erring on the conservative side and probably losing a little power against the optimal setup (whatever it is), but so be it. The plan was never to get into serious re-contouring, but after seeing how bad the intakes were, I couldn't just leave them, and like I said, it would be really hard to do worse than the stock ports. If I end up doing worse anyway, well, that's alright too.

It's amusing to have done that and now read that Cokernut's engine guy came to the same conclusions I did, and really strange that such a poorly designed intake port sits directly across from one of the best exhaust ports I've ever seen in a stock engine. Suddenly, cavernous header primaries are starting to make a lot more sense.
 

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Reflect,
A couple of question please if you would.
Did you not touch the exhaust port at all, only the intake?
What kind of fill material did you use to raise the floor of the port?
Would you be so kind as to post some pics explaining how you changed the radii?
Really great stuff and thanks for sharing your work.
 

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Discussion Starter #7
Reflect,
A couple of question please if you would.
Did you not touch the exhaust port at all, only the intake?
What kind of fill material did you use to raise the floor of the port?
Would you be so kind as to post some pics explaining how you changed the radii?
Really great stuff and thanks for sharing your work.
Heh. We'll see how great it is when it goes together. I'll post up with details once I get the ports finished. Should be in the next day or two.
 

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"Really great stuff and thanks for sharing your work."

+ 1

I find your port work very interesting too and also hope you will post some pics or even crude diagrams if no pics.

Sounds like you have some experience porting other heads, your follow up info would make for interesting reading.

ted.

ps. How can the "head be overexhausted" if the "headers are too narrow". Don't quite understand that.
 

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I hope it works out for you .One thing I will say porting these heads right is nothing like any other head you have seen .I wouldnt touch one with out a flow bench and much testing.
You are right about the exhaust pipes the stock headers are to small .But there is some work to be done on the exhaust ports to.
Alot of people have ported these heads but only a few have done them right.
 

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Discussion Starter #10
Thanks for the word of warning, Mike, but I'm already well aware. I overstated my optimism pretty substantially in that second post. (I blame lack of sleep.)

As before, it's like someone did a crap porting job on the intakes before the head left the factory, and the easiest thing to do with a bad porting job is to make it into an even worse porting job. Without a little experience fixing busted port work (much of which I perpetrated in the first place... got to learn somehow, right?), I wouldn't be trying this, and while I expect that what I'm doing will improve things, I'm prepared to tear it all apart and find a flowbench to borrow if it comes back really short on the dyno. I'm glad to share my thoughts with anyone who wants to hear them, but this is pretty far from something I'd recommend anyone actually try unless the're equipped with a background in doing this sort of thing, a massive overestimation of their own ability with a die grinder, and a nearly-inhuman lack of sense.

(... like me.)

Still waiting on the ports to fully harden, and then I'm in business. Should have (mostly useless) pictures of holes in metal partially filled with plastic tomorrow night, and perhaps some words and diagrams that will attempt to explain what's actually going on. Penultimate judgment comes whenever the bike is together and gets put on a dyno, which could be a few weeks yet. Final judgment comes about 10,000 miles later or when it breaks, whichever comes first.
 

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Discussion Starter #11
No photos and no diagrams. Gouged the #1 port too deep with a sanding roll, so I had to grind down and re-fill the port. That ate my photo taking and drawing time for the night. The rest of 'em look alright, but they all still need a little clean up. They'll get pretty for the camera tomorrow, and in the mean time I'll go over a little bit of the theory that's cause me to do this.

What follows isn't going to be a primer on porting. If you don't already know the basics, there are a lot of good resources out there, so no need for me to duplicate that effort. If you don't already know the basics, IM(never H)O you also don't have any business even contemplating doing your own port work on this head. There's a lot of room for improvement on the intake, but there's always much more room for damage, and this particular port makes it easy (and tempting) to make a mess of things.

Also, I should mention that what follows are my observations based on my experience. I have no official qualifications to do this, and I haven't backed any of it up on a flowbench this time around, nor do I plan to. If you can trust your dyno and flowbench guys completely, and they tell you otherwise, by all means skip this, unless you just want to hear a crackpot theory of what's wrong with the intake port and how to fix it.

The big problem with the stock intake port is the short side radius, or rather the near-complete lack thereof. The port floor is low, and it just kind of falls off into the valve seat rather than making a proper short side turn. I shouldn't even guess at what happens to the flow there, because I just don't know. If I had to anyway, I'd say that you have a backflowing eddy just past the turn that's going to shroud the near side of the valve. That's probably not accurate, but it's equally beside the point, because whatever is actually happening has the same effect: preventing efficient flow through the near side of the valve.

Complicating matters, the rest of the port is pretty good. The long side is almost perfectly set up to flow a lot of intake charge (not that that's hard to do on a DOHC, parallel engine), and anything you do to the short side stands to disturb that.

When somebody wrecks a port job, they usually try to straighten the port floors too much, meaning that they run out of room before they get a chance to make a good turn on the short side, and often get a rather smooth but overly long radius on the long side, which is exactly what's happening here. As a result, the far side of the valve wants to flow like all hell, and the near side really, really doesn't. Any attempt to add a radius to the short side will actually tighten the turn at the valve seat, which compounds the situation. Also, the choke point is really deep in the turn, and for some reason I can't figure out, this seems to somehow mitigate some of the poor flow on the short side, and moving it up to a more standard placement loses power.

What makes this head so prone to bad port jobs is that basic porting advice tells you to do exactly the wrong things, i.e. smooth the short side and clean up behind the valve slightly. You might get away with no losses from doing those, but I'd be surprised to see gains. The only way I can see to improve flow through the port in actual running conditions is to raise the port floor. So I did. With JB Weld. And dear god is it a mess.

Moroso makes an epoxy putty specifically for filling port floors. It dries pretty quick (within a day), works well once dry, and behaves itself when wet. I've used it in the past, and I recommend it without hesitation. JB Weld does none of those things, and I do not recommend it, but it was in the drawer of my toolbox and the fancy epoxy putty was a week away via special order, so I decided to give it a try. It works, but it does require an extra step, which is to come back six to eight hours after initial application and scrape half-cured JB Weld off of absolutely everything you didn't want JB Weld to get on, regardless of whether you masked it off, and regardless of whether it was even possible via the known laws of physics for JB Weld to get on it in the first place. Amazing stuff, that JB Weld.

While we're on the subject, JB Weld has another drawback, in that it polishes really easily. No carbide burr, sanding roll, or emery cloth I had, no matter how coarse, could leave texture on the surface, and they'd all load up immediately. I eventually ran a stainless brush back and forth across the fills and finally got some scratches, but they're a little small and I'm not confident that they'll last.

Back to the theory though, raising the port floor also raises the choke point, which would usually be a good thing, but it requires some care here, because it disrupts the long side flow. To complement the higher choke point, the long side needs to be cut a little deeper through the curve, and the roof needs to be raised just before the curve as well. I set the choke point a little tighter than before and about even with the valve guide, as seems standard, which involved taking even more out of the roof and pocket. This should normalize the charge velocity within the port, and it will also partly offset the volume lost to the filled floor. The higher, tighter choke should help keep things moving, but this is not supposed to be a "high velocity" port, so I do want to maintain volume as much as I can. I don't drink that particular Kool-Aid, because I think it's a response to a design fad that happened with intake ports for a few years and has since mostly gone away. I'm all for big ports with good shapes (read into that what you will).

All of the evaluation and shaping is done by sight and touch, so it's a little difficult to explain exactly what I'm shooting for. When it feels about right, it's as close as it's going to get without being put on a bench, so I clean up any rough edges and call it done. The exhaust port already just kind of feels right, and I didn't see anything I'd change, so I just crammed a polishing buff down it and called it a day. Knowing when to stop is really important, and little changes are a lot better than big changes in this particular area.

Well, anyway, more tomorrow, when I'll actually have something to show.
 

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Discussion Starter #12
...

Well, anyway, more tomorrow, when I'll actually have something to show.
Heh. Well, that turned out to be wishful thinking.

It's cold enough that the JB Weld took two days to cure to the point where it would shape well, so I didn't get to finish the ports 'til yesterday. They look... okay. Not amazing, but I'm a lot happier with them now than I was before.

I am beginning to think that the world does not want this to happen, though. First the screwup gouging the port, then the slow-drying JB Weld, then last night, Netflix suddenly died in the middle of the porting job, which signaled the night-long cessation of internet service to the house, so no post. It was back in the morning. Tonight, after dinner, I went down to take some pictures, and my camera took one out-of-focus shot of the exhaust port and then refused to take any more. Swapped memory cards, swapped batteries, removed and reinstalled the lens, turned the thing off and on a few times... nothing. Now I get to sort that out.

Also, the dog ate my homework, if that counts for anything.

In the mean time, here it is, a crappy picture of a slightly polished exhaust port.



Amazing, no?

Actually, no. There's still far too much texture inside the port, but the space is pretty small in there, which means I'd have to get (make) really small tools to polish it all, and I wasn't about to do that. I'm just going to rely on the good basic configuration keeping up with the rest of the engine and the pipe.

With the lack of actual pictures, I made the following diagrams to show basically what I did. In practice, they're probably much better than actual pictures (since actual pictures will just show an intake port smeared with JB Weld). Here's (very rough approximation of) a stock port:



Based on that, here's roughly what I changed:



The blue is filler, the green is removed material. The white bracket is the choke point. See? Ran over it with abrasive rolls, rounded everything as best I could, and then shaped the final short side curve with emery cloth. It was messy and it took forever for a relatively small change, but the final shape is better, so I'll take it.
 

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Based on that, here's roughly what I changed:



The blue is filler, the green is removed material. The white bracket is the choke point. See? Ran over it with abrasive rolls, rounded everything as best I could, and then shaped the final short side curve with emery cloth. It was messy and it took forever for a relatively small change, but the final shape is better, so I'll take it.
Okay, so you built up the port floor and decreased the sharpness of the short turn radius and then maintained port dimensions by opening up the port roof/long turn radius. Was there any increase in overall port cross-sectional area?

And, more importantly, how did it work out? Any b4 and after dyno work? How about flow bench readings?

Regards,

--Rich
 

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Also just did MotoMan's High Velocity Ports acc.:

Part 1 : http://mototuneusa.com/power_news_--_homework.htm
Part 2 : http://mototuneusa.com/power_news_--_supersonic_nozzle.htm

To have the epoxy bonding properly, cleaning is essential, of course only when the boss is not at home...





Next step is to enlarge the surface with hammer & chisel




Pieces of plastic tubes are fitted into the valve seats to prevent the epoxy of pouring out towards the combustion chamber and working as a mould form.
The final height of the choke point should to be 65% of the valve outer diameters, so with my standard 31 mm valves this choke point height is to be 20 mm. In order to have enough material to grind a smooth radius, the epoxy is now filled up to aprox 16mm



24 h of cureing




Remove the moulds and start grinding



The dust will be everywhere





The result:






Now I'm waiting for the snow to be gone...
 

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Well, regardless of what Moto Man says, I'd guess about all you might see is a bump in low rpm torque. You will see a loss in high rpm hp. My professionally ported TPUSA head looks nothing like this, and all Moto Man conspiracies aside, I think they know know what they are doing, holding the Salt Flats records and all.

To get velocity porting to work well, the floors should be tilted towards (or away) from each other, not be parallel as yours are. This promotes chamber swirl. The stock ports are effectively tilted towards each other (being roundish) and they do promote mixing.

Fortunately, a little work with your Dremel and you can reverse this mod, so you've not ruined anything and it's a fun experiment to try. I cracked up at the picture of the head in the dishwasher. Oh the memories that brings back. Just last weekend I washed all my brake parts while the misses was out, using degreaser instead of soap ! She came home and was so happy I had emptied the dishwasher of the dishes from the night before, and was none the wiser !
 

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Gentlemen's dish washing

Hi NorthernThrux,

We certainly know how to please our Firt Ladies :D

I had exactly the same concerns about MotoMan's HV-ports, but when I saw the way Honda has improved power on their CRF250 X to the R version, I couldn't resist to give it a try on my Bonnie:



Found here:
http://www.google.ch/imgres?q=honda+intake+ports&hl=de&biw=1268&bih=608&tbm=isch&tbnid=uzFshgj2mJtG2M:&imgrefurl=http://rickramsey.net/CRF250Xbigbore.htm&docid=w3SGoZ0THOnFLM&imgurl=http://rickramsey.net/CRF250Xlg/IntakePorts.jpg&w=903&h=301&ei=NmALT-aBBImp4gS4pdmRCA&zoom=1&iact=hc&vpx=107&vpy=143&dur=756&hovh=129&hovw=389&tx=188&ty=82&sig=111829502103591276715&page=4&tbnh=54&tbnw=163&start=55&ndsp=18&ved=1t:429,r:12,s:55

I'm optimistic that it's working fine, if not, the dremel is still warm :(

BTW, do you have some pictures of your TPUSA ports?
 

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I trust you ran a baseline dyno to compare against? Interested in the outcome...

...but likely beyond anything I would want to attempt. The cost of a new dishwasher kinda puts it out of reach.

Cheers,

--Rich
 

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Whats wrong with moto mans ideas ? Hes not working with them same port problems he has a small bore with over sized ports we have a big bore with under sized ports.
Good luck with that lol.
Dont show pics of your ports northern there not for everyones eyes lol.
 
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