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#225874 - 11/29/08 3:47 am Re: Stock cylinder head porting. [Re: John Healy]  
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Steve in Tulsa Offline
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OK , question:
I would have said the swirl causes a more consistent, homogeneous mixture. Less swirl, more fuel clumping which occurs with heated fuel. The homogeneous mixture burns more evenly over time. Hence a cooler more efficient burn without ignition of fuel "clumps".
Wrong ?

T. BTW, good discussion

Last edited by Steve in Tulsa; 11/29/08 3:54 am.

Steve in Tulsa
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#225878 - 11/29/08 4:04 am Re: Stock cylinder head porting. [Re: Steve in Tulsa]  
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trumpetloon Offline
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georgia
Steve... ??? Heat causes fuel evaporation. It can (in the extreme) cause bad things to happen, but fuel clumping is not on the list.

The effect of swirl is to break up the fuel clumps... then they burn (not explode) evenly... and more of the molecules burn in each stroke making more power, but less heat. Which makes more HP but less heat each time the plug fires. Got it?


1974 TR5T
#225880 - 11/29/08 4:20 am Re: Stock cylinder head porting. [Re: trumpetloon]  
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Steve in Tulsa Offline
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Quote:
Less swirl, more fuel clumping


Right, like I said.

But, yes, got it bigt

Like I said, good discussion. And I always learn bigt


Steve in Tulsa
#225882 - 11/29/08 5:00 am Re: Stock cylinder head porting. [Re: Steve in Tulsa]  
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Derry Hincks Offline
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A couple of questions:

1. Are both the splayed and parallel ports the same size? Although the parallel port is restricted because of the insert if overall it is a larger diameter it may flow more air. Reminds me of A series BMC head modifications in the past.

2. How can burning more fuel generate less heat? Surely the fire with more wood on it gets hotter and lasts longer.


Derry.

1969 T100S under reconstruction
GSX-R750K2 (having been rebuilt from a crashed wreck)
#225896 - 11/29/08 7:45 am Re: Stock cylinder head porting. [Re: Derry Hincks]  
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Blapper Offline
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Quote:
IIRC the parallel ports are better for power and emissions


Sounds like I was right then?

redwine

#225898 - 11/29/08 9:09 am Re: Stock cylinder head porting. [Re: Blapper]  
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HawaiianTiger Online content
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Mr. T oh if you had been around when triumph was designing their awful cylinder head they might have made some improvements so that their little motorcycle would actually run right for a while without, seizing, holeing pistons, pinging, knocking, burping and stumbling etc etc. Just a call to Norton would have saved them (and us) endless grief. So we have to re-engineer the bikes when we have no right nor resources to do so just to get down the round a few more miles? After you've seen something of the era with a real combustion chamber (ie. Jaguar)you have to admit the Triumph was a joke. We do the best we can on these but really we should be spared all the high tech explanations that do nothing to help. Save it for a more sohpisticated engine.
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
#225900 - 11/29/08 10:03 am Re: Stock cylinder head porting. [Re: hh]  
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Originally Posted By: hh
If the top of the seat on the valve head is below the floor of the chamber (holding the head upside down in your hand,) you have valve seat recession. But a little bit is tolerable. If the entire valve head is flush or below the floor of the chamber, you've definitely got issues and should either fit larger valves or replace the seats.


cheers, will check my head out later.
eek

#225917 - 11/29/08 1:29 pm Re: Stock cylinder head porting. [Re: HawaiianTiger]  
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Mark Parker Offline
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Mick if the valve seats are wide, which is usual if its done a few miles, having good 3 angle valve seats cut can give better performance.


mark
#225919 - 11/29/08 1:34 pm Re: Stock cylinder head porting. [Re: HawaiianTiger]  
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Britbodger R.I.P. Offline
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Originally Posted By: HawaiianTiger
Mr. T oh if you had been around when triumph was designing their awful cylinder head they might have made some improvements so that their little motorcycle would actually run right for a while without, seizing, holeing pistons, pinging, knocking, burping and stumbling etc etc. Just a call to Norton would have saved them (and us) endless grief. So we have to re-engineer the bikes when we have no right nor resources to do so just to get down the round a few more miles? After you've seen something of the era with a real combustion chamber (ie. Jaguar)you have to admit the Triumph was a joke. We do the best we can on these but really we should be spared all the high tech explanations that do nothing to help. Save it for a more sohpisticated engine.

Bill


I agree with you, but being the Triumph devotees that we is, we tends to ignore facts. Its in our nature crazy. Switching to a Norton just goes against the grain. Thats just the way it is grin

BTW, as an aside, way back then when Jaguar bought Daimler, who's engines were apparently designed by Turner, found that the humble pushrod Daimler engine with its "Triumph" hemispherical combustion chambers put out more power than the Jaguar DOHC engine of larger capacity! Needless to say though they put the Jag engine in the Daimler badged Jag.

beerchug

#225938 - 11/29/08 4:01 pm Re: Stock cylinder head porting. [Re: Britbodger R.I.P.]  
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phantom309 Offline
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spfld vt
There is only one norton out there that has even come close to the triumph on the track .For having such a good combustion chamber we don't see any more power out of them.WE thought triumphs broke alot untill you see a norton at the track.:)


Tim Joyce
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#225939 - 11/29/08 4:28 pm Re: Stock cylinder head porting. [Re: Derry Hincks]  
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Originally Posted By: Derry Hincks
How can burning more fuel generate less heat? Surely the fire with more wood on it gets hotter and lasts longer.


Derry,

Perhaps not necessarily burning *more* fuel, but burning the fuel more *efficiently*....depends on what kind of wood you're burning....a little bit of oak will burn hotter and longed than alot of pine......

Now, to throw a little more fuel on the fire (pun intended), what happens to swirl characteristics when you introduce ethanol?

Great discussion!

Cheers,

Steve


'77 T140J
"Vintage Bike". What's in your garage?

"The paying customer is always right."

Fitting round pegs into square holes since 1961...
#225943 - 11/29/08 4:41 pm Re: Stock cylinder head porting. [Re: phantom309]  
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Houston Texas
Originally Posted By: phantom309
There is only one norton out there that has even come close to the triumph on the track .For having such a good combustion chamber we don't see any more power out of them.WE thought triumphs broke alot untill you see a norton at the track.:)


Have to agree with you there Tim. Something to do with the rider as well though. bigt

My assessment for what its worth is that the Norton theoretically does have a better flowing head but that Triumph's total engine package seems to be more amenable to performance upgrades.

Think Kenny Cummins is getting there with his Norton though in the BEARS class - well he already has got there! You needs to get back into BEARS to cut him back down to size. Just kidding Kenny if you lurks on this site grin.

My 2c

#225945 - 11/29/08 4:55 pm Re: Stock cylinder head porting. [Re: Britbodger R.I.P.]  
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Blapper Offline
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Before you two get started on a meeting of the mutual admiration society, this here's the Triumph forum - keep that stuff for the competition forum! grin

We're going to have to throw a bucket of water over you if you don't stop!

redwine

#225959 - 11/29/08 6:46 pm Re: Stock cylinder head porting. [Re: Blapper]  
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joepenoso Offline
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toronto
So which stock 650 head flows the best?
joepenoso

#226025 - 11/30/08 3:36 am Re: Stock cylinder head porting. [Re: joepenoso]  
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HawaiianTiger Online content
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IMO 54-55 T110 iron head. Well, you asked. My old T110 ran with Bonnies all day long and never overheated. I did put larger valves and ran a 389 carb to be fair but it had stock T110 cams. Valves look tiny compared to the Bonnie. Other than that the tuner I know pays good money for 63-65 TR6 heads but he ain't letting on to exactly why.
Bill

Last edited by HawaiianTiger; 11/30/08 3:37 am.

Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
#226028 - 11/30/08 5:20 am Re: Stock cylinder head porting. [Re: Blapper]  
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phantom309 Offline
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spfld vt
Originally Posted By: Blapper
Before you two get started on a meeting of the mutual admiration society, this here's the Triumph forum - keep that stuff for the competition forum! grin

We're going to have to throw a bucket of water over you if you don't stop!

redwine
we would but they are talkin about Nortons too.:)


Tim Joyce
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#226035 - 11/30/08 7:20 am Re: Stock cylinder head porting. [Re: phantom309]  
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Mark Parker Offline
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Some magazine, I think it was classic bike, did flow bench testing on some various Triumph heads and compared them, I cannot remember which flowed the most, but the flowbench operator was surprised at how good they were.
When it comes to valve size, there is an optimum size relationship between carb and inlet valve sizes, and the tech papers MAP have in their catalogue put optimum carb size as 86% of inlet valve size, so running a 30mm carb with a 40.5mm valve is not very close to optimum, which should use a 35mm carb with that valve. This might explain why the bigger valve head seems a questionable performance upgrade. Going to 35mm carbs would optimise that relationship with opened up ports, but then port shape becomes very important because although a bigger port will flow more on a flow bench, on the motor gas speed controls when the motor has power, and you may have to wait to 5000RPM to get good power starting. So if you open the port for a very good volume of flow, the next thing to do with the flow bench would be to find and fill dead areas in the port, usually the port floor just running up to and at the turn under the guide, (looking at it, when the gas turns I would expect it to be forced by inertia to the outside of the turn and any on the open inside short radius if anything may just make turbulence and upset flow)By making the port as small as possible in this area while maintaining your good flow means that on the motor at less than maximum RPM the gas speed in the port is always faster earlier, more mixture goes in and you have more power earlier and it will stay up into high RPM as well.
I've just done this on my A65 (without the benifit of a flow bench)combined with 3 angle valve seats and it's amazing how it now goes, starts with a GRR then quickly changes to a ZZZZZ as it goes unrelenting up into high RPM, so cool, free HP just by changing the opened up head a little with some JB weld, and taking some time with the valve seats.


mark
#226154 - 12/01/08 12:18 am Re: Stock cylinder head porting. [Re: Mark Parker]  
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John Healy Online content
John Healy  Online Content



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Boston, Massachusetts
Quote:
So which stock 650 head flows the best?


Flows or works? The 1963 works best in the range of 1963 to 1970 Bonneville heads on a stock 1963 to 1970 motor. But, then it all depends upon what one believes what works means. If you want a stock 1970 Bonneville to pull right up to 110mph, put a small port, small intake/exhaust valve, 1963 Bonneville head on it.


#226175 - 12/01/08 2:53 am Re: Stock cylinder head porting. [Re: John Healy]  
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trumpetloon Offline
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georgia
Hey Bill; would you really want a bolted up crank in your Thunderbird? That seems a step in the wrong direction for sure. wink


1974 TR5T
#226251 - 12/01/08 6:56 pm Re: Stock cylinder head porting. [Re: trumpetloon]  
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HawaiianTiger Online content
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Originally Posted By: trumpetloon
Hey Bill; would you really want a bolted up crank in your Thunderbird? That seems a step in the wrong direction for sure. wink

Well, I wouldn't but if it was magafluxed and balanced with all new hardware to put it together it should be fine as long as you don't really hot-rod the motor.
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Flying Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
#226344 - 12/02/08 1:39 pm Re: Stock cylinder head porting. [Re: mick2]  
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joepenoso Offline
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toronto
This leads to a question why did Triumph, that was so successful in competition, start out with a successful street porting/ valve size and then start to enlarge both with negative results. I even think the final port valve sizes were too big for the 750 models with thier mild exhaust porting and ultra low compression.
joepenoso

#226375 - 12/02/08 5:03 pm Re: Stock cylinder head porting. [Re: joepenoso]  
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John Healy Online content
John Healy  Online Content



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Boston, Massachusetts
Quote:
start out with a successful street porting/ valve size and then start to enlarge both with negative results.


The same way a lot of things go awry! The marketing department starts doing the engineering. At the time (1963) BSA had the "Big Valve" A10 Super Rocket. Not to be outdone - " " (you fill in the blank).

Kevin Cameron wrote an article about this in the 2005-4 Vintage Bike. Because "mean intake velocity" is calculated by multiplying mean piston speed at the rpm we are interested in, times the ratio of the piston area to the intake port area it wasn't until they increased the cylinder bore to make it a 750 did the larger port start to "work" for this motor.


#226469 - 12/03/08 10:42 am Re: Stock cylinder head porting. [Re: John Healy]  
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Mark Parker Offline
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John when they went to the bigger valves did they fit bigger carbs as well? As I mention in a post above it would seem there is a proportion that works best between carb and valve sizes, and with the bigger valves and same carb size Triumph would have moved even further from it.
So if the 650 with bigger valves was slower than one with smaller valves, maybe its because they were restricted by the small carbs. The 750 was always going to have more grunt but maybe it's also missing out by having the far from optimum valve to carb sizing?
What if the bigger valves in the 650 and the enlarged ports near them slowed gas speed in the midrange and took power away, then when it climbed to the RPM where that new big valve size should have been working best it's so restricted by the little carbs it doesn't go into a higher RPM power zone that should have given it more top end power and speed?
By illistration we went with a more extreme set up and put 44.5mm inlet valves and 38mm carbs on a BSA 650, but they happen to be very close in that optimum size relationship. Almost everyone says they are too big, but in the RPM range where the set up worked it worked very well, there is no way a std carbed and valved 650 BSA could stay near this in top end power or top speed.
I only have a little video of it from the late 90's (where it's got a missfire at about 7,400RPM, that overcome it reved quite a bit higher) You can see that it goes quite well especially above 5,000 even pulling quite tall gearing. So maybe the problem with the bigger valve 650's is more the miss-match in carb-port-valve sizing than the valve size itself.



This shows it driving off and shows it was also quite tractable at lower rpm.



mark
#226492 - 12/03/08 2:15 pm Re: Stock cylinder head porting. [Re: Mark Parker]  
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John Healy Online content
John Healy  Online Content



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Boston, Massachusetts
Quote:
John when they went to the bigger valves did they fit bigger carbs as well?


Yes, they increased carb size along with the valve and the port.

On these mid-sixties T120's we were fond of using 1" thick spacer blocks between the carb and manifold. The block had a restriction. We would taper the block's bore to 1" to 1 1/16" i.d. depending upon what we were doing and which head we were working with. The long taper (3/4") on the carb side and a short taper (1/4") on the manifold side. The bike was much more responsive and would pull taller gearing without getting fussy. It also gave us back some of the top end we were loosing with the stock head.

Drawing air, and thus air velocity through the port, with a 71mm bore is quite different than your 75mm BSA and the 76mm T140 (we too have used 36mm MKII and MKII Smoothbore's on the T140). And it is all about air velocity in the port. It isn't any good to have high flow numbers on a flow bench if on the motor it takes a long time for the air to get moving and finally reach the combustion chamber to find that the intake valve is closed. For the high flow numbers you get on the flow bench from a larger port to work one must keep the intake valve open longer after bottom dead center. Of course there comes a point of diminishing returns of how large a port and how late the intake cam timing.

It is this "extra" packing of the cylinder after bottom dead center when the piston has changed direction and is going up (and you think that it would start to blow the air back through the intake port) that gives the increase in performance. But this will only occur when improved flow is packaged with the proper intake cam closing point. But one must remember that time is the enemy. If it takes too long to get the air moving in the port, it doesn't matter that you can get high flow numbers on the flow bench, at some point you MUST close the inlet valve. It is a little study in inertia.

There is a lot going on here and I am sure there are those of you that can explain this much better than I can, but this is the basic stuff.
john


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