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A better 2 valve head for Triumphs #759398 12/15/18 2:18 pm
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in a perfect world of course...I have two Ducatis, a 96 900 air cooled 2 valve and a 98 ST2 944cc, Ducati's only 2 valve liquid engine.. The ST2 had an oil leak ,so I pulled off the front head and cylinder to fix it...Italians do dumb stuff but the quality of their castings is outstanding and despite being somewhat complicated, it's not all that difficult to work on...
Take a look at this Ducati head, notice the some what shallow valve angle and "quench" type combustion chamber allowing relatively high compression on regular grade fuel..Ok, the Ducati 944 has a 3-11/16 bore with room for larger valves without a steep valve angle..But the valves are nearly the same size at later 650 Triumphs. The ports are only 2 MM larger but better shaped...This engine is not considered a performance engine , 83-85 HP at 7500 RPM with strong midrange torque.
On a Triumph ,to change valve angle is restricted by the pushrod tubes, but a clever guy coulddesign slightly angled tubes and longer rocker arms..A clever guy could machine a new head from billet aluminum, maybe... but I find it interesting .. Yes, there are 8 valve Triumph heads but considering the potential, two valves would be adequate, and different...

The Ducati head . The two valve engines, air or liquid cooled use no head gaskets...The cylinder has a raised lip fitting in to head and ,O rings used for coolant and oil passages...

[Linked Image]

While my Triumph head would be OHV, this is what the no valve spring Desmodromic valve action looks like.The small torsion spring is just for keeping the valve closed on lash,

[Linked Image]


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
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Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759416 12/15/18 8:14 pm
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Tony,
Maybe you could try this. You'll need a B50 motor to start with, unless you can figure out how to do it to your Triumph. Of course, it's no longer a pushrod motor.
Tom

[Linked Image]

Last edited by koncretekid; 12/15/18 8:20 pm.

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Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759449 12/16/18 11:55 am
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Well that's interesting...The combustion chamber of the 2 valve Ducati above loos very similar to the Sportster engine used in the Buell..And the Dodge hemi used in newer Ram trucks..Of course with Triumph's the crank limits power so I'm thinking of this more for running on lower octane fuel..


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759567 12/17/18 1:12 pm
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Allan Gill Offline
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have you considered doing anything with the T100 daytona motor Tony? they were very competative with what the factory did, in your hands it could be as or more impressive than the 650 motor.


beerchug
Re: A better 2 valve head for Triumphs [Re: Allan Gill] #759571 12/17/18 2:06 pm
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I thought about it, my rider friend has a large pile of Triumph 500 engine parts...But..If I do anything it would be XB9R 980cc Buell short stroke engine for the 1000 cc pushrod class or perhaps with 883 Sportster cylinders to run in the 750 class.


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759591 12/17/18 3:26 pm
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There have been several OHC Triumph 650 motor built, back in the pre-unit days. One used a chain drive to the camshft, with sprockets on the original cam, and chains running through the push rod tubes, in one example.

Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759604 12/17/18 4:46 pm
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That would be an immense amount of work since the pushrod tubes are centred on the cams unless the sprockets were extremely small diameter which causes high wear. Then the chain has to run from exhaust to intake cams unless they use two chains, one from each cam to the top. External belt or chain is workable but ruins the traditional looks.
Breathing is more of a problem than RPM. As I showed on the triples forum, changing from the two valve to a four valve increased the flow by 30% and that is with 0.10" less lift. That could be a bolt-on change.

Re: A better 2 valve head for Triumphs [Re: DMadigan] #759605 12/17/18 4:52 pm
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I wanted to retain a pushrod operation using a head with a redesigned combustion chamber,


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759644 12/17/18 10:45 pm
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SCTA rule 7.J.9 and Loriing 7.D.4.11Class PF and PG (pushrod fuel and gas)............".heads shall have the same number of valves as originally produced as a production engine." But a Triumph is allowed a 4 valve head because the very late models were sold with a version of the 4 valve Weslake (I think) design.

Our BSA's are out of luck, because none were produced as such.

So other than those, Weslakes are allowed in "A" Special Build class, as well as the Honda CX500 and 650's in all classes.

By the way, I have looked at Buell heads and you're right - - they look like you could drive a truck thru those ports compared to our Brit bikes.

Tom


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Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759656 12/18/18 12:10 am
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Quote
By the way, I have looked at Buell heads and you're right


Port diameter, and how the engine is going to be used, is directly related to swept volume of the cylinder. With the Buell having a minimum of 125cc more displacement than the Triumph 750 and 175cc more displacement than the BSA 650, it isn't any surprise that it would have large ports.


Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759658 12/18/18 12:17 am
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A while before he passed Kenny Augistine was working of a Triumph 750 head. I have been led to believe when the interested party found out how much it was going to cost the project was abandoned. With more work to do, the modified head was projected to develop decent HP, and a workable torque curve, at pretty low valve openings. Yes, it did have "D" exhaust ports but were modest compared to ones I have seen from others.


Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759660 12/18/18 12:39 am
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Kenny Roberts' XS750 OW72 had the head changed and went from 58 HP to 90 HP. Probably the same could be done with the two valve Triumph.

Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759736 12/18/18 9:37 pm
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John said cost, that's why I won't do it, that, and it's beyond my skill level....and you get to pay twice, once for the head and valve train and the second time when the crank breaks... grin


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: A better 2 valve head for Triumphs [Re: DMadigan] #759750 12/19/18 3:04 am
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yes it was an immense amount of work, I never found details on it. just a couple small photos.

Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759751 12/19/18 3:06 am
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yes it was an immense amount of work, I never found details on it. just a couple small photos.

Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #759753 12/19/18 3:32 am
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Any time the power goes up the weakest link will eventually break. You can centre bearing the crank as I did with the A65 which makes offsetting the crank pins easier.
On cost, there is a lot of information out there so the development would be relatively short. As I showed on the 12 valve triple head, a model can be drawn, 3D printed and tested fairly quickly. A wax model can be printed and investment cast for relatively low cost, less than the cost of welding and machining a stock head.
Closing the valve angle and pushrod operation can be accomplished by rotating the pushrods outward a la Rickman 8 valve. The rockerbox would be cast with the head as Rickman to eliminate leaks and make the head more rigid.
Is this for the 500 or 750?

Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #761882 01/08/19 3:04 am
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In England, Keith Blaney made a DOHC head for the A50/A65, for Chris Vincent. I have read that Gary Bryant of RGB owns it, it is said to be complete. It ran on the dyno, not sure if it was ever raced.

Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #761897 01/08/19 4:56 am
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Thanks for taking the time to post your st2 parts..neat stuff to look at....Maybe this information can help

There is more than enough valve in a Triumph for most applications. In the 650 format there is too much valve and port to keep the airspeed up. (stock limiting port velocity is 520feet per second in the intake port which is too low. 620 is my personal goal and others have reached mach 0.6 resulting in over 650fps and super fast intake ports) For the folks here that speed the language the choking rpm of a stock T120 head is just under 7800 rpm which is too high for any stock crankshaft and stock rod/piston to stay together longer than a 1/4 mile. Reducing the valve and port size will make lots more power

Reducing the valve sizes to match the bore diameter will get you a machine that "feels like it is 200cc" bigger and produce a solid 60hp at the rear wheel over the stock 34-44hp (depending on what day of the week and how well the beer was flowing at the factory)

Raising the intakes 1/8" is a ton of work and yielded only 3cfm @25" more than a well developed head in stock dimensions

Where I like to concentrate the work is in the combustion chamber. Replicating the 1986 HD Sportster 1100 head (same at Buell Thunderbolt and 2004-2006 HD sportster) allows a very low dome piston and wonderful burn characteristics improving power, efficiency and overall timing (31 deg max on 89 octane)

The valve size recipe follows all formats of racing and manufacturing today and can usually be found in machines like your ST2 - 2 valve engines only - 4 valvers cover your eyes:

Best intake valve diameter range is 52-53.5% of bore diameter - the lower the better and will be dependent on the efficiency of the combustion chamber (no squish..no good)
Best exhaust valve diameter 72-78% of the Intake valve - Depending on exhaust type - Open race pipe for peak rpm power 72% - Muffled exhaust because of neighbors 75-78% - Stock exhaust need not apply for this job

This means the following:
A 650 Triumph with a .5mm overbore will work best with intake and exhaust valves of 1.46" and 1.09" - Call your local valve maker for some custom pieces
A 750 Trumpet and the BSA 650 bored up 1.5mm (my favorite) Can use the stock intake valve of 1.59 and drop down in size on the exhaust to a 1.18" for a huge gain in overlap flow getting the volumetric efficiency over the 100% mark (cams and port/combustion work required) My current goal is 108 and shooting for 110% VE

The Triumph Engine with its stroke of 82mm and the limiting RPM of 7800 (4200fpm) is in my opinion and experience the absolute red zone for the crankshaft design. Throw a 90 deg crank in there and a really really great outrigger bearing kit and maybe you can reach for 4400fpm piston speed average but its a fractional power increase and not worth it (opinion) 4400fpm = 8178rpm = BOOM!


I suggest all the energy be spent on the crankshaft. It is the official weak link. We can buy excellent pistons, excellent rods and even trick valve-train parts. Cranks will kill...just like the drug that inherited its name.

4 Valvers - Here is the rub
There is more flow under the curve with 4 valves...but no more top end horsepower because you can not rev the engine higher than is safe. It is harder to install 4 tiny vales in the cylinder than to make the exhaust valve smaller and Whammy! Your on the back wheel showing off at the next Delta road ride.

HillBilly - I am curious about your ST2. My 900SS hits the 52/74% valve size window on the nose, but Ducati was known to play with valve dimensions in the middle of a production run to remedy a poorly flowing head casting. (The "big valve" bikes)
Your Ducati should have a bore of 94mm meaning it should have Intake/Exhaust valve sizes close to 49/37mm respectively. I am curious what you find
- Based on what I have tinkered with in the 900 ish ducati range your bike can safely run to 8000rpm and would make 80 wheel hp at that point. The power is in there with little modification. The machine will operate at a 95% efficiency range. The camshaft timing is off from the factory...don't ask me why...ask Bike Boy



Or maybe you already know all this. Thanks for humoring me anyway.




Last edited by Denis J; 01/09/19 12:41 am.

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Re: A better 2 valve head for Triumphs [Re: DMadigan] #761898 01/08/19 4:58 am
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Originally Posted by DMadigan
Kenny Roberts' XS750 OW72 had the head changed and went from 58 HP to 90 HP. Probably the same could be done with the two valve Triumph.



That was a short stroke long rod engine with an offset piston pin. I was under the impression the engine was making 75 hp before the custom head. (These are methanol machines). I am working off hearsay - I may have incorrect info.


...no idea what your doing
Re: A better 2 valve head for Triumphs [Re: Allan Gill] #761899 01/08/19 5:01 am
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Denis J Offline
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Originally Posted by Allan Gill
have you considered doing anything with the T100 daytona motor Tony? they were very competative with what the factory did, in your hands it could be as or more impressive than the 650 motor.



This peaks my interest..what can you do? I am working on 500cc heads at this moment. I had just over [email protected]" and was super excited, but my port was a reversion nightmare and likely would result in a bike that would need to be pushed off the curb. I had airspeed figures as low as 480fps at .380" lift. - bummer.


...no idea what your doing
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #761947 01/08/19 7:13 pm
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I have two Ducatis, a 96 900M and the 98 944 ST2.I also have . The air cooled belt cam drive engine is not state of the art breathing and never was..But it makes decent power over a wide RPM range. The ST2 is detuned a bit for sport/touring work and is fuel injected making about 78-80 HP at the rear wheel at 7500 rpm..It will rev freely to 8500 but makes little additional power. The 96 900 monster is a carb bike and the last of the V2 heads with bigger valves and cams, Stock it makes 73-75HP at the rear wheel.. Mine is well tuned so it's maybe 80HP. at 7500 and will also rev 8500 rpm easily...
My LSR 650 Triumph head has raised intake port floors, not difficult with the proper epoxy..The ports are tapered from 34MM to around 32 ,but remember the port is D not round .Stock valve sizes with a burr finish around the intake seats.. I didn't do the port work and don't know about the flow numbers...But it is a tick behind the fastest land speed racing modified production bike, the Triumph of Kevin Robert's on this site. Kevin's bike head , mine and the BSA running close, all have heads done by Rob Hall.. My bike was tuned on a Superflow Dyno and It's the only dyno chart I've seen on a Triumph...The graph is on other threads here but in a nutshell the engine makes 55 rear wheel HP at 6950-7050 rpm ,peak torque is 46 ft lbs at 5100 rpm.. At 7000 RPM the engine still has 40 ft lbs...it starts on one kick and idles at 1000 rpm...The engine has moderate 10.5 close quench pistons and Sifton 390 cams..By making power at a lower rpm, the crank lasts longer..Since the dyno I did change the exhaust timing and shortened the pipes so it probably has a few more HP.
My main interest in a different combustion chamber is for a faster burn that'll tolerate 89 octane fuel and perhaps make a bit more power...70 rwhp , if possible from a 2 valve 650, would be a very expensive build and need to rev and likely be soft below 4000 rpm...
I recently did work to my 79T140D...Closed up the quench to .034 ,but using stock pistons ,a proper valve job and I changed the cam timing..This has the late parallel port head with higher velocity ports...I believe that and the tight quench will allow the engine to tolerate 90 octane gas with no detonation with an actual 8.7 static compression ratio..I also should have better throttle response and power..A brief road test during a winter thaw seemed to confirm this..


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #761971 01/08/19 10:35 pm
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Denis J Offline
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Hillbilly

I have not had the chance to tinker on the T140E head yet..I always thought they might be better for a street bike out of the box and maybe lend more material for work.

Raising the ports..sorry I did not clarify...I meant literally raising them, not just filling them in. Welding the head and adjusting the locations of all the misc important stuff in the way.

Quench pistons...I have heard of these and I think EV offers a set for the BSA. They look like the old 2 stroke pistons that had a dam type wall to prevent the fresh charge from leaving out of the exhaust.
I can't seem to wrap my head around how to create a quench with a classic hemi chamber and not kill the burn rate. Welding up heads and machining takes gobs of time. Do you have the pistons made or are they off the shelf?

I can honestly say no build that has come across my bench has been cheap and I would love to build a methanol racer for someone with all the info and specs I have now. Building a 650 would be fun..but the build really likes 750+ and the displacement lends to the 70hp marker much better.

Are any of you guys running a billet crank? I would like to meet Rob Hall and Kevin Roberts and talk flow and performance since learning never ends.

There is an A65 on the salt? I would love to see that engine!


Good notes here. Thanks again!


...no idea what your doing
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #761977 01/08/19 10:57 pm
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The quench in a hemi engine is the narrow band arrounf the circumference of the piston and head..If this is as closer than .050 it will induce a turbulence for a faster burn.If the quench,like on a Triumph,the closer the better to a point..Less total ignition timing can be used , a leaner part throttle mixture, more power. There is no downside unless the piston smacks the head. This isn't for everyone or needed by everyone but it is for me because I like to see the results.... if any...

This is my 79 T140D cylinder..The barrel deck was milled .022", then adjust the quench with base gasket copper shims and no paper base gasket..The piston here sits a few thousands above the deck. I use shorter pushrods and tubes to match.

[Linked Image]

This is on my 650 race bike..10.5 low dome pistons....038




[Linked Image]


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #761988 01/09/19 12:20 am
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Denis J Offline
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Copy that and thank you..I am familiar with quench. What I was interested in was the pistons you use the remedy the lack of a quench band on the head itself. I see your mods and that looks great.

I am looking to create a quench band 8mm wide and 30 degrees in the Triumph/BSA head...custom pistons to match.
Thank you for the tip on .050" clearance - I am familiar with .060" and was using that in my calcs.

The pistons in your first picture look like the units I have used in an A65. I see a nice band that looks like my 30 degree bands. The look massaged..Did you modify the head to match?


Here is a picture from Sorenson that shows a the camber that will give any 2 valve air cooled engine a million horsepower
[Linked Image]




...no idea what your doing
Re: A better 2 valve head for Triumphs [Re: Hillbilly bike] #768751 03/20/19 11:48 pm
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Hillbilly why not use an A65? Then you can run a std head casting without lots of modifying to get the same thing? Plus it's bigger bore shorter stroke? I'm getting around 200cfm @ 28"w with my big engine 883 road bike using .410" valve lift, lots of power through the range to 8,000 without power falling off. Anything from 135-142cfm can be had with stock valves and port size, going up in size can get anything in between to suit engine capacity and use. Stock A65s flows around 109cfm probably similar to a stock Triumph. But the BSA has a much better casting, rocker supports, combustion chamber and valve angles, only spoilt by the factory machining of the inlet ports.


The modern Triumph 8v heads flow around 180cfm stock, a modified A65 head can do that.


mark
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