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Re: The what if A65 67hp challenge. [Re: Hillbilly bike] #784776 09/19/19 1:35 pm
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Allan Gill Online Happy
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Originally Posted by Hillbilly bike
I was in a discussion with several successful engine builders, auto drag racers....They claim from experience that if you have heads with identical flows rates, but one has higher velocity ports,when cammed and tuned for best power, the lower velocity ports will make more high end power and the vehicle will be faster on the track...



Are they using turbos, super chargers or other means which mean the gas/air velocity is not controlled or over come by an external mean.


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Re: The what if A65 67hp challenge. [Re: Allan Gill] #784781 09/19/19 2:20 pm
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Originally Posted by Allan Gill
Originally Posted by Hillbilly bike
I was in a discussion with several successful engine builders, auto drag racers....They claim from experience that if you have heads with identical flows rates, but one has higher velocity ports,when cammed and tuned for best power, the lower velocity ports will make more high end power and the vehicle will be faster on the track...



Are they using turbos, super chargers or other means which mean the gas/air velocity is not controlled or over come by an external mean.

N/A ohv...


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784787 09/19/19 4:09 pm
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Thanks for the advice Nick, it was touch and not go with the last set until the seats were cut deeper, might lose some weight off the piston and gain a little clearance.


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
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Re: The what if A65 67hp challenge. [Re: Mark Parker] #784820 09/20/19 2:01 am
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Gavin the 44.5mm valves when the port is good flow 200cfm the 42mm MAP valve is similar to the P&M, both are excellent, you could possibly have new valve seats fitted to the big valve head you have. Flow through the MAP 42mm valve is now showing 168.6cfm at stock valve lift with manifold and bell. 160 with just the manifold, which is 34mm. This is the Thunderbolt head frown

If the head could be welded down in the pushrod tunnel and built up, the port could then be widened by 5mm or so more to good effect. I'm pretty sure this could be done without interfering with the pushrods. A MIG may get in there better than a TIG and a welding guru (not me) could probably do it easy. The blue arrow points at the curve in the casting that is the port outer wall. The redarrow is the hole for the guide. In the yellow circle is the alloy plate I JBwelded on. If there is no plate over the break through hole the JBweld can/will crack. This is not a good place to have JBweld as the softer material on the inner wall always results in a bump because it sands away easier than the alloy. It doesn't matter on the floor of the port because its all JBweld.

[Linked Image from i.postimg.cc]

Another view of the plate JBwelded on, this gives no problem in use.

[Linked Image from i.postimg.cc]

Views of the head:

[Linked Image from i.postimg.cc]

Possibly more suitable for a 750.

[Linked Image from i.postimg.cc]

Flow with the 34mm flatslides will be measured when they get here. The big challenge is getting the other side the same. Plus I'm not sure how wide these carbs are I can extend the manifolds a little if necessary and get the carbs further apart, I wanted to keep the port and manifold as straight as possible so the turn at the manifold head area is ok.

Last edited by Mark Parker; 09/20/19 2:05 am.

mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784824 09/20/19 4:51 am
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Im super interested in this

My numbers are very different from yours.


Full time classic motorcycle mechanic and enthusiast to a fault
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784826 09/20/19 5:44 am
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Mark, Have you thought about fairing in the guide, particularly the down stream side? A cylinder produces an oscillating wake which might be making a wider affected area than the width of the guide. Also, the thrust in the guide is fore/aft so the sides of the guide can be tapered from the roof down to the end.

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784827 09/20/19 6:03 am
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I did put the guide in the lathe and blend the end of it so is hasn't a squared off end. I could try taking a bit off the sides of one and see what it does. But welding in the pushrod tunnel I think might be the place to make big gains. It's already a bit past what a 650 could use, or what might be necessary for the 67hp. I made this guide a push fit so I can push it in and out easily. I've tried fairing before and after the guide its just that if the fairing isn't exactly right and air goes across it, I had that with one side of a head and it took ages to find what was messing one port up. Maybe I could do a better profiled flair. But I'm not messing with this port anymore unless to test the profiled guide.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784848 09/20/19 2:37 pm
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Now I'm not a real expert on engine design, but here are a few of my thoughts. I think we have to look at the history of the motorcycle to understand why the motors were made the way they were. The 90 degree (included valve angle) hemi-head made sense because they could use larger valves than they could with a flatter combustion chamber. Furthermore, it was easier to fit a carburetor and an exhaust pipe because they only had to make a 45 degree turn in the ports to get these things horizontal - - simple! It also precluded the problem fitting more massive motors under the gas tank.

Apparently, someone discovered, probably BSA, that a flatter combustion chamber allowed higher compression and made more power than the high pent roof 90 degree hemi. Hence the Gold Star had a shallower included angle (not sure what angle they started with.) Then BSA discovered that by offsetting the ports at an angle induced swirl which further enhanced combustion efficiency.

I think they knew that with the reduced included valve angle, they could get more power, but the size of the ports became a problem with the larger motors, again because the gas tank and top frame tube restricted the overall height of the motor, so the head space above the valves was minimal. So the Gold Star begot the BSA B44 which of course was a unit motor and cheaper to build, but they didn’t solve the head space until 1971 with the B50 which has a 67 degree included valve angle plus more head space allowing somewhat larger ports. Additionally, they added back the 3rd bearing on the crankshaft (per the Gold Star motor) which greatly improved the rigidity, without even changing the crank itself from the B44.

And as you know, the A65 although it has a shallower combustion chamber compared to the Triumph due to the reduced included valve angle, still did not have the raised head space like the B50, so you just can't enlarge the ports in the upper direction without running into the valve spring pockets, and if you enlarge towards the pushrod tunnel, you break thru there, and similarly, enlarging outward breaks thru the finned area as Mark had found out, unless you first build up that side up with weld, although I admit I haven't built a performance A65 - - - - yet!

Then we have V-twins like Harley, who probably stuck with flathead motors rather than improve on the knuckle head overhead valve motor due to expense. Interestingly, using the V configuration would have allowed more head space to enlarge the ports vertically, but Harley chose to copy the Gold Star with their "modern OHV motors" (according to Keith Cameron) so some things were improved but not everything. The 45 degree V design pushed the cylinders so close to each other as to require an even more torturous intake port with 2-90 degree turns. I'm surprised that no one has tried reversing the intakes and exhaust functions like Alp has done with his Triumph twins, which would seem to allow almost vertical intake ports and fewer problems getting the exhaust (much smaller than the intake ports) snaked out thru the sides of the heads. Yes, they did produce the XR or whatever it was called with the rear cylinder set up that way, but it still left the front cylinder's intake with some fitting issues. But if you look at a modern Harley intake port, you can drive a truck thru them compared to our British heads.

Now we look at modern 4 valve dual overhead cam motors, short stroke multi-cylinders to allow shorter overall height, nice flat combustion chambers, tumble instead of swirl induced induction, higher rpm with multiple crank bearings, electronic fuel injections, and say why didn't they think of that sooner? (I'll leave out the bad idea of a single overhead cam design putting the cam in the hottest part of the motor but still using rocker arms. Stan Millard proved that when his B50 flat trackers could outrun everything including Yamaha TT500s and the Rotaxes.) But as we are stuck on our old Brit designs, we suffer on doing the best we can.

Incidentally, as I don't have my own thread here, so I'll tell you what I did with my TR25 motor (BSA B25). I cut off the intake flange, moved it up about 3/16", and bored out the intake to 31.5 mm before breaking into the valve seat area. I then tried going sideways but broke thru the finned area. I use a Carillo rod, JE piston, Titanium valves (made from used Chevy NASCAR valves), Megacycle cam, chrome moly pushrods, and a Mikuni 34mm flat slide carb. These improvements along with smaller wheels, longer swingarm, and a narrower width allowed me to set a new record at Bonneville (SCTA) last weekend, of 95.2 mph breaking a 10 year-old record. I reached 97mph on my down run, but blew the mile-two back-up run when my fuel filter became clogged with rust, so I had to settle on the 1st mile 95 mph speed on both runs. So we can still improve.

Here is a photo of the bike with an AMAL GP carb, which I couldn't get to work properly.

[Linked Image from i.postimg.cc]

Here is another photo showing the finished port.

[Linked Image from i.postimg.cc]


Tom


Last edited by koncretekid; 09/20/19 2:41 pm.

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Re: The what if A65 67hp challenge. [Re: Mark Parker] #784858 09/20/19 4:52 pm
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Hey Mark

I am curious how you measured your port volume earlier. I’ve yet to try a new to me method using a rule and a burette.

Another question (thanks for entertaining my questions)
Airspeed? I haven’t seen you mention your targets... I am working with figures from other race engines hitting 108 and 112 VE that see 630-640 limiting port velocity.
A contact in NASCAR related to me 650 is target and in some cases close to 700..but these number normally choke most engines.

I tested the stock A65 heads and their potentials. Your CFm numbers are huge compared to my calcs for needed cfm at top rpm.

Lastly ( thanks again) How are you hitting these piston speeds!?
I’ve decapitated many pistons attempting over 4200fpm. I’ve learned the hard way 4000-4050 is the threshold for most engines with “performance” pistons. My custom made pistons can take 4500fpm but not my crank (500 single)

Thanks for sharing all this..I am really anxious to see how it pans out. You’re steps ahead of me.


Full time classic motorcycle mechanic and enthusiast to a fault
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784860 09/20/19 4:58 pm
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Congratulations on the record. Were you in modified class ?


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Re: The what if A65 67hp challenge. [Re: konon] #784882 09/20/19 8:27 pm
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Originally Posted by konon
Congratulations on the record. Were you in modified class ?


Thanks for the complement. 250 M-PG, which is 250cc M (modified stock frame with 4" extended swingarm), Pushrod motor on event Gasoline (ERC 110K which is about 110 octane). Bore is stock as is stroke. This same bike went 100mph at Loring, ME at the 1-1/2 mile, but of course at lower altitude.

Tom

P.S. Denis, I calculate the average piston speed of my B50, 90mm stroke at 7500 rpm to be 4425 fpm, and my TR25, 70mm stroke at 9500 rpm to be 4370 fpm. Both motors have Carillo rods and JE pistons with stock cranks.


Life's uncertain - go fast now!
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784893 09/20/19 11:03 pm
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Denis I just used a measuring cup to get a rough idea of port volume. With airspeed I'd read that the stock heads do not have high airspeed. With flow to rpm you can set yourself a limit below maximum power rpm, I've revved my 89mm stroke A65 to around 8,000rpm if you look at the graph above it make good power below that and though the dyno operator wanted to rev it more to see where power would start falling off I chose not to. It probably breaths beyond what it needs to but I doubt there is a reason to have it breath less, I doubt it would gain anywhere from breathing less. It just pulls well from virtually nothing, usually not below 2,500.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784913 09/21/19 2:30 am
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Denis J Online Content
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Originally Posted by Mark Parker
With airspeed I'd read that the stock heads do not have high airspeed. With flow to rpm you can set yourself a limit below maximum power rpm, I've revved my 89mm stroke A65 to around 8,000rpm if you look at the graph above it make good power below that and though the dyno operator wanted to rev it more to see where power would start falling off I chose not to. It probably breaths beyond what it needs to but I doubt there is a reason to have it breath less, I doubt it would gain anywhere from breathing less. It just pulls well from virtually nothing, usually not below 2,500.



Mark, Maybe you have your figures crossed? Low-er airspeed higher potential RPM peak power...Higher airspeed lower potential peak RPM horsepower. (I use the Lower=Lazy and Higher=choke)
If the airspeed is too high for a target RPM the intake port will choke. This is usually at .5-.55 mach or roughly 650 fps in my garage.
I tested a box-stock Hornet head with 30mm ports at 725 fps through the 30mm AMAL. On paper and on the dyno the bike made peak power at 7000 on the dot. The intake airspeed limited the RPM potential.

4600 feet per minute piston speed!!! Holy how! I have destroyed pistons from JE, Wiseco and all the other wannabe's trying to attempt this. Trying to meet Nascar/F1 figures of 4800. A great friend and veteran engine builder has found the happy medium for an overdeveloped AHRMA 350 single to be 4200. (42.2 hp at the rear wheel). Based on his racing experience I found 4000-4200 to be the maximum average. Beyond that parts take on new shapes. I shoulda kept the bits for decoration.

4600 is a dream goal! That makes for a stock stroke A65 9450rpm - A screamer. I need your metal recipe. I have been leaning for a source of maraging steel that is not trying to take my retirement in payment

I really appreciate you sharing your work. It is great to have another person as crazy as some of us to uncork the potential of the A65


Full time classic motorcycle mechanic and enthusiast to a fault
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784921 09/21/19 3:20 am
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I used to run a round ported head on the 883 when it was 810cc the head used 44.5mm intakes with 38mm carbs it made power to around 7500rpm 55hp on the data logger. I fitted the big bore cyl and though it had more power on the data logger it was below 6,000 and around 60-65hp. I fitted offset rocker buttons and moved the power up to 65-6700rpm and over 70hp on the data logger, then it fell away sharply. It was good up to there. That head flowed around 160cfm. When I oval ported it the port volume was the same, as was the valves and carbs but flow is now around 200cfm and it just makes more power and keeps pulling to higher rpm. I'm using JE B44 pistons in a Nicasil bore and alloy drag race rods plus 90degree crank which reduces dynamic load by around 45%. Whatever the air speed is in that head doesn't seem to hinder it. I'll just try the good flowing little head on something and see what it does.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784931 09/21/19 6:46 am
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Denis, what hp did you get from the Hornet? Do you have graphs? My plan is to test my stock, other than a roller conversion, 650 Firebird with one or two small oval port heads and see if I can get 59-60rwhp, equivalent to around 67hp at the crank.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784952 09/21/19 12:30 pm
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Hey OT!, Nice work with the 250! Hope to see you next year. PRT

Re: The what if A65 67hp challenge. [Re: Mark Parker] #784961 09/21/19 2:26 pm
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Tom, have you been able to get any of the dyno readouts on the turbo or the MPG bikes?


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: Mark Parker] #784986 09/21/19 7:21 pm
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Denis J Online Content
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Originally Posted by Mark Parker
Denis, what hp did you get from the Hornet? Do you have graphs? My plan is to test my stock, other than a roller conversion, 650 Firebird with one or two small oval port heads and see if I can get 59-60rwhp, equivalent to around 67hp at the crank.



Like an idiot I gave the original to the owner and since I have tried to get a copy from him with no luck. I'm gonna ping him again.
It made 52 hp/7000rpm at the rear wheel on a Dynastar dyno. I was surprised. I did not expect over 45
The only deviation from stock was the carbs - AMAL Concentric 30mm.


My head is spinning! I have been running numbers on your engine and I am super impressed/motivated! Your motor is blowing my mind. Back to the drawing board for me..


EDIT:
I was wrong- The gent reminded me on a call last night. I had apparently told him the motorcycle might make 35 hp and it made 42 - not 52

Sorry all. I'm the guy with his foot in his mouth today.

Last edited by Denis J; 09/26/19 3:48 pm.

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Re: The what if A65 67hp challenge. [Re: Mark Parker] #785047 09/22/19 4:34 am
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If you were getting 52 brake at the back wheel from a STANDARD 650, you were doing bloody well with an a65!
It took me a damn long time to get much more than that from a very modified 750 kitted one. I remember being very
pi$$ed off getting around 55 after all the work we'd done, another 2 years before we saw 60 and that was at 7500+.

Re: The what if A65 67hp challenge. [Re: koncretekid] #785051 09/22/19 5:39 am
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That's very impressive from the 250 KK. Do you have any flow readings on the head or any dyno graphs?

I'm looking at one of, I think Pushrod Tom's, dynographs from the Hornet in 2010, two runs on the graph the difference being 250 and 260 mains. It has a graph of air fuel. If both are being graphed in real time it's interesting seeing the power loss with too rich and too lean conditions.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #785064 09/22/19 11:11 am
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Originally Posted by Mark Parker


I'm looking at one of, I think Pushrod Tom's, dynographs from the Hornet in 2010, two runs on the graph the difference being 250 and 260 mains. It has a graph of air fuel. If both are being graphed in real time it's interesting seeing the power loss with too rich and too lean conditions.

So are they 60 hp?


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: Mark Parker] #785065 09/22/19 11:20 am
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If they were 2010, I would say no. PRT

Re: The what if A65 67hp challenge. [Re: Mark Parker] #785067 09/22/19 11:40 am
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Not this one, it's from 2010, 51.32rwhp. Hope it's ok to put it on here. It's interesting the difference of one jet size. Around 12.5-1 is supposed to be the best air/fuel ratio for power. My 883 was too lean on the dyno the richest it got which was at over 7,000 and was 14.4-1 which is way off, it started massively lean then gradually got richer as rpm rose, but I don't know just what that means in hp loss. I did notice an improvement through the mid range with richer mains.

[Linked Image from i.postimg.cc]

I'm hoping Tom might share his latest graphs which are at higher power levels. For perspective the best stock Commandos are around 48rwhp.


mark
Re: The what if A65 67hp challenge. [Re: Mark Parker] #785069 09/22/19 12:43 pm
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I saw Tom's Hornet at the land speed racing track two times he raced in the same class as my 650 Triumph I believe the Hornet engine is modified, quite a bit modified at least by 2017....At any rate no BSA has been able to catch my Triumph at 133 mph or Kevin Roberts Triumph at 135 mph...Just some good natured prodding here...


79 T140D, 96 900M Ducati ....On a bike you can out run the demons..
Re: The what if A65 67hp challenge. [Re: Mark Parker] #785183 09/23/19 11:35 am
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You Triumph guys are what propels my efforts. Not an easy task! I'm pretty sure we can do it but everything must be perfect as you know. That picture is a great bit of nostalgia and a reminder of where we were back then although it does not tell the details which were more complicated than dyno work. I would say that 12.5-12.8 is a good target for straight up race gas but some of the fuels we use want more. PRT

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