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Intake valve shape

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GuS

Posts: 360

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Location: Bergen, Norway

Post Thu Jan 08, 2015 5:23 pm

Intake valve shape

Hi all.

The 45 performance handbook by Panic states the top corner if the intake valve shuld be left with a sharp corner for better flow.
The HD KR performance manual states that this corner should be slightly radiused for the better flow.

My guess would have been to radius the corner to remove sharp edges and improve flow, but i believe Panic got a good reason for his recommendation. Later knowledge from flow bench tests?

Any experiece where to go with this?

Regards
GuS
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37ULH

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Post Thu Jan 08, 2015 9:10 pm

Re: Intake valve shape

Tried to send a PM but if you post your query at the following address perhaps the author will clarify his thoughts.
http://www.hydra-glide.com/phpBB3/viewf ... 98a5e7b1e4
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45Brit

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Post Fri Jan 09, 2015 8:42 am

Re: Intake valve shape

I've always understood that valve seats should be minimised to reduce resustance to flow; but if HD say to do any given thing, they are probably right (unless your name is Sifton or Leinweber, at any rate)
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Cotten

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Post Fri Jan 09, 2015 9:02 am

Re: Intake valve shape

As far as I can remember, Folks,

It was in the '80s or so that flow and dyno studies suggested that the sharper the edges the better, counter-intuitive as it may seem.
It was also about the time that cutting seats became more practical than grinding, producing a sharper line between angles.

....Cotten
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GuS

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Location: Bergen, Norway

Post Fri Jan 09, 2015 4:27 pm

Re: Intake valve shape

Thanks folks.


There is some informaton around. One artickle at Beauty of speed stating that some motors may benefit from sharp edged valve top and some might not. Here is what the HD competition racer handbook says about shaping the intake valves for the KRs.

Image

Was wondering if there were later flow bench tests or other experience behind the idea to sharpen the top valve corner in these flatheads.
37. Thanks for the tips. I knew abut that other board, but im kind of lazy when it comes to changeing internet bar, and havent been there in years. I miss Panic arund here. Isnt it about time to open up for him?
Hey it's a big world out there and only so few of us addicted to these old miracle machines
GuS
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Cotten

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Post Fri Jan 09, 2015 4:45 pm

Re: Intake valve shape

GuS!

You are probably aware that production H-Ds were normally 45 degrees. Indians were 35, so 30 is pretty diesel.

Everything is a give and take; Do you expect to compete?

....Cotten
PS: Its a new forum as far as I am concerned, and I would welcome Mr. Diamond's return.
But then I probably won't be un-barred from the Yucky Urinal, Shovelhead.us, The Horse... etc.,.. either.
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GuS

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Post Sun Jan 11, 2015 1:43 pm

Re: Intake valve shape

Cotten.
R, Ws and Ks 45 deg. KR 30 deg. WR i'm not sure, but believe 30deg.

Racing, no. Not this one, But always trying to learn.
GuS
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45Brit

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Post Mon Jan 12, 2015 1:40 am

Re: Intake valve shape

My Jawas have valve seat angles nearer 45 deg than 30, because there are some compromises made for reliability in tbe design. It's commonly known that there is a very small extra power gain by reducing tbe angle and recutting the valve seats accordingly, but that comes at the cost of significant,y reduced valve life (it doesn't really affect the seats, because the seat area is the same and the contact area with the surrounding metal, also the same) and most riders opt for the reliability because their funds are finite, they can't actually USE the small incremental power - or lose it in some other oart of the set-up - and you don't win by not finishing.

My recommendation in cases of this sort is that the gains achieved are of no value in road use, may be detrimental, and the cost and effort would be better expended on some other aspect of the machine.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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Hopper

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Post Wed Jan 21, 2015 8:49 pm

Re: Intake valve shape

Some flow bench guys in the performance car world have found that the sharp edge on the intake valve reduces backflow of fresh charge out of the combustion chamber into the intake port when the crank has gone past BDC but intake valve is still open.
Others say to use a radius.
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barry

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Post Fri Jan 23, 2015 2:09 pm

Re: Intake valve shape

the flatheads used 30 degrees for the intakes to straighten out the flow.you can in no way compare these with an ohv motor due to valve position,port shape,combustion area,etc. sifton pretty much wrote the book on making this engine run(discounting tuners such as bernt of course) on making the flattie run... the design changes in the 55r parts and the 67 up mids reflect his ideas.
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GuS

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Location: Bergen, Norway

Post Sun Jan 25, 2015 4:59 pm

Re: Intake valve shape

Barry,45 and Hopper, thanks for the input.
The HD competition hadbook where the reccomendation to break the corner on both KR inlet and outlet valve, i believe is after the yr. Barry mention. The same handbook reccomend to not break the XLR inlet valve corners.

When i installed the KNS 30 deg intake valves some yrs back, i decided to follow the Panic reccomendation to leave a sharp edged intake valve. I reduced the OD slightly, leaving the valve head quite thick. Since i have the top end open ive decided to take of some meat off the valve head above the seat, reducing the valve thicknes. The KNS valve in the picture (left) is after i reduced the head thickness. To the right is a KH valve with 45 deg seat.

I will most likely leave the sharp corner, but still havent made up my mind...

Btw. The KNS valves seem to be made of some really good material. They have been in there for some 5000 km and show no sign of wear.

Image


GuS
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thefrenchowl

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Post Mon Jan 26, 2015 8:02 am

Re: Intake valve shape

Since on side valve the flow has to do a 180 turn from up the valve to down the cylinder, seems obvious to me that 30 degs seat on them will work better than 45 degs... Same idea for them being as "flat" as possible... 7 deg on inlets, 11 degs on exhausts, actual seat about 20 thou wide

These thin 30 degs stainless steel stellite valves in my KHK (now supercharged on methanol for the past 4 years due to Bonneville Salt Flats use) have been in that engine for the best part of 20 years, no signs of wear yet, same for seats...

Patrick
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GuS

Posts: 360

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Location: Bergen, Norway

Post Mon Jan 26, 2015 2:56 pm

Re: Intake valve shape

Patrick.
Thank you.
Seat width about 0.020?
I did them at 0.079, angle @ 9 degrees. At that time it seemed enough.
Maybe I'll make the extra cut down to 7 deg. In fact i gave up cutting as the cut always came out rough no matter which speed and tool i tried. Ended up making a fixture for the Dremel, using the lathe and Dremel to shape the valve and cut the seat angle.

GuS
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45Brit

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Post Mon Jan 26, 2015 11:29 pm

Re: Intake valve shape

Since we are talking about methanol, my 350cc JAP has valves as sharp as they can be consistent with mechanical reliability (NOT durability, which is a different matter). It definitely increases the "sharpness" of the motor but they last about 3 meetings, before being changed (I have a workmate who does NDT checks for me, that or I start to notice compression or erosion issues). I wouldn't attempt this with petrol.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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45Brit

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Joined: Tue Nov 27, 2007 2:29 am

Post Mon Jan 26, 2015 11:31 pm

Re: Intake valve shape

thefrenchowl wrote:Since on side valve the flow has to do a 180 turn from up the valve to down the cylinder, seems obvious to me that 30 degs seat on them will work better than 45 degs... Same idea for them being as "flat" as possible... 7 deg on inlets, 11 degs on exhausts, actual seat about 20 thou wide

These thin 30 degs stainless steel stellite valves in my KHK (now supercharged on methanol for the past 4 years due to Bonneville Salt Flats use) have been in that engine for the best part of 20 years, no signs of wear yet, same for seats...

Patrick


It's not that simple, gas flow in side valve engines is a very complex issue.

Definitely agree that material quality is very important.
Shoot, a man could have a good weekend in Dallas with all that stuff...
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thefrenchowl

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Post Wed Jan 28, 2015 6:43 am

Re: Intake valve shape

Hi 45Brit

I did not design these valves shapes and angles..

Harley designed/refined them over 36 years of trying to get power out of the 750 WR and KR and eventually reaching the dizzy heights of 150mph laps at Daytona ; - ) Plus other tricks like tipped valves and pop up pistons

So they learned the hard way what was needed in the race shop, on the dyno and on the tracks and I'll happily go along with their findings without having to reinvent the wheel...

See you around, long time no see...

Patrick
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45Brit

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Joined: Tue Nov 27, 2007 2:29 am

Post Sat Jan 31, 2015 1:58 am

Re: Intake valve shape

Well, yes... Previous comments about overall engine set-up apply. I have three Jawa engines with varying combinations of set-up and significantly different characteristics. I know that for about £2k I can build an engine that would be significantly faster than any if them, and have a substantially higher wear rate on various components. Or, I can have a reliable engine which is consistently fast enough for most purposes, for a great deal less. We usually take two bikes and ride whichever one seems better on the day - air temperature and humidity have a noticeable effect, for one thing. We changed the jetting on one bike mid-season with good resukts; but we've run the same settings before to no effect in the past, some minor changes as the engine wears, I suppose. One of the three heads is definitely fastest, for no readily apparent reason - I attribute this to some subtle dufference in the porting, standard of finish in the ports, or both.

Changing the valve profile on the JAP has immediate and obvious effects. It's all a matter of where I want to be on the speed/reliability/durability/ride ability scale.

I'm sure the WR and especially, the KR are just the same, for the same reasons
Shoot, a man could have a good weekend in Dallas with all that stuff...
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thefrenchowl

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Post Sun Feb 01, 2015 4:53 am

Re: Intake valve shape

I entirely agree with you about set up, but the basic hard won knowledge for the hardware has already been found by factories with untold money power...

With these valves in my 900cc KHK, plus supercharger plus methanol, I get 121.775mph at some altitude... The factory bench mark is 152mph at sea level on the Daytona bowl with 750cc and twin carb normally aspirated...

And you're not the only one wondering where the power sometimes come...

When designing the alloy XR, Dick O'Brien and his crew found a particular head casting that was flowing way better than any other with a rather rough finish... They tried to duplicate it but couldn't... That head eventually was lost and Dick wondered if its new owner kept it as is or went ahead and polished it to the nth degree and lost for ever its good characteristics...

Patrick
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45Brit

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Joined: Tue Nov 27, 2007 2:29 am

Post Sun Feb 01, 2015 8:19 am

Re: Intake valve shape

Well, yes. The modern track racing Jawas are directly descended from the late-60s 2-valve, and there is still a 2-valve version for ice-racing. My Jawas aren't particularly fast as modern Classic racers go, but my son can turn times at places like Kings Lynn that would have been World Championship standard in the 1960s, the bikes are that much faster because tbe factory has progressively implemented its development into spares for the older engines. Stand a modern repro piston and valve set next to an original 1970s one and the differences are immediately obvious.

There are BSA 250cc on the grasstrack scene that are faster than 500s were, twenty years ago. You still occasionally see them on small, local tracks, even now.

It's the same process in operation.

152mph at Daytona on petrol is fairly going some. We went to Richard Petty Driving Experience at Daytona in '13 and the boys clocked 155mph and 171mph respectively!
Shoot, a man could have a good weekend in Dallas with all that stuff...

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