HPRE

Menu

Members Rides

Constellation Road Test


in
Members Rides

NField Gear

77 Guests, 0 Users
Welcome, Guest. Please login or register.
Did you miss your activation email?
October 19, 2017, 02:27:42 am

Login with username, password and session length

 

Author Topic: HMC 612cc crank  (Read 715 times)

oTTo

  • Grand Gearhead
  • *****
  • Posts: 2,701
  • Karma: 0
Re: HMC 612cc crank
« Reply #15 on: October 10, 2017, 11:06:44 am »
Thanks Tom, yes I'm aware of the principles. I may go for 36mm though first as this seams to be fairly easy to realize in the stock throttle body. 38mm may need the carb.

ace.cafe

  • Grand Gearhead
  • *****
  • Posts: 12,689
  • Karma: 0
  • World leaders in performance/racing Bullets
Re: HMC 612cc crank
« Reply #16 on: October 10, 2017, 06:07:17 pm »
Thanks Tom, yes I'm aware of the principles. I may go for 36mm though first as this seams to be fairly easy to realize in the stock throttle body. 38mm may need the carb.

Okay, the bare Ace head without manifold can flow 215 cfm at full lift.
The 34mm throttle body, not including the area restricted by the throttle plate  (which I have no figure for) has an area of 1.407 square inches.
In theory, a perfect orifice of 1 square inch can flow 146 cfm. So, 1.407 sq in can theoretically flow 205.422 cfm. Then, you will have to subtract something for the throttle plate area at full open.
So clearly, the 34mm throttle body,  even though it probably can flow near perfect as an orifice, is restricting flow to somewhat less than the Ace head intake tract can flow. About 10 cfm, or even less if you factor in the throttle plate area , lat full lift.

However,  if we look at a 36mm throttle body,  not including throttle plate area, we have about 1.577 sq in area. At a perfect orifice flow rate of 146 cfm per sq in, it should flow 230 cfm. If we figure a loss of 10-15 cfm for the throttle plate,  we get in a neighborhood that matches or exceeds the Ace head intake tract alone. So, in this case the restriction is basically solved.

In theory, it should be good for at least 2 more hp at the rear wheel. I made a calculation that showed 39.8 rwhp from the 535 with the 36mm benefits. Not sure if it will pan out accurately,  but it's  maybe possible.

It's worth a try.
« Last Edit: October 10, 2017, 06:11:08 pm by ace.cafe »

Aus.GT

  • Bulleteer
  • ***
  • Posts: 197
  • Karma: 0
Re: HMC 612cc crank
« Reply #17 on: October 11, 2017, 01:53:02 am »
89mm can be realized in the existing sleeve and is probably the smarter choice. Regarding the piston, the valves are bit off centre on the ace head if I remember correctly, if I have that info than I can paint up the piston and we can see with some companies, I doubt that we find anything out of the shelf which is perfect fit.

The HD piston still looks heavy to me, I would estimate that we can save appx. 10% weight on the stock GT piston, that could be worth something.

Hey oTTo I'm keen for an 89mm piston as well if your going down that path.
1988 Gilera Saturno 500
2014 Continental GT
1985 Ducati Mille S2

oTTo

  • Grand Gearhead
  • *****
  • Posts: 2,701
  • Karma: 0
Re: HMC 612cc crank
« Reply #18 on: October 11, 2017, 02:19:25 am »
Hey oTTo I'm keen for an 89mm piston as well if your going down that path.

That would be great, because we may have to order atleast 4. I think 89mm shall be it, without the need of making a new sleeve for the barrel. And of course it's ought to be light, we can land at about 380-390grams vs. 411grams for the stock piston in my opinion.

Aus.GT

  • Bulleteer
  • ***
  • Posts: 197
  • Karma: 0
Re: HMC 612cc crank
« Reply #19 on: October 11, 2017, 04:51:21 am »
Excellent, lighter weight even better.
Cheers.
1988 Gilera Saturno 500
2014 Continental GT
1985 Ducati Mille S2

ace.cafe

  • Grand Gearhead
  • *****
  • Posts: 12,689
  • Karma: 0
  • World leaders in performance/racing Bullets
Re: HMC 612cc crank
« Reply #20 on: October 11, 2017, 06:52:27 am »
The key to keeping the weight down is to spend some money on a shorter stiffer pin of good steel like H13, and use a thinner pin wall thickness to take advantage of the steel strength. That can save 28 grams right there. We used a H13 pin 1/2" shorter on the Iron Barrel Fireball,  and used a tapered bore in the pin with the stronger material. Lighter and stiffer, both.
Also, a flat crown has the least material because it gives the shortest distance from edge to edge. And it has the least thermal gain because of the smallest possible exposed surface area. And it gives uninterrupted flame travel path. All good.
« Last Edit: October 11, 2017, 06:56:19 am by ace.cafe »

oTTo

  • Grand Gearhead
  • *****
  • Posts: 2,701
  • Karma: 0
Re: HMC 612cc crank
« Reply #21 on: October 11, 2017, 12:11:30 pm »
Flat top with with 89mm barrel should give 11:1 compression. I tested in my bike 95 octane fuel without any issues and that has 10:1 at pressent. So that should be ok, 1 point on the compression might be good for approx. half a horse too.
« Last Edit: October 11, 2017, 12:15:18 pm by oTTo »

KD5ITM

  • Grand Gearhead
  • *****
  • Posts: 911
  • Karma: 0
Re: HMC 612cc crank
« Reply #22 on: October 12, 2017, 08:22:10 am »
 I saw this crank advertised on Facebook by Hitchcock's a few days ago. Thought it would be nice. But I guess it's not worth it if the bike runs out of breath too soon. I've always wondered, why could Norton back in the 60s build a bike with 50 horse but yet Royal Enfield in 2017 can't build a bike with 30 horse? Is it the mentality of the way of thinking in India, is it just that Royal Enfield doesn't have the means to produce more horsepower or is Royal Enfield just scared to make a little more horsepower?
2014 Continental GT - red
1979 Hurst/Olds W-30 - whit and gold
1964 Volvo PV544 - desert sand
1961 Willys Jeep Utility Wagon - saturn yellow
2014 Trek Madone 5.9
2013 Specialized Carve Pro

Richard230

  • Grand Gearhead
  • *****
  • Posts: 1,470
  • Karma: 0
Re: HMC 612cc crank
« Reply #23 on: October 12, 2017, 08:49:31 am »
I saw this crank advertised on Facebook by Hitchcock's a few days ago. Thought it would be nice. But I guess it's not worth it if the bike runs out of breath too soon. I've always wondered, why could Norton back in the 60s build a bike with 50 horse but yet Royal Enfield in 2017 can't build a bike with 30 horse? Is it the mentality of the way of thinking in India, is it just that Royal Enfield doesn't have the means to produce more horsepower or is Royal Enfield just scared to make a little more horsepower?

I think it is because they don't need much horsepower to get around India in style.  ;)
2011 Royal Enfield B5 500 and 2014 14.2 kWh Zero S

Bullet Whisperer

  • Grand Gearhead
  • *****
  • Posts: 871
  • Karma: 0
Re: HMC 612cc crank
« Reply #24 on: October 12, 2017, 11:49:40 am »
I saw this crank advertised on Facebook by Hitchcock's a few days ago. Thought it would be nice. But I guess it's not worth it if the bike runs out of breath too soon. I've always wondered, why could Norton back in the 60s build a bike with 50 horse but yet Royal Enfield in 2017 can't build a bike with 30 horse? Is it the mentality of the way of thinking in India, is it just that Royal Enfield doesn't have the means to produce more horsepower or is Royal Enfield just scared to make a little more horsepower?
Just took a look at their FB page and it seems they also have a 4 valve head in the pipeline for the UCE engines  8)
 B.W.

ace.cafe

  • Grand Gearhead
  • *****
  • Posts: 12,689
  • Karma: 0
  • World leaders in performance/racing Bullets
Re: HMC 612cc crank
« Reply #25 on: October 12, 2017, 04:37:33 pm »
I think a 2 valve will get the job done just fine.
 ;)

gizzo

  • Grand Gearhead
  • *****
  • Posts: 1,464
  • Karma: 0
  • Live slow, die whenever
Re: HMC 612cc crank
« Reply #26 on: October 13, 2017, 12:05:19 am »
I saw this crank advertised on Facebook by Hitchcock's a few days ago. Thought it would be nice. But I guess it's not worth it if the bike runs out of breath too soon. I've always wondered, why could Norton back in the 60s build a bike with 50 horse but yet Royal Enfield in 2017 can't build a bike with 30 horse? Is it the mentality of the way of thinking in India, is it just that Royal Enfield doesn't have the means to produce more horsepower or is Royal Enfield just scared to make a little more horsepower?
A bit of all of the above. There's plenty of info out there they could use to get more power if they wanted but they're Indians, they know best and they won't be told. + A Norton Manx making 50HP is good for the IoMTT but it's not going to last for years of road riding. It just isn't. And it won't idle, let alone at 50rpm the way the Indians dig it. A friend rides a KTM RC390 single. It makes 40hp. She loves it but it's highly strung and I don't find it relaxing one bit. That's not really the behaviour I'd want in a RE.
simon from south Australia
Continental GT
Suzuki Savage bobber
Pantah
Monster
DR250
TRX850

Bullet Whisperer

  • Grand Gearhead
  • *****
  • Posts: 871
  • Karma: 0
Re: HMC 612cc crank
« Reply #27 on: October 13, 2017, 01:38:45 am »
A bit of all of the above. There's plenty of info out there they could use to get more power if they wanted but they're Indians, they know best and they won't be told. + A Norton Manx making 50HP is good for the IoMTT but it's not going to last for years of road riding. It just isn't. And it won't idle, let alone at 50rpm the way the Indians dig it. A friend rides a KTM RC390 single. It makes 40hp. She loves it but it's highly strung and I don't find it relaxing one bit. That's not really the behaviour I'd want in a RE.
Here is an RE engine capable of 9500 rpm, it would also idle at less than 1000 rpm if the 1 1/2" GP carb had an idle screw. It doesn't spit, pop and bang and is not 'highly strung', the race engines that do are usually not very well set up.
 B.W.
https://youtu.be/ekZgB6DWz9A

oTTo

  • Grand Gearhead
  • *****
  • Posts: 2,701
  • Karma: 0
Re: HMC 612cc crank
« Reply #28 on: October 13, 2017, 01:59:35 am »
Yes but it's a 350. The 500 would need a seriously shorter stroke for those revs. A 4-valve head could be starting to pay off at these revs too. Basically one would land up with a KTM450 type of engine in the end with some 95+mm piston and a stroke 60-70mm. Very costly to realize in a 500 uce.
« Last Edit: October 13, 2017, 02:02:39 am by oTTo »

Bullet Whisperer

  • Grand Gearhead
  • *****
  • Posts: 871
  • Karma: 0
Re: HMC 612cc crank
« Reply #29 on: October 13, 2017, 02:06:46 am »
You don't need 9500 rpm from a 500 engine, I was just demonstrating that a highly tuned engine can still be flexible and not 'highly strung'. Incidentally, the Honda CRF 450 engines peak at well over 45 bhp, with 4 valves and at little, if any over 7000 rpm.
 B.W.