[Jako]

Can this be really happening ? Hitchcock's 4 valve heads and long stroke crank

[Otto_Ing]

  ....I dig it.

Four valves and a stroker? Kind of contradictory setup.

[Adrian II]

Well, that is their facebook page so I assume it's really happening.

Not sure it needs the long stroke crank but we'll see how this pans out compared with Ace's Billet Head Fireball conversions.

Now why didn't they offer this for the AVL models?

A.

[malky]

I bet you the kit will cost more than what some GT's are selling for in the UK. I have every confidence it'll be good, but I'd make sure the bike was a long term keeper before shelling out.

[Adrian II]

Ace's stuff is not cheap either, people have to cover their costs at least or it's not worth doing commerically, which is why there are no more AVL Fireball heads for the moment.

However I don't think we could ever accuse Mr. H. of under-pricing.

HMC will have to judge the market carefully, I wonder how many of their super special 5 speed boxes are unsold at 6 or 7 times the price of a pefectly adequate Indian 5 speed box. No use getting a batch of 100 4 valve heads made if the price scares the customers off, we know the long-stroke cranks will hurt the wallet enough.

On the other hand, a hybrid kit fitted to a set of C.I. cases might make for a very nice engine...

A.

[malky]

I'd like to get one of these to play with.
Not much chance.

[ace.cafe]

It can be good if they do it right.
It comes down to the 4-valve has more flow area, and needs less lift to reach the necessary flow. The 2-valve has less flow area, and needs more lift to get there.

Bottom line is that both types can service the necessary flow at the rpm ranges involved. Six to one, half-dozen to the other.

The other aspects besides number of valves will be at least as important,  if not more so.

At least I won't be so alone losing money doing this stuff now.
 

[Otto_Ing]

HMC will have to judge the market carefully, I wonder how many of their super special 5 speed boxes are unsold at 6 or 7 times the price of a pefectly adequate Indian 5 speed box. No use getting a batch of 100 4 valve heads made if the price scares the customers off, we know the long-stroke cranks will hurt the wallet enough.
A.

100 would be a number, that could help with the cost substantially, but 100 heads on the RE market...

[ace.cafe]

100 would be a number, that could help with the cost substantially, but 100 heads on the RE market...

Maybe the catch phrases will help.

You know, the general market seems convinced that OHC and/or 4-Valve arrangements are "modern requirements ", even though they rarely understand any of the underlying matters about why, or indeed, if.

A 100+mm stroke is piston speed limited in rpm. Lightweight multiple valve arrangements and/or direct actuating cams are of very limited value in such a platform, and increase cost and complexity. However, they can still be a very good performing package if the application is well designed. So it can be a real good thing in spite of the potential "overkill" nature of the application.

We shall have to wait and see how it comes out. I am as interested as anyone about it.

[Otto_Ing]

Absolutely, it will be exciting see this develop. The market reaction even more so...

[Arizoni]

It's not as though a long stroke, 4 valve head is something new.

In 1911, Indian had a 61 cubic inch, 8 valve, V Twin engine powering some of their racing motorcycles. 

[Adrian II]

That's true, Royal Enfield also had some 4 valve singles in their 1930's model line-up.

If the new 4 valve head is any good (let's hope Hitchcock's have fewer foundry problems than they did with the last batch of big head castings) it will probably work very well with a stock crank as a 535, no need for the 112mm stroke carank, and as such would make an interesting comparison to Ace's high-lift 2 valve billet head.

So to build the hybrid engine we need a set of late C.I. crankcases, a 500 AVL/Electra-X crankshaft modified for the C.I. Bullet big-end oil feed, 500 UCE barrel plus the new head and whatever piston the new kit uses. That means I will have to try and track down ANOTHER Redditch frame, sigh... 

A.

[Adrian II]

Also, regarding the benefits of keeping the stock stroke for these engines, remember our friend da punds ran his big head Fireball as a 612 for a while, but he put it back to 90mm stroke and was happier with it as a 535.

A.

[ace.cafe]

Well, regarding a hybrid package, the pushrod oiling system that we use cannot work with solid tappets. So the CI external oil line to the head would plumb into the oil temp sensor location for oil feed. This is one reason why we retained the UCE oil feed passages in our head. It can do the oil feed lthat way, and we have changeable oil spray jets which allow you to change orifice size to suit the engine oil delivery pressure and volume. So you can use tighter orifices for a lower oil feed like a CI or AVL and still get a suitable squirt velocity to get the oil up on to everything in the top end.

For more general info regarding a hybrid:

The stud pattern is the same, but new stud lengths are needed to make.

The head does not use a spigot like the CI, but a CI barrel could have the spigot milled off, or just use an AVL or UCE type barrel and suitable length con rod.

CGT 535 piston with rings can be used.

Regarding 612 or 535, there are numerous discussion points.

First, I already mentioned piston speeds are significantly higher with the 612. This is good for lower rpm torque, so that is a plus. However,  it gets into the area of too-high piston speeds earlier then too, and that limits safe rpms to a reduced level than the 500/535. So, it would typically be considered as a lower revver than a 500/535.

Also, the bigger displacement draws harder on the intake system at all revs. This is again good for low rpm torque,  but runs out of power earlier than a 500/535 , given the same port size. Again, reinforcing that lower revving character of that long stroke package.

We have found that the long stroke crank just revs up a bit slower too, so it doesn't accelerate as quick.

Now, this is all fine for certain applications, such as making a lot of torque beneath a 5500 rpm rev limiter like we have in a UCE. Or, for use in a sidecar pulling application.

For higher rpm applications, we'would feel happier with the 90mm stroke, or even shorter. The 4-valve system would have more benefit at higher rpms, IMO.

I do think that if Hitchcock can make a good quantity of these as castings, he could bring the price down into a somewhat more affordable range.
I simply cannot do that with the individual billet manufacturing process, and I  cannot afford to make 100 units at a run. I don't have funds anywhere near that amount.

[malky]

It will be most interesting to see the outcome. I have this strange formula which equates to Pounds or Dollars spent, in relation to increase in performance and usability. I am guilty of forgetting that either I or someone I know has the ability to quietly get on with the job and hope for the best. My old 500 Bullet would go "off the clock" but realistically it was probably doing in the region of low to mid 90's on standard gearing (it had a steel rod). Left with standard gearing meant it was tractable from around 30mph to flat out in top, which made it ideal for the type of roads I ride, and my riding style. My mate threw a shed load of money at his bike, built close to the spec of Hitchcock's "end to end" Bullet. OK it probably had a 20mph+ advantage on mine in a straight line, but on a twisty road it was a pig. It wasn't overgeared in respect of straight line top end speed, but where my bike made up, was as result of better midrange power (for which it was intentionally set up for and not having to "play tunes" on the gearbox. So for a difference of over £2000, is 20 - 25 mph extra, worth it. OK I spent a lot of time and got a lot of work done FOC but still ?

Finally, a question.
Somewhere in my collection of notes, which I can't find, I have a letter I got pre internet days, from a guy in the States who successfully raced a flat track bike with a Fury motor. He was using modified Chevy con rod blanks (i.e. before they were split and machined ) anyone know what they were ?

[Otto_Ing]

A finely tuned 2V engine makes better music...

https://youtu.be/hPxGmNIXFow

...the snarl on decel is what I want. 

[ace.cafe]

It will be most interesting to see the outcome. I have this strange formula which equates to Pounds or Dollars spent, in relation to increase in performance and usability. I am guilty of forgetting that either I or someone I know has the ability to quietly get on with the job and hope for the best. My old 500 Bullet would go "off the clock" but realistically it was probably doing in the region of low to mid 90's on standard gearing (it had a steel rod). Left with standard gearing meant it was tractable from around 30mph to flat out in top, which made it ideal for the type of roads I ride, and my riding style. My mate threw a shed load of money at his bike, built close to the spec of Hitchcock's "end to end" Bullet. OK it probably had a 20mph+ advantage on mine in a straight line, but on a twisty road it was a pig. It wasn't overgeared in respect of straight line top end speed, but where my bike made up, was as result of better midrange power (for which it was intentionally set up for and not having to "play tunes" on the gearbox. So for a difference of over £2000, is 20 - 25 mph extra, worth it. OK I spent a lot of time and got a lot of work done FOC but still ?

Finally, a question.
Somewhere in my collection of notes, which I can't find, I have a letter I got pre internet days, from a guy in the States who successfully raced a flat track bike with a Fury motor. He was using modified Chevy con rod blanks (i.e. before they were split and machined ) anyone know what they were ?

Yes, it was Elliot Schultz,  and Shell Thuet built the Fury  motors. They later used a Carrillo rod made for the Fury with a roller big end. They used Harmon & Collins racing cams, which were basically what Bullet Whisperer has in his 500 racer.

They were pretty high rpm engines, but not as high as Bullet Whisperer's.  As full race power plants,  they were not particularly tractable for lower rpms.

Regarding your mate's bike, Hitchcock has always made his designs like that, which weaken the lower and midrange rpms in favor of more top end power.
Our Fireballs do not do that, and we actually increase power in the whole rpm range with our kit, and still make a lot of high end power. It is a matter of different approaches to the project.

[Adrian II]

A finely tuned 2V engine makes better music...

https://youtu.be/hPxGmNIXFow

...the snarl on decel is what I want. 

For those outside the UK, two of the popular motorcycle roads in southern England are the A272 and the A32. That video was taken at Loomies' cafe a few miles out of Fareham (near Portsmouth) where these two roads meet.

Regarding your mate's bike, Hitchcock has always made his designs like that, which weaken the lower and midrange rpms in favor of more top end power.
Our Fireballs do not do that, and we actually increase power in the whole rpm range with our kit, and still make a lot of high end power. It is a matter of different approaches to the project.

I do wonder what Hitchcocks' are up to with the long stoke crank for the GT, then, given its disadvantages for a performance engine, unless they have identified a vast but currently frustrated market for CGT sidecar outfits! There are a few, but I think there are other bikes which would be better suited. No doubt they will be putting their prototype on the dyno (track as well, hopefully) so that they have some performance figures to help market the finished kits.

I guess the thinking is "there's no substitute for cubes" is driving this, regardless of how the extra cubes are delivered. A bore increase up from 87mm might be better, if it can be done without the inconvenience of having to open out the crankcase mouth for a bigger cylinder liner. If Hitchcocks want to keep it bolt on (or at worst strip down and re-fit) then there are probably limited options in terms of cylinder liner thickness. CMW tried an over-bored Electra-X taken out to 570cc a few years back, it seemed to sink into obscurity.

A.

[malky]

Yes, it was Elliot Schultz,  and Shell Thuet built the Fury  motors.

Thanks. Got it.

[Kevin Mahoney]

Alan doesn't make anything that isn't good.

[malky]

Alan doesn't make anything that isn't good.

I completely agree, the point I was making (perhaps not very well) is that you'd have to be totally committed to the bike to spend the money, quality doesn't come cheap. 

[ace.cafe]

For those outside the UK, two of the popular motorcycle roads in southern England are the A272 and the A32. That video was taken at Loomies' cafe a few miles out of Fareham (near Portsmouth) where these two roads meet.
I do wonder what Hitchcocks' are up to with the long stoke crank for the GT, then, given its disadvantages for a performance engine, unless they have identified a vast but currently frustrated market for CGT sidecar outfits! There are a few, but I think there are other bikes which would be better suited. No doubt they will be putting their prototype on the dyno (track as well, hopefully) so that they have some performance figures to help market the finished kits.

I guess the thinking is "there's no substitute for cubes" is driving this, regardless of how the extra cubes are delivered. A bore increase up from 87mm might be better, if it can be done without the inconvenience of having to open out the crankcase mouth for a bigger cylinder liner. If Hitchcocks want to keep it bolt on (or at worst strip down and re-fit) then there are probably limited options in terms of cylinder liner thickness. CMW tried an over-bored Electra-X taken out to 570cc a few years back, it seemed to sink into obscurity.

A.

Adrian,
I think you have it right either the "more cubes" concept.

If the aim is not more revs, then more torque is the only remaining answer for power. For a given rpm limit, the one with more torque will be the one with more horsepower. So, there is a sound reasoning behind his approach.
I expect it will have a bigger size inlet, and probably a carburetor, to feed the bigger engine with air.

Almost all recent design trends in 4-valve engines follow the larger bore and shorter stroke approach. But if revs are not being sought, it can breathe very well for a long stroke application for mighty torque.

4-valves have the advantage of lots of valve area, and this is available even at very low lifts, so flow increases quite early in the cycle. This is great for breathing.  They don't need as much lift to flow sufficient air, and the individual  valves are smaller and lighter mass. This is great for valve control.

However,  these attributes normally are needed for higher revving systems, which a long stroke Bullet isn't.

Also, there very small squish area in a 4-valve chamber, but perhaps at the high piston speeds it will be sufficient.  The central spark plug is a good benefit too.

I am quite favorable toward multiple valve designs. It is generally a good thing. I used 2-valve design because I had lots of lift, and I knew it could feed the need at less expense than a multi-valve for my design.

[Kevin Mahoney]

I completely agree, the point I was making (perhaps not very well) is that you'd have to be totally committed to the bike to spend the money, quality doesn't come cheap. 

You aren't kidding about that. I wouldn't put that kind of money into one. Go buy a Honda and put new sheetmetal on it to suit your desires. I think that if it is not what you want right out of the box performance wise you may be barking up the wrong tree