Fullauto head before and after comparisons (2014)

With all due deference to Jim Comstock, I wonder about the relevance of using a flow bench in improving inlet port shapes. In my discussion with others about the various programmable ignition systems, the Dynatek technique of using a vacuum switch to change from a high advance curve to a retard curve if the throttle is wide open at high revs, has brought the comment that 'it is hard to see it working with a pulsing inlet tract'. My feeling is that what is in the inlet port (and the exhaust) at high revs is essentially a sound wave. So the question should be does good results on a low velocity flow bench really mean a performance improvement ? A friend of mine was a senior research scientist who ran the transonic wind tunnel in an aeronautical research facility. It is a considerably different game
 
acotrel said:
With all due deference to Jim Comstock, I wonder about the relevance of using a flow bench in improving inlet port shapes. In my discussion with others about the various programmable ignition systems, the Dynatek technique of using a vacuum switch to change from a high advance curve to a retard curve if the throttle is wide open at high revs, has brought the comment that 'it is hard to see it working with a pulsing inlet tract'. My feeling is that what is in the inlet port (and the exhaust) at high revs is essentially a sound wave. So the question should be does good results on a low velocity flow bench really mean a performance improvement ? A friend of mine was a senior research scientist who ran the transonic wind tunnel in an aeronautical research facility. It is a considerably different game
Click to expand...

Tis a fair point...

It would be ideal to Dyno a bike. Then remove the head and plot its flow and velocity numbers. Then re work the head (or replace it). Then plot the flow and velocity numbers of the re worked / replacement head. Then, finally, re Dyno the bike.

That would provide before / after Dyno figures to see what effect there was. It would also provide correlation between known flow / velocity increases and Dyno results.

Twud be interesting would it not...?
 
I think the problem is that at sonic velocities there are unusual effects caused by the shapes of objects in the flow. On my own bike I've fitted 34mm carbs and tapered the ports the 2mm per side back to the original 30mm within 25mm of the gasket face. If that taper is wrong there might be a high pressure obstruction about halfway down the port at certain revs. When I reshaped the ports, I was only guessing what would work. The trouble is that if it is wrong, I would never know. Any loss of power over a small part of the rev range would probably go undetected. I've never used a dyno to tune my bike, and I question it's sensitivity to measure torque accurately. The only way that I know when I've increased torque is by raising the overall gearing, and if it still accelerates the same .... ?
 
The way I read Jim's own comments are that the flowbench is a tool used in the development process.

Don't forget he has his own dyno as well. And from what I see the development works includes the use of both.

The flowbench figures are offered as means of comarison of 'potential' flow, mainly of the port itself, but also including manifolds/carbs.
 
I remember many years ago there was a bloke in Geelong who got a road race 250cc Ducati going quick using a flow bench, however I think he was also using methanol/nitro. And a lot of the guys took their superbikes to him. Back then most of them used Yoshimura cams which were not really race cams. I've always believed in porting the inlets to the max, however it might be tantamount to tuning the bike to a standstill in the case of a commando engine. I believe that with the commando there is a strict rev limit and I am still expecting the big bang at 7,000 RPM. I'm sure the valve gear will keep up, however those heavy 850 pistons on aluminium rods ? ?
 
Brooking 850 said:
here are a couple of charts to ponder over
RH10 off my race motor and a FullAuto head
Regards Mike
http://s295.photobucket.com/user/jimsch ... .jpeg.html
http://i295.photobucket.com/albums/mm12 ... 9a985.jpeg
http://s295.photobucket.com/user/jimsch ... 3.jpg.html
http://i295.photobucket.com/albums/mm12 ... 614133.jpg
http://s295.photobucket.com/user/jimsch ... f.jpg.html
http://i295.photobucket.com/albums/mm12 ... 02b58f.jpg
Click to expand...

Good stuff Mike, did you retro fit the Fullauto onto the same bike / engine? And have you any riding comparisons?
 
Fast Eddie, no unfortunately, Full Auto head was a trade deal out of the US for a motor build, using billet cases and a billet crank, but that is a long way off.
It was just by an unfortunate crank case failure that I had the RH10 off my race bike motor, so thought I would get them flowed together while I had the chance.
I am happy with the results from the RH10 head and will continue to use that . Once the billet crank motor is completed, will then get to use the Full Auto.
Mind you I could always use the RH10 on my road registered Roadster and the Full Auto on the race bike in the meantime!!
Food for thought? Nah, happy to leave the Roadster well alone, and ride it as often as weather allows without fiddling with it.
Regards Mike
 
Mike,

That will be a very trick motor to put into a Commando frame for racing......you should find the limits of it pretty easy....

Any thoughts on a more trick chassis for it?

Steve
 
Good looking stuff, and always good to buy local if you might need repairs....

To be fair the price works out similar to buying a Titchmarsh Seeley frame and swinging arm here in UK.

The cost will be in wheels, suspension and tanks.....tanks in particular are getting a bit over the top.

Of course my Rickman uses only one tank and I could get a replica of the frame and swinging arm for about £2300. I have had tanks made for much less than Seeley ones are being sold at.

As a project an SBR framed bike, or any Seeley replica, might be a significant investment, but if your track skills develop it may be a good way to go.
 
SteveA said:
Good looking stuff, and always good to buy local if you might need repairs....

To be fair the price works out similar to buying a Titchmarsh Seeley frame and swinging arm here in UK.

The cost will be in wheels, suspension and tanks.....tanks in particular are getting a bit over the top.

Of course my Rickman uses only one tank and I could get a replica of the frame and swinging arm for about £2300. I have had tanks made for much less than Seeley ones are being sold at.

As a project an SBR framed bike, or any Seeley replica, might be a significant investment, but if your track skills develop it may be a good way to go.
Click to expand...

If you want your track skills to develop it may be a good way to go. The Seeley inspires a lot of confidence, however getting the steering geometry right is important. If you are racing the bike has to do something for you, and using a converted road bike is usually not anywhere near the optimum. Don't start racing by crashing all over the landscape like I did, you might not get to your second race. If you are going to do it, make the commitment and do it properly. Don't kid yourself there is a cheap option. You are a long time dead.
 
If you use a Seeley frame with a 6 speed CR box for racing, the commando motor does not have to be really flash if you are a half-decent rider. Fullauto heads are obviously beautiful things, however a near standard commando motor set up right is quick enough for most riders. It depends on what your competition are riding. If it is anything modern with 4 cylinders and of similar capacity, or a two stroke of almost any capacity, forget it.
 
Alan, I have posted these before, here is a link covering the rules for the different classes racing under the New Zealand Classic Racing Register(NZCMRR)
I race in the Open Post Classic (OPC), the Open Modified (OM) has slightly different rules due to the earlier class date limit, but both race together to keep the grid numbers up.
Also there is another registry, The New Zealand Post Classic Racing Association (NZPCRA) which is predominately pre 1989.
I am eligible to race under both registries if I choose to do so, but in the NZPCRA, there are more multi valve, multi cylinder bikes, in the NZCMRR, most of the bikes are similar to mine.
You will see the barry Sheene Oceanic Challenge is on again end of Oct, 2 x rounds a year, 1 x in Aus, 1 x in NZ to keep Trans Tasman the rivalry alive.

http://www.nzcmrr.com/events/events
http://nzpostclassics.org.nz/
If you looking at race results, in the OPC my race number is 454, haven't hardly competed this year due to conflicting dates with work committments, contested 2 x rounds last year
REgards Mike
 
I understand there is one race meeting in NZ at which only non-Japanese bikes are permitted to race. I wouldn't place that sort of restriction however I suggest the TYPE of bike is important. If the other bikes in the race all have two valve air cooled twin or three cylinder motors of similar capacity, it is a level playing field. They all have similar tuning problems. In that scenario an old commando or triumph 750 is excellent. I like my competition to all be riding 851 Ducatis. Then we would really race.
With our current situation in Australia, if racing is only about winning I would only own a two stroke bike. My Norton is a waste of space.
 
'New Zealand Classic Motorcycle Racing Register Inc. Technical Rules
Revised: June 2007
1.AIMS AND OBJECTIVES.The Register is dedicated to the preservation and use of pre 1976 British, European and
American motorcycles. No Japanese machines will be accepted.'

When I was in NZ many years ago, they were all driving old British shit heaps because of their import laws, and I assume the same applied to bikes. We on the mainland were not so lucky. We had the influx of Japanese bikes in the 60s and the mentality became 'throw-away' when they became depleted. Many of the old British bikes ended up the same way, and a lot got exported back to the UK in the 80s and 90s, when their true value was recognised by the much smarter Poms.
 
Just got my RH10 head back from the machineshop ,bead cleaned ,new bronze guides fitted,cut and ground seats,new intake seals. 30 mm. int.ports. For the Mk111 proj. :D
 
Matt, NZ wouldn't be a bad option, however I cannot figure out how to get there. It is difficult enough for me trying to swindle ways to get onto a race circuit here in Victoria. The easier option would be to get more involved with Winton Raceway and start some bike events with decent race classes to give a more level playing field. The trouble is that the politics of doing it are a pain in the backside. The other thing is that if I am running an event I cannot ride in it, so I'd have to find another victim to do the hard work. Our local classic racing is not as well coordinated as it might be, and there are a lot of petty jealousies. Some of this garbage promoted by people who have never raced. My problem is that I am getting past it. I still love my Norton, and I really want to race it a couple more times. I believe it will do extremely well next time out. I know I have to do it soon, you are a long time dead and you have to get your priorities right.
I will have to do a rethink about getting stressed again. I've had a double bypass, three strokes and a carotid artery clearance, so I'm brand new again however there is risk in making the wrong choices. The political bullshit is a killer.
 
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