Topic: 970cc "sohc4us-auto" Idea...............

[kaceyf2]

Just been thinking, (oh no not a f***in gain!) I hear you say!!
Here it is, 970cc jobs have difficulties with barrels etc etc etc yes? air gaps blah blah etc.oil seeps etc blah......a lot of us know about.....
Well, japauto,made there own block yes??? to overcome hondas block probs, yes?
WELL, I thinks, with CNC machines making a piss easy job of this, IF we had a block manufactured for oour SOHC club members AND BETTER still, have it manufactured to be a few mm taller (say three or 4mm) (that would give folk the option of maching a bit off if they didn't need it) Then , we could use cb900 rods (that are three mm longer) etc etc blah .......

ALL it needs is for a few of us to get together to do this...just think of the advantages, we would open up another  NEW chapter of history for these old girls "THE SOHC4US AUTO 970cc BLOCK!"

AND GIVE US THE OPTION for club members to have a relatively cheap 970cc build, instead of just dreaming and daydreaming etc?


THOUGHTS?

[eengler2]

Would be nice, but probably not going to happen. I had a modified 3000gt twin turbo. Many people have lots of problems with the transfer cases in cars with highhorse power. It took someone many months, and lots of money to design and cut just the case.

[MRieck]

Just been thinking, (oh no not a f***in gain!) I hear you say!!
Here it is, 970cc jobs have difficulties with barrels etc etc etc yes? air gaps blah blah etc.oil seeps etc blah......a lot of us know about.....
Well, japauto,made there own block yes??? to overcome hondas block probs, yes?
WELL, I thinks, with CNC machines making a piss easy job of this, IF we had a block manufactured for oour SOHC club members AND BETTER still, have it manufactured to be a few mm taller (say three or 4mm) (that would give folk the option of maching a bit off if they didn't need it) Then , we could use cb900 rods (that are three mm longer) etc etc blah .......

ALL it needs is for a few of us to get together to do this...just think of the advantages, we would open up another  NEW chapter of history for these old girls "THE SOHC4US AUTO 970cc BLOCK!"

AND GIVE US THE OPTION for club members to have a relatively cheap 970cc build, instead of just dreaming and daydreaming etc?


THOUGHTS?

An interesting idea. I like the part about the extra deck height. Making it out of billet is a good idea but expensive...you need a big block of aluminum! Casting a piece than CNC'ing it is very possible. I don't how many pieces it would take to justify cost of a mold etc. No matter what it would still lack air channels(like the old RC cylinders) which creates a lot of heat. A fun idea but I don't think it is feasible.

[KB02]

I don't know, MReick... With the right amount of engineering going into it to compinsate for all considerations, it might not be a bad idea. The extra deck height might make getting it in and out of the frame a little more of a pain in the butt, though.

The end product would probably cost a couple times more that the entire amount I plan to spend on my project (which keeps growin all the time), but it would be cool.

[Geeto67]

if you are going to make a hughe cylinder block for these engines, then at least make them water cooled. Water cooling will allow you top run tighter tolerances and allow you to go even bigger while still maintaining street driveability.

Personally I think the cost is prohibitive as each new peice will end up costing more than the RC stuff costs when it comes up on ebay every once in a while.

[MRieck]

 I'm sure I've seen pics of a CB750 engine that had a water jacket built around the cylinders. I can't remember where though.

[ttr400]

Interesting idea and not impossible to do, I have been toying with the idea of machining a barrel for my 400 four with the cooling fins as per oe, why you might ask well because I can and I just love to produce CNC machined parts.
I priced a billet of aluminium grade 6082 t6 same as 6061 t6 which is used in the states, the weight of the billet for the 400F is 11.745 kg price to me here is $85.00, probably a bit bigger for the 750, to calculate the weight L x W x H x 0.0029 divided by 1000 = KG. @ $7.26 per kg.
If I ever get it together I will let you all know!

Kevin.

[MRieck]

 I think the best solution would be machine the block and forgo cast iron sleeves. The bores can be plated like modern engines. This would help with cooling to begin with plus the extra material betwwen the bores which would probably be thick enough to machine airways. The cylinder would also be lighter and stronger. The XJR uses this kind of set up.

[dusterdude]

mike,what kind of plating is done on the newer engines?

[MRieck]

mike,what kind of plating is done on the newer engines?

Nickasil in general.  http://www.mt-llc.com/index_home.shtml   These guys do nice work.

[eldar]

Something like this would be cool. Now I suppose the heads would need to be pimped a little and of course if someone milled the block, but would the case need any mods to it besides maybe using the final drive of a 750A?

[dusterdude]

mike,what kind of plating is done on the newer engines?

Nickasil in general.  http://www.mt-llc.com/index_home.shtml   These guys do nice work.

groovy

[kaceyf2]

So, generally speaking  "a nice idea" But we all have to accept the french can do what we cant? OK.
The price quoted for billet dont seem that much, considering what the end product will be.
I will endeavour to plague the people in the Uk with cnc machines, I am an optimist and wont be put off by "cant doers" After all, last three years has seen the "home-made five AND  six cylinder h2 kawasaki  two stroke and eight cylinder z900 four stroke, both SEVENTIES machines!!
I admit I missed thinking if three or four mm might mean the motor not slipping back into the frame so easy,  but hey for 970cc, I would raise those rails a tad!
someone must know someone with a cnc machine......or do we even let those foks that make catologue chops with billet s & s barrells and heads do better?  ENTHUSIASM please!

[eldar]

if I had the dough and equipment, I would try it.

[MRieck]

 I have a friend that certainly has the knowledge and equipment to do it- that isn't the problem. Go to SuperBike Mikes or Muzzy's web site and see how much a large bore Hayabusa or ZX-12 billet block costs.

[Geeto67]

In finland, three guys created a billet h2 kawasaki 2 stroke engine completely out of billet. Along the way they improved the gearbox and a few other small things but really it looks just like a production h2 engine. It cost them $10,000 to do and I think for the same amount they will duplicate it.

Eventually the cost doesn't become the issue, the practicality of it becomes the issue. 2 stroke street bike engines are somewhat of a novelty, even back in the 70's. They can easily handle the hp loads that modern sport bikes can they are just no longer emissions complaint.

When you start talking about a big bore 4 stroke cb750 engine with nickasil liners and so forth what you end up talking about is basically a modern cbr1000. And let me tell you it is way easier to build a vintage looking chassis for a modern engine than it is to try and improve a vintage engine with modern touches to put in a vintage chassis. These days a guy with autocad has all the resources and more at his laptop that all the Honda engineers had in 1968.

You want a modern cb750? design a frame, bodywork, etc for a modern engine, not the other way around. After that is what honda did with their cb750 concept (never shown in USA by the way). They used a nighthawk powertrain and built a vintage chassis around it. Then again in japan they still make the DOHC cb750F supersport in the same paint schemes they had in the 1980's.