Topic: RC block

[cbr954]

Here is the latest.  I PM'ed RCjr the other day asking about the big block.  And to start with I really thank him for taking the time to respond to me, on Thanksgiving no less!  He said they ran them on the street but did things to keep things cool as possible(oil cooler and good oil).  Going all out with compression, maxed out bore size and hot timing could be risky on the street.  RCjr said he will talk to his dad about it too just to get his take.  It was great to get his personal take and his personal experience on the matter.  Thanks again RCjr!! 

[Sam Green Racing]

Well being the #1 supporter of his fan club, what did you expect.
Lots of performace parts can be used on the street, it's how you use them.

Sam.

[Leino]

I asked RC Jr a couple of questions and now it seems I'll be roadracing next year 

[Ichiban 4]

Ichi, take a look at this, it should be right up your street but if you thought it was difficult keeping the rear cylinders cool, I wonder how this guy went on (Square Four X 2)  http://www.google.co.uk/imgres?imgurl=http://3.bp.blogspot.com/_lVCC9aDALT4/SdcBoEfN-0I/AAAAAAAAHT8/UccMnAgWVn4/s400/healey.4.2.jpg&imgrefurl=http://thevintagent.blogspot.com/2009/04/2009-bay-area-motorcycle-show-pt-1.html&usg=__KGjzpSkKtwU-soKalvr0rfqpirI=&h=400&w=374&sz=42&hl=en&start=66&zoom=1&tbnid=7o_DtIKiM3Gd6M:&tbnh=124&tbnw=116&ei=O0uvUP3MD8LG0QW-lIGABA&prev=/search%3Fq%3Dhealy%2Bsquare%2Bfour%2Bsprint%2Bbike%26start%3D60%26hl%3Den%26sa%3DN%26gbv%3D2%26tbm%3Disch&itbs=1

I found this while searching for a sprint bike that I used to race against in the mid 70s. It was a Square Four in a modern frame called a Healy Square Four. The builders name was Tim Healy (I think).
These bikes were ok in the English climate but when pushed hard would give problems to the rear cylinders.
Like the Honda Benly, getting cool air to the right place was a problem when the bike was subjected to prolonged running.
I think the same applies to the RC blocks. They might have been streetable if ridden at a sensible pace but as has been said, push them hard under race conditions and they will let you down.

Sam.

_______________________________________________________________________

Thanks for that Sam!  Don't want to hijack this thread..but wanted to say that I've seen other iterations of 2-engined Square Fours also.  Given all their ideosyncracies..especially the overheating problems..would guess that issue would be exacerbated by having two engines in tandem like that.  As your link explained tho..Square Fours became novelties among bikers even while they were still being made. 

Remembering those times: there were no other four cylinder production bikes being made/available @ the time (guess there were the Mammoths w/ NSU engines..but never saw any on the road)..so riding one..with it's characteristic Offenhauser exhaust note..was considered "cool". [Some Harley riders disagreed with our enthusiasm..but the rivalry between HD and other marques/brands didn't seem as sharp as today]

I continue to feel they're a cool bike to have..ride a little.  But @ the prices they command nowadays (seen some advertised for over 50K)..I'm content to just look and reminisce.  Besides..I really do love the SOHC 4's..which are much more affordable and practical..as much or more than the Ariel's nowadays.

Oh..wanted to thank cbr954 for his comments/contacting RCjr.  Kind of corroborates what I remembered..and possibly clarifies the RC block issue a little better..i.e. for street use..use oil coolers.

Al / Ichi

[Terry in Australia]

I've got an RC block here, I don't know much about it's history, but it's cracked in the webs between 1&2, and 3&4. The guy who sent it to me swore that it wasn't cracked when he sent it and suggested that it may have been dropped in transit, but I think he just missed the cracks, you have to look hard to see them. He was good enough to refund my money, less shipping, so I wasn't too upset, although he took it pretty badly. 

The sleeves were buggered, so I heated the block in my oven and dropped them out, and you can clearly see that the web is cracked the full length of the webs, and oil has travelled from one end to the other. I'd thought about getting them welded up, but Brian talked me out of it, really, without air gaps between the cylinders and no finning on an aircooled cylinder block, you're asking for trouble on a streetbike.

I think Mike's new blocks would be fine, the benefit being that there is no wafer-thin steel sleeves to worry about, and the Nikasil coating and generous finning should mean that the cylinders will last a long time. Much better than dodgy RC blocks and bored out OEM blocks. Spend the money and get it right first time. Cheers, Terry.    

[Bill/BentON Racing]

+1,The way to go today,best of everything with Mike's block! Bill

[cbr954]

Yes that would be the best way to go but I bought the RC block, pistons and Golden rods for less than half the price of the new block.  Yes I agree Mikes block would be the best,  I just cant afford the best.  Oh well.  Thanks for everyones input I do appreciate it.

[754]

 So how much do yu want for the RC block, Terry ?  Just checked one of my catalogs they offered them for Kawi, anyone ever seen one ?

[BLUE71TURBO]

So how much do yu want for the RC block, Terry ?  Just checked one of my catalogs they offered them for Kawi, anyone ever seen one ?

               Yep, i had a chance to buy a nice one but i want to get a bigblock from MTC or from others.  The RC Kawi block sold for $350.00   

[bear]

Yep,
You can use an RC Big Block in a street bike if,

You don't run to big a bore.
You don't run to much compreshon.
You don't run up against to many traffic lights.
You don't flog it ie ride it to hard.
You don't ride it when it's to hot.
 

Cheers,
Brian

[MRieck]

So how much do yu want for the RC block, Terry ?  Just checked one of my catalogs they offered them for Kawi, anyone ever seen one ?

               Yep, i had a chance to buy a nice one but i want to get a bigblock from MTC or from others.  The RC Kawi block sold for $350.00   

Oh I can tell you some stories about those pieces.

[754]

 Lots of broken parts in the racing game...its just offerings  to the gods of speed..

[MRieck]

Lots of broken parts in the racing game...its just offerings  to the gods of speed..

My stories are before a piston is even installed.

[Bill/BentON Racing]

A Mike Rieck BIG Block sure seems to me the ONLY way to go if you want the best of everything! My .02.Bill

[luhojs]

Yep,
You can use an RC Big Block in a street bike if,

You don't run to big a bore.
You don't run to much compreshon.
You don't run up against to many traffic lights.
You don't flog it ie ride it to hard.
You don't ride it when it's to hot.
 

Cheers,
Brian

OK good advice but not really hard numbers in there. When did they fail on you? under what circumstances? what temp? engine? ambient? usage? tune-up fat or lean? oil-cooler? what oil?80%full throttle or 30%? etc.?etc?

I am open to learn from fellow riders' experiences. In forty years of building and riding bikes however I have met and had the displeasure to come across a gargantuan number of "in the general direction but really nowhere near the goal" type of people. Your racing pedigree does bestow merit upon you. It gives credit to your writings, however in this case of solid aluminum (US spelling) cylinder blocks from the RC heyday era I would not discount it that easily.
Firstly there are people who have ridden bikes with these blocks on the road without special care or anything. Secondly a quick thinkover will reveal that heat dispersal is through the exhaust and cylinderhead mainly. Besides that tuning as in AFR (Air Fuel Ratio) is a big factor in heat management. Consider a gasoline engine. Some say the 14.7  stoic ratio is maybe ok for MPG ratios but 12.5 is the way to go for all out power. Note the latter will run significantly cooler (because of the cooling effect from the excess fuel) and might foul parts of the engine at a considerable rate.
Perhaps another thread to go deeper into tuning of aircooled bikes since I have a stable of only aircooled bikes.

Bottom line: I think you can get away with riding you CB 750 with a RC alu block in normal day use/traffic. Just not in all circumstances and in all places for an arbitrary length of time.

If you don't believe me ... just dare me

[754]

 I agree with a lot of that..if you want to go really big..ie 1000cc or more on a 750,  you better not be expecting longer engine life or extreme reliability..

[bear]

Yep,
You can use an RC Big Block in a street bike if,

You don't run to big a bore.
You don't run to much compression.
You don't run up against to many traffic lights.
You don't flog it ie ride it to hard.
You don't ride it when it's to hot.
 

Cheers,
Brian

OK good advice but not really hard numbers in there. When did they fail on you? under what circumstances? what temp? engine? ambient? usage? tuneup fat or lean? oil-cooler? what oil?80%full throttle or 30%? etc.?etc?

I am open to learn from fellow riders' experiences. In forty years of building and riding bikes however I have met and had the displeasure to come across a gargantuan number of "in the general direction but really nowhere near the goal" type of people. Your racing pedigree does bestow merit upon you. It gives credit to your writings, however in this case of solid aluminum (US spelling) cylinder blocks from the RC heyday era I would not discount it that easily.
Firstly there are people who have ridden bikes with these blocks on the road without special care or anything. Secondly a quick thinkover will reveal that heat dispersal is through the exhaust and cylinderhead mainly. Besides that tuning as in AFR (Air Fuel Ratio) is a big factor in heat management. Consider a gasoline engine. Some say the 14.7  stoic ratio is maybe ok for MPG ratios but 12.5 is the way to go for all out power. Note the latter will run significantly cooler (because of the cooling effect from the excess fuel) and might foul parts of the engine at a considerable rate.
Perhaps another thread to go deeper into tuning of aircooled bikes since I have a stable of only aircooled bikes.

Bottom line: I think you can get away with riding you CB 750 with a RC alu block in normal day use/traffic. Just not in all circumstances and in all places for an arbitrary length of time.

If you don't believe me ... just dare me

Hard numbers?
No...I don't have any hard numbers.
As a lot of the older heads on this forum may tell you I am by no means a "tech head"
Nor do I ride these bikes on the road.
I am in fact just a bozo from the sticks here in Australia.
But my mates and I have spent the last ten years trying to eek out every drop of usable horse power we can out of these old girls and believe me it is a real love hate relationship.
During those ten years we have tried these blocks and they could not do the job we asked them to do, simple as that.
They are I'm shore, very good at what they where designed for.
But I don't believe that was tooling around in a road bike.
As for daring you, well..............
I've contributed to this topic and given you my opinion only to save you some heart ache.
Others have a different opinion, that's fine I would certainly not hold myself up as a definitive expert.
Knock yourself out, give it a run.

Cheers,
Brian

[Terry in Australia]

Yep,
You can use an RC Big Block in a street bike if,

You don't run to big a bore.
You don't run to much compression.
You don't run up against to many traffic lights.
You don't flog it ie ride it to hard.
You don't ride it when it's to hot.
 

Cheers,
Brian

OK good advice but not really hard numbers in there. When did they fail on you? under what circumstances? what temp? engine? ambient? usage? tuneup fat or lean? oil-cooler? what oil?80%full throttle or 30%? etc.?etc?

I am open to learn from fellow riders' experiences. In forty years of building and riding bikes however I have met and had the displeasure to come across a gargantuan number of "in the general direction but really nowhere near the goal" type of people. Your racing pedigree does bestow merit upon you. It gives credit to your writings, however in this case of solid aluminum (US spelling) cylinder blocks from the RC heyday era I would not discount it that easily.
Firstly there are people who have ridden bikes with these blocks on the road without special care or anything. Secondly a quick thinkover will reveal that heat dispersal is through the exhaust and cylinderhead mainly. Besides that tuning as in AFR (Air Fuel Ratio) is a big factor in heat management. Consider a gasoline engine. Some say the 14.7  stoic ratio is maybe ok for MPG ratios but 12.5 is the way to go for all out power. Note the latter will run significantly cooler (because of the cooling effect from the excess fuel) and might foul parts of the engine at a considerable rate.
Perhaps another thread to go deeper into tuning of aircooled bikes since I have a stable of only aircooled bikes.

Bottom line: I think you can get away with riding you CB 750 with a RC alu block in normal day use/traffic. Just not in all circumstances and in all places for an arbitrary length of time.

If you don't believe me ... just dare me

Hard numbers?
No...I don't have any hard numbers.
As a lot of the older heads on this forum may tell you I am by no means a "tech head"
Nor do I ride these bikes on the road.
I am in fact just a bozo from the sticks here in Australia.
But my mates and I have spent the last ten years trying to eek out every drop of usable horse power we can out of these old girls and believe me it is a real love hate relationship.
During those ten years we have tried these blocks and they could not do the job we asked them to do, simple as that.
They are I'm shore, very good at what they where designed for.
But I don't believe that was tooling around in a road bike.
As for daring you, well..............
I've contributed to this topic and given you my opinion only to save you some heart ache.
Others have a different opinion, that's fine I would certainly not hold myself up as a definitive expert.
Knock yourself out, give it a run.

Cheers,
Brian

Ha ha, I loved the "If you don't believe me ... just dare me" comment too Brian, reminded me of the line from Mac Davis' song "Oh Lord it's hard to be humble" song, that goes:

"Some people say I'm egotistical, but I don't even know what that means,
I guess that it's got something to do with the way I fill out my skin-tight blue jeans"

Cheers, Terry.

[Retro Rocket]

I agree with a lot of that..if you want to go really big..ie 1000cc or more on a 750,  you better not be expecting longer engine life or extreme reliability..

And why not Frank.?  Mikes modern blocks, Jays modern pistons, friction coatings , Diamond primary chains, Better clutches and plenty more, i am expecting my bike to be just as reliable as it was in the first place, no reason why it won't be. Engines, even from the 80's have triple the HP of these old bikes and are reliable, discounting reliability because you can is your opinion, not a fact...

[754]

 You really expect LONGER. Life?... Great reliability is more like it..
 I have been trying  to get my buddies K1.. 160K miles on it.. Bottom end untouched.. Half those miles were with an 812 and 820 kit. The stock bores went 77k, the Bigbore wore three sets of ring..and that is not bad.

 Show me a 1000 cc 754 with a 100K set of shells in it if you can find one.. Most hopped up 754s see a lot of time over 8K..

 I think the MR block is the best ever built, one of the greatest parts for these bikes ever.. But I am under no illusion that I will have a high-miler liter engine.

[Retro Rocket]

you better not be expecting longer engine life or extreme reliability

Ok, you've changed your story , you did mention reliability as well....

Show me a 1000 cc 754 with a 100K set of shells in it if you can find one.

Considering the parts i mention are basically new, you'll have a long wait for 100,000 miler....

Most hopped up 754s see a lot of time over 8K..

Not on the street .

Considering how reliable the 750's are, with all the best parts available i expect the same reliability, i don't think the old Honda's could be more reliable.....

[754]

 Not on the street ?? my 836 saw a 10K almost every ride,except on sh!tty winter roads. why else would I have a hopped up Honda 750.n
  I am not under any delusion that a liter moter will get the lifespan that a stocker would..

[Retro Rocket]

I don't want to get into a sh1t fight over this but the way i see it, a well looked after 750/4 usually only has 2 things that wear out, both the primary and cam chains, using the stronger modern chains would extend the life of the motor before needing to be torn into. My big motor will see high revs but not often enough to make it a problem, i am looking to the improved torque to make the bike more fun to ride on the street, my high speed days were fun but are now far behind me...  Its not just about revs Frank, torque is probably more desirable than revs anyway imo. Delusion or not, maybe you need to try the parts that are available today, old school is cool but its also in the past, my big motor will be reliable, simple....

[754]

 I dont recall anyone around here ever pulling a motor down due to internal chain issues. That 160K motor has its original chains, cases have never been split.

 Personally i think it would be hard to find a liter size cb 750 with 40K on the shells..

[Retro Rocket]

Personally i think it would be hard to find a liter size cb 750 with 40K on the shells..

Why ?.   Don't you think there's any other 1000cc plus bikes with shell or slipper bearings..?  I just don't get your argument mate...