Author Topic: RC block  (Read 7606 times)

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Offline cbr954

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RC block
« on: November 19, 2012, 06:29:22 PM »
The search doesn't work so thought I would ask,  sorry if its been asked before.  I have an RC block, can they be run on the street?  It only has the 5 thick "fins",  I am wondering if it will cool enough on a streetable motor?
03 CBR954RR, 72 750 chopper(970cc
F2 head), 2017 CRF450R, 2001 CR250R, 72 CB500, 79 XR250, 04 CRF50,70's soon to be rebuilt cb750 drag bike.

Offline bear

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Re: RC block
« Reply #1 on: November 19, 2012, 07:36:59 PM »
Short answer is no.

Cheers,
Brian
The older I get the faster I was.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: RC block
« Reply #2 on: November 19, 2012, 07:38:10 PM »
Lucky guy!

My answer is it all depends on how you ride it on the street. City riding with many traffic lights and stops I'd be real careful. Street stalking, perhaps  ;D

Did you use the 'Google custom search' that's found above to the left? The search in the upper right below 'simplemachines forum' has not worked for a while.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline BLUE71TURBO

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Re: RC block
« Reply #3 on: November 19, 2012, 08:22:33 PM »
 I have never heard of any bad things about an RC block being ran on regular street driving.  I have a friend who has a turbo'd 750 with a RC big block and has no problems running on the street in traffic.  Now for a normally aspirated high compression engine....... maybe not.   :-\
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Offline 754

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Re: RC block
« Reply #4 on: November 19, 2012, 10:27:24 PM »
 Let me know if you sell it, just missed the one on here. It's for  a very good buddy of mine.
 I know of another member inherent that ran one,I was the birddog on that find.
 He has runit on the street, but more evening use when it's hot out, try to avoid getting stuck in traffic, just be a bit carefully. Don't know if he ever rode it anywhere, of any distance..
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Sam Green Racing

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Re: RC block
« Reply #5 on: November 19, 2012, 10:41:23 PM »
What sort of money do these blocks realize, I might know where there is a new one that's never been used.

Sam. ;)
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CB95 hybrid race bike
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Offline 754

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Re: RC block
« Reply #6 on: November 19, 2012, 11:08:42 PM »
 They are all over the map, pricewise. But some high priced ones are not selling..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline NitroHunter

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Re: RC block
« Reply #7 on: November 20, 2012, 11:50:05 AM »
For what it's worth, in the late 70's I knew several guys running them around So Cal in 100+ degree summers, and they were full-on RC Cobra motors, the bad-a$$ hotrods of the day. Of course oil coolers were used, and I'm sure they ran every bit as hot as my 836, but if those folks had any serious problems they never shared them with me.
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Offline cbr954

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Re: RC block
« Reply #8 on: November 20, 2012, 11:57:09 AM »
Thanks for the info guys.  i thought I had read somewhere that RC said you could run them on the street but for the life of me I cant find where I thought I read that. lol  I guess I will have to think about what I want to do exactly.
03 CBR954RR, 72 750 chopper(970cc
F2 head), 2017 CRF450R, 2001 CR250R, 72 CB500, 79 XR250, 04 CRF50,70's soon to be rebuilt cb750 drag bike.

Offline Sam Green Racing

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Re: RC block
« Reply #9 on: November 20, 2012, 12:30:42 PM »
If You want a big block for the street, speak to Mike Rieck (MRieck)

Sam. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: RC block
« Reply #10 on: November 20, 2012, 12:50:16 PM »
Thanks for the info guys.  i thought I had read somewhere that RC said you could run them on the street but for the life of me I cant find where I thought I read that. lol  I guess I will have to think about what I want to do exactly.

Maybe RCjr can speak to RCsr and let you know. We do have this inside track now.

As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline cbr954

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Re: RC block
« Reply #11 on: November 20, 2012, 04:44:01 PM »
I thought about asking RCjr but I didn't want to bother him, maybe I will PM him.
03 CBR954RR, 72 750 chopper(970cc
F2 head), 2017 CRF450R, 2001 CR250R, 72 CB500, 79 XR250, 04 CRF50,70's soon to be rebuilt cb750 drag bike.

Offline bear

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Re: RC block
« Reply #12 on: November 20, 2012, 05:12:46 PM »
We have tried running these barrels twice and cracked them pretty well straight away on both occasions.

Cheers,
Brian
The older I get the faster I was.

Offline cbr954

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Re: RC block
« Reply #13 on: November 20, 2012, 05:16:44 PM »
Where did they crack?
03 CBR954RR, 72 750 chopper(970cc
F2 head), 2017 CRF450R, 2001 CR250R, 72 CB500, 79 XR250, 04 CRF50,70's soon to be rebuilt cb750 drag bike.

Offline MRieck

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Re: RC block
« Reply #14 on: November 20, 2012, 06:16:31 PM »
Where did they crack?
Between the bores but that is only second hand info
Owner of the "Million Dollar CB"

Offline bear

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Re: RC block
« Reply #15 on: November 20, 2012, 07:04:17 PM »
Where did they crack?
Between the bores but that is only second hand info

Your right mate.
Between 1 & 2 both times from memory.
The pistons where pretty well shagged as well.
They where just getting to hot.

Cheers,
Brian
The older I get the faster I was.

Offline BLUE71TURBO

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Re: RC block
« Reply #16 on: November 21, 2012, 12:10:06 AM »
Where did they crack?
Between the bores but that is only second hand info

Your right mate.
Between 1 & 2 both times from memory.
The pistons where pretty well shagged as well.
They where just getting to hot.

Cheers,
Brian

                      Maybe a little too lean ?   Not enough air flow ?    ???
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Offline 754

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Re: RC block
« Reply #17 on: November 21, 2012, 07:41:25 AM »
Okay that is racing, lot more heat than the street..
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Sam Green Racing

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Re: RC block
« Reply #18 on: November 21, 2012, 08:28:04 AM »
Where did they crack?
Between the bores but that is only second hand info

Your right mate.
Between 1 & 2 both times from memory.
The pistons where pretty well shagged as well.
They where just getting to hot.

Cheers,
Brian

                        Not enough air flow ?    ???

Not enough fins Jon Boy for prolonged racing.
They like their modern counterparts they are good for drag racing and not much else.
The early Benlys were ok on the road but as soon as you tried to race them, the rear of the left piston would show signs of nipping up.
Honda found this out during the 59 TT and fitted scoops to take air around the cam tunnel to the rear of the left side of the block.

Sam. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline Ichiban 4

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Re: RC block
« Reply #19 on: November 22, 2012, 08:53:26 PM »
Not sure if this applies to RC blocks..

But when we ran the Ariel Square Fours..in Southern California heat..the rear cylinders tended to overheat..leading to pre-ignition..rough running.  Two things that made a significant difference were: running external oil cooler (stock didn't have them)..and painting cylinders black..rather than stock aluminum. The black paint reduced heat by 75 to 100 degrees F.  Reportedly due to better heat dissipation.

Restored Square Fours I've seen in later years..all run external oil coolers..so must be something to that.  Also have seen RC blocks run on the street in So. California (where I'm from originally)..and as mentioned elsewhere here..w/o problems.  So..just assuming that with prudence..caution..the RC blocks can be run on the street okay.

For what it's worth..

Ichi
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Offline johno

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Re: RC block
« Reply #20 on: November 22, 2012, 11:53:40 PM »
Bloody hell ichiban you must be an old fart, arial square fours  :D  my dad had them when he was a boy. ;) your info is spot on , thats just what my dad was always complaining about ;D
ciao Johno
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Offline Ichiban 4

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Re: RC block
« Reply #21 on: November 23, 2012, 12:17:03 AM »
Well..uh thanks Johno..I think.

Yeah..guess I'm getting to be an old fart nowadays..tho remember some of this stuff like it was yesterday.
And yes..I was riding my Square Four when they were still being made.  Possibly your dad and I are around the same age (late 60's)?

The rear cylinder overheating issue was a continual irritation to those of us riding in the hot climate of S. California..which was imprinted on me to the extent that I remembered that almost immediately upon reading about the RC block overheating issues/concerns.

BTW: I've always felt that it was my experience with the Square Fours..that led me to ride the Honda fours..as the former had a lot of mechanical glitches..typical of post WW II engineering..which the Honda's..and Japanese technology much improved upon by the late 60's.  Have been a sucker for four cylinder bikes..the way they ride and sound..ever since!

I'm glad my "remembrances" seemed of some value.

Cheers..

Al / Ichi
Al Summers

Present: '77 550K
Past: '73 CB450(twin), '72 CB175, '68 CB350, '58 Ariel Square 4 (1000cc), '58 Matchless Typhoon (650cc single), Whizzer Motorbikes '48 -'55 (Pacemaker & Sportsman)..Vespa, Lambretta scooters..etc.

Offline Sam Green Racing

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Re: RC block
« Reply #22 on: November 23, 2012, 02:34:22 AM »
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. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike

Offline 754

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Re: RC block
« Reply #23 on: November 23, 2012, 07:19:40 AM »
 Depends which race conditions you mean,
 drag racing..no problem.
 Street riding, not sitting at stoplights, should be ok
 Rodracing, could run real hot..depending on fairing.
 Sidecar racing,enclosed firing..going to get pretty hot.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Sam Green Racing

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Re: RC block
« Reply #24 on: November 23, 2012, 07:38:47 AM »
And that's it in a nut shell Frankie. ;)
C95 sprint bike.
CB95 hybrid race bike
CB95 race bike
CB92
RS 175. sprint/land speed bike
JMR Racing CB750A street ET drag bike