Author Topic: Stronger rods-do I need them?  (Read 2560 times)

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Offline KayOne

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Stronger rods-do I need them?
« on: January 11, 2014, 11:02:18 am »
I have placed an order to Cycle-X and am beginning to second guess myself. Building a K1 with a Wiseco 836 kit and CX-2 (Webcam 41a) cam. Ordered studs, HD primary chain, tensioners yada yada. Should I bite the bullet for the $600 Cycle-X rods?

Not planning on riding like a redline ranger but I want to be able to wail on it without worrying. Plus I don't want to be rebuilding the engine again in my lifetime.
CB750 K1 restored
1979 CB750Fz - original except for exhaust, 14000km
1984 VF45F Interceptor - all original, 12000 km
1968 S90 - all original, 2100 miles
1973 H2a, Restored
1973 H1D, next project
CB750K1 (sold)
1976 KZ900 (sold)
1981 CB900F (under restoration)
2015 Yamaha FJ09, my appliance rider

Offline Old Scrambler

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Re: Stronger rods-do I need them?
« Reply #1 on: January 11, 2014, 11:52:48 am »
My 2-cents based on a similar build from 7-years ago...........With good bearings, compression of less than 11 to 1, oil-journals, and oil............the standard rods can be expected to provide a long life for that set up. What you have is a mid-range torque improvement. "Wailing on it" implies high-RPM but exceeding the 8,000 red-line is not advised.  BTW.........do you have decades or only a few years left?   
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
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'67 Triumph T100C
'73 750K3 Owned since New
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Offline KayOne

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Re: Stronger rods-do I need them?
« Reply #2 on: January 11, 2014, 12:01:54 pm »
Thanks for the insight Scrambler. I'm hoping decades. Think I'm similar in age to many forum members. I was in high school when the CB750 came out. I will never forget the scene in the spring of 1970 in front of the school. A Gasser style Toyota Corolla with a built SBC vs a KO. Race only went to 70 or 80 mph. The Corolla had the jump but the KO handed him his _ss once he got it rolling.
CB750 K1 restored
1979 CB750Fz - original except for exhaust, 14000km
1984 VF45F Interceptor - all original, 12000 km
1968 S90 - all original, 2100 miles
1973 H2a, Restored
1973 H1D, next project
CB750K1 (sold)
1976 KZ900 (sold)
1981 CB900F (under restoration)
2015 Yamaha FJ09, my appliance rider

Offline 754

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Re: Stronger rods-do I need them?
« Reply #3 on: January 11, 2014, 01:06:06 pm »
My 836 with stock rods, did at least 500 passes in the 1/8 mile, scads of burnouts, ran it to 10-11K constantly.. That said they can break, but the majority seem to do fine.
 No guarantees if racing though..

 My 836 was together around 24 years, the last 6 or 8. Running without aircleaners..  Your mileage may vary....
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 PeWe

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Re: Stronger rods-do I need them?
« Reply #4 on: January 11, 2014, 01:08:46 pm »
I had those thoughts too. I came to the conclusion that replacing existing rods need new and correct bearings+ balance of the entire crank that made me to think about a complete crank with those rods... "super" crank.... I did not have the money... but it should have completed the bottom end for future use and increased the feeling what I know and nobody can see. HD prime chains from CCC was one improvement though.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline PeWe

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Re: Stronger rods-do I need them?
« Reply #5 on: January 11, 2014, 01:13:15 pm »
I bought a cheap future upgrade when I visited a bike scrap yard. Rods from HONDA DOHC 900. Look the same as CB750 but with a little bit more meat and 1.5mm longer.  Will give more CR.... compensate with extra base gasket. Maybe need to carve the head too...
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline MRieck

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Re: Stronger rods-do I need them?
« Reply #6 on: January 11, 2014, 01:51:42 pm »
Get the F2 bolts and nuts...cheap insurance.
Owner of the "Million Dollar CB"

Offline KayOne

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Re: Stronger rods-do I need them?
« Reply #7 on: January 11, 2014, 02:33:48 pm »
Sounds like a done deal. F2 bolts already installed in rods. Now I can save the $ toward the crank rebuild on the H1.

Thanks for everybody's input. I appreciate the experience and knowledge forum members so generously share.
CB750 K1 restored
1979 CB750Fz - original except for exhaust, 14000km
1984 VF45F Interceptor - all original, 12000 km
1968 S90 - all original, 2100 miles
1973 H2a, Restored
1973 H1D, next project
CB750K1 (sold)
1976 KZ900 (sold)
1981 CB900F (under restoration)
2015 Yamaha FJ09, my appliance rider

Offline Don R

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Re: Stronger rods-do I need them?
« Reply #8 on: January 11, 2014, 02:42:52 pm »
Well, if we knew the difference was going on an H1 we might have led you in a different direction. Just kidding. We love em all.
No matter how many times you paint over a shadow, it's still there.
 CEO at the no kill motorcycle shop.
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Offline Old Scrambler

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Re: Stronger rods-do I need them?
« Reply #9 on: January 12, 2014, 01:48:48 pm »
But some more than others...............My sandcast never lost to an H1 in more than one street-drag near LAX in late '70-early ''71.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
'67 Triumph T100C
'73 750K3 Owned since New
'77 750F2 Cafe Project
2020 ROYAL ENFIELD Himalayan

Offline KayOne

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Re: Stronger rods-do I need them?
« Reply #10 on: January 12, 2014, 02:42:00 pm »
Scrambler, I have an H2 also  ;D Kidding aside, I love late 60's and early 70's vintage Honda and Kawasaki triples and 900's. I'm glad that companies like Honda and Kawasaki had the balls to push the envelope.
CB750 K1 restored
1979 CB750Fz - original except for exhaust, 14000km
1984 VF45F Interceptor - all original, 12000 km
1968 S90 - all original, 2100 miles
1973 H2a, Restored
1973 H1D, next project
CB750K1 (sold)
1976 KZ900 (sold)
1981 CB900F (under restoration)
2015 Yamaha FJ09, my appliance rider

Offline scottly

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Re: Stronger rods-do I need them?
« Reply #11 on: January 12, 2014, 06:28:46 pm »
I'm kind of surprised no one has mentioned polishing the beams and/or shot-peening the stock rods?  ???
Don't fix it if it ain't broke!
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Stronger rods-do I need them?
« Reply #12 on: January 12, 2014, 07:09:16 pm »
But some more than others...............My sandcast never lost to an H1 in more than one street-drag near LAX in late '70-early ''71.

The local H1 guys quit 'picking on me' after I smoked both that tried on my F0. All I needed to convince them was 3rd gear.

And now, back to rods..... If you go bigger than 850 invest in some kind of new aftermarket rods.... or take your chances.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline Doctor_D

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Re: Stronger rods-do I need them?
« Reply #13 on: January 12, 2014, 08:13:06 pm »
I'm kind of surprised no one has mentioned polishing the beams and/or shot-peening the stock rods?  ???

Anyone that did a search on the topic would come up with that answer (in addition to adding stronger rod bolts).
Take care,
David
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1975 CB 750F - Project page: http://forums.sohc4.net/index.php?topic=66026.msg725479#msg725479
1978 CX500
1971 Norton Commando

Offline Sprocketwerx

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Re: Stronger rods-do I need them?
« Reply #14 on: January 13, 2014, 07:33:52 am »
I'm building a relatively mild (10.5:1) 970, and it's been suggested to just use a good set of stock rods, shot-peened. Polishing the beam adds another bit of work (and personal satisfaction) so I'll prob go that route.
It's not going in a race bike (for my survior chopper), so I doubt I'll push it hard enough/long enough to hurt it. Still it won't get babied ;)
Dan "Sprocket" Harris
Sprocketwerx Motorsports

Offline cbr954

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Re: Stronger rods-do I need them?
« Reply #15 on: January 13, 2014, 11:38:49 am »
I had APE shot peen my stock rods for my first 836 build.  I am using the Super Rods for my 970 build.
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.