Topic: CB750 Rod Talk: Weights, suitability, etc.

[MCRider]

While still recovering from a cold, I drug out my rods to weigh on my new (to me) triple beam balance and compare the obvious differences and anticipate the not so obvious:
From left to right: MC Forged Aluminum; Honda CB900 stockers; CR750 RC Engineering Forged Big Bolt; unknown (lets call them Action 4 as they were making rods back then) forged small bolt; and finally CB750 stockers.:
http://i313.photobucket.com/albums/ll384/rondison/Phaedrus/P9020001.jpg[/img]http://i313.photobucket.com/albums/ll384/rondison/Phaedrus/P9020003.jpg[/img]
The MC Aluminum rods were bought from eBay for $100 on a whim. I've heard enough negatives (the bearing must be drilled and the cases must be notched) to make them fit I've eliminated them from the running. #2 the CB900 rods were bought from Cycle Re-Cylce as they had been selling them to 3/4 midget racers. These guys ran alchohol and made a lot of high RPM horsepower. They are slightly longer than CB750 (1/16 or 1/8) but the midget guys cut their pistons down and used them. Not a serious consideration on my part, but in for the reference. Then the CR750 RC Engineering Rods. Paid $105 on eBay for the set. These are not reworked stockers, they are forged from scratch and have a small end bushing and very big bolts. Then the Action 4s, also forged from scratch, beefy, with a small end bushing but surprisingly, very small bolts, maybe smaller than stock! I have Action 4s in Phaedrus I, but I think they were the reworked stockers, heat treated and shot peened, but with stock bolts. Far right are CB750 stockers.
Weights:
1. MC 274g
2. CB900 390g
3. CR750 376.5g
4. Action 4s 396.5 (w/big end bearing)
5 CB750 359
Throw out the Aluminum, here's a shot of the side view:
here's a shot of the front:
and a shot of the bolts

With the CR weight checking in at less than 5% over stock (less than the stock CB900) and with the big bolts and beefy sides (see what I did to a stock rod with a 750cc race motor)


the CR750 rod has bubbled back up to 1st place for Phaedrus II. Especially since they are already paid for. I will look for and consider second opinions. Looking at the inside of the big end the line between the top of the rod and the cap is not visible.

Comments considered.

[MRieck]

 Those CR750 rods absolutely suck.

[sparty]

Those CR750 rods absolutely suck.

Don't hold back Mike...    As Mike likes to say "old crap is still old crap".

Sparty

[kghost]

I lost track because your talking about 5 rods and theres only 4 in the picture....

Plus something is wonky with the pictures....

[MRieck]

Those CR750 rods absolutely suck.

Don't hold back Mike...    As Mike likes to say "old crap is still old crap".

Sparty

Art....in the case of those CR rods...."newer crap is the same, or worse, than old crap".

[MCRider]

I lost track because your talking about 5 rods and theres only 4 in the picture....

Plus something is wonky with the pictures....

Should be 5 in the first picture.  I disqualified the aluminum rod on the left as too difficult to install and not suitable for long term street bike use. Then just talked about the remaining 4 rods.

Sorry about the pictures, they work for me.  

[MRieck]

Personally....unless you invest in a set of Carrillo's, Falicon's or I'd guess these new CycleX rods (don't know anything about except from pics)......you may very well be dissappointed with performance in the end.

[MRieck]

MC....I'll post some pics of the CR 750 big ends from an NOS set I have. Garbage brother....absolute junk.

[MCRider]

Personally....unless you invest in a set of Carrillo's, Falicon's or I'd guess these new CycleX rods (don't know anything about except from pics)......you may very well be dissappointed with performance in the end.

I appreciate the comment, but we may have different definitions of "disappointed". I mean are they going to fail?  Can they not be installed for some reason. Are they going to perform worse than CB900 rods would, or the Action4 rods I had in my build from 1980?

On a streetbike the ultimate lightweight crank/rod/piston set up makes the throttle response jerky, my 888cc pistons and crank are already lighter than stock, I don't need a "lightswitch" on/off motor.

I'm not trying to set the world on fire, no dyno horsepower shootouts, but I don't want to bend one just because I have the occasional fling into the red zone. $1000 more bucks would go a long way to other parts of the project that would give me more noticable return, like suspension bits and good tires.

[MCRider]

MC....I'll post some pics of the CR 750 big ends from an NOS set I have. Garbage brother....absolute junk.

Thanks I'd like to see what you're talking about.

[Jerry Rxman Griffin aka MuthaF'er]

I do not believe the "CR750" rods that you, I, and Mike have are a RC product nor do I believe that they are a true CR750 product either. I also have a set of RC bushed rods that are the peened stock rods with the larger bolts which are his mid-level rod between the stock peened rod with standard bolts and his forged aluminum super rod. When I get my new set from Big Jay I'll take a picture with his APE rods, Carrillo rods already mounted on the APE crank, "CR750" rods, RC rods and stock rods. We should have quite the rod gallery between us. Only ones missing will be the aluminum ones that you have and the CycleX rods. Oh yeah, the Carrillos are about 10% lighter than the stockers.  

[RRRToolSolutions]

Here are pics of my CB750 K4 stockers and Carrillos - The only numbers I really remember are these -

Stock torque = 14.5 lbs/feet
Carrillo torque = 43 lbs/feet (to achieve the specified bolt stretch)

Regards,
Gordon

[MRieck]

MC....I'll post some pics of the CR 750 big ends from an NOS set I have. Garbage brother....absolute junk.

Thanks I'd like to see what you're talking about.

My big beef involves the big ends. Several were cut so large honing didn't even touch some spots. Also....one of the big ends has 3 (not the appropriate 2) bearing reliefs cut into into it. Not confidence inspiring at all but what can you expect for such short money

[MCRider]

I lost track because your talking about 5 rods and theres only 4 in the picture....

Plus something is wonky with the pictures....

 I disqualified the aluminum rod on the left as too difficult to install and not suitable for long term street bike use.

Drilling 1 retaining hole in the bearing shell (to keep it from spinning on the crank) and notching the cylinders for clearance make them too dificult to install ?
 I put a set of the MC aluminum rods in a bike(836) and put 10,000 miles on it before I sold it(5 yrs ago) and it is still going strong. I've used them before and I'll use them again.
   $1000 for a set of rods? I'll pass, thank you.

Thanks for posting that. That was just what I was fishing for, some real time experience. I'll file this for future reference. 

[MCRider]

Here are pics of my CB750 K4 stockers and Carrillos - The only numbers I really remember are these -

Stock torque = 14.5 lbs/feet
Carrillo torque = 43 lbs/feet (to achieve the specified bolt stretch)

Regards,
Gordon


SNIP

Thanks. Your stocker at 355.4 is close to mine at 359g. I went back and weighed the others to find that they vary quite a bit in weight, and my weights turned out to be a fair average of each set of four.

The CB900 rod I weighed came in at 390g, but the third one I weighed was a whoppping 405g.

Your Carrillos sure are purdy! Certainly the way to go if budget allows.

And I'm sure the recent APE rod purchase was a very decent deal.

[MCRider]

I do not believe the "CR750" rods that you, I, and Mike have are a RC product nor do I believe that they are a true CR750 product either. I also have a set of RC bushed rods that are the peened stock rods with the larger bolts which are his mid-level rod between the stock peened rod with standard bolts and his forged aluminum super rod. When I get my new set from Big Jay I'll take a picture with his APE rods, Carrillo rods already mounted on the APE crank, "CR750" rods, RC rods and stock rods. We should have quite the rod gallery between us. Only ones missing will be the aluminum ones that you have and the CycleX rods. Oh yeah, the Carrillos are about 10% lighter than the stockers.  

yes I was told by Axle the Satanic Mechanic the CR rods were RC Eng product, and that stuck in my mind, but after reviewing our conversation,  he and I both decided the origin is inconclusive.  All that were listed in Axle's RC Catalog were the reworked stockers and the Golden Rods, anodized alloy.  There was never a consideration on my part they were some sort of official Honda CR part.

It would be interesting to see what data and perspective you have. The CycleX rods photograph well on their website and at $599 are priced well for the non-all out builder.  http://www.cyclexchange.net/Superrods%20Page.htm

[Soos]

Those Cycle-X rods Look NICE, anyone run a set yet??


l8r

[Jerry Rxman Griffin aka MuthaF'er]

MC,

I could be wrong but from my research RC made 3 different rods. Entry level was shot peened stock rods, stock bolts, with bushings inserted for the wrist pins. Mid grade was the same rod with larger 5/16" (think thats the correct size?) bolts, and the Golden Rod you mention being the top of the line.

I'm with Mike on those CR750 rods as far as the quality of manufacture. I actually have 6 of those heavy bastards and couldn't get a set of 4 to come close enough in weights to consider using them. A NOS "set" of them recently went for $765 on EBay. At that price I'd definitely consider a set of Big Jay's APE rods or even the CycleX ones if we had any info on them.   

[MCRider]

MC,

I could be wrong but from my research RC made 3 different rods. Entry level was shot peened stock rods, stock bolts, with bushings inserted for the wrist pins. Mid grade was the same rod with larger 5/16" (think thats the correct size?) bolts, and the Golden Rod you mention being the top of the line.

I'm with Mike on those CR750 rods as far as the quality of manufacture. I actually have 6 of those heavy bastards and couldn't get a set of 4 to come close enough in weights to consider using them. A NOS "set" of them recently went for $765 on EBay. At that price I'd definitely consider a set of Big Jay's APE rods or even the CycleX ones if we had any info on them.   

I think you are right on the RC Eng line-up. So the CR750 rods fall into limbo of unknown manufacture/distributor. And you are right on the weight discrepancy, though I found that to be true with all the rods I have. The average weight of the CRs is less than the average weight of the CB900F rods, so for a 900cc motor I wouldn't say they are too heavy. I've requested weights on the APE rods and the CycleX rods with no return so far. I suspect they will come in near the CR750 rods, though maybe closer to each other.  I'll report back.

I didn't catch the CR set selling for $765 but I'd drop them in a heartbeat for that kind of money.

[RRRToolSolutions]

Yes, my stockers had the weight variations too. Here is another one of my stockers -

The Carillos came with documents in each box and the packing list with #317 on the set of 4 - I found those had .3 grams (point 3) difference from the heaviest to lightest. The stockers had had over 4 grams difference.

Gordon

[MCRider]

Yes, my stockers had the weight variations too. Here is another one of my stockers -

The Carillos came with documents in each box and the packing list with #317 on the set of 4 - I found those had .3 grams (point 3) difference from the heaviest to lightest. The stockers had had over 4 grams difference.

Gordon

SNIP

The CB900F rods were over 20g different from lightest to heaviest. More than the CR750 rods.  Now 1 example of each does not condemn (or confirm) the lot in either case, I'm just reporting what I have. Though in the case of the Carillos, I'd say .3 probably confirms that they are the best sideways with Falicon I suspect.

Where did you get that scale? Nice

Edit: Never mind, I see them all over eBay for less than I paid for my triple beam. 

[MRieck]

 I'm assuming Jay's rods are A beam Carrillo's which will be even lighter than the H beam's.

[RRRToolSolutions]

It's a jewlry scale - $50 off of the internet. I used it to check and match pistons weights, rod pins, and rods - all to within .3 grams of each other. I was able to match the different components to get the reciprocating weights to my targets. The only work I had to do was on the pistons for the final balance. I did not have my crank lightened, but it was balanced - straight out of the engine  - it would not even light the strobe. The strobe is set to identify the exact location (target) area for material removal. The machinist commented that the Honda 750 cranks were among the best he has ever measured.

Buy the scale - it adds to the project and piece of mind.

Gordon

[MCRider]

I'm assuming Jay's rods are A beam Carrillo's which will be even lighter than the H beam's.

Well that would be a deal. I didn't pay much attention to the thread, thinking I had it covered.

[MCRider]

It's a jewlry scale - $50 off of the internet. I used it to check and match pistons weights, rod pins, and rods - all to within .3 grams of each other. I was able to match the different components to get the reciprocating weights to my targets. The only work I had to do was on the pistons for the final balance. I did not have my crank lightened, but it was balanced - straight out of the engine  - it would not even light the strobe. The strobe is set to identify the exact location (target) area for material removal. The machinist commented that the Honda 750 cranks were among the best he has ever measured.

Buy the scale - it adds to the project and piece of mind.

Gordon

SNIP

My T-Beam does fine, its just a lot slower.