Topic: RC Connecting Rods VS. Carrillo

[newday777]

I'm asking for the comparison of the 2 brands

Are there any drawbacks to using a set of good condition RC Engineering Heat Treated Performance Connecting Rods vs getting new Carrillo Rods(for lots more money)?
I'm getting ready to build an 836 or bigger, (maybe Mike's Billet jug 72mm)with an RC 315 cam and polished ports.

[Bankerdanny]

It's hard to imagine that for a street rider there is any benefit to the RC's or the Carrillos. Although I suppose it depends on how hard you plan to ride it on the street.

[Jerry Rxman Griffin aka MuthaF'er]

A 836 does not need Carrillos. A 1000 on the other hand may be different depending on how you build it up and ride it.

[newday777]

Thanks guys.....but....I asked for a comparison, not if needed......

[Flyin900]

It's hard to imagine that for a street rider there is any benefit to the RC's or the Carrillos. Although I suppose it depends on how hard you plan to ride it on the street.

How many on here would have used either product? As noted really not a street machine item. Why don’t you contact a proper high end motor builder, who would have the background and experience to give you some answers?

[samm_j2]

What about upgraded rods on an 836 if taken to the track regularly but still not breaking 10k rpm?
Not to hijack the thread. Just curious...

[BPellerine]

you might get a better answer in the perfomance section

[Jerry Rxman Griffin aka MuthaF'er]

Comparison: Carrillos will be lighter and stronger and much more expensive

[gschuld]

I think you will find there are roughly three major factors for rod strength needs in our motors.

1–Rpm.  An engine with an 8500rpm redline will need less rod than a 11,000 Yoshi screamer.  Stock rods in a high rpm engine is simply asking for trouble.
2-piston weight.  Take 72mm pistons.  There are lead like 255 gram MTC 12.5:1 pistons and 190 gram JE flat top pistons.  Factory pistons are around 150 grams FWIW. More piston weight, more strain on rods(gets worse with increasing rpm)
3-overall torque(power) output.  The greater the total force, the more the rod is loaded.

All that said, Frankie has been running the same set of RC modified factory rods in a 72mm (1026cc) high compression drag race engine with heavy MTC pistons and an RC 327 cam, making power up to 10,000 rpm for YEARS.  That’s a punishing load on a set of rods.

So practically speaking, a good condition set of RC modified rods is plenty strong for just about any sane NA sohc4 engine.

Carrillos offer the modest performance benefit of lighter weight, pride of ownership, and significant expense.  I own sets of both(among others) and love them equally.😉

George

[gschuld]

What about upgraded rods on an 836 if taken to the track regularly but still not breaking 10k rpm?
Not to hijack the thread. Just curious...

The factory rod bolts are the weak link on the factory rods when increasing performance well beyond stock.  First step up is to swap in cb750 sohc F2 rod bolts for a modestly higher safety factor.

A cheap upgrade is swapping in DOHC 900 rods. 1.12mm longer than Cb750 sohc rods, but other wise drop in once you raise the cylinder.  1mm larger diameter rod bolts.  Good used rods are cheap.

Options tend to get more expensive from there. 

George

[newday777]

Thank you George. Well said. That's what I was looking for.

[gschuld]

👍

In the future, questions of this nature will likely get more attention (from the high performance minded guys) in the high performance section.  But the subject is totally pertinent to this area, so no complaints here.

George

[newday777]

Looking at the description(before you post here...) of the HP and Racing section, I thought I might get some complaints there as I wasn't planning on 'racing' and going marginal HP.
Is 836 big enough bore for there? Or is it bigger as in resleeve to get 900cc and above? The stipulations aren't well defined.

[gschuld]

Well, once you are asking about Carrillo and RC rods, that easily qualifies….😎

Most people in the high performance section aren’t competing with their engines.  That’s a pretty low number of members overall.  The high performance section is aimed at both racing and higher performance street use.

Frankly, even a performance cam swap inquiry in an otherwise dead stock engine qualifies IMHO.

Absolutely, an 836 build with some goodies inside is probably the most common engine people in the high performance section own themselves.  Lots of discussions about bigger and or more complex builds, but much of that knowledge trickles down to more modest performance engines.

I’m a little embarrassed to admit that I rarely venture outside the high performance and classified sections.  Normally I would have missed that thread of yours.  I’m merely an “enthusiast”, lots of guys in the high performance section are proper hands on high test wrenches.  Which is where I’ve absorbed the bulk of my high performance Cb750 Jeopardy knowledge base 😁

George

[newday777]

Cool.
I met Mike R this past Sunday and just getting into the planning of some mods to go with the 315 cam. He doesn't have any more of his Billet jugs........

[gschuld]

You can’t do much better than Mike R for your needs.  You are in good hands.

George

[MRieck]

You can’t do much better than Mike R for your needs.  You are in good hands.

George

Thank you George. Stu and I had a very pleasant conversation last Sunday......he got a killer deal on the 315 cam. The RC rods have different bolts...that and beam work. I am not sure if they were shot peened....been a real long time since I handled a set. Carrillo's are Carrillo's. If imitation is the finest form of flattery Carrillo holds the record. They are lighter than stock and infinitely stronger. I good compromise are the Super Rods CycleX sells.

[gschuld]

FWIW, these are RC modified factory rods.  Don’t mind the darker than normal color, I had a batch of rods cryo treated and I put these in too.  Cryo turns them a shade or two darker.

402 grams each with bearing shells.

George

[gschuld]

RC rods next to older style Carrillo rods (straight beams)

359 grams each with bearing shells.  Or 10.3% lighter than RC rods.

George

[gschuld]

I’ve had a few sets of RC rods, and FWIW, they all had that exact same rod bolts and never had any beam smoothing or cleaning/polishing done to them.

RC stamped their rods on one side of the rods are the crank journal gap.  If they are all stamped RC, I’d say an owner messed with them at some point.

George

[newday777]

Thanks George that is good information. I have the set of RC on the way.

[gschuld]

Ok, I’m glad I included the catalog image.  RC Engineering offered 2 versions of modified factory rods.

One set had oversized rod bolts with deep 12 point nuts.  They required carefully enlarging the bolt holes to accept them.  The other set had the same bronze bushed ends but factory or factory type 6 point nuts on I’m guessing a factory bolt size.

I’ve had several sets of the 12 point bolts version, but not the other type you appear to be getting.

Won’t know until those arrive to measure and inspect.

In the photos:

Close up of your rod
Close up of catalog high performance rod
Close up of my RC supet high performance rod 
Catalog description of the RC high performance rod

George

[MRieck]

RC rods next to older style Carrillo rods (straight beams)

359 grams each with bearing shells.  Or 10.3% lighter than RC rods.

George

As mentioned, that's an old style Carrillo.....the newer rod weighs 316 grams. Just for reference the Crower rods APE used to sell weighed 378 grams. Each bearing shell weighs 13 grams......26 grams per rod.

[MRieck]

I’ve had a few sets of RC rods, and FWIW, they all had that exact same rod bolts and never had any beam smoothing or cleaning/polishing done to them.

RC stamped their rods on one side of the rods are the crank journal gap.  If they are all stamped RC, I’d say an owner messed with them at some point.

George

Funn.... that super duty rod in the catalog pic has definitely had the beams polished.

[ekpent]

 Are the old RC Golden Rods just pretty much wall hangers nowadays ?