Topic: mystery racing engine

[macvit7906]

Did OP ever find out any history on this engine, perhaps trying to figure out who owned the machine, or the estate it came from.  Could be interesting.

Unfortunately not. total barn find. I bought it off of a junkyard that had picked it up by chance a few months earlier.

Racing engine thrown into a stock frame. I could try to contact the junkyard again but I'm not optimistic.

[Tim2005]

UPDATE:

With the help of an awesome SOHC forum member, the transmission is a confirmed RSC close ratio racing transmission.

ratios:

24/41
27/38
30/36
30/32
34/31

Definitely happy with the barn find now - anyone interested in these let me know!

Great, glad that's been confirmed. As for selling, there's a for sale list in the High Performance and Racing Forum on here, that might be the best place for this

[Cb750 Racer]

RSC (Racing Service Center) was the name of Honda's factory racing parts program.  I am not sure if RSC parts were sold to the general public or not.  If not , you are gonna want to start doing some research on the history of your bike.

Some RSC stuff was available to outside the factory teams, I don't have much detail of it except I know one of my 750s has RSC rods in it that were installed new by a performance shop back in the day. Also there were some RSC parts made for 400Fs, but I don't think there was ever a factory 400F racer.

I wonder what rods this one has?

Interesting. Yeah pistons definitely say RSC. I'll take the washer off the cam and see what we got.

I'm cracking the case today and I'll post some pics. Definitely some nice performance parts in this bike.
Unfortunately, not sure how I could find out anymore history about it. The owner passed away and this was acquired at an estate sale. At first it look like a pile of dust!

Here is the lightened alternator. NICE. Would you guys recommend keeping this for everyday street riding?

That shift drum sticks out to me. Reminds me of the early prototype rotors. That crank is identical to my RC crank, Ball bearings tapped and all. The counterwights of the cranks we're cut like that from the factory but yours do look deeper, almost notched up. Stange for sure. My RC worked stock rods had the same bolts and were also smoothed/polished. I was told by Kenny over at Cycle X that they were most likely GoldWing rod bolts which was common on these roadrace engines.

[BomberMann650]

Op hit a jackpot.

Fwiw, keep it all.

Sink your budget into the chassis. 

[macvit7906]

Op hit a jackpot.

Fwiw, keep it all.

Sink your budget into the chassis.

What changes/modifications to the chassis would you recommend?

[macvit7906]

That shift drum sticks out to me. Reminds me of the early prototype rotors. That crank is identical to my RC crank, Ball bearings tapped and all. The counterwights of the cranks we're cut like that from the factory but yours do look deeper, almost notched up. Stange for sure. My RC worked stock rods had the same bolts and were also smoothed/polished. I was told by Kenny over at Cycle X that they were most likely GoldWing rod bolts which was common on these roadrace engines.
[/quote]

It may have been an RC crank, but I've already gotten the crank back from cycleX freshly lightened, balanced, and polished.
Wow! they do great work!

question: whats a good torque spec to torque the timing stud to? red locktite?

Shift drum looked like a stock K5 drum to me. Just to be safe I've already purchased a stock F0 shift drum and arm set.

[BomberMann650]

Op hit a jackpot.

Fwiw, keep it all.

Sink your budget into the chassis.

What changes/modifications to the chassis would you recommend?

Good motors need good brakes.
Good brakes need good suspensions.

Thats really all there is to it. 

Even if you don't convert the swingarm and forks to something radical.  Replacing the guts of stock forks with racetech and progressive kits will improve the functionality up front.  Adapted brake calipers and rotors are smart update too.
Twin shock setups are solid.  Any quality rear shock will do what you want of it.  There are some posts here about getting a slightly longer wheelbase with a cb550 swingarm swap.  Iirc. 

And since you got yourself a monster motor.  Might as well get the powerarc optical ignition pre-programmed from cycleX.  Worth every penny.

There are some ways to gusset and cross brace frames.  Did some of that for the xs750 with the help of a buddy.  I never rode the bike pre-rebuild.  But my exhaust fabricator said my xs felt tighter than the same year stock xs he had in his dealership.  It was a fun exercise in theory and didn't require too many fabrication tools.  Could be worth it with a punched out hopped up rig like yours.  Something to consider.

Oh, and don't underestimate the benefit of a cnc'd triple tree setup with a fork brace.

[Terry in Australia]

I just scored the same cam on Ebay Oz to go on my 970 build, does anyone have any timing specs for it? Looks like Norris became Megacycle cams, so I'm wondering if Megacycle continue to make a cam with a similar grind? Even the good ol' Satanic Mechanic's site doesn't appear to mention it?