CB77 performance valve rocker arms?

[MisterB]

Hi all,

My first post, so go easy on me :)

I'm helping my friend rebuild / restore his first CB77 based race bike, that he built 30 years ago, and only recently found via Ebay and bought back.

The engine is far from standard and is supercharged and will run magneto ignition.

Back in the day one of the many problems he faced was breaking rocker arms as the engine had very high lift cams. He tells me that back in the 80s someone in the states made roller rocker arms / and or stronger rocker arms.

A search of the internet doesn't show up much, other than a reference to a big bore kit which included roller rocker arms made by a company called Harmon and Collins (Kenny Harmon and Cliff Collins). But there the trail goes cold.

Does anyone know more and if stronger 'performance' rocker arms are still available.

Thanks, Lee

[G-Man]

Hi Lee

That looks like a fun project! I only know of the Harmon and Collins ones but that was a long time back. I have these custom-made roller-rockers that came with some race engine parts and, I think, that Tim Miller on this site has made his own more recently.

Is your friend going to race it again? Have you got any power / performance numbers for that rig?

G

[Waveblaster]

I posted this a while ago

http://eattherichuk.blogspot.com.au/201 ... art-2.html

different but nice to see another modded version

[MisterB]

Thanks for the info, I'll pass it on. The bike is a sprint / drag bike running on Nitro, best times were low 10's for the quarter mile back in the 80s. The rebuild will include a Sprintex blower, SU carb and a three speed transmission using parts from a CB750.

[G-Man]

Lee

Great pictures, thanks.

I notice a plate under the barrel. Is that to accomodate a long-stroke crank? CB450? I have a similar plate on a "500" CB72 engine which uses a combination of parts from CB72 and CB450 cranks. Also CB450 pistons, I think.

Looking forward to details as you do the rebuild.

G

[MisterB]

The plate under the barrels is to lower the compression. When using a blower running at around 30psi and Nitro a higher CR isn't a good idea.

Jeff says he is planning on having a run of ten or so barrels cast which will be stronger than OE and have room take a bore giving up to 500cc.

He is busy modifying the frame this week..

[GORDON BROWN]

Hello Lee

Here are some more variations on the roller rocker theme. The broken one could be a Harmon and Collins ( it belongs to a friend ) and the other is from a set I have ( poor pictures ) they are big alloy things and heavier than the STD ones, they came from the USA but unfortunately I don't have the maker. I think a guy called Ken Rolland ? imported them and that was probably early 90's.
G-Man, the ones you have look like a lot of work has gone into them, were they made by George Flick ? ( hope I have the spelling right ).
I think I used my ones with a Megacycle cam at one time but having read about them later ! think the cam should really be a specific grind for the roller rockers. Perhaps someone else on the site will have a better idea about this.

Gordon