Topic: Rocker arms and needle bearings?

[josephus]

I am just wondering if it would be worth the time to turn the rocker shafts down to used needle bearings? Anyone got any idea? maybe ideas on modifing the rocker arms for roller tips.

[Sam Green Racing]

It would be easier to make new rocker arms.

Sam.

[Big Jay]

It was done back in the day by Amol Precision. We sold them. Never really caught on.

[cavebear]

I have a 1150cc  bored and stroked turbo engine with the needle bearing shafts. Bike will be run for the first time at Union grove Wisc next summer and the Texas Mile next fall. Shafts will be inspected  after those runs.   

[Don R]

My big block just lost a rocker arm bearing. The new billet oil pump processed a half dozen needles. It aint pretty. I caught it in time to save the engine, only cost the price of a nice 750.

[turboguzzi]

hei josephus, why not introduce yourself and tell us what you are building, you might get more concise info than by asking "what if i do this or that"

those sohcs have pretty well established go fast tricks (even if people like MEC are happy to invent new ones )

[josephus]

i have played with these 750's since i was about 15. I also completed a 2year course in mc/atv repair and MUI on engines while in the Marines. I am tring to find out what has been done with these and what has not. Like running a vacum in the engine case.or maybe i know it sounds stupid but a modified rifle bore in the intakes.I try to follow the rules Lighten,polish,better flow,and prevent parisitic loss.But i am always up for something new or a better way of building. Thanks again for the input!

[FuZZie]

i know it sounds stupid but a modified rifle bore in the intakes.

Swirling flow or vortex don't sound stupid to me, want to explain a bit and kick the idea around?

[turboguzzi]

many if not all motogp run vaccum in the cases, either electrical pump or exhaust venturi, i gave it a try but didnt go as far as doing a dyno run with and without.

i think its a matter of how much gain for the effort, vaccum could yeld a few percentage more hp, needle rockers - dont think you'll even see the gain in a dyno run, but i could be wrong

 

[gnarlycharlie4u]

i know it sounds stupid but a modified rifle bore in the intakes.

Swirling flow or vortex don't sound stupid to me, want to explain a bit and kick the idea around?

seconded.
I've been considering rifling the intake tract and etching the piston domes for better atomization and intake for a while now.
Theoretically it's GENIUS. I'm not sure how it will affect things practically though.

As far as the needle bearings, I'm pretty sure you'd be better off just making new rocker arms out of titanium or something if you're going that far.
The margin of error for screwing up your rocker ratio is pretty high. Plus there are already plenty of tips and tricks for getting those rockers to REALLY perform without bearings.

I'd say your efforts are better spent on NOS early rocker shafts and some Flora-Polymer coating on the rockers and shafts.

[MCRider]

I'd agree with gnarley. Some low friction coatings might be better than adding moving parts.

I had my pins and rockers Cryogenically treated. I prefer this idea to coatings as nothing is added that can come off. No real way to gauge the value however. Who's going to do before and after dyno runs on something like that?

Good for bragging rights. 

http://www.nitrofreeze.com/racing.html

[gnarlycharlie4u]

I'd agree with gnarley. Some low friction coatings might be better than adding moving parts.

I had my pins and rockers Cryogenically treated. I prefer this idea to coatings as nothing is added that can come off. No real way to gauge the value however. Who's going to do before and after dyno runs on something like that?

Good for bragging rights. 

http://www.nitrofreeze.com/racing.html

I know for a fact [spoiler]and by fact i mean other's anecdotal evidence [/spoiler] that this is an excellent choice for durability and a must if you're going to be trimming some weight from the rockers.

[MCRider]

In an Occam's Razor sort of way,
http://en.wikipedia.org/wiki/Occam's_razor
I'd have to go with lightening, polishing, Cryo and coatings route. Simple and sweet.

My guess is coatings have come a long way and my fear of them "coming off" is unfounded.

[gnarlycharlie4u]

In an Occam's Razor sort of way,
http://en.wikipedia.org/wiki/Occam's_razor
I'd have to go with lightening, polishing, Cryo and coatings route. Simple and sweet.

My guess is coatings have come a long way and my fear of them "coming off" is unfounded.

yeah... if you're doing something to make them come off, then your rocker arms are probably buggered anyway, and the coating is going to be the least of your worries.

[754]

 Strociek in Illinois, made rollers for H-D. I think for a while he offered them for 750s. (does not mean they actually were made)


 If Anyone can post a pic of ANY sort of roller rocker for CB 750 Please post a pic if you can

[turboguzzi]

rocker rollers and needle shaft bearings are not the same thing....

[josephus]

in thoery water moves similar to air. so i was thinking of a way to make a kind of "vortex" in the intake tract. kinda like the tornado effect when water is drained out of a sink or tub or a real good one your toilet. i figure it would be almost like four mini turbos at mid to high rpms. the dodge magnum 318 used swirl ports with about a 40hp gain! but the cut grooves right above the valves on the intakes only. by looking at the intake tract it looks like the mixture would want to dump staight down. i have lightened my rocker arms with a bench grinder and then heated them and dropped them in oil and the bike did rev easier! as well i did hollow the camshaft. hey weight is weight no matter were it comes from. also thinking of a putting 450 magneto assebly on the crank the starter gear fits but ive got to put a bigger taper inside the rotor to fit the crank.an idea that just hit why not ditch the steel rockers and go with some aluminum ones ? might be good for racing wouldnt expect them to last on the road. as i normally ride my bike hard and fast. 

[754]

 If you ran an aluminum rocker, what would you use for the part that wears against the cam??.... easy to solve on a pushrod rocker, but not on the cb 750 type..

[cbr954]

A person could make a roller tip rocker arm kind of like the newer ohc Ford motors.  They use a rocker arm setup that has a roller where it makes contact with the camshaft.  While your at it you might as well make it out of titanium, light and strong.

[754]

 So you have your rocker with roller tip, how are you adjusting valve lash?.. not a lot of room in there for shims, and how do you change them ?

[cbr954]

The roller would be on the side of the rocker that rides on the camshaft not on the adjuster end.

[Big Jay]

Then you would need someone who could design a lobe profile for the roller. They are completely different.

[MRieck]

Hard welding (on rockers and cam) works well and helps decrease friction. Use a zinc additive too.

[josephus]

i dont know maybe modified head to use air operated valves. yeup titanium would be better but costs more. Anyone make an aluminum alloy cb750 frame? THANK YOU everyone for all the input any more ideas are welcome!

[lucky]

i have played with these 750's since i was about 15. I also completed a 2year course in mc/atv repair and MUI on engines while in the Marines. I am tring to find out what has been done with these and what has not. Like running a vacum in the engine case.or maybe i know it sounds stupid but a modified rifle bore in the intakes.I try to follow the rules Lighten,polish,better flow,and prevent parisitic loss.But i am always up for something new or a better way of building. Thanks again for the input!

It has already been proven and a SAE paper written on using crankcase gases for supercharging and it was found to be a insignificant increase

A SAE paper written on filling holes in the flywheels of two stroke engines to increase  compression, was found to have an insignificant increase in performance.