Topic: CB750 Cylinder Head Valve Angles

[BMHS]

Guys,
I'm in the process of machining a fixture to mount a CB750 cylinder head on my mill to machine the valve seats with 3D profile seat tooling. I measured the intake guide angle at 27 degrees and the exhaust guide at 29 degrees. Does anyone out there disagree with these numbers. I have checked a 77 K and a 78 F2 head, and they semed to be the same. I would hate to do the tooling plate twice.
Any help is appreciated.
Brian

[Retro Rocket]

Send a PM to head guru MRieck. If he doesn't know then no one will....

http://forums.sohc4.net/index.php?action=profile;u=49

Mick

[Sam Green Racing]

Brian, the job you are undertaking requires an expert machinist, why do you need a second opinion on your ability to measure the valve angles ? Sorry if this sounds like disbelief but I have read all your posts and it sounds like you shouldn't be asking this question or am I missing something ?

Sam.

[turboguzzi]

Brian, the job you are undertaking requires an expert machinist, why do you need a second opinion on your ability to measure the valve angles ? Sorry if this sounds like disbelief but I have read all your posts and it sounds like you shouldn't be asking this question or am I missing something ?

Sam.

wouldnt trust any claimed figures either, you should measure or more exactly, zero in till you get matching angle with a dial gauge. the 3D seat machine i saw in a show had screw controlled degree table to set the head up, would borrow such for the job. quicker

TG

[simon#42]

i thought the f2 had a different exhaust valve angle [ to fit a larger valve in ] , this is why the valve guides wear so quickly

[Jerry Rxman Griffin aka MuthaF'er]

i thought the f2 had a different exhaust valve angle [ to fit a larger valve in ] , this is why the valve guides wear so quickly

+1

Are you positive about your ID of the heads? The K should have 392 on the top fin intake side by #3. The F2/F3 should have
410.

[BMHS]

Guys,
I rarely do this, because I perfer my work to speak for me, but maybe it's needed:
I an old guy, 63 years young
* I started FlowRite Systems in 1976, and for 12 years it was one of the leading cylinder head shops in the nation. We specialized in short track / NASCAR small block heads, and AMA SuperBike 1000 cc engine heads. I have done port / flow work for American Honda Racing, Yamaha USA Racing, and countless private AMA SuperBike racers. My heads hold approximately 8 land speed records at Bonneville including having done the heads on Don Vesco's land speed record Kawasaki streamliner. I also own the record for the worlds fastest Whizzer, 63 MPH.
*I have designed from scratch DFX Cosworth 4 valve replacement heads for the INDY DFW engine.
* I was the US Engine Manager for the Jaguar World Endurance team, We won Daytona 24, LeMans 24, the IMSA Championship, and the World Championship.
* I designed & built Alan Kulwicki's NASCAR engines.
* I have worked for Mercury Marine, Briggs & Stratton, and Kohler Engines, where I design & test industrial engines today. All the valve seat angles & contours at Kohler have been designed by myself or with my guidance.

I learned over 40 years ago to ask questions, and to listen to others that may have information that maybe new to me. The way you win world championships is to listen, & to not assume that you have all the knowledge, & to try to be humble.
Brian

[scunny]

nice CV. I'm all ears on this.

[Jerry Rxman Griffin aka MuthaF'er]

Brian,

Nice resume! Congratulations on all the accomplishments. We are generally used to guys with limited/varying degrees of knowledge and welcome your expertise to our insanity. Thanks for explaining. I try not to be judgemental and carefully attempt to base responses on what is written. I'm not an expert either and I have never had a F2/F3 head so I can not directly speak of them other than the historical writings of their problems with premature valve guide wear. This was allegedly due to a changed valve angle that was necessary to use larger valves in BOTH the intake and exhaust while still using the same basic cam, cam towers and rocker arms. This is why I inquired about your 2 heads.

Now that I've said all that I'd refer you to 2 guys that have worked with these heads since the beginning: MRieck (Mike Rieck) and Big Jay of APE fame. I'd bet either of these 2 guys will provide the info you need.

Hang around. It'll be good to have you on board! Never enough of the "older" guys with the experience to be found.

Jerry   

[BMHS]

Honestly,
I try to keep my background to myself. Nobody wants a heavy weight around, only to find out that with these engines, he's still learning. All engines are basically the same, but it's all the little scrap that one needs to pick up, to keep these old engines alive. I'm all ear's. I did email Mike last night, he has not gotten back yet. I plan to go completely through the valve train geometry, making sure that the rocker arm contact point is dead center on the valve stem at mid lift. If it's not, the guides will wear. All this is for a 836cc kitted engine that I'm doing this winter, with a Weber cam to my specs, 102 IN C/L & 110 EX C/L, mild lift, new 29 CR's, my exhaust, etc. I did get 12 special cylinder sleeves made up to improve the wall thickness of the 836 bored cylinders. They are way too thin at the bottom, where they are unsupported by the aluminum casting. I could distort a test sleeve bored to spec with my hands. More on that later.
Brian

[Big Jay]

 I'd refer you to 2 guys that have worked with these heads since the beginning: MRieck (Mike Rieck) and Big Jay of APE fame. I'd bet either of these 2 guys will provide the info you need.

Jerry    

Actually the fact that we use a Serdi, we don't know the angle because the table is fully adjustable and the initial setting is done with a small bubble level attached to the carbide pilot that is in the guide. That gets it very close, then the full air float on the Serdi head takes over and puts it dead on.

[mlinder]

Honestly,
I try to keep my background to myself. Nobody wants a heavy weight around, only to find out that with these engines, he's still learning. All engines are basically the same, but it's all the little scrap that one needs to pick up, to keep these old engines alive. I'm all ear's. I did email Mike last night, he has not gotten back yet. I plan to go completely through the valve train geometry, making sure that the rocker arm contact point is dead center on the valve stem at mid lift. If it's not, the guides will wear. All this is for a 836cc kitted engine that I'm doing this winter, with a Weber cam to my specs, 102 IN C/L & 110 EX C/L, mild lift, new 29 CR's, my exhaust, etc. I did get 12 special cylinder sleeves made up to improve the wall thickness of the 836 bored cylinders. They are way too thin at the bottom, where they are unsupported by the aluminum casting. I could distort a test sleeve bored to spec with my hands. More on that later.
Brian

Mike is super busy right now, far as I can tell. If he has the info (or doesn't, either way), I'm sure he'll get back to you ASAP.

Hello.

[turboguzzi]

 I'd refer you to 2 guys that have worked with these heads since the beginning: MRieck (Mike Rieck) and Big Jay of APE fame. I'd bet either of these 2 guys will provide the info you need.

Jerry    

Actually the fact that we use a Serdi, we don't know the angle because the table is fully adjustable and the initial setting is done with a small bubble level attached to the carbide pilot that is in the guide. That gets it very close, then the full air float on the Serdi head takes over and puts it dead on.

Jay, have you seen these new cnc seat cutters where the tip of the tool can move axially according to a CAD program? fully blended seats (or whatever profile) in something like 20 seconds.... cant remember the name of the company making them

[Sam Green Racing]

Brian, please forgive me for my little ploy forcing you to come clean on who you were.
I did say that I had read all your posts (and many more on other forums) and there is plenty of room on this forum for another BIG GUN.
If you look back to what Jerry Griffin said, "I try not to be judgemental and carefully attempt to base responses on what is written". On the other hand, I myself try to get a better understanding of new posters by reading between the lines and checking out earlier post from the poster.
A few months back, we had a poster asking what seemed to me like a silly question, and me knowing that the guy knew or should have known what he was talking about was not carefull enough with my reply and it looked like I was having a go at him, It got sorted and the guy turned out (as I expected) to be a current factory race team technician.
At times I really do forget what brought me to this forum, I had built a multi championship winning/record breaking CR750 and when it started to get pushed, turned to the internet looking for parts to make it faster. I had been tuning and racing a particular type of Honda for years but soon found out how little I knew about the CR I had built.
Here's hoping you find all the answers to your questions in here.

Sam.

[kos]

Brian,

Nice resume! Congratulations on all the accomplishments. We are generally used to guys with limited/varying degrees of knowledge and welcome your expertise to our insanity. Thanks for explaining. I try not to be judgemental and carefully attempt to base responses on what is written. I'm not an expert either and I have never had a F2/F3 head so I can not directly speak of them other than the historical writings of their problems with premature valve guide wear. This was allegedly due to a changed valve angle that was necessary to use larger valves in BOTH the intake and exhaust while still using the same basic cam, cam towers and rocker arms. This is why I inquired about your 2 heads.

Now that I've said all that I'd refer you to 2 guys that have worked with these heads since the beginning: MRieck (Mike Rieck) and Big Jay of APE fame. I'd bet either of these 2 guys will provide the info you need.


Think about it...both K head and F2 head have the same rocker arm towers and same rocker arms....how would a different valve angle work in the F2 head? ie: how would valve tip match the adjuster screw as rocker arm moved thru it's travel range?


KOS





Hang around. It'll be good to have you on board! Never enough of the "older" guys with the experience to be found.

Jerry   

[kos]

27 and 29


KOS

[Bill/BentON Racing]

Welcome aboard.More on that exhaust please. Nice resume.......we like stories and pics! ,Bill

[kos]

 I'd refer you to 2 guys that have worked with these heads since the beginning: MRieck (Mike Rieck) and Big Jay of APE fame. I'd bet either of these 2 guys will provide the info you need.

Jerry    

Actually the fact that we use a Serdi, we don't know the angle because the table is fully adjustable and the initial setting is done with a small bubble level attached to the carbide pilot that is in the guide. That gets it very close, then the full air float on the Serdi head takes over and puts it dead on.

Jay, have you seen these new cnc seat cutters where the tip of the tool can move axially according to a CAD program? fully blended seats (or whatever profile) in something like 20 seconds.... cant remember the name of the company making them

The machine that is the one to have now is Newmen. It uses live pilots not dead ones like Serdi and Sunnen use. Live pilots spin inside guide on Newmen. Dead pilots stick in guide and a from cutting tool cuts seats, throats, etc all at once.

[Big Jay]

Serdi pilots spin in the guide. Valve seat grinders, Neway cutters, etc. use a dead pilot.  The only advantage to the Newen is the ability to program a custom seat cut instead of having to have a special cutter made. But after you have all the custom cutters, there is not much of an advantage.

[turboguzzi]

ok, so now to the million dollar question, whats best for our sohc's, fully blended or multi angle?

[kos]

Serdi pilots spin in the guide. Valve seat grinders, Neway cutters, etc. use a dead pilot.  The only advantage to the Newen is the ability to program a custom seat cut instead of having to have a special cutter made. But after you have all the custom cutters, there is not much of an advantage.

Big Jay is correct....Serdi is live. My bad...too much work to doehere in shop not enough time taken writting my response. I stand corrected.

Sorry about that.

[Big Jay]

ok, so now to the million dollar question, whats best for our sohc's, fully blended or multi angle?

We use a full radius under the 45 for nearly all high performance applications. We have some 30/45/60 cutters we use on some totally stock rebuilds and some Harleys®

[BMHS]

I checked a F2 head the other night, and the valve angles are the same @ 27 & 29. The real difference between the heads is that Honda lowered the valve/seats approximately 1.5mm to 2mm, so that the valves would clear each other during overlap. That also causes the chamber to have more volume. Since this engine will be a Wiseco 836 kitted engine with my new thicker bottom sleeves, I'm checking the cc's of both heads to calculate the effects on the compression ratio. I want it to be 10.5/1 when I'm done. I already know that it will take a deck surface milling to normalize the cc's & compression ratio.
One of the guys posting asked about the exhaust system, so I have attached a few photo's.
Brian

[BMHS]

Guy's, one of the photo's that I sent did not go through. Here it is.
Brian

[MRieck]

I checked a F2 head the other night, and the valve angles are the same @ 27 & 29. The real difference between the heads is that Honda lowered the valve/seats approximately 1.5mm to 2mm, so that the valves would clear each other during overlap. That also causes the chamber to have more volume. Since this engine will be a Wiseco 836 kitted engine with my new thicker bottom sleeves, I'm checking the cc's of both heads to calculate the effects on the compression ratio. I want it to be 10.5/1 when I'm done. I already know that it will take a deck surface milling to normalize the cc's & compression ratio.
One of the guys posting asked about the exhaust system, so I have attached a few photo's.
Brian

That's interesting Brian. I was told by a regional Honda service rep (when the bike came out) that the exhaust angle was different by a degree or 2. Well...so much for that.  

[Jerry Rxman Griffin aka MuthaF'er]

Myth Busters at work! That's good info.