1961 CB72 Project

[sdaigle240]

http://www.ijirset.com/upload/august/56_ENHANCEMENT.pdf

Awesome read. if you have any other technical papers of that nature id love to read them, no matter the topic....as long as its about things with engines and wheels.

Id be curious to know more about the ignition retard. I imagine they adjusted it for each configuration until the air fuel mixtures matched the stock engine. thats a quite complicated operation on an EFI, requiring dyno tuning to get the mixtures right across the board in all situations. I wrote the fuel and timing maps for my track car so this is more than this interesting stuff to me. regardless of what they did the fact that it made more power with less timing is impressive. great read.

[G-Man]

Steve

I've always been interested in combustion chambers and combustion process since before my university days. The article was based on a small diesel engine and they are different (as I'm sure you know) in that they operate on a 'stratified charge' principle where the mixture is not homogenous like a gasoline engine. The mixture is rich around the injector where fuel is being introduced into clean air and gets leaner toward the outer edges of the chamber.

I have been reading this book, on and off, since I was 14. Phil Irving was the man behind the Vincent-HRD motorcycle among other things. I still have my original copy with its dust-jacket.

http://tuningforspeed.com/files/Tuning_for_Speed.pdf

A brilliant man. His book is just a very nice read that you can go back to any time. The principles still work today, and his philosophy is spot-on. The great thing about his suggestions is that you can use them on a road engine without using the extra performance and you have an engine which runs at a lower stress level to give the same performance with longer life.

G

http://www.ijirset.com/upload/august/56_ENHANCEMENT.pdf

Awesome read. if you have any other technical papers of that nature id love to read them, no matter the topic....as long as its about things with engines and wheels.

Id be curious to know more about the ignition retard. I imagine they adjusted it for each configuration until the air fuel mixtures matched the stock engine. thats a quite complicated operation on an EFI, requiring dyno tuning to get the mixtures right across the board in all situations. I wrote the fuel and timing maps for my track car so this is more than this interesting stuff to me. regardless of what they did the fact that it made more power with less timing is impressive. great read.

[G-Man]

Also...

Some interesting notes from 'Pops' Yoshimura. It's early days stuff but his results speak for themselves. Enjoy!










G

[jerry]

Dear G man, The WOW may well have been shouted. Article by Pops is always a brilliant reference point for the Hondas as is Phil Irving's writings for all of motorcycles and cars. So much has not changed in principles.
All the best Jerry

[G-Man]

Jerry

In the Yoshimura article, he spoke about using cut down (Honda?) inlet valves as exhaust valves for his race bikes. Do you think that was OK for short race durations without any treatment of the face?

G

[jerry]

Graham. As said much has been written about how things were done in the 'Old" days. If one was to build a Yoshi engine and bike as Pops did in the era it would definitely not be the front running combination in competition. With the greater understanding of combustion chamber and piston crown design compression ratios of 12.3 to 1 is possible using premium petrol in a 500 single 2 valve. I promise you it is all so different now. If you check the IOM Classic TT results from the previous week end and then to collate and analyse all the info you will see that both time and design development has changed outcomes from the Classic period. 2 valve Single is faster than 4 valve single. 4valve twin is faster than 4 valve triple. Unfortunately there are too many that do not understand enough about swirl , tumble, squish, combustion chamber design, inlet/exhaust valve ratios, valve sizes, port design, bowl shapes, ignition curves, g forces conrod stroke ratios etc, etc. With what gets written at times sometimes I go WOW. I love the fact that we are all enthusiasts regarding our bikes and we all have different levels of understanding but sometimes strange things are said and written. I will write an analogy " I have been in a helicopter a few times and I know very little about them. If I were to make a statement about how to fly one Sarals may just think or reply WOW. All the best Jerry (Yes I do get myself into trouble voicing my opinions. My wife and daughters often remind me that I am old, ugly, delusional and outnumbered)

[G-Man]

Jerry

Thanks for the observations. Been having such a good time on vacation, I'd forgotten about the Classic TT.... :-(

I understand those thoughts. I have been professionally involved wth designing all kinds of things over the years. Motorcycle stuff, for me, is just a hobby and fascination. The difference between a 1950's Gilera and a 2015 Yamaha M1 is on one level, very little, and on another an ocean apart.

We just need a few 'classic' two-strokes to come along and throw things into confusion......

As for the last statement - so very true. Still cabable of paying for a few things, though.... :-)

G