Don Terrill’s Speed-Talk

hoffman900 wrote: ↑Tue Sep 17, 2019 12:48 pm

Truckedup wrote: ↑Fri Sep 20, 2019 6:52 am

hoffman900 wrote: ↑Tue Sep 17, 2019 12:48 pm

Not sure where that is measured at though. You could always email Kevin Cameron. Yoshimura, Dan Crower, Honda, YEC (Yamaha), all advertise some racing camshaft numbers if that will help.

4vpc wrote: ↑Sat Sep 21, 2019 5:02 am

With respect he just comes across as another guy with an opinion in that video.

Truckedup wrote: ↑Sat Sep 21, 2019 7:52 am

4vpc wrote: ↑Sat Sep 21, 2019 5:02 am

With respect he just comes across as another guy with an opinion in that video.

Because it's somewhat relevant, I would be interested in your opinion on the topic ...

4vpc wrote: ↑Sun Sep 22, 2019 6:28 pm

Truckedup wrote: ↑Sat Sep 21, 2019 7:52 am

4vpc wrote: ↑Sat Sep 21, 2019 5:02 am

With respect he just comes across as another guy with an opinion in that video.

Because it's somewhat relevant, I would be interested in your opinion on the topic ...

We don't need another opinion, we need some facts He doesn't mention any testing he's done on the subject.
In his vid he claims that tight squish isn't used on production engines because they aren't accurate enough, that's not true at all, we're not in the 1940s any more.
DV says it's because emissions go up when squish is tight, A. Graham Bell on the other hand says that the mixture can actually get trapped between two parallel surfaces, that he's removed squish pads and seen a power increase on some engines, many turbo guys are making more power (because of lesser det' limits) by also removing squish pads.
Me? I sit on the fence observing because I don't have the funds to test. I sometimes think that if I won that big cash prize i'd buy some time, some equipment and do some testing of my own, but that's just a dream.

Truckedup wrote: ↑Mon Sep 23, 2019 6:24 am

4vpc wrote: ↑Sun Sep 22, 2019 6:28 pm

Truckedup wrote: ↑Sat Sep 21, 2019 7:52 am

Because it's somewhat relevant, I would be interested in your opinion on the topic ...

We don't need another opinion, we need some facts He doesn't mention any testing he's done on the subject.
In his vid he claims that tight squish isn't used on production engines because they aren't accurate enough, that's not true at all, we're not in the 1940s any more.
DV says it's because emissions go up when squish is tight, A. Graham Bell on the other hand says that the mixture can actually get trapped between two parallel surfaces, that he's removed squish pads and seen a power increase on some engines, many turbo guys are making more power (because of lesser det' limits) by also removing squish pads.
Me? I sit on the fence observing because I don't have the funds to test. I sometimes think that if I won that big cash prize i'd buy some time, some equipment and do some testing of my own, but that's just a dream.

That's stuff Cameron does on videos isfor the general motorcycle riders, not hard core tuners. He can be hard core, do some research on him..And yes, production bikes especially in the recent past do avoid tight squish even when it's not emissions related to avoid contact damage ...He did say that in the video...

ozyfordman wrote: ↑Mon Sep 09, 2019 7:56 am I have been asked to develop a race cylinder head for a 450 cc Yamaha single motocross bike. The bike will be used for beach racing over a 500 and 750 metre course over 4 laps around barrels st either end of the beach. The rider is competitive in motocross and enduros.The class is very competitive with a good deal of rule interpretation and very little scrutineering. I would like to explore the poly quad concept and better understand the benefits of this valve layout. A quick search here was unsuccessful. Not asking for a handout but would like to hear the benefits and the theories on how the benefits are achieved. I believe DV has been instrumental in the development of this technology and it is mentioned in one of his books.Is this technology making it into mainstream 4 valve performance mods, or is it still in the top secret department. Any feedback would be appreciated on this topic. I have access to an S&G machine and a flow bench. I have to admit to only working on 2 valve stuff to this point but have an experienced mentor on 4 valve motor cycle race engines. Any thoughts that you care to share will help as I am not clear on the theory.