Author Topic: more Yoshimura secrets (Read 12474 times)

turboguzzi · « **Reply #25 on:** July 22, 2009, 04:37:07 AM »

OK, time to pull out those useless things called magazines.... remember them?

in cycle's novemebr 1978 feature on the racecrafters kawasaki, pierre des roches says he uses a larger than stock inlet, 36,5 with a stock EX of 30. dia ratio is 82%, area ratio 67%

in a local mag about a race tuned aircooled ducati motor the (only relatively modern two-valve design that still gets tuner's attention and developement) IN is 47, EX 40, dia ratio 85% , 72%. So Rod, your numbers are good and so are the stock numbers of the 500! 27.6 IN, 23.4 EX gives exactly the same ratio as in the race Duc!

Good to know. I will sleep better tonight.

Bill/BentON Racing · « **Reply #26 on:** July 22, 2009, 04:46:09 AM »

TG,good info,sleep well,didn't CR 750's have larger intakes and smaller exhaust valves?1.5 mm in,.5 mm ex??Bill

turboguzzi · « **Reply #27 on:** July 22, 2009, 06:04:56 AM »

Quote from: bellcow54 on July 22, 2009, 04:46:09 AM

TG,good info,sleep well,didn't CR 750's have larger intakes and smaller exhaust valves?1.5 mm in,.5 mm ex??Bill

Dont know much about CR 750's.....

turboguzzi · « **Reply #28 on:** July 22, 2009, 01:14:14 PM »

HB continues to bombard us

this time: crank, ports, manifolds, head

my comments (added as red arrows over the pics)? the weight reduction idea on the crank is super cool and super simple,

instead of knife edgine on a lathe with the accompamnnyg danger, he just cut the side of the webs, brilliant, will do it.

ports / manifolds: cant think of why the strong S would work, now that I see a good side view, it doesnt make any sense other than to make the cast manfiold easy to produce. Even worse is the fact that to match this manifold, the enlargement of the inlet port was done towards the bottom, essentillay increasing the bend the air has to go through. I did it the other way round, i.e. pushed the top edge of the port up to "open up" the bend in the port.

head, hard to see, but looks like pops might have cancelled the 15 degs chamfer and opend the the chamber to be more hemisferic. problem is that it elimenates the squish area.

with all due respect to pops (or his workers) craft, high performance mods ahve evolved since the mid seventies, so some of these mods migh not be so hot anymore. A proper dyno check with a good "pops motor" could tell if these work as they should

turboguzzi · « **Reply #29 on:** July 22, 2009, 01:17:32 PM »

would of course be lovely to know the figures of those cams, heard tons about the "isle of man" cam

HB-1

would still be good to see a pic of the piston, the valves from a side shot, some more port report....

at your leisure,

TG

bwaller · « **Reply #30 on:** July 22, 2009, 06:38:38 PM »

You're right TG, that chamber is much larger at the expense of the squish ring. I know a stock chamber is 13cc, but wonder what advantage going bigger would give except to better match a bigger bore? The Yosh pistons I've seen (funjimmy has some 59mm) didn't have much dome so I wonder what pistons were planned for that head so-as to build compression with that larger chamber?

The cylinder head shown in the old Yosh catalog I have has that squish ring removed as well, but the combustion chamber does not appear to be as large as HB-1fan's. I bet that head was shaped for bigger 61mm pistons, and I think I read that Drew fiqured the pistons he got may not have been for that engine?

In light of all the performance searching they went through those manifolds are a little puzzling. Kayaker had shorter manifolds for his Mikunis and I just fiqured those were Yosh, but probably not seeing as how Pops always leaned to Keihin??

Jerry Rxman Griffin aka MuthaF'er · « **Reply #31 on:** July 22, 2009, 10:44:14 PM »

TG,

Been watching you guys play. Very interesting. Who actually has possession of those cams? Might I suggest that they be sent to Megacycle. I believe Megacycle has a "cam genie" or something like that which would be able to read it and duplicate it.

Jerry

Bill/BentON Racing · « **Reply #32 on:** July 23, 2009, 06:08:12 PM »

I have a NOS Yoshimura B grind aka Isle of Man,TT,Took pics last nite,hard to see the B on end of cam but it's there!Thought of you guys as I unwrapped it.Megacycle wants to borrow they sure can.Anyone know who to contact?I will contact Drew(guys bike I'm building)and he can post pics! Bill

MRieck · « **Reply #33 on:** July 23, 2009, 08:05:37 PM »

Quote from: bellcow54 on July 23, 2009, 06:08:12 PM

I have a NOS Yoshimura B grind aka Isle of Man,TT,Took pics last nite,hard to see the B on end of cam but it's there!Thought of you guys as I unwrapped it.Megacycle wants to borrow they sure can.Anyone know who to contact?I will contact Drew(guys bike I'm building)and he can post pics! Bill

Bill....you'd have to talk to Barbara @Megacycle about that. That is a great offer on your part.
Mike

Bill/BentON Racing · « **Reply #34 on:** July 23, 2009, 08:20:43 PM »

MR,thanks,I will and keep you posted.A $20.00 investment from the past might pay off,Bought an A grind $10.00 and B'S were $20,00.Thank You Greg Tysor.Was Tucker or Rocky rep at the time.Should have bought then all!,Bill

Sam Green Racing · « **Reply #35 on:** July 23, 2009, 08:29:59 PM »

Hi Bill, I see in your signature you have a RS125, do you still race it or any of your other bikes?

Sorry for the hijack.

Sam.

MRieck · « **Reply #36 on:** July 23, 2009, 08:32:10 PM »

Quote from: bellcow54 on July 23, 2009, 08:20:43 PM

MR,thanks,I will and keep you posted.A $20.00 investment from the past might pay off,Bought an A grind $10.00 and B'S were $20,00.Thank You Greg Tysor.Was Tucker or Rocky rep at the time.Should have bought then all!,Bill

Oh boy.... that is "Old School".

BTW...Tucker and Rocky are the same company.

MRieck · « **Reply #37 on:** July 23, 2009, 08:34:30 PM »

Quote from: Samcr750 on July 23, 2009, 08:29:59 PM

Hi Bill, I see in your signature you have a RS125, do you still race it or any of your other bikes?

Sorry for the hijack.

Sam.

Always tuned in to weed wacker stuff Sam.

Sam Green Racing · « **Reply #38 on:** July 23, 2009, 08:38:48 PM »

You just hijacked my hijack Michael

TG will be falling out with us.

anyway, there's no weeds in my garden as you well know

Sam.

Bill/BentON Racing · « **Reply #39 on:** July 23, 2009, 08:41:25 PM »

Sam,I did not race the RS125,It's pretty pristine,has 5 races on it,TG,MR,Bwaller,MC,yourself and many others on this forum have got me pumped up.I think I am coming back or at least build and put some fast kid on it,Oh yeah and HB-1,you too and what about those rings?Tucker and Rocky were once separate.Sam your answer on alum ring was cute!,Bill

MRieck · « **Reply #40 on:** July 23, 2009, 09:13:32 PM »

Quote from: bellcow54 on July 23, 2009, 08:41:25 PM

Sam,I did not race the RS125,It's pretty pristine,has 5 races on it,TG,MR,Bwaller,MC,yourself and many others on this forum have got me pumped up.I think I am coming back or at least build and put some fast kid on it,Oh yeah and HB-1,you too and what about those rings?Tucker and Rocky were once separate.Sam your answer on alum ring was cute!,Bill

You got me there Bill....that is REAL old school.

MRieck · « **Reply #41 on:** July 23, 2009, 09:14:54 PM »

Quote from: Samcr750 on July 23, 2009, 08:38:48 PM

You just hijacked my hijack Michael TG will be falling out with us. anyway, there's no weeds in my garden as you well know

Sam.

God.....dust doesn't settle on that garden.

Sam Green Racing · « **Reply #42 on:** July 23, 2009, 09:21:39 PM »

No....it's too wet.

Sam.

MRieck · « **Reply #43 on:** July 23, 2009, 09:23:34 PM »

Quote from: bellcow54 on July 23, 2009, 08:41:25 PM

Sam,I did not race the RS125,It's pretty pristine,has 5 races on it,TG,MR,Bwaller,MC,yourself and many others on this forum have got me pumped up.I think I am coming back or at least build and put some fast kid on it,Oh yeah and HB-1,you too and what about those rings?Tucker and Rocky were once separate.Sam your answer on alum ring was cute!,Bill

That would be nice to put a young person on some racing equipment....especially backed by an expert. I have 2 sons but neither showed the interest.....Christ...they could have had a lot of professiopnal support. Anyway....one really likes baseball and the other tennis...that's the way it goes BUT the younger one into baseball would certainly like to go round a track as fast as he can.....and he is beginning to understand what I ....and my friends....can do. He is only 12 years old so we'll see.

MRieck · « **Reply #44 on:** July 23, 2009, 09:26:11 PM »

Quote from: Samcr750 on July 23, 2009, 09:21:39 PM

No....it's too wet.

Sam.

Slug control Sam.....boy...I feel like I never left.

Bill/BentON Racing · « **Reply #45 on:** July 23, 2009, 09:28:29 PM »

MR,Old School Rules!,Something about age and treachery,Sam you a hoot!,looks like tomorrow on cam pics,Oh it is tomorrow,anyway just finished Drew's engine,see ya'll later,will call Barbara @ megacycle later this morning.Bill

MRieck · « **Reply #46 on:** July 23, 2009, 09:29:36 PM »

Quote from: bwaller on July 22, 2009, 06:38:38 PM

You're right TG, that chamber is much larger at the expense of the squish ring. I know a stock chamber is 13cc, but wonder what advantage going bigger would give except to better match a bigger bore? The Yosh pistons I've seen (funjimmy has some 59mm) didn't have much dome so I wonder what pistons were planned for that head so-as to build compression with that larger chamber?

The cylinder head shown in the old Yosh catalog I have has that squish ring removed as well, but the combustion chamber does not appear to be as large as HB-1fan's. I bet that head was shaped for bigger 61mm pistons, and I think I read that Drew fiqured the pistons he got may not have been for that engine?

In light of all the performance searching they went through those manifolds are a little puzzling. Kayaker had shorter manifolds for his Mikunis and I just fiqured those were Yosh, but probably not seeing as how Pops always leaned to Keihin??

Just to remind you gents what we are talking about!!!!!

MRieck · « **Reply #47 on:** July 23, 2009, 09:33:04 PM »

Quote from: bellcow54 on July 23, 2009, 09:28:29 PM

MR,Old School Rules!,Something about age and treachery,Sam you a hoot!,looks like tomorrow on cam pics,Oh it is tomorrow,anyway just finished Drew's engine,see ya'll later,will call Barbara @ megacycle later this morning.Bill

Peace out Bro. I'm off too.

Ecosse · « **Reply #48 on:** July 23, 2009, 11:24:10 PM »

Quote from: MRieck on July 23, 2009, 09:23:34 PM

...BUT the younger one into baseball would certainly like to go round a track as fast as he can.....and he is beginning to understand what I ....and my friends....can do. He is only 12 years old so we'll see.

well then it's not too late to ~~corrupt~~ gently influence him. ya need to be subtle about it... i've 'influenced a few friend's kids into gear head pursuits.

turboguzzi · « **Reply #49 on:** July 24, 2009, 01:52:30 PM »

kidnapping my own thread, but I'd say it has to come from his own will, would never ever try to convince ANYBODY, kid or grown up, to ride, would never want the responsability if something happens.

If someone takes on riding by his own will then fine, I'll help and teach as much as I can.

Back to the subject of the thread, HB1-fan, were stil missing the piston pics!

TG

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Author Topic: more Yoshimura secrets (Read 12474 times)