Author Topic: more Yoshimura secrets (Read 12620 times)

turboguzzi · « **on:** July 19, 2009, 03:48:19 PM »

More stuff from HB-1fan!

Like I said after seeing Drew's manifolds, they do have a nice downdraft angle but now I can see for sure that they have this very bad S-Kink which just cant help flow. Seeing how the parting line in the casting goes, I'd say that strange S-kink was more a result of keeping these simple to cast.

Of more interest is the porting. Looks VERY hogged out to me. the only way to really know what pops, the master, did in this head would e to do a silicon casting of the port. HB, would you be up to this?

Could be great to see some picutres of the ports also looking form the combustion chamber as well as the same angle just without the manifolds.

Also a shot of the pistons would be interesting

Thanks

TG

HB-1fan · « **Reply #1 on:** July 19, 2009, 05:24:18 PM »

I'm going there with the camera tommorrow! I'm going to get it all out and take pics. Any more detailed requests??

HB

Bill/BentON Racing · « **Reply #2 on:** July 19, 2009, 06:42:21 PM »

Kaz sold me his last blk pipe way back in 91,He was so funny that day,Wait Bill,I go to old warehouse across the street,(he told me he was the janitor when I first called)did this regularly if he didn't know or remember you,He came back ..finally,Bill I find @,one chrome,one black,I keep chrome sell you black,thats what i wanted,any interest if I did a run of these,was exact copy of Pops pipe,Pops told him it was OK.I have it on the race bike but have not ever ran it.Ya'll let me know,Bill,Kaz Yoshima is who I am speaking of.

kayaker43 · « **Reply #3 on:** July 19, 2009, 07:08:39 PM »

Looks like the S bend was an attempt to raise the carbs more than change their spacing??? Maybe the CR30/31 carbs were taller and hit the cases? I think all the CR's had adjustable spacing so that wasn't the reason? Maybe to reduce width for knee clearance?

Also I would think they would have ended in a spigot rather than a flange and used short hoses to couple them?? I'm also surprised they don't appear much shorter than the stockers when you account for the missing rubber manifolds. I ran shorter stubby manifolds with my Z1 carbs and it seemed to match well with the shorter pipe primaries and cam timing,.. all to move the power peak higher.

The CB500R also appears to have shorter manifolds like I used. It also appears that the CR carbs have plenty of room underneath them???
http://forums.sohc4.net/index.php?topic=37074.0

HB-1fan · « **Reply #4 on:** July 19, 2009, 08:00:10 PM »

Bill,
I'm pretty sure that is Kaz's pipe on the bike on the cover of the clymer with the hi-po section in the back. Also, I heard once that Kaz was POPS son in law.

HB

Bill/BentON Racing · « **Reply #5 on:** July 20, 2009, 07:44:34 AM »

HB-1,there was definitely a relationship there,I ran Yoshima's pipe for 3 seasons,the new one is the one on there now.Bill

MRieck · « **Reply #6 on:** July 20, 2009, 09:33:03 AM »

Quote from: turboguzzi on July 19, 2009, 03:48:19 PM

More stuff from HB-1fan!

Like I said after seeing Drew's manifolds, they do have a nice downdraft angle but now I can see for sure that they have this very bad S-Kink which just cant help flow. Seeing how the parting line in the casting goes, I'd say that strange S-kink was more a result of keeping these simple to cast.

Of more interest is the porting. Looks VERY hogged out to me. the only way to really know what pops, the master, did in this head would e to do a silicon casting of the port. HB, would you be up to this?

Could be great to see some picutres of the ports also looking form the combustion chamber as well as the same angle just without the manifolds.

Also a shot of the pistons would be interesting

Thanks

TG

You should see the ports/manifolds that bwaller will be racing. That Yosh head still has the cast iron guides....odd.

turboguzzi · « **Reply #7 on:** July 20, 2009, 10:06:57 AM »

Quote from: MRieck on July 20, 2009, 09:33:03 AM

You should see the ports/manifolds that bwaller will be racing. That Yosh head still has the cast iron guides....odd.

Iron, shmiron, let the horsies talk....

Looking fwd to see what Bwaller's scoot will do on the dyno, so that for next year you can prepare me an even better head

What exhaust system are you planning for him?

TG

MRieck · « **Reply #8 on:** July 20, 2009, 06:44:51 PM »

Quote from: turboguzzi on July 20, 2009, 10:06:57 AM

Quote from: MRieck on July 20, 2009, 09:33:03 AM
You should see the ports/manifolds that bwaller will be racing. That Yosh head still has the cast iron guides....odd.

Iron, shmiron, let the horsies talk....

Looking fwd to see what Bwaller's scoot will do on the dyno, so that for next year you can prepare me an even better head

What exhaust system are you planning for him?

TG

I forget what he is going to run TG. My contribution in is pretty much over at this point (except for ocassional feedback)....

I'm doing the waiting game just like you. I'm sure it will perform well.

Bill/BentON Racing · « **Reply #9 on:** July 20, 2009, 08:50:19 PM »

TG,I look forward to seeing you guys #'s.What did yours do on dyno originally and now?I would love to see Bwallers ports,his bike and TG's have lots of developement time and $$$$$$$$.Wish you both luck and Bwaller you gonna be ready for season opener?Have not been to Canada but might have to go to see yours run,TG you still got Rossi's cell number? Freddie and Nicky I've met and admire but Rossi is the MAN!!,Bill

bwaller · « **Reply #10 on:** July 20, 2009, 09:33:39 PM »

Mike is a real polished craftsman (no pun intended) and has all the experience and contacts that have been a big help. I'll get some pics up once I get to assembly. I'm waiting for pistons to be ready, part of the delay was my feet dragging getting the crown design right, or at least I sure hope it's right.

So at this point I'm all talk and no-go!

TG on the other hand has been good to show all his development work and it's been paying off. I look forward to seeing what his renewed engine will give too. We have all been following his improvement on the track the last couple years.

MRieck · « **Reply #11 on:** July 21, 2009, 05:00:15 AM »

As a side note.....it really is too bad you can't fit a larger intake valve in the 550 head.....it would really help.

Bill/BentON Racing · « **Reply #12 on:** July 21, 2009, 05:05:40 AM »

Amen to that ,gotta get it in there first,but my buddy (Joe Hutcheson) said there wre times they had to add material,later model heads? Came with too big port,I would have to ask for more details.,Bill

bwaller · « **Reply #13 on:** July 21, 2009, 05:46:50 AM »

Quote from: MRieck on July 21, 2009, 05:00:15 AM

As a side note.....it really is too bad you can't fit a larger intake valve in the 550 head.....it would really help.

I agree Mike at least larger intakes would be nice. Speedracer made up some oversize and I looked at Kibblewhite XL250 intakes. I'm afraid to make them work would mean setting them quite deep in the seat and for 1mm larger..... POPS Rieck opened the seats as large as possible for a stock valve, probably not much lost over the larger alternative.

DavePhipps · « **Reply #14 on:** July 21, 2009, 05:55:09 AM »

Hmmm. I think I saw some oversized valves being sold on Ebay. I thnk my search was for cb550 exhaust and one of the items was oversized valves. I'll see if I can find it again later.

DavePhipps · « **Reply #15 on:** July 21, 2009, 06:47:31 AM »

Here they are

http://cgi.ebay.com/ebaymotors/HONDA-SOHC-CB500-CB550-OVERSIZE-VALVES-INTAKE-EXHAUST_W0QQcmdZViewItemQQ_trkparmsZ65Q3a1Q7c66Q3a2Q7c39Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem45ed2eb699QQitemZ300332005017QQptZMotorcyclesQ5fPartsQ5fAccessories

turboguzzi · « **Reply #16 on:** July 21, 2009, 07:09:52 AM »

Quote from: davephipps on July 21, 2009, 06:47:31 AM

Here they are

http://cgi.ebay.com/ebaymotors/HONDA-SOHC-CB500-CB550-OVERSIZE-VALVES-INTAKE-EXHAUST_W0QQcmdZViewItemQQ_trkparmsZ65Q3a1Q7c66Q3a2Q7c39Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem45ed2eb699QQitemZ300332005017QQptZMotorcyclesQ5fPartsQ5fAccessories

he is a forum member, it's from speedracer the REAL dowdraft guy, (30 degs, not 10 like me....)

Rod · « **Reply #17 on:** July 21, 2009, 09:19:54 AM »

Quote from: davephipps on July 21, 2009, 06:47:31 AM

Here they are

http://cgi.ebay.com/ebaymotors/HONDA-SOHC-CB500-CB550-OVERSIZE-VALVES-INTAKE-EXHAUST_W0QQcmdZViewItemQQ_trkparmsZ65Q3a1Q7c66Q3a2Q7c39Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem45ed2eb699QQitemZ300332005017QQptZMotorcyclesQ5fPartsQ5fAccessories

These look pretty tasty, but possibly raises the question of inlet/exhaust ratios. As I understand it, as CR and general level of tuning increase e.g. trick cam, so i/e ratio should be reduced - not only to avoid possibility of valve interference, but also aspiration issues due to longer duration on cam timing. I found some stuff a while ago that indicated for tuned engines the exhaust dia should be no more than 84% of inlet dia, and preferably down towards 82 - 81% if your running high cr and full race cam. In other words, if you tune a road engine for the track but keep standard valve sizes, or increase both inlet and exhaust pro rata, the i/e ratio is almost certainly too large and you will be sacrificing some power. I know this goes against the convention that bigger is always better - be interested to hear views on this. TG I wonder if this would explain your friends problems with running big valves in his 500, if the i/e ratio is way too high the aspiration issues would increase as he comes down from peak revs (timing overlap), therefore he has to keep the motor spinning to be making good power, there-by reducing usable power band?

turboguzzi · « **Reply #18 on:** July 21, 2009, 03:31:34 PM »

Mmmm. good point but I wonder if you did not get confused along the way....

The bible of motors, "the internal combustion engine in theory and practice" says that yes, ratio for high performance should be 82% but of AREA, not diameter!

the inlet on a 500 is 27.6, so a 82% diameter exhaust valve would be 22.6, way smaller that the 23.4 of the stock valve.

On the other hand, the 23.4 mm of the exhaust valve gives only 71% of the area of the intake!

Another possibility is that in order to calculate the ratio, I need to measure the smallest actual internal at the valve seat area.

Now I am confused too

Could it be that the 500's are limited by their exhaust valve rather than their inlets? that would be one hell of a finding...

anybody wants to chime in with some numbers?

TG

MRieck · « **Reply #19 on:** July 21, 2009, 03:50:37 PM »

I have read that the ID of the intake seat should be 87 or 88% of the intake valve OD. I've used 90% for years (as have meny others) with great results.

turboguzzi · « **Reply #20 on:** July 21, 2009, 03:56:58 PM »

Quote from: MRieck on July 21, 2009, 03:50:37 PM

I have read that the ID of the intake seat should be 87 or 88% of the intake valve OD. I've used 90% for years (as have meny others) with great results.

Good, so stock 500 seat ID to Inlet OD is spot on: 27.6 X 0.9 = 24.2 (which by the way, leaves precious little space to do a three angle job)

but what about exhaust valve size in relationship to inlet?

TG

MRieck · « **Reply #21 on:** July 21, 2009, 05:01:49 PM »

Quote from: turboguzzi on July 21, 2009, 03:56:58 PM

Quote from: MRieck on July 21, 2009, 03:50:37 PM
I have read that the ID of the intake seat should be 87 or 88% of the intake valve OD. I've used 90% for years (as have meny others) with great results.

Good, so stock 500 seat ID to Inlet OD is spot on: 27.6 X 0.9 = 24.2 (which by the way, leaves precious little space to do a three angle job)

but what about exhaust valve size in relationship to inlet?

TG

That was my point earlier. So....you want all the secrets now?

Honestly....exhaust ratio depends on the shape of the port especially the floor IMO. To be honest....I very rarely use an oversize exhaust valve. On newer heads I rarely use OS valves on either side.

MRieck · « **Reply #22 on:** July 21, 2009, 05:04:38 PM »

Quote from: turboguzzi on July 21, 2009, 03:56:58 PM

Quote from: MRieck on July 21, 2009, 03:50:37 PM
I have read that the ID of the intake seat should be 87 or 88% of the intake valve OD. I've used 90% for years (as have meny others) with great results.

Good, so stock 500 seat ID to Inlet OD is spot on: 27.6 X 0.9 = 24.2 (which by the way, leaves precious little space to do a three angle job)

but what about exhaust valve size in relationship to inlet?

TG

Ain't that the truth.

HB-1fan · « **Reply #23 on:** July 21, 2009, 05:23:22 PM »

TG, I sent a few more pics. I will send a bunch more in a couple of days. To much glare on most of them.
I did mic the inlet where the manifold bolts to the head. It was hogged out to 30mm.
The I.D. of the seat was 27.5 and the O.D. of the valve was just under 28mm.

HB

Rod · « **Reply #24 on:** July 22, 2009, 02:31:29 AM »

Hi TG and MR, interesting stuff. I found the tables I have for valve ratios, for normally aspirated race engines its indicating ratio by valve dia as 81-84%, and ratio by valve surface area as 65-70%. For low state of tune 87-89% and 75-80% respectively - these are quite different from the values you guys are quoting so I'm wondering if my data is for car engines i.e. bigger bore and not way over-square like bike engines (bore/stroke ratio)? MR good point that its not only just about the valve dia alone.

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Author Topic: more Yoshimura secrets (Read 12620 times)