Author Topic: yoshi exhaust (Read 21426 times)

paddy paul · « **on:** January 21, 2010, 08:43:59 AM »

Can anyone please give me the dimensions for the original yosimura exhaust, the hand built ones, for the 750 I'm needing the pipe diameater and the radius of the bends, overall length, etc, or does anyone know where I can get specs, I have asked a few members who have them on there bikes , but I have received no replies, any info would be greatly appreciated, Thanks

wannabridin · « **Reply #1 on:** January 21, 2010, 01:31:53 PM »

sorry that i don't know any of the info, but are you interested in making sets? i'm that they have a one piece hand bent downpipe on each cylinder and that the pipe out of the collector is hand bend and one piece as well. the hardest part about reproducing them is that "Pops" is dead and those radius' are quite complicated. this is just what i've gathered from leeching on the boards...

paddy paul · « **Reply #2 on:** January 21, 2010, 07:43:54 PM »

yes, I'm going to try and reproduce, as close as I can, his design, I just love the look of them, It's just a matter of getting some info on a set, I guess I will do like pops and just start bending until I get it right.. I just wish I could my hands on a set to go off of, Carpy's are good but they are the later style so I will just start building and see where it goes..

Ricky_Racer · « **Reply #3 on:** January 21, 2010, 07:59:02 PM »

Paddy, have you hand bent sand-filled exhaust before? If so, I'm sure we'd all like to see pics of your progress. Thanks. RR

paddy paul · « **Reply #4 on:** January 22, 2010, 06:20:08 AM »

Yes, back when I was a young man, I worked for a guy who ran a trucking business, but I spent more time building and working on his race cars then I did being a diesel mechanic, He would build all the frames for his cars from the ground up, so I spent a lot of time with the mandrel tube bender, granted it's been 20 years but I think I could get back in the swing of things.

I have found a supplier for the materials on the web and the price is about 100 bucks for the tubing,collector, baffle,etc . the cost of the actual parts is quite cheap, but I'm going to have to get a decent mandrel/tube bender and the dies so the cost of the tooling is whats going to cost me. also found a shop in Farmington NM that will ceramic coat them at a reasonable price, if I go that route.

I hope to build a decent prototype that I would be proud to run on my bike, and then I would like to offer sets to the members here, Carpy's pipes are great ,but they are the later style, Jus tneed to wait for some tax money, pay off a few bills and I will be ready, I hope to have a set ready by early summer and I will keep everone posted of my progress...

bubbafun101 · « **Reply #5 on:** January 22, 2010, 03:36:04 PM »

I am so down with this thread. Been wanting that sexy hand bent exhaust since I first saw it. Until I get the dough (Yamiya has hand bent) I took a old Kirker, which I disassembled for the down pipes. Next I went to Baxters auto supply and purchased 40 dollars of pipe and a 4 into 1 collector with a 22 degree tapper. After a stripped the chrome of the down pipes (today) I will begin mock up with collector (Saturday) and work on a tail piece the first of the week. Yes I will post pics. Hoping it sounds good, it should, but I might insert a baffle if I am convinced by the local constabulary that my noisy bike is disturbing my fellow citizens!! Dimensions for optimum 4-1 exhaust is listed in Satanic Mechanic under exhaust (RH lower 1/3rd). Good luck to all of us.

gane · « **Reply #6 on:** January 22, 2010, 07:23:50 PM »

Paddy, I know it's not what your' looking for, but... I have one of the later "machine bent" Yosimura Race 4/1 pipes on my '76 K. It's intact, but doesn't have the the continous smooth bend headers of Pop's "hand built" pipe. If intested, I would loan it to you in exchange for say, an uncoated prototype. leve me a PM if intrested, I live in Boulder.G

MRieck · « **Reply #7 on:** January 22, 2010, 07:41:57 PM »

I really think some tapered pieces right off of the exhaust ports will help no matter what you do. Seriously.

wannabridin · « **Reply #8 on:** January 22, 2010, 09:03:42 PM »

uh oh mike, 5000 posts!!! nicely done!!!

now reply to my PM, haha, just joking, i wish my carpy had tapered pipes...

paddy paul · « **Reply #9 on:** January 22, 2010, 09:37:44 PM »

Mike and wanna b, what type of taper do you mean? reducing the pipe down to a smaller diameter, or the overall size of the pipe? more info please...

kos · « **Reply #10 on:** January 23, 2010, 08:08:44 AM »

I have an original hand bent pipe form Pop's Y...but cannot let go of it for a few months to let you copy. Why don't you purchase a Yamiya pipe, as I have sold some of those and compared them to my original and they are "spot-on" as far as being correct. In fact they are a bit better, especially in the area of the collector where the four pipes meet. Pop's pipe really sucks in that department compared to today's standards.

Also note: I think after time and research you will find what I have found the three or four times I have entertained the thought of making these. There are a lot of pipe benders, fabricators who will tell you no probelem to make... BUT after actually seeing the pipe...the realize that it cannot be done with today's standard mandrel bending systems out there. There are a constantly changing radius on each of the four head pipes and that is only done by hand. When you get to hand making each separate part....your expenses goes up exponentially until you reach the conclusion I did. Purchases a Yamiya pipe...it is a bargain ant twice the price.

Also, There is a guy who can do this type of hand made stuff, Rob North in San Diego, CA... but when he made my four individual meggas for our M3 CR750 racer I needed to provide a bike with engine in it, as to allow him to flip it upside down so he could fill pipes with the proper type of sand and hand bend each pipe while on the bike. Also, it took over a year to get done and over $2500.00 It was worth it...as it made a sound like no other racing bike out there and we made a lot of impressions all over the world, which has grown my business greatly.

Mark @ M3 Racing

Ricky_Racer · « **Reply #11 on:** January 23, 2010, 09:21:54 AM »

Kos, I've been down this road as well and your comments are spot on. Even finding someone in the US to do small diameter exhaust mandrel bending (let alone hand bending) has been a challange. That's why we ended up in Switzerland for the "MV style" exhaust.

You might want to check with Rob on his schedule. He's in my area, and the last time I spoke with him (its been a while) he was booked for a couple years in advance. In fact, I need to contact him regarding fitting a set of Swarbricks to a Rickman-Honda but I may have to end up using someone else because of Rob's prior committments - and my budgetary limitations.

RR

754 · « **Reply #12 on:** January 23, 2010, 09:25:13 AM »

It is a bit of work to generate a drawing by hand. I was going to trade a yoshi pipe to another member, but was not sure it fit the bike (not 750). So I made a drawing from head to collector, of the inner edge of the curve, and emailed the info. The idea was to redraw it on carbaord or AL sheet, cut along the line, then hold on the bike to check fit.

Anyway, this drawing took me probably close to an hour to make, then I emailed by descriprtion.. and did not yet hear back. What I am trying to say, that it is tricky, to drawup, and for some to redraw.

You could get someone to simply cut templates of inside of curves and mail to you. But I have to ask the question, rather than copy, why not simply make your own design, loosely based along the Yoshi desigh.. which is already out there.?

If you use a set of 3 rolls with proper radius, you should be able to do the changing radius bends, fairly quickly.. a local frame builder uses one on frame tubing all the time..

kos · « **Reply #13 on:** January 23, 2010, 09:34:08 AM »

Rob Norths schedule?

I forgot to add that...he might never get caught up, that is why I waited almost 1 1/2 years to get mine done and I had a customer who would go down and "bug" and "bother" him to get back on the build... almost every other day!

Nice to be wanted.

KOS

PS: And what is sad about this entire situation...Rob is training no one to carry on, when he leaves us. Not an apprentice in sight 'round his shop! Sad.

Ricky_Racer · « **Reply #14 on:** January 23, 2010, 10:00:34 AM »

I agree, Kos, about the potential loss of Rob's knowledge. I even jokingly told him I'd work for him for free, even if it meant just cleaning up (it needs it!) his shop. Unfortunately, I started down this road much too late and with too few developed skills. Rob is brilliant, and his loss would be sad. Hopefully that time is far in the future.

Rob mentioned that he had someone working with him at one time, but the young man didn't have sufficient work ethic for Rob. Wasted opportunity. RR

Ricky_Racer · « **Reply #15 on:** January 23, 2010, 10:05:24 AM »

Anyway, back to the first generation Yoshi... As can be seen from the pic, the difficulty with reproducing the exhaust is the changing radius compound curve. It must be hand bent.

Your suggestion to start from scratch, staying within the capabilities of the mandrel bender/operator is probably a good one. I sure haven't had any luck in reproducing this header the way I wanted to. And the current crop of Yamiya - Carpy - Whomever - headers aren't even close to the original 1st gen, but they are a good repro of the second generation mandrel-bent Yoshi. RR

JLeather · « **Reply #16 on:** January 23, 2010, 04:58:59 PM »

I know a guy who could do it, but his shop's folding up right now. He has a 5-axis CNC mandrel bender. It'll bend a piece of pipe into a variable-radius collapsing spiral. It was like a $300k machine. He used to make ridiculous custom headers and frames and stuff, but like I said he's closed for now.

wannabridin · « **Reply #17 on:** January 23, 2010, 05:56:19 PM »

RR,

that is a beautiful set of downpipes there, but a VERY tough piece to bend regardless of how you do it!

i've put some pics of carpy's 4-1 on here in case you wanted to see some close ups of this pipe paddy, so i hope this can help!

wannabridin · « **Reply #18 on:** January 23, 2010, 05:59:33 PM »

and when i said tapered head, it meant that the radius was changing, preferably from bigger to smaller in order to help increase the velocity of exhaust gasses down pipe and increase the effective scavenging, much the way an expansion chamber on a 2-cycle exhaust pipe helps pull the exhaust gasses away from the cylinder. the restriction in diameter also helps aid in keeping proper backpressure so you don't burn out a valve.

i don't know if this is exactly true or not, but this is what i've gathered from researching and leeching off the boards here and other places...

Ricky_Racer · « **Reply #19 on:** January 23, 2010, 07:11:49 PM »

Quote from: JLeather on January 23, 2010, 04:58:59 PM

I know a guy who could do it, but his shop's folding up right now. He has a 5-axis CNC mandrel bender. It'll bend a piece of pipe into a variable-radius collapsing spiral. It was like a $300k machine. He used to make ridiculous custom headers and frames and stuff, but like I said he's closed for now.

That's too bad, John. That's exactly the level of sophistication needed to repeatedly and consistently produce a design like this. The problem with hand bent pipes, in addition to a dearth of available talent, is one of repeatability.

I really can't believe that no one in the US is filling the demand for vintage Honda (and other brands) pipes. Heck, even if someone made replacement stock header pipes it seems like there'd be plenty of work. But what do I know, anyway!

There are a ton of people around SoCal doing mandrel tube bending, but it seems that none have exhaust mandrels in the smaller diameters. $:-\$ RR

bucky katt · « **Reply #20 on:** January 23, 2010, 07:19:17 PM »

it looks to me the reason there arent more decent exhausts and other parts for our bikes is that there arent enough of em left to make it worthwhile to the manufacturers. they love the harley/cruiser crowd and the plastic sport bike crowd too because theres so damn many of em.

Ricky_Racer · « **Reply #21 on:** January 23, 2010, 07:28:40 PM »

True enough for the large manufacturers, but the small firms (like John's friend) are struggling and there are millions of vintage bikes on the road. Oh well, maybe it's just too much trouble... Anyway, this isn't what the thread is all about and it's all too frustrating so I'm bowing out. L8R! RR

paddy paul · « **Reply #22 on:** January 25, 2010, 12:09:01 PM »

I just can't see dropping 600-700 on set of Yamiya's even if I did have that type of stupid money to throw at my bike, I would rather buy the tools/tooling and make an attempt to do it myself, plus it would be great to say you have a one of a kind exhaust that you hand built. Carpy's pipes look good and they seem like they are priced fair but they are the latter design. I'm going to go ahead and try it.. I of course will keep all posted...

Still need a few measurements off of the Yoshi pipe.. the actual diameter of the pipe and what gauge/thickness that he used, any info would be greatly appreciated... Thanks

Phil · « **Reply #23 on:** January 26, 2010, 10:24:19 AM »

I bought a new 4-1 from Mark at M3. He assured me it was an exact copy (only better engineered) of the genuine Yoshimura pipe that he owns. Isn't this the case Mark? (Phil Clark, Woodbridge, UK).

wannabridin · « **Reply #24 on:** January 26, 2010, 11:18:02 AM »

wow, i wonder how much that cost!! mark makes amazing things, but they come at a price...

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Author Topic: yoshi exhaust (Read 21426 times)