RZ350 re-frame... classic 2-stroke gets modern upgrade

[Frame Maker]

Those are fantastic! Are they for stock YPVS porting? What peak RPM? It may be an optical illusion but the header / diffuser section seems quite long.
Cheers.

These are good questions which I don't have complete answers for, so I'll try to explain the criteria I gave to Brian...

I few years ago I purchased two sets of pipes from Brian one set was for an RZ350 with stock (unmodified) engine, but significant chassis mods. I also ordered a similar set for a similarly modified chassis, but with an RZ250 engine. The pipes for the RZ250 were slightly shorter and have slightly smaller stinger diameter, otherwise very similar.

The 350 specific pipes have been mounted to my prototype frame with a stock engine (photo below). I've had very little time to fine tune the jetting, but I'm happy with the performance so far. They have LOTS of low to mid-range power which is exactly what I was looking to get for street use. That said, they don't rev as high as other pipes but Brian thinks that will improve with correct jetting.

Fast forward to the current batch of pipes, I had the same requirements for good low to mid-range performance for street riding, but try to improve the top end range a little. Brian and I discussed the goal a bit more and decided to copy the basic geometry of the slightly shorter 250 pipes, but open up the stinger diameter to work with the 350 engine. So that's what you see in the pictures. I have not tried them yet so can't say one way or the other how they work.

I will say that I have numerous sets of pipes that Brian has made and none are similar to the more well known brands of pipes that most people use. For example, he's built a few sets of pipes for my RZ250 and when I asked for a more top end performance. The first set he built will rev strong to well over 11k, maybe higher. It wasn't practical for street use so he re-made them and brought the top end peak down closer to 10K. Still peaky for street use, but that's what I had asked for. He has geometry that he likes to use and I trust his judgment. When I give him a request, he tries to builds to my criteria.

That probably doesn't answer you question very well, but time will reveal how well these new pipes perform.

20220417_163006 by andbike, on Flickr

 

[Frame Maker]

The above conversation got me a bit more curious about Brian's pipes compared to "others". I decided to do a very non-scientific side by side eyeball comparison between several pipes that I have on my shelf. The pipes I compared are as listed...

- SpecII
- Factory Pipe Products
- Wicked
- Moto Carrera (early gen)
- BTRs (Brian's)
- Vanguard (for RD400)

when laid out side by side the SpecIIs, FPPs, Wickeds, and Moto Carrera's were all almost identical (measuring by eyeball). They are all so similar it almost seams like they are just copying each other.

Brian's pipes were in fact and inch or so longer in the head pipe and divergent pipe length. Then Brian's pipes were shorter in the convergent pipe. Total distance from exhaust port to beginning of the stinger ended up being similar. The most noticeable difference between Brian's pipes and the "others" is the mid-pipe diameter. Brian uses a 120mm diameter mid-pipe. The "others" are all around 100mm diameter. This is a drastic difference when looking at the pipes side by side.

The Vanguards are for an RD400 so not really comparing apples to apples, but I was curious since they are known for being a low/mid-range pipe. The head pipe + divergent pipe length is similar to Brian's pipes. The divergent pipe is a few inches longer, so overall length is a few inches longer. Mid-pipe diameter is close to 100mm.

Getting back to the mid-pipe diameter, I've had several conversations with Brian about how "fat" his pipes are. He claims to have done lots of experimenting specifically with the mid-pipe diameter and says 120mm is optimal for good torque on an RZ350. He further explains that "others" don't go that fat because they are designed for use on stock bikes with very limited space. With my frames I specifically made design considerations to allow for maximum pipe diameter and clearance.

Again, this is a very non-scientific comparison. In time I hope to report on how well the BTR pipes perform.

 

[Jung]

Thanks very much for such a comprehensive reply. I have just started rolling my own, so to speak and will be making a set for an RD project soonish. I'm using ported, non-PV Banshee barrels with a 4mm crank. Interestingly enough, using PV ports and timings, I've ended up with quite a bit of variance in the suggested pipe dimensions, particularly the belly section. I'll have to wait until I get the cylinders back so I can make a proper map but at the moment, I reckon I'm going to copy a set of Mick Abbey YPVS pipes I have, but maybe add a little to the diffuser to pull the peak under 10k. They have 110mm belly sections, so split the difference to the ones you have.

Looking forward to hear how yours work out - they are real works of art!

 

[Frame Maker]

Thanks very much for such a comprehensive reply. I have just started rolling my own, so to speak and will be making a set for an RD project soonish. I'm using ported, non-PV Banshee barrels with a 4mm crank. Interestingly enough, using PV ports and timings, I've ended up with quite a bit of variance in the suggested pipe dimensions, particularly the belly section. I'll have to wait until I get the cylinders back so I can make a proper map but at the moment, I reckon I'm going to copy a set of Mick Abbey YPVS pipes I have, but maybe add a little to the diffuser to pull the peak under 10k. They have 110mm belly sections, so split the difference to the ones you have.

Looking forward to hear how yours work out - they are real works of art!

This sounds like an amazing project and worthy of its own build thread. Is there anywhere on the webs where we can follow your progress?

I admittedly had not heard of Mick Abbey. I had to look him up and seams he is doing some impressive work. Since you are considering building your own expansion chambers I'm curious if you've looked into any of the pipe design software programs that are available? I recall Tom Turner had software available that was thought to be fairly good at the time. I see others offered now.

Anyway, would love to see some details on your project. Anything special planned for the chassis?

 

[Jung]

I haven't done a lot to start yet! I'm planning a kind of early TR3 / TZ350 replica, based on a RD350. I probably will do a monoshock swap, using a RD350LC swingarm with an old Ohlins from a Honda Hawk that looks a good fit. Thinking cut down FZR600 forks and yokes for the front end, which seems a popular conversion and they're really cheap. The engine I've had for twenty something years - it's a YPVS but with a TZ350 gearbox and dry clutch. No top end, hence the banshee barrels. Anyway, that's quite enough digression from me.

On the software - I've tried three, two freeware ones that I'll dig out and twostrokewizard, which is relatively cheap download (https://buildandclick.com/)...The only pipes I've built so far, have come from dimensions I've found online. For one of the cylinders I mapped, the overall lengths were about the same across the three programs, but the belly dimensions were wildly fatter on twostrokewizard, to the point fitting them would have presented all sorts of packaging issues. All of them, require certain assumptions about power output / rev ceiling / EGT / BMEP etc. The gold standard for software seems to be EngMod2t (https://vannik.co.za/Contact.htm) - which is a vastly more sophisticated pack that requires a correspondingly much greater set of inputs - it's also $400!

I'm probably going to go with the known dimensions for the first set, though am interested in making a second set off the software predictions. The problem is it takes me blooming ages to make them...

Quick pic of a header coming together for a test pipe I made for a TR500 cylinder. I've only got oxy so they're all 20ga mild steel. Very amateur but I'm getting better....

 

[kpke]

Hi Jung. Cool stuff you are doing and sounds like a wonderful project.

Julian said "This sounds like an amazing project and worthy of its own build thread. Is there anywhere on the webs where we can follow your progress?"

I think he might be implying that you could start a build thread right here on BARF in this forum sub-section. But I'm not very smart so may have misinterpreted his statement.

Would love to see more of what you are doing with your mix of parts!!!

Hi Julian. Hope you are feeling good. arty

 

[Frame Maker]

Julian said "This sounds like an amazing project and worthy of its own build thread. Is there anywhere on the webs where we can follow your progress?"

I think he might be implying that you could start a build thread right here on BARF in this forum sub-section. But I'm not very smart so may have misinterpreted his statement.

Ken, I think you have a very promising career as an interpreterarty

Jung, Yes, please feel free to begin a build thread here on BARF. I think there are a few 2-stroke enthusiasts lurking who'd be interested in following your project.

 

[Frame Maker]

Its probably time for another update, but first want to say...
Happy Thanksgiving to everyone!

As some of you have seen in my post on the general sub-forum, I got a bit distracted last weekend with the purchase of a Tigcraft RZ350. I am still amazed by the awesome bike and the similarities with my RZ project. With tape measure in hand, they aren't exactly the same but still similar enough to make me think that Dave Pearce and I had similar ideas of what a good chassis should be. It will likely get its own build thread in the near future.

20221120_154520 by andbike, on Flickr

Meanwhile I've been slowly making progress on the clay model of the tail for my RZ chassis. Today I took the clay mock up and mounted it to the bike to get a better look. Here's some pics and short 20sec walk around. Obviously left and right sides are different. That is intentional as it allows for two concepts to be explored at the same time.

20221124_144906 by andbike, on Flickr

20221124_144853 by andbike, on Flickr

20221124_144915 by andbike, on Flickr

20221124_144941 by andbike, on Flickr

20221124_144953 by andbike, on Flickr

20221124_145000 by andbike, on Flickr

20221124_145014 by andbike, on Flickr

20221124_145021 by andbike, on Flickr

20221124_145033 by andbike, on Flickr

20221124_145044 by andbike, on Flickr


(click on image to open video in Flickr)

20221124_145113 by andbike, on Flickr

So now that you've see the photos and hopefully the short walk around, here's my BARF survey questions...

A- which side do you like better?

B- which side do you think looks best with the R6 tank?

C- which side do you think best represents what Yamaha would do?

D- which side do you think looks the most contemporary?

Feel free to add comments along with your replies. For example if you like one side much more than the other, or perhaps you like them equally with one side only slightly more. Or maybe you think both side need much more work and aren't doing anything for you. I'd like to hear all of your comments. Good and bad.

Thanks!

 

[budman]

I like the left.

C & D being the biggest factor.

 

[kpke]

Beautiful work sir. But it is a difficult decision as both sides are wonderful.

I am going with the left side. I could do without the winglet on the right.

Using my best CAD skills, I like this flow.

 

[Lonster]

A- which side do you like better?

B- which side do you think looks best with the R6 tank?

C- which side do you think best represents what Yamaha would do?

D- which side do you think looks the most contemporary?

Great work and pics again Julian. Keep 'em coming.

I like the right side better, but I think the left side goes better with the tank.
The Left side fills the C and D quota.
The last thing I want to do is create more work for you, but since you asked: I would love to see a smaller, more modern take on the tail. Less of a focal point and more of a diminishing detail (starts small and goes to an even smaller termination).
I think that both the Left and Right give a large, early 2000's feel, but the bike has a custom feel from the forks to the custom frame and attachments.
Going with your thread title: "RZ350 re-frame... classic 2-stroke gets modern upgrade", what do you think?
Maybe not this small or this style, but here's a quick and dirty chop as a look.

 

[Pushrod]

(Wife): "What are you looking at so intently?"

(Me): "Porn."

(Wife): "Don't you dare close your laptop. I demand to see what you have going on ! ! !"

(Wife): Whacks the back of my head with her magazine after looking at two stroke wonderfulness. "I'll never understand you."

 

[Jung]

Fantastic. I prefer the first image (the left hand side when viewed from the rear.) Looks better with the tank.

The Tigcraft is super cool - they're can't be too many of those in the US. Dave Pearce has made some amazing bikes.

What a pair!

 

[Frame Maker]

Thanks everyone for the feed back. I am also leaning toward the left side, so its nice having some confirmation on this direction.

 

[Frame Maker]

I like the right side better, but I think the left side goes better with the tank.
I would love to see a smaller, more modern take on the tail. Less of a focal point and more of a diminishing detail (starts small and goes to an even smaller termination).
I think that both the Left and Right give a large, early 2000's feel, but the bike has a custom feel from the forks to the custom frame and attachments.
Going with your thread title: "RZ350 re-frame... classic 2-stroke gets modern upgrade", what do you think?
Maybe not this small or this style, but here's a quick and dirty chop as a look.

Point well taken on overall size But looking at your photoshop image its difficult to see the form... or are you simply just emphasizing the smaller overall volume?

 

[Frame Maker]

(Wife): "What are you looking at so intently?"

(Me): "Porn."

(Wife): "Don't you dare close your laptop. I demand to see what you have going on ! ! !"

(Wife): Whacks the back of my head with her magazine after looking at two stroke wonderfulness. "I'll never understand you."

This made my day!

 

[Frame Maker]

Fantastic. I prefer the first image (the left hand side when viewed from the rear.) Looks better with the tank.

The Tigcraft is super cool - they're can't be too many of those in the US. Dave Pearce has made some amazing bikes.

What a pair!

Thanks!

 

[Lonster]

Point well taken on overall size But looking at your photoshop image its difficult to see the form... or are you simply just emphasizing the smaller overall volume?

Yes. It's just a grab from a new Aprilia Tuono.

 

[budman]

This made my day!

I loved it too.

 

[Frame Maker]

This weekend more progress was made on modeling of the tail. Specifically I worked on the left side. I agree with Lonster's comments that both tail concepts look a bit large.

With the left side, I did make it a little smaller by mostly removing material from the sides and and bottom. I also shifted the mass forward by 3 inches. I think this was exactly what was needed. It still has the same height, but looks more compact and better proportioned to the bike. What do you guys think? Was this the right direction?

At this point I'm probably going to scan the left side (even in this rough form) then continue to refine in CAD.




Here's the re-worked clay from Saturday...

20221204_125952 by andbike, on Flickr

20221204_125940 by andbike, on Flickr

20221204_130033 by andbike, on Flickr




I've also added a "bone line" to the lower side as seen in this photo. The additional line helps break up the visual mass. It also adds a design element that I think helps tie in with the tank (which has many design "lines").

20221204_130045 by andbike, on Flickr




Click on this image to link 12sec video:

20221204_124758 by andbike, on Flickr




Am I going in the right direction with this exploration