WCM Redbull YZR500 Project

[crxmotorsports]

Hello everyone.

After 3 years of admiring all of your projects and collecting parts to start my own YZR replica bike, I am now beginning to get to work. I wanted to share the journey and welcome all of your experience, knowledge and suggestions to do this the right way. While my NSR250 is fun, I have always wanted to do a 500.

End goal is a John Hopkins replica bike with modern suspension and handling for afternoon rides through Appalachian foothills twisty roads and intermediate level riding ability trackdays. My initial plans were using a 2006 R6 frame as the base since it was simple to source and title in the US and similarity to the YZR. I have followed a few of the R6 builds on here and elsewhere along the way, but noone really had kept good measurements. So, I began mocking up the engine location, but am realizing it is a bit outside of my skillset to fabricate what is required. After several hours on the phone with Steve at Speedwerks who has done many quality 500 conversions, I am at a bit at a crossroads. With the R6 being a frame designed with the engine as a stressed member, he thought it best to explore all options. There have been builds with the engine supported by the base of the upper cylinders, and others with a subframe fabricated and adapted to the R6 frame, the way the engine was supported in the original RZ. My original plan was to go the fabricated subframe adapted to the R6 route to eliminate the original front engine mount interference with the carbs. It would also properly support the engine. What are your opinions for a moderately skilled rider not needing the last few tenths of perfection with continuing using the R6 frame? It may be a bit more flexible than optimal, but for this application does it make sense, or would a more appropriate FZR or 3MA frame be a better build? Finding and titling them in the US was what originally kept me away from those options.

Below are some photos of where I am currently. Let me know if they are not visible, this is the first time I have done a build thread or used google photos hosting. Thanks for your input and suggestions.






End Goal:

[Questo vecchio rz]

These conversions have been done dozens of ways, in various chassis.
There are opinions and some strong opinions regarding different mounting methods, you should search here and read them all to form a opinion of your own. They all have worked, and some with many years of use. There's not one method I personally would recommend, but if I had a choice it would certainly call for a deletion of a cradle. Keep in mind, there are the issues you will read about, I believe some of the the points are valid for sure, but I also believe a solid jib is perfectly acheviable. As far as being flexible..that's wide open to what one considers "flexible" IMO I wouldn't personally want to exceed more movement than what OEM allows.

Basically ,As far as your project looks in photos, "if you can mount it , and everything fits ... and your comfortable...fo it.

If the shoe fits wear it

[Luther]

I'll echo what Questo says. I would want to keep a cradle to a minimum just because. On the other hand for frame strength its best to do the right thing as we are just caretakers of these projects and who knows who will ride it how hard in the future. If the cradles hidden and make the rest of build easier and more functional i'd go that route.
Can you do a side pic and link to R6 builds here your copying

[steveho]

For what it’s worth....
It all depends on what YOU want at the end of the day. In my view, for a YZR500 replica, the R6 frame is not ideal. It is too wide, as it accommodates an inline 4. A 3MA conversion would give a more authentic replica as the narrow frame suits the V4 engine better. I am biased as that is what I am building, but appreciate your issue with titling such a frame in the US.
However, the 3MA frame is not without issue, due to the cutout required in the RH rail and the front biased weight distribution. The R6 route probably gives the best approach to all round chassis performance (modern rake and trail numbers). The issue about frame stiffness with the RD engine mounted is probably not critical, as if you use all 3 engine mounts, you can’t help but triangulate the frame/engine. Tyre choice etc dictates ultimate grip levels anyway.
But, what about stock RD/RZ frame, maybe RZV, with modern front/rear ends with a decent (new) shock? Undoubtedly the easiest route.....

Don’t let me appear negative and put you off the R6 approach. Will be fun to do and produce a great result. I hope John Hopkins will be impressed!

In the end, go with what floats your boat. Have fun & good luck.

[crxmotorsports]

Yes I have read the Suspended VS Cradled thread many times, but there are 2 pages of useful info and 3+ pages of name calling/arguing!

I liked this one aside from the R6 stock mounts completely shrouding the carbs not allowing good intake flow or airboxes to be used.
https://www.rzrd500.com/500phpBB3/viewtopic.php?t=10206

Here is another take with better carb clearance:
https://www.rzrd500.com/500phpBB3/viewt ... =7&t=14949

I am contemplating having him build a nice beefy set of CNC mounts that utilize the cylinder base mounts (with longer studs to accomodate quality mounts) similar to something like this to suspend the engine:




Another option is a partial cradle like was done on this Costin replica frame:



A rear cradle seems doable as well, but as with the 3MA frame, the right side needs recessed and boxed in for the kick start.





I had not noticed how much wider the frame was until it was just pointed out in this thread. I will have to double check the MotoForza YZR fairings I have to see how that will work out. My other issue is finding a tank that has the shape of this generation YZR. I have reached out to Wolfgang about the carbon replica he currently has with my measurements. If anyone has an opinion, let me know. Thanks again for the input.

[Questo vecchio rz]

Hey guys, what would you say to each of you measuring your frames?
I'm curious as to the width, etc... dimensions of the R6 vs the 3Ma frames.
The modern Inline 4 motors are substantially smaller in every way than the bikes of the 90s & early 2000s, particularly the mid 2000s middleweight machines as they were designed as the new predominate sport bike class, once 750s we're deemed irrelevant.
I suspect the width just may not be as great as it's perceived to be ? Guessing the 3Ma is smaller, but just by how much? I'm also thinking the R6 later generation frames are much lighter as well.
Curious to know.

[steveho]

Hey guys, what would you say to each of you measuring your frames?
I'm curious as to the width, etc... dimensions of the R6 vs the 3Ma frames.
The modern Inline 4 motors are substantially smaller in every way than the bikes of the 90s & early 2000s, particularly the mid 2000s middleweight machines as they were designed as the new predominate sport bike class, once 750s we're deemed irrelevant.
I suspect the width just may not be as great as it's perceived to be ? Guessing the 3Ma is smaller, but just by how much? I'm also thinking the R6 later generation frames are much lighter as well.
Curious to know.

Apologies for the radio silence.
Just measured my 3MA frame, and the main spars are parallel and measure 12 1/4” (outside dimension). Also measured my stock RD500 frame and that is around 12 1/8”
I too would be interested to hear of some R6 measurements, but would guess around 4+” wider at the greatest. Anyone?

[crxmotorsports]

The spars are definitely not parallel on the R6.

At the front it measures 70mm inside and 155mm outside (2.75"inside / 6.1" outside)

At the widest point in the middle is is 320mm inside and 385mm outside (12.6"/15.15")

At the rear just in front of the seat subframe mounts it is 255mm inside and 290mm outside (10"/11.4")

[steveho]

Interesting numbers. The stock 3MA tank is wider than the frame, so the R6 frame being wider may not visually look an issue. Bear in mind that the original GP bikes had huge 32 litre tanks, so they may have dominated the visual look. The 3MA frame has to have major surgery to remove the stock engine mounting castings, with a lot of welding in of plates and cradle with the associated heat. So the R6 approach could be the way to go as a more modern approach. Make your decision and go with it! Good luck! Look forward to seeing how it pans out.

[cobraace]

just for comparison my project is a 2005 R1
At the widest inside 13" outside 14 3/4 "
At the rear inside 12" outside 13"

My 1996 NSR250
At the widest inside 10 1/2" outside 12 1/2"
At the rear same I think the R1 is as small as a 100 can get

My GSXR and ZX at widest are over 18" they look huge compared to the R1 or fat

beautiful ethnic girl names

[crxmotorsports]

Anyone on this forum in the UK have contact with Nigel Kimber at NK racing? I sent this frame to him over 3 years ago and all I keep getting when I email is "still working on it". He just keeps blowing me off even with all of the positive work people here have had with him. 3+ years to weld up some mounts seems a bit excessive.

[Smoker]

Sorry to hear your frame is taking so long. My experience with Nigel making one-off titanium parts went well, but it was long ago. He told me ahead of time, he wouldn't be able to start on them for 2 1/2 months, which was accurate.

I would ask Paul rd84 for advice. Not saying he would want to get involved with any dispute, but he's extremely knowledgeable, in the UK, and is still an active member of this site.

Was there ever any time estimate given by Nigel?

One more thing. Edit your post and get rid of the "s" word. Not accurate, and won't help you get your frame done.

[giron]

Here is different approach. How about a TZ250 frame. The reverse cylinder. This bike has the YZR500 swingarm and the gas tank with the RZ500 engine. The TZ250 frame is very close to the YZR500 frame since both frames were measured next to each other.

[crxmotorsports]

Smoker

The frame was sent in the summer of 2020 with an expected completion sometime after the first of the year. Covid happened and delayed a lot of things which I was very understanding of. But since 2022 I've emailed every couple of months asking for an update and every time the response is "still working on it" with expected completions of anywhere from a month to a couple of weeks. This has been going on for over a year now.

[Smoker]

Well, I've been looking forward to seeing your project get built. Not much custom bike action, these days.

I don't really see what kind of help you're looking for, though. If it's not done yet, it's not done.