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Probably a direct swap...

I'd say this is the prototype. Hopefully the production model (though limited) is a bit more finished looking.

 If typical they are looking to sell them all first to get the money to actually build 24. Do they even have tooling? It's got to be $150k+. ~$3.6m total. Pay now. Ride later. Unless we go out of business before you get yours. It's a one-off custom at this point. Selling a dream...

IR8D8R

Yeah, I wondered about the mono shock mount part. The RZ has dogbones.

I have a 120/80 rear tire on now and I don't care to go any wider. I'd just like to have less than a RCH clearance between the tire and swingarm. I ground the gussets and used an extra link in the chain but the adjusters are all the way out. About 3.5-4mm clearance on either side. 2.75" rim.

The pic Uwe posted does not look like an RZ. Unless the axle tabs were cut off. Hard to tell since it's so nicely finished. The one I posted as an LC looks more like it...  I think I found the answer (photo).

I guess you always have to take what AI says with a grain of salt. Same with internet searches and things sellers post. My discussion with AI had a number of flaws that I recognized. Having never spent much time with either RZ or LC I didn't know the difference. I wasn't really aware they were such different motorcycles. Beyond the YPVS system, rear drum and styling. Why did they go back to a drum brake anyway?
 I can get an RZ swingarm for $130. Cheapest aftermarket is ~$850. Steel is fine. I can save the most weight by losing 40 lbs. Seems there are a lot of improperly done arms out there bases on Mark's comment about shock placement.
 There doesn't seem to be a definitive answer as to what the best swap candidate is. We've had various threads without a conclusion.
 I really don't want an RD400+1", which seems to be the most common choice available as far as Motolanna and SR aftermarket pieces. I don't want to change to a rear disc so I'd have to modify a 400 arm anyway for the 350 brake stay. Which I've also strongly considered. That is more of a "sideways" move. Like everyone else, I'd love to find a DG swingarm for a 350 for a reasonable price.
 Thanks for the input guys. The more ideas the better.

IR8D8R

 Stresa posted a photo in this thread of a swingarm captioned as a RD350 YPVS a while back.
https://www.2strokeworld.net/forum/index.php?topic=4031.

 It looks like a RD350LC arm. Doing some rabbit-hole research, I see that the watercooled to aircooled swingarm swap is not uncommon. Requires some cutting and welding to convert to twin shocks and clean up/patch some unnecessary things.

 I didn't realize that the LC and RZ swingarms were so different having never compared them side by side. Which is a better swap candidate? Main goal is additional tire clearance. Anyone have experience with the subject?

Thanks!
IR8D8R

The Veloce Aperion X-8 1000cc 280 hp.

https://www.bikebound.com/2026/06/25/veloce-aperion/

If you can afford to buy one of the planned 24...
 
IR8D8R

Cognito Moto has RD400 conversion stems for various front ends. ...triple trees etc. Seems to be a primary focus for them along with hub conversions.

A bit pricey IMO, but billet parts usually are. 350/400 steering head dimensions are the same so the stems should be interchangeable. From my limited discussions with them they have the information to match basically any stem/tree or hub combination for custom orders and a flat rate custom stem price.

https://cognitomoto.com/search?q=Yamaha+RD+400+fork+conversion+parts&options%5Bprefix%5D=last.

IR8D8R

There should be a website up to apply for tariff refunds.
https://www.cbp.gov/trade/programs-administration/trade-remedies/ieepa-duty-refunds.

IR8D8R

Does anyone have the VM28-418 flat slides on an RD350?

I got a pair for a good price.
 Supposedly these are a replacement for the OEM VM28. I don't know why they use the VM designation on these or if/how they differ from a TM28.

What emulsion tube and needles should I use?

Is there a particular air jet size? I have the Dave F mod on my stock carbs so I presume the jetting will be different.

The bike has a PD/Vape, FPP chambers, Chuck Q. Harry Barlow boost bottle on RZ manifolds, YZ 125 fiber petals on stock reeds, and stock port timing.

Spec on these say the spigots are 33 mm. Stock is 32? Any problems mounting?

Will these use the stock throttle cables or do I need to buy new cables? No oil pump. I was considering a Domino dual-cable throttle.

Thanks!

IR8D8R

Looks like zinc or solder. Is it soft? I wonder if they seal the seams with something?

$300. Pipe spotters. What make are they?

https://www.ebay.com/itm/147168685842?

Vintage for sure. Get a tetanus shot.

Not mine etc...

IR8D8R

  I swear I will never complain about RD throttle cable splitters again...

I picked up a Chinese Vevor Foredom knockoff flex-shaft grinder and a right angle attachment on Amazon for ~$150. That's really the setup you want for port grinding cylinders. Dremels don't have enough power. I've used air die grinders on cast iron ports and they're so noisy and really require a big compressor tank and 2 cylinder compressor head. My 20 Gallon 5hp Sears compressor won't keep up so I have 2 compressors feeding the same air line. Super noisy with all that running in my shop.

A real Foredom is almost $300 without the right angle handpiece which is almost as much as the tool. I'm pretty happy with the Vevor even though I'm not fond of sending my money to China. My only complaint is that the foot switch is not variable speed. Just on/off.

IR8D8R

Reciprocal tariffs are painful too. I just had to pay $4000 customs on a 10 year old $20k instrument that will be returned to the U.S. after it's used to calibrate equipment in Africa. It's a free-for-all.

Hope U.S. customs doesn't hit me on the way back. Pretty sure they will.

IR8D8R

Not any different here in the greater Knoxville area. I think there are 4 HD dealers here?

Smoky Mountain HD is more gift shop, nightclub, and attraction than a dealership. The Gatlinburg of motorcycle dealers. Just 'glide baggers though. No choppers or customs to speak of.

IR8D8R

I haven't been on Facebook in about 10 years but had to access because I got a notice that someone had accessed my old account. Facebook marketplace seems about as high quality as Craigslist used to be.

So likely to have been put together out of bitsa? What would a reasonable price for this be if everything posted here is true (I have no doubt it is). Just curious.

Do LC cylinders fit these engine cases?

IR8D8R