Pasis Yamaha RZ 350 YPVS

[Pasis]

Hi all!
My name is Alexander, and I recently fulfilled my dream which is already 20 years old!).
By a miraculous coincidence, I managed to buy a Yamaha rz 350 83-84 + donor rz 250r. These motorcycles from the Japanese market came to our country, as I understand it, about 20 years ago. Around the same time, I was trying to find one, but in our country it is a very rare motorcycle, and then I could not do it. Later, I occasionally came across them in ads, but usually it was a set of problems, and then I got carried away with four-stroke engines and installing turbos on them).

In recent years, I've gotten a little fed up with sportbikes and racing and turned my attention more to hard enduro, and this year I bought a Sherco 300 2t motorcycle. For the first 10 moto hours, I was overcome by doubts whether I did the right thing, and whether it was better to buy a 4t model. But after the first trip to the mountains, I realized that this is what I need! And the more I rode it, the more I got high from it. To be fair, I'll say that I haven't ridden 2t bikes in over 20 years and they were old bikes. I rode MX Japanese 2t motorcycles a couple of times, but that was also about 15 years ago.

And then I again got the idea to buy a 2t road motorcycle to try what it is, and use it as a weekend motorcycle for driving on the roads outside the city.
I was looking for several models such as TDR 250, R1-Z, and RD\RZ 250-350. All these motorcycles are quite rare in our country, but by a happy coincidence, I found a RZ 350 while traveling around the country, with one of my friends. It turns out that he bought it for himself to restore, and this time he showed it to me when I stopped by to visit him. And now, a few months later, he offered me to buy it from him, and I could not refuse).

In general, the condition of the motorcycle is below average. Some parts are missing, some parts are damaged.
So now I'm kind of confused as to which way to go next. Initially, I had the idea to restore it to the standard form, and ride the way they rode in the 80s ... And then start making modifications.
But after studying the condition in more detail, I realized that it might make sense to skip the first stage and immediately start with the second. Since some parts, such as the front fork, the engine is damaged. And in general, the suspension, brakes and wheels from the early 80s are far from my desires for the handling of a motorcycle.

I will describe what I got.
The 350 engine has destroyed 31K cylinders, apparently someone tried to adapt them to pistons from another motorcycle. The YPVS (in cylinders) from the 350 engine is also lost.
The head is also damaged.
No exhaust pipes for 350
The front suspension pipes have many defects. True, I have a second fork from 250, but it is not much different.
It also seems that I do not have CDI from 350 and even 250.
The back light is broken.

But I have 4 engines, one of them is 29k and three of them are 29L. Three of them have defects with cylinders. But there is a set of 51l cylinders that is not bad at first glance. And exhaust pipes for 51l.

Now I have such a concept in my head. The motorcycle should have a classic appearance. I want to replace the suspension and brakes with more modern ones, for example, rgv 250 or GSXR 600 srad or k1 or R6. Wheels 17 inches, rear no more than 150-160mm.

As for the engine, the question is more complex. I want to get an engine that can be driven comfortably enough outside the city. Not for racing. I think 70rwhp will be enough for me.
And here I have several options, as I understand it. Or try to find 31k cylinders and bore them for new pistons or I can immediately buy new cylinders from a banshee, for pistons 392-421. As well as a +4mm crankshaft, and new exhaust pipes, carburetors, V-Force 4 valves, and ignition, as well as other necessary parts.

I understand that a YPVS engine looks more attractive for my purposes, but my guess is that the banshee 421 cylinders should negate the lack of an YPVS system, and I can get a nice-to-drive engine. Maybe I'm wrong, and I'll be glad to hear advice. I am new to the topic of these RZ motorcycles, and have been studying this and other forums for several weeks in search of interesting questions.

Thank you!

[kpke]

That looks like a nice bike to start with and a good pile of extra parts. Way to go. It sounds like you have done quite a bit of research on what to do with this RZ. You have some excellent ideas. Continue this build thread on this forum and you will get a lot of support and feedback. Spend a little time here reading what others have done would be helpful also.

I have several motorcycles but my favorite one to ride is a hot rodded RZ350 on mountain roads. They can be a tremendous amount of fun.

[Pasis]

Thank you! Yes, I am now spending my free time studying this useful forum.
I also subscribed to your channel, it's quite interesting!

[kpke]

I also subscribed to your channel, it's quite interesting!

Thanks Pasis

[tacky1]

Looks like a great project to start with, Lots of spares, so hopefully you can get a full runner out of the lot :)

[JonW]

Thats a great project. It sounds to me like its going to need at least the engine sorting out and maybe some suspension work.

Its great that youve done much digging and reading around the bikes and the options before you posted, that great and shows that you obviously know bikes and have been interested in these for years. Youre one of us! And... Youre in good hands on the forums with these bikes, people are very knowledgeable and helpful.

As you say you either need to restore or mod it, but its not going to be reliable or much fun if you just do some of the work, it sounds like youre going to have to do the whole thing and do it properly to get a usable bike.

Youve not said what carbs you have... i dont see any... I'll assume no carbs... my thoughts:

- If you can rebore the 31Ks then you need PVs (250 dont fit), you can buy new billet ones in the UK or used ones, plus exhausts (the 51L wont rev out) and a CDI. And... you need 1UA or 31K carbs really... or PWK28s... those are the ones most people use.

- If you go Athena or other big bore you will need those cyls plus exhausts (slip fit, not bolt on) and carbs and an ignitech or zeeltronic ignition.

- if you go 51L you'll need 51L-50 CDI if you want the correct one (else get a zeel/iggy) and 1GA carbs (or the linked JDM ones, 1GAs are more plentiful(?) and easier to tune i think). You can use the 29L PVs if you have lots of them as they are the same as 51L.

So... that said:

- The 51L is a great engine and will make 50bhp and revs really nicely, some say it is more powerful than a 350, but then not all 350s run their full bhp so it can be faster etc. It'll work with your pipes so is probably the best value to get running as you have most of the bits?

- You step up another 8ish bhp if you go 350 with the 31Ks, but will need pipes (cheap ones are out there if you shop round, like K2TEC) and you can find a 52Y-50 and convert the bike to that CDI, else run a zeel/iggy. Any used 29L CDI is usually broken, dont bother with it.

- Big bore... you can spend what you like on this build but get 75-100 RWHP... I wrote a big bore primer once on my site, it highlighted that at the time it was often a cheaper way than a 350 rebuild, but... maybe times have changed. Big bore wasnt cheap for me... carbs, CDI, pipes, rad, uprated oil pump, filters and the list goes on...

So... yeah... I have built all these variations and some. 350 is easy to use anywhere and lots of parts out there worldwide... but... as many on here know I really like the 51L 250 for its cool technology with the boyesen port (the only RD/RZ ever licenced to have it), its rarity (JDM and ADM only as far as i can tell and 2yrs only), revvy nature (the 350 crank is weighted for 250 pistons) and its good in the city... whereas my Athena 421 is much better out of town on less crowded roads. I have plans to build another 51L to partner what i call my '251LC', but rather than in an LC this one will be in a late model RZ frame in a JDM way... if i ever get round to all my projects. :)

You can still read some of my info about those builds on here, rdlccrazy and also on the stored pages of my old 2smoked website on the wayback machine.

HTH

[Pasis]

Thanks for the detailed answer.
As for the carburetors, I have 3 sets of mikuni, it looks like they are standard carburetors, although my measurements showed that they have a cone diameter of 27mm, not 26.
I can buy other carburetors, for example smart carb 28. I even had thoughts about efi.
I have a set of cylinders and a 31K head, but they can be said to be destroyed. I will attach a photo.
There is also a set of cylinders 29l and two sets of 51l. One of the 51l looks good, the rest may need boring, I need to take measurements. Assembling a 51l engine looks tempting, it will probably be easier and cheaper, but still I want to get an engine with a volume of 350-420. It might be a good idea to build two engines.
As for the exhaust pipes, yes I have for 51l set, at first glance they are not so bad in condition, except for the mufflers, they have damage from falls. True, I do not know the condition of these pipes inside, I suspect that there will be a lot of carbon deposits that will need to be removed somehow.

I should probably look for dyno graphs for a 350 engine with ypvs and a banshee, as well as a 421 with about 70hp, to evaluate the performance of the ypvs system. Also, I would like to ask if there are any problems with overheating of the exhaust port area on cylinders with ypvs? As I see that water access to this area is very limited.
It would probably be ideal to make a 400-420 engine with a PV system. I think I have even seen aftermarket cylinders with a PV system that runs on vacuum.

[JonW]

what do the seperate carbs have as codes on the side panels? I cant really make them out, 4L3 perhaps on the one with the correct side showing? linked ones are 51L maybe?

The 31Ks look pretty trashed :(

If i was you I would assume all cylinders would need to be rebored at the very least, thats standard with 2 strokes. rarely can you just fit another new piston and go again when you buy a box of spares.

The YPVS is very reliable, I wouldnt worry about it. Yamaha made these 35+ years ago and they still run well.

My advice: I would start with one single engine project and get that working, do the cheapest and quickest unless you are rich and have lots of time to play. When youve got that running and the bike is usable you might branch out and make a more powerful engine. The work you put into the bike remains when you make and fit another engine. Nothing about a full rebuild is cheap or quick sadly. Do it once and do it right though and you'll have a great base for other power options later.

[(F5)]

Well I'd have to agree that is sound advise. So many bikes get stalled for overambitious scope.

2 strokes that get left in un ideal conditions get micro rust on the rods that will trash the crank. Looking at the other parts I'd kind of expect that.

So maybe an aftermarket, perhaps +4mm crank, rebuild new bore, clean up parts an some pwk28 carbs that perk things up nicely and can be found new listed for kx85. Your biggest cost will be pipes. That will see you near 70hp with right pipes anyway.

[Pasis]

29k is written on two carburetors, and 29l on the second pair, apparently these are sets from 350 and 250.

The only relatively cheap way to get this bike to ride is to build a 250 engine. But as you mention above, I will most likely still need to buy new pistons and bore cylinders, and may also need to repair or change the crankshaft.
Therefore ... the question arises of the expediency of working on the 250 engine. Especially since my dream was more connected with the volume of 350). I can spend $3-4k on the engine, pipes, carburetors, ignition to make an efficient and balanced power plant. But I have no experience with similar motorcycles, so I study configurations.
For me, at the moment, the biggest question is whether to go the way of the engine with YPVS or go the way of the cylinder banshee.

On the other hand, you are also right, and more than once I fell into a tuning hole, from which it is not always possible to get out successfully and quickly. After all, in addition to the engine, I need to pay attention and funds to the chassis, suspension, painting and other little things. To have a beautiful and balanced motorcycle. And given that I have other projects, this may be delayed for various reasons).

By the way, can you tell me where I can buy new chrome tubes for my '83 front suspension?
I also have the front suspension from the 250, it seems to be in better condition, but I don't have a second brake caliper and front fender for it. I have attached a photo of the bike with the fork as I have it. Is it any better than the one that is installed on my motorcycle?

[Pasis]

I also had a question, if I look for cylinders and head for 350, is there any difference between cylinders 29k, 31k, 1UA, 48H? Which of them would be preferred?

[JonW]

I also had a question, if I look for cylinders and head for 350, is there any difference between cylinders 29k, 31k, 1UA, 48H? Which of them would be preferred?

There are differences, but to be honest they are close enough that it wouldnt be a big deal.

[JonW]

>29k is written on two carburetors, and 29l on the second pair, apparently these are sets from 350 and 250.

29K is a linked 350 carb, 29L is an 83/4 250 carb

>The only relatively cheap way to get this bike to ride is to build a 250 engine. But as you mention above, I will most likely still need to buy new pistons and bore cylinders, and may also need to repair or change the crankshaft.
Therefore ... the question arises of the expediency of working on the 250 engine. Especially since my dream was more connected with the volume of 350). I can spend $3-4k on the engine, pipes, carburetors, ignition to make an efficient and balanced power plant. But I have no experience with similar motorcycles, so I study configurations.
For me, at the moment, the biggest question is whether to go the way of the engine with YPVS or go the way of the cylinder banshee.

I agree, its hard to know what to do. You should read as many threads as possible and work out what is right for you. The YPVS is more liveable, the banshee style is more powerful but the PVs were made for a reason. Buying PV banshee cylinders is a very expensive way forwards, as opposed to the 250 stuff you have. With that in mind, what i can say is that the cheapest will be to build your 51Ls. you only need pistons and a rebore and a crank. Everything else needs more more and that means more money.

However, I did write an article on my old website that talked about big bore engines in the mid 2010s. Sure things have changed, not least the prices. But, for a newbie there is much to be gained from reading it i think. You might find a better formatted version on the wayback machine than this, but this is what i found:
https://web.archive.org/web/20150310180 ... rimer.html

>On the other hand, you are also right, and more than once I fell into a tuning hole, from which it is not always possible to get out successfully and quickly. After all, in addition to the engine, I need to pay attention and funds to the chassis, suspension, painting and other little things. To have a beautiful and balanced motorcycle. And given that I have other projects, this may be delayed for various reasons).

Yeah, weve all been there. We have a saying that is 'to bite off more than you can chew'. I have a bunch of unfinished projects and a bunch of projects to do... they all require money and time. I only have so much of those commodities to go round. Thats why i advocate to build the chassis and get an engine in it and then run it and decide what you want to to do. If you want to tune and 'go big' then thats great but it will take longer, cost more and also there will be hassles and setbacks along the way as you wont have so many people (or a manual) to help you.

>By the way, can you tell me where I can buy new chrome tubes for my '83 front suspension?

Lots of sellers... ebay, yambits, rdlccrazy, webike etc... I would try to buy Japanese or European quality and not chinese. 83 has a 'waisted stem' at the top, but you dont need to buy that if you dont care about originality.

>I also have the front suspension from the 250, it seems to be in better condition, but I don't have a second brake caliper and front fender for it. I have attached a photo of the bike with the fork as I have it. Is it any better than the one that is installed on my motorcycle?

These are better forks, but they are not as tall, you can use the 83/4 legs with these bottoms to fix that - others have done that on here and the info is worth seeking out.
They have better brakes, you just need a caliper... or even better (if fitting a big engine) get some Triumph/Nissan calipers as there are some with the 83mm spacing.
This is any article i wrote on this, maybe you can find one with the photos out there? if you do please report that back so others can see it as people still like that info.
https://web.archive.org/web/20150310180 ... ipers.html

BTW The 250 and 350 is the same in RZ for the forks.

I can never say this enough and have said it for years... I know its not what people want to do, they are excited and what to start the project but... I really think the best thing you can do is to read as much as you can before you settle on a plan and start to spend money.

In the meantime start with the chassis. There is a lot of work to do there, plus you dont yet know how hard getting parts will be I fear. parts supply has repaidly decreased the past few years with all those Covid builds...

You will also quickly find that this is also one of those areas that you can go standard or start to modify. When you read around you'll find that many of us have felt that Yamaha's <60bhp at the crank was best transmitted to the road via the parts Yamaha intended, but others found more modern motorcycles to use parts from... with varying degrees of success and of course, different compromises. Plus, what was cheap in 2010 isnt cheap now... eg. RGV parts. So you may need a new plan if wanting to go that route for financial sense if nothing else.

I will say this... with 100bhp I would not want the 83/4 forks and those OEM brakes... but maybe thats just me... however, if you build a 250 with the later fork bottoms and the Triumph calipers you will probably be happy... probably. Bear in mind what happens to thin forks when you fit big brakes tho... then you wonder about newer forks...

And... the OEM wheels are heavy... and so the spending and the decisions go on.

Plus, there are so many cool parts available now just for the chassis. There are some lovely rearsets you can buy etc. Or maybe what you want is an RS250 roller and stuff a big banshee motor in that... like the old TSS500, lets not go there...

My point is that in 2023 the parts supply for the RZ is hard anywhere but where you live its perhaps even harder? I just dont know... But maybe there are lots of another bike you can use for forks and brakes and swingarm and wheels? I just dont know what it is.

Also worth bearing in mind is to work out what youre actually trying to achieve. Maybe you can build something to rival a CBR600 on a certain road... but I really think that it will cost more and never be as reliable. And while the CBR is just a fridge of a machine and lacks the 2 stroke soul, its been said here a lot (usually by bare of course) but if its a CBR that you want, then you should really cut your losses and buy one of those - you'll save a lot of time and money etc.

Jokes aside, Im not being 'funny', just being sensible and a realist. This is an 80s 2 stroke. It wont be reliable if you tune it (sorry but it really wont) and it wont have the suspension and brakes to keep up with the modern bikes... unless you modify it. If you do that then you'll never have the budget and RnD team that the manufacturers had for the last 35 years, its just you, some spanners and the internet...

Ok, im trivialising it, but just be aware of what youre trying to build is what im saying. Will it be fun to build and own? yes. Will be a nightmare to build and own? yeah... Has this stopped all of us doing it (often more than once)? Nah... Welcome to the rollercoaster. #2strokeLife :)

[MK]

Concerning the ignition I'd recommend to switch to a programmable DC CDI anyway. Why? Because it works with any combination of rotor/stator, replaces the CDI and PV controller at once and adds some decent performance with an invest of some 300 Eur.

Check out the electronics chapter of my RD500 manual for details: https://www.rd350lc.de/downloads/MK-Dok ... Seiten.pdf
I do have a German and English language 350 version available for purchase. Feel free to ask anyone around here, if that's a good investment.

The RD350YPVS maintenence manual in German language can be downloaded here https://www.rd350lc.de/downloads/MK-Dok ... Seiten.pdf

My 0.02 $ on your endeavor.
You carefully avoided to mention where you're from. That's unusual and would point to being a currently "unpopular" region. Your bike list let's me guess it's Russia. (I don't care anyway)

Assuming RD parts are hard to get and maybe expensive and considering your budget, then the "full build" with a 421cc Cheetah cub or whatever will be difficult. Plus the reliability significantly goes down the drain, the more performance you add.

For your budget, I'd recommend a decent suspension with 17 inch rims and an engine overhaul. If the crank is required a hot rod or trinity +4 crank is a good choice.
If it's hard to get the YPVS parts: Alibaba offers quite cheap Banshee cylinders that fit the RD crankcase. But those need to be ported and equipped with decent pistons. An Athena cylinder kit may also be in the affordable range (also needs additional work and has no PV)

You can build a decent pair of pipes on your own. Check this out
https://www.rd350lc.de/downloads/MK-Dok ... glisch.pdf
If you need dxf's for laser cutting the parts, check here:
https://www.rd350lc.de/downloads/MK-Dok ... thread.zip

[Pasis]

Thanks for the detailed answer, you give a lot of useful information!
I read your articles, they were really helpful, sorry the site is no longer working.
Actually, at the moment I'm interested in the config that Wicked uses on his bikes. This is a +5 mm crankshaft (is it possible to use it on a standard crankcase?) and pistons from a yamaha blaster. As I understand it, this option makes it possible to get about 400-410cc. However, I don't fully understand why they don't use the usual +4mm and 68mm pistons (thickness of the sleeve becomes too thin? And also from changing the required height of the ports in the cylinder for the crankshaft + 4-5mm?). I was also surprised by the fact that they use pvk 39 carburetors on their motorcycles. It looks like too big carburetors for such an engine.

Yes, I noticed that it became more difficult to find parts from rgv. This was not uncommon before.
By the way, maybe you remember, is the length of the rgv pendulum the same as the standard one or is it longer?
I am also considering other options for upgrading the chassis. But I want to keep the recognizable appearance of this model, in terms of design.

Yes, I absolutely agree with you and understand what kind of motorcycle it is. I don't need сbr). If I needed it, I would buy it. I do not have a goal to compete with someone and set records on this motorcycle, for this I have other motorcycles. For now, the goal is to make a weekend bike so I can ride around the city and enjoy the two-stroke engine, but the bike must have good handling.