[SnS_12]

Last hurrah

With just a day left to draw the curtains on 2024, we are now closer than ever on firing up the RZ. Since, my friend Tony was rebuilding the crank himself we didn’t rush through the process and fitted back everything together only when we were 100% sure. Now, the bottom part of the engine is done and only the blocks and pistons will need some shaper work before they are fitted on. So, now the engine has all new oil seals and bearings and good we opened the engine as there was dirt particles which could only be accessed after opening the engine. The clutch plates were replaced as well along with the new springs I had sourced from Yambits. The pressure plates unfortunately are not of the correct size for some reason so were not fitted on, but the ones on the bike are in good shape so we are good on that. Also, the new clutch worm kit would go on too before the magnet cover is fitted on.

This build has turned out to be a mammoth one and I prefer posting regular updates than writing down the whole build thread post completion as it would mean I could possibly end up missing out on a lot of small details/updates with the timelines involved and the amount of photos one would have to sort out at the end of it. There aren’t many early Yamaha RZ 350 in India and certainly none as comprehensively rebuilt and documented like BLA (thinking of calling it by its registration identity) so updating has been an absolute pleasure

Now, for some pictures…

New bearings and Long branded connecting rods



Four crank bearings in total. Two on each side of labyrinth seal and one each end of the crank webs



The internals are now nice and clean



Installed after proper truing and now ready for action



Top portion of the crankcase along with the block and head



From left the kick gear and shaft, clutch bell and primary gear



Top view



Bottom portion of the casing..



Crank opening coveted up to prevent dust from entering



Clutch cover with the water pump



New clutch springs bolted down



New clutch plates



New water pump pipe



Up close





Top view with the O ring



New studs. 20 in total



All set to unleash hell at 10k+ rpm

[SnS_12]

Expect the unexpected

The engine on the RZ is one thing we were not going to touch from day one and this was supposed to be more off a cosmetic rebuild than a mechanical and though the engine would have run in the condition it was in I for sure wouldn’t have a sound sleep especially after seeing the state of the right piston. This bike was last owned by a passionate collector and the surprises we have come across in the last few months is something you don’t expect from a bike like this and especially when it was part of such a collection. So, in the end it’s not just the owner but the mechanic who has done the work on the bike that equally matters.

Coming to the engine the progress in the last week has been slow as I had mentioned the blocks require shappering especially to remove the rough and sharp edges around the ports. That, work is yet to be completed and then we wound out the blocks and head needed lapping as well as the surface was not even thanks to the previous mechanic who had manually tightened the head and block and not as per factory torque specifications. Small details like this is what defines a good and proper rebuild. And, since this is a liquid cooled engine and unevenness in the head can lead to the coolant entering the compression chamber and we can say goodbye to the engine. Also, the woodruff key has had its fair share of contributions to the issues we have faced with this engine. Whoever, last put this engine together had cut the woodruff key and that had created a groove on the magnet which was holding it from coming out and that is what led us to ultimately cut the inner holder of the magnet. Further, while installing the new magnet the replacement woodruff key that I got from Yambits was bigger in dimension and had to shaped to size to fit in correctly and that process took an entire day.

So, as we tackle and resolve one issue at a time , we can just pray that we don’t encounter any further surprises and we can fire the engine asap..

Pictures of small but significant work done while we wait for the engine to be assembled back…

Lapping of the head. Done over a piece of plain glass as it has a uniform surface with water and abrasive material. A slow and tiring process but much required



The head surface was quite uneven and required the most effort.



You can see the centre portion still doesn’t have the smooth surface like the other portion of the head. So, a few more lapping sessions are required.



Trying my hand on lapping the block, which got done quickly



Now to finish the shaper work



The face of the blocks are now even



The minute edges near the water jackets will be sealed by the gasket



New brake lever and master cylinder top cap. The OE one with kanji lettering will be sent for sandblasting along with my 125 parts and later for powder coating. So, till then this one will do its duty



The bottom portion has been painted as well



There was a tape covering the lens, which now has been removed.



New clutch lever



Old will be sent for sandblasting as well followed by powder coating.



The seat alignment has been fixed. The centre portion was heated with a heat gun and locked into place and has now taken its natural shape again



The seat cover will be replaced and all these gaps and alignment will be addressed then



Perfect alignment at the back though



From rear angle



Side angles



The rear fairing has been bolted on with the old bolts a d once the rear grab rail arrives will be fitted with the correct bolts



Top angle



The shape and height of the seat foam needs to be corrected too



All rubber mounts and caps have been fitted to the coolant reservoir and 2t tank



Finally sat on the bike for the first time since I bought it. I was hoping to kick start it today but I have waited patiently for so long so can do another week as well to hear it roar again with the correct engine internals.



The spare Daytona key which was missing the top plastic holder.



Tony made the cap out of brass and looks classy next to the RZ key for comparison. Key ring hole still needs to be made though. A side hole or a centre hole is the dilemma…



Something is still missing to complete the front end



Mirrors



Now looks the part



Looks really skinny without the engine and the exhaust



Especially from the rear



What a view with the mirrors on

[SnS_12]

Pictures continued

The handlebar position and feel is really aggressive and the RZ will be a hoot to ride



Side shots



Need to figure out a suitable chain guard which never came with the bike



Heavy duty main stand with a new spring and centre pin



Mirrors up close



They really complete the OE look



Time for some BLING parts



Samco hoses, same colour as the one on my 848 EVO and this shade goes well with the paint scheme as well



In total three separate pipes



This one will feed the cooled coolant to the cylinder head.



Connected to the new coolant pipe



Difficult to fit with the engine mounted on the bike and hence has been mounted on now.



New kick lever in all black



The problematic woodruff key which was cut to size by the previous mechanic and was never a perfect fit



Created a groove and got locked in position and created hell because of the wrong workmanship and created all sorts of difficulties to pullout the magnet



When the magnet is fitted correctly with the right woodruff key things are so much easier



Puller on



And the magnet is out in under a minute with minimal efforts. Always do things the correct way




Only saving grace with the wrong craftsmanship is that the bike never run properly and hence never saw real meaningful road time. Hence, parts like the gearbox don’t show the wear and tear one would expect from a 4 decade old bike



Some more parts. Made in Japan taillight lenses for my RD 125 and 200 and Made in Japan indicator lenses for the Daytona as backup



Getting there the aim was always to achieve the OE look, feel and working of the bike with zero compromise

[SnS_12]

We have Ignition

After months of ups and downs, we finally fired the bike for the first time today (8-1-25) however, we still have stuff to do before I can take it out for its maiden spin.

For the internals to settle down properly we let the bike idle for a minute and let it cool down post which the engine was run for 10 minutes and was let to cool down for another 30 minutes and this process was performed one more time with the same time intervals. Further, with Boyesen dual stage reed valves that are now installed the main jets have to be reduced to make the mixture slightly lean. Also, we now have to install the Dynatek ignition coil and then adjust the timing on the bike so that the fuelling can be adjusted accordingly and carry out any jetting that maybe required as per the behaviour of the engine. So, still sometime before we can call this rebuild a wrap

Video of the bike idling for the second 10 minute interval

https://youtu.be/qj8ahmsJp_4?feature=shared

Christmas lights are on finally with the bike idling at 1500 rpm and the temperature gauge showing idle idling temperature



Dynatek ignition coil have to be mounted on next.



Technical specifications of the Dynatek coil

[SnS_12]

Widow Maker!!!

That is what I told my friend after my first spin on the RZ. The bike just wants to lunge and the power on tap feels scary even though I didn’t go over 3k rpm. Typically the low end on the LC models is on the weaker side and it comes to life post 5k rpm only where one bas to hold on for your dear life. My first few rides on the Busa I was really intimidated by the size of it but this thing really scares the daylight of me.

Now, the last time I rode an RZ was over 15 years back and it was the YPVS version. So, this is the first time I have ever ridden the OG LC which is a non YPVS version. Further, all the magic done by friend Tony especially on the engine really shows as you just can’t hear the engine at idle and its only the exhaust sound. But, the quietness of the engine is the complete opposite when it comes to power delivery where we feel Tony has created a true Beast! I am just waiting to get done with the running in process to get a true feel of what this machine is capable off.

As, I had mentioned in my earlier post the bike was started on the 8th and over two days it went through 5 heat cycles in total and plus one complete rev out while idling to set the engine up before we put it in gear and ride it under load. The first start was just for a minute and the remaining four lasted for 10 mins each followed by a 30 minute cool down period and the last cycle was done with an overnight cool down period. Today, I had to ride the bike to provide initial feedback especially on the fuelling to see if the carb setting is on the lean side. So, after an initial shakedown ride in the vicinity I went straight to the fuel pump to fuel up followed by getting the PUC done. The bike was filled with under 5 litre of fuel and I was running it in reserve and at the fuel pump another 14 litres of fuel went in. People were just staring at the bike as this is one Yamaha to identify and especially with an old Bombay number but looks like which has just stepped out of the showroom. Even the PUC guy is like have you just restored it and I was like yes and this is my first ride on it. On, my first ride I noticed that the gear shifting was on the harder side and the throttle would stay open even when I cut it off. So, with this feedback, we opened the accelerator cable completely and even took out the needles. One of the carburettors needle looked slightly bent so that was straightened out and some settings were done on the accelerator cable. Further the slide springs were changed to a more harder one for a quicker return of the slide when the throttle is shut. On the needles the mixture was made slightly rich which would help for smoother gear shifts under load. So, as the miles pile on we will understand the bike better and keeping making small changes until we are satisfied and achieve the final desired setup.

So, until I am not comfortable with the bike and how it rides I don’t plan to get it home so maybe it would be at Tony’s for another week or two. Also, have to get the seat done which could not be done today so, hopefully that can be addressed on my next visit.

Time for some pictures…

Time to take the dust cloth off



Finally, sat on the RZ with the engine on



The smell of a two stroke is just pure heaven



Km reading before the first ride



Post fuel fill up time for the PUC



Looks complete with the engine and exhaust on



The PUC guy was impressed as well looking at the bike. Two strokes are now getting rarer on Mumbai streets and then you see a rare two stroke among a sea of four strokes



Standing at the same spot it did four months and what a transformation the RZ has had



Each and every part looks spanking new



Correct parts both inside and outside



Engine up close



Correct side panels and no rubbish fibre glass nonsense on this RZ



The rear is missing the rear grab rail and chain guard. Don’t miss my RX in the background which is getting its headlight holder worked on



The other side



Correct panel on this side too



Black kick looks so good



The new radiator cap



The three red SAMCO hoses will now be on the bike for life



The green wire is for the temperature sensor/gauge



Single choke puller for both carbs



The finished product from the side



Checking the fuel flow over 30 seconds to confirm the fuel flow is as expected which is part of tuning the bike. Small changes in such bikes make a big difference especially whatever makes a bike run lean across the rev range



Shifting through gears to confirm my feedback that the shifts are hard



BLa BLa



Time to address the carb settings



Needle setting being done



My first two stroke also my first bike and my latest two stroke in one frame



Exhaust have a unique design



The way they curve outwards

[SnS_12]

Pictures continued…

Can you spot the difference?



One side looks different from the other?



This is what happens to a copper hammer when you use it to put back a RZ 350 crank.



Old school beauties



More settings been done on the throttle cable



Dim light



Low beam. Damn thing is so powerful



Final oddo reading for the day



That’s me on my friends RZ 350 15 years back which was a YPVS version along with a RGV front and rear end.



And me now on my own RZ 350. Never in my wildest thoughts did it occur to me I could even own one let alone doing such a mammoth rebuild. The RZ was known as a giant killer back in the day and if you ask me it still is as after owning and riding a Busa and a 848 EVO I never thought I would be scared to ride a two stroke 350. This is going to be a mad mad fun two stroke in the collection

[SnS_12]

Silent as a whisper

The engine on the RZ is absolutely silent and its only the exhaust sound that you hear which is also comparatively quieter as compared to the non OE silencers which came with the bike.

https://youtube.com/watch?v=BiVNtlsP...Adb0DfgZdz4hCt

https://youtube.com/watch?v=8cqLf9yk...aegdYWVKdX6LgV

[SnS_12]

Pictures really don’t do justice to tell you the true picture of amount of pain and effort that has gone in over the past few months unless you have followed the build documented from day one, but here are a few before and after collages where the keen eye will notice even the small but significant changes to bring it to factory JDM spec…

[justin.das]

Originally Posted by SnS_12

And me now on my own RZ 350. Never in my wildest thoughts did it occur to me I could even own one let alone doing such a mammoth rebuild. The RZ was known as a giant killer back in the day and if you ask me it still is as after owning and riding a Busa and a 848 EVO I never thought I would be scared to ride a two stroke 350. This is going to be a mad mad fun two stroke in the collection

Congratulations RZ looks stunning and sounds great too. I own an Aircooled RD, and even if I have never ridden an LC I can assume how wild this one would be. Enjoy

[SnS_12]

Originally Posted by justin.das

Congratulations RZ looks stunning and sounds great too. I own an Aircooled RD, and even if I have never ridden an LC I can assume how wild this one would be. Enjoy

Thank you Justin. My RX 135, RD 125 and RD 200 are in the 18 bhp range and the RD 250 DS is around 30 bhp. Now, with the fourth oversize piston, mild port works to the intake, exhaust and transfer ports plus the Dynatek coil and Boyesen reeds are easily pushing the engine power output to over 50 bhp. So, yes, this is my wildest two stroke yet

Only, once I put in more kms and the engine starts settling in will I truly understand its evil potential but, the initial impressions are scary enough and after the Ducati 848 EVO this bike will now demand my 100% attention and commitment whenever I ride it

[justin.das]

Originally Posted by SnS_12

Thank you Justin. My RX 135, RD 125 and RD 200 are in the 18 bhp range and the RD 250 DS is around 30 bhp. Now, with the fourth oversize piston, mild port works to the intake, exhaust and transfer ports plus the Dynatek coil and Boyesen reeds are easily pushing the engine power output to over 50 bhp. So, yes, this is my wildest two stroke yet

Without YPVS how does it feel to ride? How is the power band? Is it from the bottom like a Leti or the medium to high rpm like the other variants?

[SnS_12]

Originally Posted by justin.das

Without YPVS how does it feel to ride? How is the power band? Is it from the bottom like a Leti or the medium to high rpm like the other variants?

The LC version suffered from the bottom end torque and power would come in post 5k rpm. This was tried to be rectified to a certain extent in the YPVS version with the power valve. However, on mine its a totally different story as the power comes in as soon as the clutch is disengaged and with slight throttle movement the bike lunges forward with ferocity and that is what I need to get used too. I have never ridden an non YPVS version before and didn’t ride mine before we stripped it to be restored so I don’t have a benchmark, but from what I have read and researched the RZ’s power delivery is not the way I am experiencing and GOD alone knows what will happen at the top end especially once it crosses 5k rpm. Since, its a new engine I haven’t crossed 4k rpm yet on the street and we will know its true colours/characteristics once we cross the initial 500kms of running in, when we can start opening the throttle even further.

[justin.das]

Originally Posted by SnS_12

The LC version suffered from the bottom end torque and power would come in post 5k rpm. This was tried to be rectified to a certain extent in the YPVS version with the power valve. However, on mine its a totally different story as the power comes in as soon as the clutch is disengaged and with slight throttle movement the bike lunges forward with ferocity and that is what I need to get used too. I have never ridden an non YPVS version before and didn’t ride mine before we stripped it to be restored so I don’t have a benchmark, but from what I have read and researched the RZ’s power delivery is not the way I am experiencing and GOD alone knows what will happen at the top end especially once it crosses 5k rpm. Since, its a new engine I haven’t crossed 4k rpm yet on the street and we will know its true colours/characteristics once we cross the initial 500kms of running in, when we can start opening the throttle even further.

In that case, Better Hang on to handle it once it crosses 5k Rpm . Is your stock carb up jetted? I think the TM 28 will be the better for this build. I am using TM28 on my RD and its fueling is perfectly fine in all rpm ranges. Is your air filter stock?

[SnS_12]

Originally Posted by justin.das

In that case, Better Hang on to handle it once it crosses 5k Rpm . Is your stock carb up jetted? I think the TM 28 will be the better for this build. I am using TM28 on my RD and its fueling is perfectly fine in all rpm ranges. Is your air filter stock?

Yes, I have to hold tight even at standstill to get my muscle memory right. People, are asking me when the Ducati makes more power why does the RZ scare you so much and the reason is the Ducati has better tyres, better chassis and most importantly much powerful brakes, which the RZ doesn’t have and that is why I cannot make a mistake as I will be dead meat for sure.

I can change the braking and handling to a great degree with upgraded brake and suspensions but I wanted to make it an OE spec . That is why even though I have got flat slides (28mm) I am still using the OE 26mm carbs. The RD 250 DS has 28mm carbs on the other hand. The settings and jets are all stock at the moment as when you go upsize on pistons the jetting tends to get more richer because of the additional bore size but the Boyesen reeds also require you to go lower on the main jets. So, for now we are running stock settings and depending on the engine feedback as the miles pile on we will make required changes.

[justin.das]

Originally Posted by SnS_12

People, are asking me when the Ducati makes more power why does the RZ scare you so much and the reason is the Ducati has better tyres, better chassis and most importantly much powerful brakes, which the RZ doesn’t have and that is why I cannot make a mistake as I will be dead meat for sure.

I can relate to that, Even AirCooled RD's if ridden hard will scare the hell out of anyone and that's all because of this scary and unpredictable nature these bikes have legendary status.

Originally Posted by SnS_12

I can change the braking and handling to a great degree with upgraded brake and suspensions but I wanted to make it an OE spec .

I completely agree with this point.I also love to keep things stock and mine also is running stock parts other than carbs which I opted against decades-old beaten-up original carbs.

Originally Posted by SnS_12

The settings and jets are all stock at the moment as when you go upsize on pistons the jetting tends to get more richer because of the additional bore size but the Boyesen reeds also require you to go lower on the main jets. So, for now we are running stock settings and depending on the engine feedback as the miles pile on we will make required changes.

Ok, I agree that's the right approach for a jetting ride then adjust accordingly, As you said Boyesen with the twin-stage system may be sensitive to jetting. I was using my stock carbs for years and changed to TM 28's on my last rebuild and it's a pleasant experience to date. My bike is running stock barrels with stock ignition setup and original airbox. Only the air filter is replaced with stock replacement K&N. I am using a set of new original Yamaha RD350 Reeds with up-jetted TM28s.