Talk to me about Yamaha RD/RZ two stroke engines

[HenryDorsetCase]

OK, I am getting ahead of myself slightly (I have a bike to sell and some debt to pay first, but I foresee another project coming along). I would kind of like my next project to be a Yamaha 2T: If I am cashed up and the right RD400F, or G comes along, then I might buy that, but people want a lot of money for them these days.

I also rode extensively back in the day an RZ350, which I enjoyed, and I thought that maybe that might be a better base for a project. I do have some questions which I am sure the clever bastards on KB can help me with:

Are RD250 and RD350 (and RZ) crankcases and gearboxes the same? (I've seen things advertised as RD250LC with 350 heads and barrels but unless the crank had longer stroke it might not convert a 250 to a 350 would it?. But if the crankcases and bore centres etc were the same, then you could change a 250 to a 350 relatively easily.?

Who in NZ is "The guy" to send one of these motors to for rebuild? Looking for a strong streetbike motor, not a handgrenade.

Where could I get some pipes from/made if I end up using a different chassis/running gear?

I did like the YPVS system and would think using that would be good. I only ever rode one when it was new up to about 3 years old so it worked flawlessly, but are they reliable in the long term? fixable?

Who's got one for sale?

got any good web links for further reading?

Thanks gentlemen.

[Spearfish]

Interesting project proposal...
Thanks gentlemen.

Your welcome

[gijoe1313]

Now that's some interesting questions, since I do have a RZ250 and RZ350 at the moment ... my 250 needs some TLC to get running right again, but the 350 is a pearl (was Chanceyy's old ride!)

Will have to go fossicking around my materials and handbooks to see what I can dig up!

[Katman]

Are RD250 and RD350 (and RZ) crankcases and gearboxes the same? (I've seen things advertised as RD250LC with 350 heads and barrels but unless the crank had longer stroke it might not convert a 250 to a 350 would it?. But if the crankcases and bore centres etc were the same, then you could change a 250 to a 350 relatively easily.?

The 250 and 350 both have a 54mm stroke.

[geoffm]

What doe Sir what to know?

For a street bike - the RZ (YPVS in Brit speak) is the best choice - more power, easier to get parts and info. Some Banshee parts fit. They are all budget bikes and well abused by now, so plan for some work.

Join the RD board - http://www.yamaha-rd.com/forum/. Anything you want to know (including the right shade of green for the anodised bolts ( - apparently it varied...) there will be an anorak to tell you.

Cycleworks did chambers for them - I have a set on the LC and to be honest they are average at best- and at the current price of $1200 (were $500 10 years ago) are waaay over priced. Get a set of Nikons, Allspeeds (http://gibsonexhausts.co.uk/) or best of all Kenny's pipes from the UK. The best I had on my RZ back in the day were Ledar pipes, made by the late, great Leon Moss - the pipes Yamaha should have put on them in the first place.

Kiehen PWK28 carbs are a popular upgrade - from KR1s and various copies.

[geoffm]

another note - an easy mod in the day was a Yamma Gamma - RG250 frame with LC or RZ motor. There are instructions out there for the mod. TH RG frame was considered more robust than the Yamaha. Best I have seen was a nice TZR framed conversion. I don't know how much work was involved, but it looked good.

There are some after market CDIs that help a lot with performance

Also have a look at the "2 stroke shop" in oz.

LC cases and barrels are different from RZs - the transfers are different. RZs also have 1mm wider rods (so if you are using RZ crank pins on a LC crank rebuild, they need mods).
RZ pistons will work in a LC, but you should file the tang off the bottom.

Geoff

[RDjase]

another note - an easy mod in the day was a Yamma Gamma - RG250 frame with LC or RZ motor. There are instructions out there for the mod. TH RG frame was considered more robust than the Yamaha. Best I have seen was a nice TZR framed conversion. I don't know how much work was involved, but it looked good.

There are some after market CDIs that help a lot with performance

Also have a look at the "2 stroke shop" in oz.

LC cases and barrels are different from RZs - the transfers are different. RZs also have 1mm wider rods (so if you are using RZ crank pins on a LC crank rebuild, they need mods).
RZ pistons will work in a LC, but you should file the tang off the bottom.

Geoff

http://www.twostrokeshop.com/

The Two Stroke Shop does new cranks for RZ, about $600nz from memory.
I got a modifiyed RZ crank for my LC, I think they machined 0.5mm off each side and you use a 0.5mmm offset crank locator ring.

Give Steve (at 2Stroke shop) a email if you need any parts, great bloke to deal with and very helpfull.

I have got 1KT TZR250 just begging to get a RZ350 repower

Jase

[GrayWolf]

OK, I am getting ahead of myself slightly (I have a bike to sell and some debt to pay first, but I foresee another project coming along). I would kind of like my next project to be a Yamaha 2T: If I am cashed up and the right RD400F, or G comes along, then I might buy that, but people want a lot of money for them these days.
I also rode extensively back in the day an RZ350, which I enjoyed, and I thought that maybe that might be a better base for a project. I do have some questions which I am sure the clever bastards on KB can help me with:
Are RD250 and RD350 (and RZ) crankcases and gearboxes the same? (I've seen things advertised as RD250LC with 350 heads and barrels but unless the crank had longer stroke it might not convert a 250 to a 350 would it?. But if the crankcases and bore centres etc were the same, then you could change a 250 to a 350 relatively easily.?
Who in NZ is "The guy" to send one of these motors to for rebuild? Looking for a strong streetbike motor, not a handgrenade.
Where could I get some pipes from/made if I end up using a different chassis/running gear?
I did like the YPVS system and would think using that would be good.
Thanks gentlemen.

RD/RZ/LC 250/350 exactly the same bottom end, identical stroke, bigger bore on the 350. only the RD400 had a longer stroke than the 250/350 motors.
Early elsie's... (pre power valve) look for cracked pipes near the manifold.. the early ones also didnt have the torsion bars under the motor. Reed valves can be an issue if old, or as was often done the reed plates were bent back further.
RZ (power valve) I remember hearing that they can seize up.
Robust bottom end? I think the air cooled motors were built stronger, but could be wrong. Did see a beauty in the UK in the mid/late 80's an LC (early) frame with a RD400 motor, LC standard pipes and a slightly tuned motor.
IF you can get a set from the UK or??? two pipes were very well known back then, Allspeed (better mid range power) and quieter; and Micron, higher top end power and bloody loud!!!! I had Micron's on my LC's and RD.
Tuning? again might be expensive BUT! if he's still about, the LC guru was a guy called Stan Steven's in the UK..... had a shop in Sevenoaks I believe.

IF I could?? I would go the LC frame, with the air cooled donk (400)

[geoffm]

RD/RZ/LC 250/350 exactly the same bottom end, identical stroke, bigger bore on the 350. only the RD400 had a longer stroke than the 250/350 motors.
(400)

Not quite identical between Lc and RZ - as noted the big ends (and hence the crank dimensions ) differ.
Aside the top end, as I recall,250s had a different oil pump, same carbs with different jets. LC250s had a single brake disk - 350s had twin disks.

[GrayWolf]

Not quite identical between Lc and RZ - as noted the big ends (and hence the crank dimensions ) differ.
Aside the top end, as I recall,250s had a different oil pump, same carbs with different jets. LC250s had a single brake disk - 350s had twin disks.

sorry correct,
to clarify what I meant RD 250/350 identical bottom end, LC 250/350 same bottom end, RZ 250/350 same bottom end. Correct on the discs,, I think the carbs although identical were marked 4L0 (250) and 4L1 (350) for the LC's....
thanks for the memory jog.... re the oil pumps.... I may be incorrect here, but I seem to recall it was the early LC's both 250/350 had a different pump,
or the worm drive was different from later models,,,,,, My 350 was a 'hop up' from a 250 using a binned donor.... 250 bottom end and oil pump worked fine even with a tuned engine, so I am certain the oil pump between the 2 sizes was identical.

[F5 Dave]

I know where there is a Yamagama, but it is a total shed.

350 RZ YPVS (or RD in UK, they never changed to RZ name) are a great bike, but there will be some chassis & engine work to be done to make them back to great again, tyres etc need some thinking about, they don't like to be over-tyred. I converted an FZ rear wheel so I could run 130s.

I might have a low mileage complete top end & crank sitting in a lubey box (I've built a 496cc monster similar to the TSS route).

[HenryDorsetCase]

http://www.trademe.co.nz/motors/moto...-412262012.htm

I missed this. it is now sold.

I am still reading, still contemplating. On that RD forum, there are a couple with stock frames (modified) and NC30 single sided swingarms. Very cool but major work. but very cool.

[Dodgy_Matt]

http://www.trademe.co.nz/motors/moto...-412262012.htm

I missed this. it is now sold.

I am still reading, still contemplating. On that RD forum, there are a couple with stock frames (modified) and NC30 single sided swingarms. Very cool but major work. but very cool.

You sure its sold?
this is awesome
http://www.trademe.co.nz/motors/moto...-412156265.htm

[HenryDorsetCase]

You sure its sold?
this is awesome
http://www.trademe.co.nz/motors/moto...-412156265.htm

SPoke to the guy this morning when I saw the ad.

[F5 Dave]

8k for an old LC, hmm, they have cult status in the UK but here that is pushing it. To be honest the YPVS is a better bike to ride. That K model KR rep was right pretty. But also to be honest the bars on the early RZs made them a bit odd, the latter model F with the fairing & lower clip on type bars was more comfortable & better handling.