Rz350

2strokeyams · Posted: Sun Mar 06, 2011 4:36 am Post subject: Rz350

Hi guys my first post. I recently bought an Rz250 it needs some love but it's all there and was at the right money. Once I got it home I started to give it a good look over checked the numbers only to find out that it's a 350. Its got 250 barrels and 250 stickers on the bottom fairing. I'm wondering when I put (find) the 350 barrels back on will I need to change the rods or are they the same.
Any help would be great thanks.

05c50 · Posted: Sun Mar 06, 2011 7:18 am Post subject:

Welcome to VJMOG. Sorry, but I can't help with your 2 stroke, but I'm sure someone will be along soon that will have the answer. Sounds like you got a pretty good deal though.......a hundered more cc then you thought. Smile

............Paul

Bentwheel · Posted: Sun Mar 06, 2011 9:47 am Post subject:

I don't know much about the RZ, but I can tell you the RD 250 and 350 shared the same stroke. It was fairly common to simply add RD350 barrels and heads to a RD250.

ztnoo · Posted: Sun Mar 06, 2011 2:00 pm Post subject:

RZs were water coolies.
From your description, I can't honest say what you have.
If you could provide some pics, and better yet, tell us the frame VIN and the motor VIN, it might help us identify what you have.
Street Yam 250s were typically 54mm x 54mm, bore and stroke.
Street Yam 350s were typically 64mm x 54mm, bore and stroke.

RZ 350s were imported into The States, but I have no knowledge we ever received any RZ 250s here.
Canada may have, but not the US. Europe and Asia had access to RZ 250s.

Here's a couple of spec sources:
http://www.motorcyclespecs.co.za/model/yamaha/yamaha_rz250%2082.htm
http://www.bikez.com/motorcycles/yamaha_rz_350_1984.php

2strokeyams · Posted: Sun Mar 06, 2011 11:36 pm Post subject:

It is an Australian delivered 350 matching no.s I just assumed past owner had put 250 barrels( you can see the 249 cc stamp) on it so they could ride it on learner licence. But if the stroke is the same between the two then all is easy. The next thing will be waiting till a set of barrels come up on ebay. Thanks for your help.

ztnoo · Posted: Mon Mar 07, 2011 2:46 am Post subject:

Ah......now I see you.....are an Aussie. G'day!
That explains why you might have an RZ250.
I couldn't find enough detail in the specs I provided to determine if there are major differences between an RZ 250 and an RZ 350.
Of course the barrels will be different, the pistons, rings, for sure
The carbs may be the same, but I would guess the jetting is different.
There may be some other differences one wouldn't think about or assume.
It may not be quite as straightforward as you think, and if you are able to find what you need for a changeover, it probably is going to become very expensive, particularly if you are trying to find NOS parts.

Actually, after I think about it, what you may have is an RD350LC.
It's my understanding the RZ350 was called the RD350LC in all other countries but the USA.
So, you definitely have to know exact what you have to know where you want to go.
If I were you, I'd be trying to track down a service manual for your model based on the VINs, especially the motor number, then you'll know exactly what you require in the way of parts.
eBay is a great source for manuals too.

I can think of two other places which may be able to provide you with pertinent information:

http://www.aircooledrdclub.org.uk/

http://www.2strokeworld.com/forum/index.php

Regards,
Steve

2strokeyams · Posted: Mon Mar 07, 2011 3:19 am Post subject:

I'm starting to learn that nothing is easy but I want to take it back to original. I've always had a soft spot for these bikes and it will sit very well with the other Yamahas that I have. Thanks for the advice I might start collecting parts and start my Yas1 next.

ztnoo · Posted: Mon Mar 07, 2011 3:47 am Post subject:

I found an interesting book that might be just what is needed to identify your machine.
http://www.japan-dream-direct.com/product/810
Lots of great pics, but unfortunately its written in Japanese..... Sad

dirtybird · Posted: Sun May 22, 2011 12:10 am Post subject:

The bottom end, crank and rods for the Rz250 and Rz350 are the same.

rubyrider · Posted: Sun May 22, 2011 12:35 am Post subject:

Chances are that the primary gears are different between the 250 & 350; the RD series
was that way.
Also, the carbs are probably larger, not just jetted fatter....the 350 pumped a lot more
air than the 250, so needed a bigger throat, not just more fuel. (Methinks...?)
But, as it is, whats wrong with the RZ250? It is probably a real screamer, anyhow....JMO...