Rebuilt of the "other" V4

Hi Guys,

I just wanted to share the rebuilt of my Yamaha RZ500. It began 2 summers ago when my brother gave me his RZ500. The bike had been sitting for almost 10 years and needed a serious over all. The first year I stripped everything to the frame and waited a full year before I could get enough money to start the rebuilt.

For those of you who are unfamiliar with this bike, it is a 500cc 2-stroke engine. It comes with a 88 bhp, but Yamaha released a service update (TSI) in which they show the modification needed to boost the HP by 30%. Thank you, Yamaha! However, I will limit myself to the pistons, which won't do much to increase the HP, but will improve the "breating".

I began with painting the frame while I ordered pistons, gaskets, calipers, seals, chain, sprockets, tires etc etc.

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I bought a pair of Conti go and will be evaluating them this summer. I got the pistons from England and the machine shop is cutting them to TSI specs. Right now, I'm waiting for more parts to continue.

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Not happy with the white wheels, but that something for next winter.
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As soon as the barrels and pistons are coming back, I'll be doing the discovery of the engine.  I'll be cleaning the casting flaws and lining up the ports.

I know this section of the forum is being deleted faster than others, which is fair, but I hope to capture some interest in one of the classics.

We love to see a good build thread, regardless of brand. And hey, it's a V-four anyhow, right?

I pinned the topic so it doesn't get deleted, and we can all cheer you on! (or heckle you, when needed)

How about the expansion chambers, are they stock or aftermarket?

I love the look of nickel-plated aftermarket expansion chambers on a 2-stroke.


Also, are you updating the forks/wheels/brakes/swingarm/shock sometime?

Maybe some YZF600R parts might be persuaded to fit, and still keep it 100% Yamaha?



A modern Yamaha race paintjob might look nice. Bumblebee? White on blue?

Yeah, I know, it's a 350 (but it has fork/wheel mods, nice:

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And this is a model, but whatever:

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OK, here's one that's NOT a model:

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Great bike cant wait to see the finish product   !!!!!!!!!!!!

[image: View Post]Veefer800Canuck, on 16 May 2011 - 12:33 AM, said:

We love to see a good build thread, regardless of brand. And hey, it's a V-four anyhow, right?

I pinned the topic so it doesn't get deleted, and we can all cheer you on! (or heckle you, when needed)

How about the expansion chambers, are they stock or aftermarket?

I love the look of nickel-plated aftermarket expansion chambers on a 2-stroke.


Also, are you updating the forks/wheels/brakes/swingarm/shock sometime?

Maybe some YZF600R parts might be persuaded to fit, and still keep it 100% Yamaha?



A modern Yamaha race paintjob might look nice. Bumblebee? White on blue?

Yeah, I know, it's a 350 (but it has fork/wheel mods, nice:

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And this is a model, but whatever:

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Thanks Rob for pinning this thread. I appreciate it.

To answer some of your questions, although I would love to put "goodies" on it, it won't happen this season. To get collectors, the bike has to remain stock, or year appropriate modifications. So I think I could install Jim Lomas expansion chambers (EC), but not a front end from another bike. The TSI specs ask for specific dimensions for the EC, and from what I read, the JL are as close to it as it gets. The EC is the single most significant improvement one can do on a 2-stroke. When I had my TZR250, it was incredible. I had set of Jolly Moto and they sounded great too.

There was one for sale on Ebay last month. The bike was brand new! It had been stored with 300km only. Check it out.
Ultra Mint RZ500

Looks like the bike is going to be a lot of work but from what I hear they are really worth it. If you run into any snags I'm sure the guys over at the RZ Forum will be able to help you out.
I've got an 350 that I hope to do a R1 swap with some day but finding the time......

Looks great, keep us updated

Hoover

You lucky, lucky dog! I've wanted one of those since they were new...that or an RG500. I'm sooooooo jealous.

Thanks Flightar, I know how you feel. I was the same way until I got it. I saw an old add from a Yamaha dealer in Montréal dated from 1986. You could buy an RZ500 for $3997 Cdn or for the same price, a Virago.

Okay, here's an update.

The engine parts arrived, but the pistons were not cut properly. Furthermore, one cylinder is out of specs. Anyhow, I was still able to do the discovery of the engine.
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The pistons should be 8mm shorter, not the same height.
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Deck height: .045mm
Combustion chamber volume: 11cc
Total uncorrected compression ration (UCCR) is 12.6 to 1
Good, I can use regular gas.
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I also got the time area and all those useful numbers should I decide to go further with modification of the engine. The piston doesn't quite clear the ports when at BDTC, but since I won't add expansion chambers this year, I won't raise them. Which will save a whole bag of other mods that will come with that.
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Finally I cleaned the casting of the barrels. Now the air/fuel mixture will be flowing smoothly.

See the flat edges on the aluminum divider and the sleeve. These need to be grinded into a less obstructive way.
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In no time, I cleaned everything up and it will make the engine run that much better.
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It might be a couple of week before the next update, but it will be a good one.

Well, it's been a while, but some major development since.

First of, I got the pistons back and I if you check the pictures below, you can see the difference between the old ones and the new and improved ones. 8mm shorter and the skirt has been trimmed to the TSI specs. Which will allow more flow into the combustion chambers.
The outside pistons are the ones that have been modified.
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I put it back together about 2 weeks ago, and it went really well. Taking my time, I made sure it was all in fitting perfectly and that everything was well adjusted. For instance, the power valves(YPVS) need to be adjusted with the cable and lined up. I had an issue with the motor that moves them, but I was able to fix it.


Between the 2 barrels, you can see the YPVS. These restrict the exhaust ports to give more bottom end.
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In the middle of the 2 banks is the mechanism that controls the YPVS. This was a bit trickier to do than I was expecting. The poor quality of pictures in the manual didn't help at all.
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Heads on! Notice that the reed valve blocks are on the cylinders for the upper cylinders(left side on picture) and on the base for the bottom one (right). If you check the first pic on this post, you'll see the pistons with the windows. The windowed pistons were for the upper cylinders. Now, all for pistons are the same.
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Checking for air leaks! It is crucial for a 2-stroke engine not to have any air leaks. If so, it can cause massive failure of the engine. To test it, you need to plug the exhaust and intake. Then put a 5 psi of pressure. Check for leaks around the base, intake, injection hose. On the picture, you can easily see the blocks that seal the intake, and the exhaust on the bottom cylinders.
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Putting it in isn't a very difficult job.
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Yesterday, I fixed a gas can to start it. It fired almost immediately and purred like a kitty. That was AWESOME!!!!
Of course, there is still a lot of work to do and a great amount of adjustments. A couple of small set backs as well. For instance a couple of coolant leaks, one fixed, the other to be. Also, the wire nightmare isn't finished. I need to reroute a few, and check the tach. However, I'm really glad that it is running and that is a major milestone.

More pictures to come.

Congrats!! Looks great! Can't wait to take it out for a spin!!!!!!    :)))

Nice work! Glad to see you're tinkering and looking forward to the finished project! :beer:

Is this the bike? :fing02:
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Love the work you have done, I did the same to a Honda NS400

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I think the RZ500 is the best looking of the 500 2 strokes. Congrats on having such a lovely old smoker! Can't wait to see the finished results!

I learned a lot about two strokes just from reading your build thread. How is it progressing?

This company has some unbelievable hardware for two strokes:

http://www.twostrokeshop.com/

coming from mopeds and knowing what 75cc's of 2 stroke can do.....
500cc of V4 2 stroke power YOWZERS!

I have 2 kidneys, yet no RZ500. Wanna work with me?

That's one too many Timmy, as you suggest, you could spare one and try and trade it for a test ride ...

ST1100

Nice to see it's moving forward. What's that purple "thing" on the right?? C'mon now, what's the scoop??

ST1100

Very impressive, Veefer800Canuck
It's an old picture when I was in Québec and got the bike out of the shed. I had friend's ST1100 (a V4 by the way) for vehicle while I was there.
SG

The front brake rotors and body colour gave it away.

Pfew!! I was afraid for a second that you had bought "one of those"..... J/k
C

Sorry about the lack of updates. It is running, but of course, making the engine run brought up a few unwanted problems. Oil leak, water leak and charging system not charging. This bike will be on the road this summer. But. . . right now, I am having the wheels powder coated with oem colors, replace the wheel bearings and seals. As always, getting parts can be a lenghty process and getting money to continue the project can be a louzy process.

As for learning about 2-stroke, I am learning as well. Unbelievable how much science is actually involved in the building of an engine. The good news is, the ratio $/power is a LOT less than a 4 stroke. On the other hand, not many guys really understand that breed.

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Nice to see it's moving forward. What's that purple "thing" on the right?? C'mon now, what's the scoop??