The Burning Question...?

[lucky mike]

Tuning a near forty year old 500cc two-stroke engine to achieve 100 horsepower involves a complex and meticulous process. The way I've come to understand it, reading thru these pages, the modification process typically includes upgrading various components such as the main cranks, the intake and exhaust systems, cylinder heads, pistons, and the ignition system to name a few. Additionally, optimizing fuel delivery and ignition timing is crucial for achieving the desired power output without compromising reliability. Costs can vary based on the quality and brand of the aftermarket parts used, as well as the expertise of the technicians performing the tuning. Professional services, dyno testing, and multiple iterations to fine-tune the engine contribute to the overall expense.
So how many today dollars will I need to part with,to have someone build this engine for me?

[kpke]

Where in the world would you like for this work to be performed?

In the US Wilson Performance can help you with pricing.

[lucky mike]

I'm genuinely interested in hearing about the experiences of forum members who have successfully achieved 100hp results with their RZ builds. While I understand that the process can be challenging, I believe that those who have gone through it can provide valuable insights into the commitment, challenges, and costs involved. I apologize if my question seems insensitive; I simply want to learn from the firsthand experiences of individuals who have fully committed to building their RZ to this caliber.

[giron]

As far as making 100 HP from an RZ500 is really a dream. I have an RZV500 and I opted for pipes and carburetors. You are better off not sinking any money into a RZ500 engine. You are better off putting your money into an RG500

[lucky mike]

The paucity of responses in relation to the substantial view count hints at several possibilities.

Firstly, Giron's assertion that achieving 100hp from the RZ engine is either implausible, excessively challenging, or financially burdensome gains credibility.

Secondly, it appears that only a very limited number of forum members have ventured into tuning their RZ engines to reach such elevated power levels.

Lastly, there might exist individuals within the forum community who have successfully attained the coveted power output but are either too humble or hesitant to disclose the genuine costs involved.

My research continues...

[giron]

What I was trying to convey. What I heard from builders. When you have an RZ500. You should have an RG500. This way you can see for yourself how nicer an RG500 is over the RZ500.
Try looking for an RG500 and you can see the limitations of the RZ500

[lucky mike]

I appreciate the insights offered by builders and their recommendation to compare the Yamaha RZ500 with the Suzuki RG500. It's crucial to recognize the influential role that individual preferences play in shaping how one perceives the superiority of one motorcycle over another. The notion that owning both implies a universal standard of "niceness" doesn't necessarily align with the diverse preferences and skill sets of every rider.

Each motorcycle boasts distinct strengths and weaknesses, contributing to its unique character. Acknowledging these nuances is vital for a more profound appreciation of the diverse experiences each bike offers, a fact that I am well aware of.

[tacky1]

I tuned both mine, One had a Bill Wilson st3 tunes, Both had 34mm carbs, pipes, Billet heads, VForce reeds, Wiseco pistons and a lot of other work, Both were fast, A lot faster than stock, A lot faster than my stock RG500s (both have carbon rotary valves, Bored out carbs and pipes)
I did upgrade the suspension and brakes on both bikes, Thats a must... They just wallow around, not the best handling bikes on the planet and the brakes dont leave anything to talk about.
I rode both for a few years and loved them, massive improvement on the top end, They really screamed.
Both are sold, I have another one half built,

[drunkula6]

Mike,

I'm currently in the process of rebuilding the RZ500 engine that I adopted from a friend when he died from ALS. I think I can give you a bit of a starting point for an answer to your money question. So far, my estimated cost for this rebuild is close to $6000 U.S. dollars. Now, there are a couple of things to take into account with that number.

1. I'm turning the wrenches myself. Multiply accordingly for someone else to do it for you.
2. Therefore, that 6 grand is just for parts and machine work. Somebody else has been inside my motor and done some questionable things which will cost me more money to fix.
3. That price isn't final. Apparently, one of my cranks is being a bastard to true, and more hours (and people) spent on screwing around with a crank probably won't help it to be any cheaper in the end.
4. My cost is for a "stock" rebuild. Although I did spend $1300 on a set of flatslide carbs hoping they would help with the "constantly pissing gas on the floor" problem I've fought with for a couple of years on the original carbs. I don't even care if I get any more power out of it with the carbs. Expect to add more money for fancy ports and pipes and whatnot.
5. I'm not trying to build a dyno queen. I just want the bike to run reliably.

With weird tire sizes and 1985 suspension and brake technology, the 88 horsepower the bike was rated at is plenty. When it ran (and probably not as well as it will when I'm done rebuilding it considering what I found inside the motor), it chewed up a back tire in nothing flat. Truly, 88 horsepower on a 140mm wide bias ply tire can be absolutely terrifying. It either wheelies or won't hook up and spins the tire.

I don't want to discourage you from seeking 100 horsepower. I'm not going to tell you the Suzuki is better, it's still 1980s tech and I'm biased towards Yamahas and Ducatis. I'm sure it's been done based upon all the lurking I've done on this forum. But you're going to have to empty your wallet starting with the number I gave you and multiply accordingly. This very well might be one of those "if you have to ask how much it costs, you can't afford it" questions. And then you might as well spend another fortune fixing the wheels, frame, suspension, and brakes to cope with the additional power. Then what you end up with won't necessarily be a RZ500 anymore. So, in my honest opinion, if you want 100 horsepower, buy a nice modern motorcycle that isn't made of unobtainium, makes 100 horsepower from the factory, and dump gas and oil into it and ride it forever.

[giron]

I heard complains on Bill Wilson engines. I sat in a conversation with Bill Wilson and Brian Turfrey. Bill kept trying to get specs on Brian’s pipes. Brian was not going for it.
The interesting part was when Brian was building an RZ500 engine. Brian called Bill Wilson and asked Bill
on Gus cranks where the rods were rubbing on the case. Brian pointed it out. Bill was surprised. Now as far as pistons use Yamaha. Wiseco pistons are junk

[giron]

I forgot to mention a bike magazine from the 1980 where they did a comparison a NS400R, RZV500 and a RG500. They found the NS400R the best handling. The RG500 felt like a race bike when it came under acceleration. The RZV500 was the slow in steering and felt like under power in comparing to the RG500

[lucky mike]

So, here's where I currently stand. It's winter here in Ontario, also known as the season to tear down your next project and pass the time in darkness and cold, gearing up for the upcoming riding season.

My RZ is stripped down to parts small enough to fit into plastic tubs and repurposed yogurt containers. I'll be overhauling every component on the motorcycle that uses rubber seals, bushings, or copper crush washers. A steady stream of parts, surprisingly still available from Yamaha, is arriving daily, and my daily delivery of boxes and bags to my front door is dwarfing that of my wife's, which is a little concerning to me given the time of year, and I'm on a first name basis with the courier drivers.

I have no interest in grafting modern suspension components onto my RZ for the simple reason that it ceases to be an RZ once it undergoes these changes, as pointed out by Drunkula6. The only modification I will personally make to the original components will be the addition of vacuum ports to the stock carburetors. I've already purchased a four-channel digital synchronizer that I'm very much looking forward to fiddling with.

Wilson Performance and ATR, both in North America, are names that appear frequently across this forum. I will be reaching out to both and having lengthy discussions with each before I decide if my crated engine travels south to the U.S or stays in Ontario and travels north to Peterborough. The build criteria is simple. Can you build me a 100hp engine that is reliable and bolts directly back into the stock frame?

I am no stranger to motorcycle maintenance and tuning, but I am well aware of my limitations of time and expertise. I will not be attempting to strip down the engine, sending the various components out to be modified, although I recognize a potential dollar savings, this is less concerning to me; I want to ride it this spring.

to be continued...

[tacky1]

I heard complains on Bill Wilson engines. I sat in a conversation with Bill Wilson and Brian Turfrey. Bill kept trying to get specs on Brian’s pipes. Brian was not going for it.
The interesting part was when Brian was building an RZ500 engine. Brian called Bill Wilson and asked Bill
on Gus cranks where the rods were rubbing on the case. Brian pointed it out. Bill was surprised. Now as far as pistons use Yamaha. Wiseco pistons are junk

I run Wisecos in most of my street and dirt bikes and never had one fail.
How did you come up with the Wiseco junk.

[Jeff B]

I want to ride it this spring.

I suspect most of the quality engine builders are too busy to meet your timeline. It took months to get my Jolly Moto exhaust from overseas.

To add to the piston discussion: I run oem pistons, but if I were to do it over I'd go with Mitaka. Very much like oem but cheaper.

[giron]

I seen the builder open up an RZ500 engine with Wiseco pistons. The Wiseco pistons can’t go the distance like Yamaha pistons. Tacky your Wiseco pistons lasted that long since you have various bikes and not ride the bikes with Wiseco pistons very often