Denny Aungst’s ’84 Yamaha RZ350L Kenny Roberts “Signature Edition”

The Background Story:

This motorcycle was just what I was looking for. I was racing Banshees on the national AMA and then the pro-circuit in ’91 and ’92 and was really fond of the RZ 350 engine. This unit makes lots of power. As I learned more about the Banshee, I found out that it's predecessor was the inspiration for the engine and that it had quite a history of racing victories. I wanted one bad ever since.

Well, I found one at the house of an employee of ours. I immediately bought it (for WAY too much money) and proceeded to rebuild it. For example, the bike was wrecked. The water pump was leaking antifreeze into the crankcase and had the crank scored, needing a complete rebuild. The bike took a lot of money to completely go over, but when it was done, I rode it all over the country and enjoyed it completely.

Then in late ’96, I broke up with a girl who took me for some serious dough. (example: $1,500.00 phone bill to her secret boyfriend in Desert Storm.) So I sold it to a good buddy for a major loss. Bummer.

Years later, I ordered a special edition Silver Yamaha R1 in ’01 to match the new Spyder I just bought. Melissa really talked me into not following through with the purchase and to chase after the RZ350 that I talked about while we were dating.

So, I had been trying to buy it back. My friend didn't want to sell but finally gave in in the spring of ’02. He had quite the bad luck with the bike. When he first got it, he was racing, and beating an FZR600 for fun and lost it in a corner breaking his legs only weeks before he was to go in the service. With the legs pinned he couldn’t follow through with a military career. Eventually he got it back on the road and riding again. Didn’t he have the bike seize while out riding. Then he got someone to pull start the bike so he could ride it home. Let’s just say that was a bad move.

So, here I am. I got the RZ back but it was wrecked (twice), the right cylinder had exploded, the crank and cases were ruined as the rod went through the case and wedged in there like a pretzel, the battery was shot, and nothing seemed to work. Looks like I had quite a project.

Click here to return to my “car collection” pages or the links above to return to the main site.

I no longer own this motorcycle. It has been sold since October 2009.

Under Construction: An Online RZ350 Service Manual

To publish some of the tuning issues I have come across over the years of owning one of these spectacular but finicky motorcycles, I have constructed a section of the web site dedicated to the RZ350. It is complete with an online Service Manual, downloadable PDF files of the service manual, parts fiche, and carburetor tuning manual, some problem area tech tips, and some of my old racing photos and videos. If you have something of relevance or a tip to add to the site, please email me.

Check out these two scans from the sales brochure. Click to enlarge.

Cool link: 2-Stroke Engine Basics

Click above for my Dirt Bikes &Old Racing Photos.

See my old Racing Videos by clicking below.

To the right is the first picture I took after bringing it home to get started on putting the bike back on the road. The picture actually looks a bit better than it really was at the time.

To the left is a picture of the box of parts for the engine the previous owner handed me to take along. He pulled it apart to see what came apart and then just set it aside.

To the right is the gas tank showing it's dents from the previous owner laying it down. Not only dented, the gas tank was leaking where it rusted through around the petcock, so, back to Zechman’s. Yamaha wanted a staggering 1,200 dollars for a new fuel tank. It did have all the new decals included, but back to Ebay I went.

I replaced tank with a used tank I found. It was very solid and very nice, but as most RZ350s, it was shipped with a ding. Not long after, I got Frank Tankalavage to remove the ding and it looks like new. What I realized is that the the steering stops needed to be built up. It was a chronic problem with most of the bikes allowing the bars under stress to flex and hit the tank at full turn against the stops. We welded stops larger to slightly limit travel.

A starting assessment of the motor cycle gave me a list of the most obvious problem areas I need to look into.

What really stood out? Like I mentioned before, a piston exploded in the right cylinder, the rod was stuck through the case, and the crank was twisted and froze fast. What do you do? Well, after a trip to Zechman’s Yamaha, I found out the prices for the parts I needed.

Each cylinder cost $517 ($1034). The cylinder head cost $536. The crankshaft cost $904. Now, without gaskets, pistons, rings, or end bearings, one power-valve that is broken, intake boots that are ripped, top case half that is cracked, spark plugs, and whatever else that may crop up, I still would have well over 2,600 dollars in fixing up my engine and I am estimating way over $3000 to finish it.

I decided to try scrounging used parts off Ebay and that will be addressed at a later point. I have already made a few good purchases, but I was now focussing on the engine. Wouldn't you know, I came across a complete engine for sale out of a demolished ‘85 RZ. I bid to get it. The total price came to $1050 + shipping and insurance. I found out later that the '85 models had a different set of plugs on the wiring harness for the magneto, but I had the '84 setup available.

I was told this engine had only 5,600 miles on it and it was stock bore. I was a bit skeptical, but after examination upon receiving the engine made me believe the claim. A bore scope revealed the top of the piston showed stock bore. The cylinders had the original semi-gloss finish and wasn't even wore from the clutch cable like all higher mileage RZs. The rest of the engine was extremely clean and the nuts weren't scarred as if they were ever removed. I really believe it was an honest ad for a low mileage piece.

Want to see more pictures? I have a page with photos of the engine from Ebay, A little more detail about the purchase, and the best part, lots of photograph’s of the donor motorcycle that was wrecked. The seller even sent photos of the bike that he got to replace it which was another VERY nice, VERY low mileage, but yellow and black RZ350. (His original was red and white) Click the page below or photo to the left...

RZ 350 page 2 (The search for an engine)

So, now that the engine made it to the shop, I began to replace it into the frame. It went rather smoothly until I started to hook up the wiring. Like I mentioned before, the '85 models had a different set of plugs on the wiring harness for the magneto, but I had the '84 setup available from my old engine and transfered it to the new engine. That was not my only issue with the wires. I found some broken wiring for the charging system wires and the holders for the fuses were bad. I repaired wires and replaced with mini-fuses for convenience.

Once they were repaired, I found why this bike overheated for the previous owner. It was due to a leaking radiator cap and filler neck. Check yours if you want. I have noticed the neck is prone to corroding away causing the antifreeze to freely flow onto the overflow, but not be pulled back into the engine during cool down. Eventually you could be running without ANY coolant in the engine. I replaced with new cap, fill neck and radiator hoses for good measure. See more photos and details by clicking the link below:

RZ 350 page 3 (Engine replacement, coolant neck,and wiring repair)

RZ 350 page 4 (This page was supposed to be for the original engine rebuild but I have sold everything)

Now that I got it running, the next thing was to get the bike ready for inspection. After I went over it, the were a couple more issues to be addressed. First I replaced the rear brake lining as you can see in the picture to the left.

While I was at it, the rear rear tire was too big. I installed a new tire in correct size and brand. (These bikes respond much better when equipped with the original sizes front and rear in my opinion.) That was not all. Because of the larger tire, the inner rear fenders were cut and wore through due to larger tire. I bought a used inner fender from Ebay and installed it.

The throttle was sticking, so I replaced entire cable with new cable. and got the carbs cleaned and adjusted properly. This is very imperative with the twin carbs. Want some tips for a Banshee and RZ carb set? Want to solve a possible hard starting problem? See my Online RZ350 Service Manual and click on the tips section or download the Mikuni carb manual.

I also preferred and wanted the stock mirrors rather than short aftermarkets, so I installed used set of stock mirrors from Ebay. The battery also wouldn't hold a charge, so I replaced it and mounted 1.5 amp maintenance charging system.

Due to the new laws enacted by Pennsylvania, I needed correct exhaust for emission inspections. This was one of the very few motorcycle to ever be equipped with one. These were actually unavailable through Yamaha, so back to Ebay. I bought and installed the original pipes.) Want to see more photos of the installation of the converters, heat sensors, and warning system, click the link below.

RZ 350 page 5 (Original exhaust and air injection installation)

I actually liked the look and sound of the original system over my ALLSPEED. My impressions of ride-ability were very good. After re-jetting the carbs, I notice much more bottom end power and smoother power-band which makes it much easier and comfortable on the street. There is a loss on top end, however that someone would miss if they intended to run the bike at the track someday. Over all, I was happy with the change.

So now we were legal and out I went for my first real ride. I knew the tank was a bit low on fuel, but figured I would make it back with the reserve tank if I had to. That was a bad decision. When the bike sputtered I reached down to switch it over. The bike still quit over in the Pottsville area. Here I found out that the fuel tank valve was non-functional. Once I called my brother in law to pick up up I got it home to investigate. All I had to do was repair a blocked vacuum port from mud wasp.

We rode it often and it really worked well. We decided we needed a 4-stroke engine to power us on the longer trips and purchased a Harley. This started a downswing in my riding of this bike.

Sometime later, I picked up another titled RZ chassis from someone in the Annville area for parts. I set it aside hoping to put together a “Spec II” full fairing bike. You can see some pictures of this project bike at my RZ 350 page 6.

This year, 2009, I bought a new Harley and was offered a deal by an earlier owner than myself to purchase all my RZ stuff. Sometimes you gotta move on. This owner is planning a full restoration of both bikes. I haven’t rode it in some time and may eventually miss it, but I think it is in better hands.

So in the end, I was the fifth AND seventh owner of the bike. Now it is back in the hands of Nick Modesto, who was originally the second owner of this particular machine. WHat a roller coaster ride. Think it’ll stay here now or wind up in the hands of the first purchaser or maybe someone new? Obviously only time will tell.