Introduced for the 1973 model year, the Yamaha RD350 was destined to become one of the most beloved and popular two-stroke sport motorcycles in history. For $900, you could bring home a 39-hp two-stroke reed-valve twin that could hit 100+ mph…and it could handle, too!
“The RD350 was THE Seventies poor boy racer. It was relatively cheap, relatively easy to work on and fast through the twisties. Unlike the many stoplight-to-stoplight dragsters of the early Seventies that had to be muscled through corners, the RD was light and flickable, just the thing an aspiring racer needed to hone cornering skills. ‘It was brutal, fast and wheelie prone…’” —Motorcycle Classics
Back in 2018, we featured a boardtrack-inspired RD350 from a young builder / ice racer named Jake Drummond, who spent two years building the bike in the corner of his father’s hangar in the aviation capital of Oshkosh, Wisconsin. From that first build, we knew Jake had a very bright future ahead of him as a builder and fabricator.
Since then, his Yamaha MT-07 “The Omen” has graced the pages of Bike EXIF, his custom-built mini Mad Dog tracker was one of our more popular builds of 2021, and he took one very cool job:
“After nine years working for Sonex Aircraft building experimental aircraft and UAVs, I took a job with Polaris/Indian running the metal shop for the Industrial Design Department.”
At last month’s Mama Tried Show, Jake showed up with something we’d never seen before: the Yamaha RD350-powered hillclimber you see here! We immediately reached out to him, begging to know more. Jake says he picked up the bike for just $500. Though it was already set up as a hillclimber, it was in very rough shape.
“That said, there was no way I was going to pass up a $500 RD! Not only was it a great deal, but I also saw quite a bit of potential in the bike. I thought I could just throw some plastics on it and rip, but as usual, things got carried away.”
The bike is actually a bit of a Yamaha “bitsa,” featuring a ’70 DT1 250 frame, ’73 RD350 engine, ’82 YZ250 seat, and IT250 forks. Jake cleaned up the frame and engine mounts, gusseted the chassis, fitted some Preston Petty plastics, and mounted up a set of 17.5” Walker Evans snowmobile shocks with a lots of adjustment.
The killswitch utilizes a Fender guitar tether, and Jake is an artist with aluminum, so an alloy gas tank was a must:
“To round out the vintage YZ look, I built an aluminum gas tank with moto-style shrouds. It’s all made from .063” 6061, so it’s nice and lightweight. I think it really brought the whole bike together.”
Given that Jake lives in snow-covered Minnesota, he hasn’t been able to get it out in the dirt yet, but it shows promise on the tarmac:
“I have ridden the bike on the street a few times, and it will definitely make you giggle. I always forget how fast RDs are…. It definitely lights the tire real quick on pavement.”
Below, we talk to Jake for the full details on this RD350-powered hillclimber, along with more photos from David Carlo (@davidcarlophotography) and Matt Gustafson (@very.dumb).
Yamaha RD Hillclimber: Builder Interview
• What’s the make, model, and year of the donor bike?
This bike is a mix of quite a few different models. The engine is a 1973 RD350, the frame is a modified 1970 Yamaha DT1, the seat is from a 1982 YZ250, and the forks are from a Yamaha IT250.
• Why was this bike built?
I originally found this bike on Facebook Marketplace for $500. It was already set up as a hill climber, but it was in real rough shape and there was zero thought put into aesthetics at all. That said, there was no way I was going to pass up a $500 RD! It even came with a bunch of spare heads, new pistons, and gearing. Not only was it a great deal, but I also saw quite a bit of potential in the bike. I thought I could just throw some plastics on it and rip, but as usual, things got carried away.
• What was the design concept and what influenced the build?
The seat influenced the design big time. 1982 was the first year that the seat went up onto the gas tank in the YZ250s, which is pretty neat. I thought I could build a cool tank that would follow the lines of the seat nicely and keep the vintage YZ vibes.
• What custom work was done to the bike?
I started by cleaning up the frame. I relocated the battery and detabbed the subframe. The fabrication done to fit the RD engine into the DT1 frame was very rough, so I had some fixing to do there as well. I also added some gussets for a little piece of mind. Then I fit some Yamaha yellow Preston Petty fenders and oval number plates.
The shocks the bike came with were shot and I just happened to run across some 17.5” Walker Evans snowmobile shocks for free so decided to use those. Just had to build new shock mounts. They feel good and have a lot of adjustment!
To round out the vintage YZ look, I built an aluminum gas tank with moto-style shrouds. It’s all made from .063” 6061, so it’s nice and lightweight. I think it really brought the whole bike together.
One kind of neat part on this bike is the Fender guitar tether/killswitch. The bike originally came with a small 3mm aux plug as a kill switch, but I thought it could be way cooler. So I hit the interwebs looking for a port that I could plug a nice cable into. I ended up finding a pretty robust barrel style port that I could clamp to the handlebars. I CNCed a little clamp and voila.
Other custom parts include modern YZ450 foot peg mounts, CNC chain guard, CNC front number plates mounts, and chain guides.
• Any idea of horsepower, weight, and/or performance numbers?
Stock RDs with expansion chambers are about 50hp, but I don’t think this one is stock. It’s running 32mm carbs vs. the stock 28s, and it also uses a shorter plug than stock, so the heads must be shaved. I haven’t had it apart yet to see what kind of porting has been done but it feels very strong! I would guess that the bike weighs about 250lbs.
• Can you tell us what it’s like to ride this bike?
Since I live in Minnesota I haven’t had a chance to ride this bike on dirt yet. I have ridden the bike on the street a few times, and it will definitely make you giggle. I always forget how fast RDs are. The powerband is a pretty unique feeling on these things. It definitely lights the tire real quick on pavement. I plan to take it to some local hillclimbs in Minnesota and Wisconsin this year. Can’t wait to see how it feels then.
It’s front brake only so that feels a little spooky at times. Might have to change that!
The most notable thing about riding this thing is that it is very loud!! Earplugs are a pretty good idea.
Was there anything done during this build that you are particularly proud of?
I’m proud of the fact that it is so wildly different from anything I’ve done. I’ve never even thought about building a hillclimber until I stumbled upon this one. I’m stoked that I did!
I want to give a big shout-out to my buddy Rich Christoph. He and his family have been super cool to my girlfriend Taylor and I since we moved from Wisconsin. He is letting me work out of his shop which has been a huge life saver. This would not have been possible without him! He is also a real talented dude. He designed one of my favorite production bikes ever, the Indian FTR1200.