How to Build a Competitive Kart Racing Engine (Stock Appearing)

A little advice on checking the valves for leaks: DON'T use water. I've seen so many people do this thinking that because water doesn't drip out the intake or exhaust, that there's no leaks. The reason you don't use water is because you're putting water on previously oil coated surfaces that are polished, which makes them slightly hydrophobic. With the surface tension that water has on that hydrophobic surface, it can float above small gaps and not bleed through. Instead, use a solvent like acetone, xylene, or even gasoline. They have lower surface tension, and will actively leech through any gaps or leaks in the valves. Hope this helps.

Man! This is GREAT! I'm a 42 year old automotive master technician and I had NO IDEA they made sooo many parts for small engines! You just opened a whole new world up to me! Coolest thing I've seen in years!

im afraid you are now part of the automotive community and you may never stop making automotive content. Congratulations!

This is one of the best engine build videos I've ever watched. If a person can quickly and simply explain a complicated subject then they actually know what they're talking about. 10/10

Alright, I don't have interest in go karting,, and I haven't messed with engine building for almost 20 years, but I watched this entire video because I follow your interests that you share via videos and the podcast. You have gained so much knowledge from when you started this hobby, which is really awesome to see. Your knowledge and passion is clear in this video. Kudos, and keep it up!

You are the cleanest mechanic I have ever seen. You rock Dave. “Some of us don’t have friends “ You always crack me up with your humor.

When resurfacing a head with the flat glass/sandpaper technique, work the head in a figure 8 motion to avoid uneven material removal.

When i first came across this video and had little to no experience with building or modifying these (or any) engines, I never got past the first couple of minutes. Now that I have modified several engines and I'm always swapping or grinding something to pull that little bit extra power out of them, this video is way easier to keep up with. I like the fast pace you've managed while being as thorough as this video is. One of the best clone building videos on YouTube, and Im confident because I think I've seen most of them. Great job.

That brought back memories of my younger days messing around with cars. I did the heads on a 1990 Thunderbird I bought for $500 while I had it parked on a jobsite I was working at 20 years ago, and that was the last time I did any serious engine work. Now I'm thinking gas powered table saw... :) Awesome video, David!

Ive been telling people for years to flip these small engines to lubricate them before the first start Its good to see someone actually doing it

I was an engineering technician at Briggs & Stratton and worked on kart engines as well as the dragster engines. Fascinating, I never realized the fanatical customer base for these engines.

When i raced box stock i took new head gaskets to a shop with a 300 ton press. I made 2 steel plates 2" thick , put the gaskets between them and reduced them to the minimum allowed thickness. It helped get that fraction of compression other builders didnt have. Every tiny bit helps as you know. Great video!

I started racing when I was 15 sprint kart racing (short course asphalt). It was a great place to learn to drive. Then I got into road racing karts. It was huge in the 80s. Every Christmas our family would race at Daytona. The smallest class I would run still had 50 or 60 karts. Some classes (usually Yamaha) had over 100 entries. It was the most fun times I had with my dad, not just the racing but the hours of preparation we spent in the shop and the travel to the races. It was all good, and I learned so much. It was a great way to grow up. Thanks for bring back the memories, even though we ran two strokes 😜. Be safe and have fun 👍

Racers today do not know how lucky they are having videos like this. When I started in the 80s, racers would tell you a little & the rest was bullcrap. You had to get pieces from different racers and put them together to get the whole picture.

Watching from the perspective of someone who grew up on an automotive machine shop, looks like you did a great job. You can build a flow bench and actually play with porting a lot more. There is even a way to smoke it and actually see the flow characteristics and what a subtle change can do.

My wife wants to get back into gokart racing, she would've been doing races and shit when she was a kid but her dad started making excuses to take her. I'm getting it soon to rebuild and get her back into it. Definitely saving this video, you did an amazing job describing everything and explaining exactly why you make the modifications and their purpose for you. 10\10 my guy!

The best way to check for proper valve sealing is with a vacuum pump. It’s easy to make a plastic plate (add a quick disconnect to the plate) that bolts to the head and use a MityVac vacuum/pressure tester and you’re good to go.

Man I have never been into kart racing but I have to say I thoroughly enjoyed this video. From the detailed explanations to your fantastic cinematography and production. Absolutely amazing job with this video. 👏

Pretty cool! I built Hi-Po 'Lawnmower' engines in the 70s. Back then, the trick was to use Tecumseh engines (Forced Oiling) and we even converted some from vertical to horizontal flow, shaved the heck outta the heads and changed the oiling pickup. Ignition timing was adjustable on those engines as well. We used 5 HP camshafts in 3.5 HP engines and used two McCulloch chainsaw carbs on an Aluminum manifold. We started these engines on Gasoline then once warmed up, they were run on Methanol-Acetone mixture. Pretty heady stuff for a 15-year-old with a very smart Power Technology teacher and a small dynamometer.

Idk how yt brought me here, but as a mechanic that worked in a bikeshop and tuned engines myself, I was very pleased to watch this. You explain things very well for starters with no needed fluff or editing. Great stuff! Hope you have a great day good sir.