I just started racing 1/8th scale off-road this spring after racing electric for 19 years. It's taken a lot of learning and work but I'm starting to get a little bit of a handle on it. Here's the important things I've learned so far:
- Get a temp gun. Raytek makes the most popular one.
- Ask around on here to find out what temperature ranges, glow plug and exhaust pipe works best for the engine you choose. Also find out if there are exhaust manifold gaskets available and whether they're included with the engine. (The OS RG motor doesn't have exhaust gaskets included with them, but they're available, and necessary)
- Also ask around to find out what clutch shoe and spring (if applicable) combo works best for the clutch you choose
- Use high-temp RTV on the following areas: Engine back plate, base of the carb, base of the high-speed needle
- Use JB Weld on the exhaust pipe pressure fitting
- Triple super ultra check your vehicle regularly for exhaust and fuel leaks. I found exhaust leaks that had cropped up on my car several tanks after I got it that were affecting performance. Don't forget to check the back of the engine and the exhaust pipe pressure fitting as well.
- Replace your fuel tubing regularly. Sometimes leaks develop in the tubing that you won't see until you remove the whole tube
- Make sure you see smoke when you jump on the throttle anywhere in the rev range. If you don't see smoke, you're too lean! For good examples of how much smoke you should see and when, head over to http://neo-buggy.net
set yourself up an account, then go look in the video archive section and watch what the pro's cars look like on the track
- Don't perform needle adjustments before the engine is up to full operating temp. I've actually found that my needle adjustments that I make on the street in front of the house, even after I get the engine to temp, aren't quite right when I'm on the track. I usually have to richen both needles up a little.
- Adjust your high speed needle to get your overall engine temp first, then work on the low speed needle
- If your vehicle idles wonderfully for 30 seconds or more and drives away without any stumbling, your low end needle is way too lean. The motor should start loading up after about 10 seconds of idling at most.
- Easy way to adjust low speed needle: Get your high speed needle set, get the engine to full temp, then stop and idle for 5 seconds. Mash the throttle. You should get a good puff of smoke, and the motor should even stumble just a hair when the needle's right. If you get no smoke, or a little smoke and the vehicle pulls away with no stumble at all, you're too lean. Once you've gotten that set properly, run the vehicle around some and double check your temp again. You might need to move the high speed needle a little to get back to the temp range you want to be in.
- Check your clutch bell bearings regularly. If they starting binding, you'll get weird stalling issues that can send you on a wild goose chase.
Piece of cake, right?
I wish they had fuel injection systems for these things. hehehe