Need Mods to Improve Power/Efficiency of Honda GX35 + Electric Starter & EFI Install

[shellboi]

I'm an engineering student working on a vehicle project involving a Honda GX35 engine, and I’m looking for ways to improve its power and efficiency (efficiency takes priority). I also need to install an electric starter and convert it to an electronic fuel injection (EFI) system as a requirement.


My Goals:
Increase power and/or efficiency – Looking for performance mods (intake, exhaust, tuning, etc.).
Install an electric starter – Any kits or DIY solutions for this?
Convert to EFI – Are there small EFI kits that work with the GX35? Any recommendations on sensors, injectors, or controllers?


If anyone has experience with these kinds of mods, I’d love some guidance on what parts to use, what challenges to expect, and any resources that could help. Thanks!

 

[Darren]

The start of a 265cc Ducar cast build with full efi control, GX200 clone

Introduced myself in the appropriate section, made sure I could continue with this build before starting a thread. Step one was the flywheel. The Flywheel is finished, well it's really just a trigger wheel with extra bits... I've now purchased most of the bits for the engine mechanical part...

www.diygokarts.com

Still ongoing, now changed to a NO2C board, should have it up and running the weekend

 

[Hellion]

The Honda GX35 is a 4-stroke single-cylinder gasoline engine of 35cc displacement that produces about 1.3HP. Like the GS series it has a belt driven overhead cam but it is basically a brush cutter engine. Neat!

 

[Hellion]

Was this engine your personal choice or the instructor's?

1.) Increase power and/or efficiency – Looking for performance mods (intake, exhaust, tuning, etc.).
Put a straight pipe on it. Doubt you will find one pre-made because, ta-daa, this is a commercial weed eater engine.

2.) Install an electric starter – Any kits or DIY solutions for this?
For a feasible starter the obvious component would be a toothed flywheel (a gear mounted to it). How about a friction wheel starter?

3.) Convert to EFI – Are there small EFI kits that work with the GX35? Any recommendations on sensors, injectors, or controllers?
No idea. If I told you I'd be doing all your work for you.

 

[65ShelbyClone]

I'm an engineering student working on a vehicle project involving a Honda GX35 engine, and I’m looking for ways to improve its power and efficiency (efficiency takes priority). I also need to install an electric starter and convert it to an electronic fuel injection (EFI) system as a requirement.


My Goals:
Increase power and/or efficiency – Looking for performance mods (intake, exhaust, tuning, etc.).
Install an electric starter – Any kits or DIY solutions for this?
Convert to EFI – Are there small EFI kits that work with the GX35? Any recommendations on sensors, injectors, or controllers?


If anyone has experience with these kinds of mods, I’d love some guidance on what parts to use, what challenges to expect, and any resources that could help. Thanks!

So how is it going/how did it go?

For a small EFI controller that has the software already done for you, a Speeduino NO2C seems like a good candidate. It's the same footprint as an Arduino Mega 2560 and has two injector and ignition channels (NO2C = no overhang 2 channel), among many other features, and is about $65 for a kit.

Modest increases in power are fairly straightforward and would involve optimizing the intake and exhaust and, if you're brave, making improvements to the valves and ports (easier said that done due to the monohead design). Actual increases in efficiency/brake specific fuel consumption (BSFC) are probably more elusinve I would think. Load-based ignition timing facilitated by an EFI controller and mixture control with wideband O2 feedback is an obvious place to start.