Why do you recommend V-Twins over the Single Cylinders?
Both engines will accomplish the task of repowering your golf cart and give you more power, however, there is a distinct value difference between the two which you shouldn't ignore.
The smaller engines(420-460cc) have a few major drawbacks which require alternate solutions to overcome which in turn costs you more money and more importantly, more time.
Drawbacks of 420s:
1. Insufficient Charging Output - These smaller engines have 2amp charging coils which will not keep your battery charged. Many people will say the v-twins have weak charging systems but with 10amps of power they are 5x more powerful than the 420s and we've never had issues with batteries dying. In order to fix this you need to either add an external alternator or use a Starter/Generator which adds costs.
2. Splash Lubrication - This was covered a few months back in a previous article but essentially these engines last 1/4 as long as the V-Twins on average because they don't have pressurized lubrication. Read my article here for more details. (This does not apply to the new 459cc engines from Harbor Freight)
3. Minor Power Increase - The 420cc is little more than 100cc larger than the factory engine and thus, the power increase is not as drastic as most people want or expect from spending $1200+ on an engine swap. We find that many people end up switching to the larger 670cc engine within a years time, simply for the massive power increase it provides. The 670s are over double the displacement of the stock engine and the power increase is dramatic, its a completely different cart and increases the carts functionality and utility significantly more than a 420. Our customers tell us that a 420 feels like 50% more power than stock and the 670 feels like double the 420.
4. Lighter Duty / Lower Quality - The 420s are much lighter duty engines and the build quality tends to be much lower than the 670 simply because of the price point they are selling them for. Its a common thing to blow up/burn out starters on 420s but 670s have monster starters that last for many years. The same goes pretty much every part on a 420cc engine, they are roughly 50% smaller and can take much less abuse.
5. Noise & Vibration - Single cylinder engines are nearly impossible to balance, especially straight from China. These engines tend to vibrate severely compared to a V-twin which has opposing cylinders to cancel out some of the vibration.
Noise is also a huge factor, the V-twins tend to have a much deeper tone (think Harley) vs the Singles which are tingy and high pitched. Your ears will perceive the smaller engines as being much louder as higher pitch noises travel faster and easier through the atmosphere.
6. Resale Value - Golf Carts that are cleanly converted to a V-twin hold significantly more value than any of the single cylinder carts. You'll routinely see V-twin carts go for $1000-$1500 more (depending on location) than any of the cheaper alternatives. This is a huge factor when you consider that the conversion cost difference is usually less than $500 to go with the better engine to begin with.
For the above reasons, we recommend a V-Twin whenever possible over a single cylinder, especially when the cart is being used for utility purposes. The exception would be un-lifted carts and those who cant have an engine idle and must retain the pedal start.
This question is getting more and more common. I'm not sure why people automatically flock to the cheapest option when it comes to golf carts, but the folks who do, definitely end up paying more in the end to do the job twice...just like anything else.
But Once, Cry Once!