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Nitrous oxide, is it a viable tuning option?

January 19th, 2010

Is nitrous oxide a viable tuning option? Yes, is the quick answer, if you’ve got an appetite for destruction…

As glamourised in films like The Fast and the Furious, nitrous oxide (N2O or NOS, the American brand commonly referred to, is a substance (gas: two parts nitrogen, one part oxygen stored in compressed liquid form in bottles) that has often been talked about when it comes to speed but rarely used when it comes to automatic scooters, relatively speaking, and it’s no surprise why. The companies that sell nitrous kits claim that they’re safe although obviously this depends on engine set-up and the rider. More often than not those who opt for nitrous tend to be the less cautious type anyway. In cases where I’ve seen nitrous used it has usually led to problems and continued expense due to things like melted pistons, broken reed petals, warped crankshafts, cracked engine cases and road accidents. In one instance during a drag race a scooter flipped due to excess gas left in the crankcase from a previous run and the rider ended up in hospital. So there’s the short answer, if you want safety and day-to-day reliability then don’t use nitrous, better to stick with tried-and-tested tuning components that can offer (in most cases) guaranteed success. The problem is, if you’ve done all that but still yearn for more power.

It has been proven with many smaller capacity two-stroke engines (Honda Melody included) that nitrous systems can be used quite effectively but can be difficult to set up. Get it wrong e.g. too lean a fuel mix and be prepared for engine rebuilds. In situations where nitrous has been used in short bursts e.g. on the drag strip, it can lead to excellent results. So far however it’s been seemingly European tuners and a minority of Brits who’ve been brave enough (or indeed, daft enough) to use nitrous as a performance enhancement. Many of the UK scooter tuners, particularly those partial to sprinting have, many a time, shunned the idea of using nitrous opting instead to go down the normally aspirated route, with the purists among them sticking to their principles of using scooter parts only on their beloved two-strokes.

Opinions aside, what does the future hold for nitrous and scooters? Well there are some UK scooter tuners who’ve used nitrous on both two- and four-stroke scooters with a great degree of success, a good example is TDR Scooters in Wellingborough who’ve used nitrous oxide on their record breaking sprint bikes:

But for regular road use, four-stroke engines could prove more reliable than their fragile two-stroke counterparts. A while back I watched some video footage of an Italian-tuned 500cc Yamaha T-Max fitted with a home-made nitrous kit. And, unless the film had been speeded up (which I find doubtful), the results seemed shocking not only because I’m more used to seeing two-strokes accelerate that quickly, but because the rider only just escaped with his life after a very near miss. In terms of practicality there’s the problem of getting gas bottles filled. Gas bottles must now be PI-marked and come with a valid test certificate before they can be re-filled by a British gas supplier. The nitrous systems that are available in kit form tend to be quite expensive, expect to pay around £400+ nowadays. And with two-strokes you need to be prepared for problems like frozen/broken reed petals, engine lubrication (lack of), ignition timing and excess gas in the crankcase can only end in tears. Generally, the con’s tend to outweigh the pro’s when it comes to using nitrous oxide on a scooter, so to this end it hasn’t really been a viable tuning option for most.

Words & Photos: Paul Robinson
Video: TDR Scooters