Feature : Riding Nitro Harleys

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Riding Nitro Harleys

by Dennis M. Fisher

I get a lot of questions about these marvels, there’s one that pops up more often than not. Why do I do it?

There’s a number of reasons – I’m competitive, I engage in activities that are challenging, stimulating, thrilling. I have my limits mind you – I don’t rock climb or jump out of airplanes. Now those things are crazy!

Dennis fisher

No, riding one of these nitromethane powered beasts is quite enough, thank you. Think for a moment – there must be a reason we don’t straddle these beasts when we fire them up. And why is there that Kevlar strap encircling the motor? And why do the pilots wear a Kevlar chest protector? There’s usually a good reason rules are formulated and all this Kevlar is no exception. The strap around the motor is an engine restraint. Why is it called that you might ask? Because nitro can go bad, and when it does, really bad things can happen. Like explosions that can send motor parts in every direction – and without the engine restraint they do. After a number of serious injuries, the rule was made. Related to the engine restraint rule is the Kevlar chest protector – when those parts let loose, entering and exiting your body can be harmful to your well-being.

My experience with these bikes is mine, and mine alone. I’ll do my best to share my thoughts, experiences, but bear in mind another rider may see things completely different.

When I went to the school to get licensed on nitro Harleys, just standing next to them during the startup was terrifying. Heck, it took me over a year to not be terrified just standing next to it. Besides the sensory overload of nitro fumes, the piercing, deafening staccato bark so unique to nitro, you suddenly become aware of what it is you have to do next. And that’s throwing a leg over this beast that will give you the ride of your life – or scare the living daylights out of you.

There is much to learn. For street bike riders, the first thing you must get is the lever that’s your clutch on your street bike is NOT – I repeat – NOT the clutch. Forgetting that concept will likely have you doing a face plant at 175 MPH quicker than you can think – this is really gonna hurt!

For the novice rider you must also learn the throttle is either wide open or closed. “Peddling” the throttle is only for the seasoned pro. Getting on and off the throttle is the quickest way to blow up a nitro motor. And that gets expensive.

Another concept is steering. You don’t. You shift your weight and DO NOT lean. These bikes keep the front wheel in the air almost half the track. Which brings me to another lesson – keep the bars straight while that wheel is in the air. Failure to comply will test your manhood (no disrespect to the women riders). The bike will feel like it’s going to wash out from underneath you, with another vision of face planting. Keep your composure, nut-up and keep the throttle pinned. It’ll drive through it. Do want your instincts tell you – getting off the throttle – and you’re on your face.

So, here’s my view of a nitro pass –

First we have the bike on the jack behind the water box. We insert the starter cart shaft in the starter plate on the motor. Standing on the right side of the bike my crew chief takes the kill switch tether on the sleeve of my leathers and inserts the clip in the kill switch to activate the ignition. Once he give the starter cart operator the signal to start spinning the motor over, he uses a pressurized spray can to start the bike on a mixture of methanol and gasoline. Once the bike fires and is running, the nitro valve is opened and you quickly hear the change in tone – and smell – and feel. Nitro Harleys literally pound the ground. You feel it in your feet, and all through your body.

Once running, I’ll throw my leg over the bike, grab a handful of rear brake (right lever) to stop the rear wheel from spinning, give my jack man a nod and he lowers the bike. Blip the throttle and we’re headed to the water box. Rolling straight through it, the jack man will wipe the front tire dry so we have some braking ability without locking up the tire. Once in the correct position, I’ll grab a handful of front brake, twist the throttle to bring the revs up to around 4000 (by sound), and warm up the Micky Thompson slick for 4 seconds or so. Let off the brake, let the tire hook and give that cute little chirp as it hooks and head to the beams.


One of the most important aspects of the run is getting lined up “in the groove” and STRAIGHT! This is another critical role of the crew chief. If he can read the track, you have a gift. Use it wisely.

Once lined up where the crew chief wants it’s time to stage. Roll slowly into the first set of beams and get the pre-stage bulbs lit. Wait for your competitor to do the same. Now there might be some unsportsmanlike competitors out there that want to get cute and “double-bulb” you. That’s when they light the pre-stage bulbs and roll right into the stage bulbs instead of following the “courtesy staging” rule. Don’t let it get you off your game. Kick their ass to the stripe, then flip them off. Some sanctioning bodies will warn competitors if they do it often.

So you’re lined up and staged. You’ve already grabbed a handful of throttle, cocked your wrist and you’re ready to launch at the first sign of the yellow bulbs lighting. This is “reaction time” and many races are lost to quicker bikes with a “hole shot” win.

You see yellow and whack the throttle as hard as you can. Try to break it. You can’t. It’s time to hang on. You’re already breathing hard, heart rate is up, if the weather’s cool you might have an issue with a fogged visor or glasses if you wear them. It’s go time, so don’t let these distractions get to you. We had a race in very cool conditions before I learned to slow my breathing and avoid breathing through my mouth – when I slammed the visor shut and exhaled through my mouth everything fogged. I knew I had to go when I saw yellow and hoped my glasses and visor would clear in the first few feet. Thankfully it did clear and we won the round.

Whacking the throttle is like being shot out of a cannon. G’s are high – 2-3 and you’re accelerating at a pace you’ve never seen before. Gear heads get all worked up over 0-60 times of 3-4 seconds. How about 0-60 in 1 second? Try to hang on gear head! The first incremental time we look at is our 60′. Anything under 1.20 seconds is good, we’ve been as quick as 1.17 seconds. It’s a combination of clutch, tire pressure, track conditions and tuning. Misread it and you leave performance on the table or blow the tire away – and maybe your motor.

The launch is crucial – get it right and the rest of the run is straight and smooth. Hook or slice and you better be on your game and ahead of the bike. Get behind it and you’re going to end up somewhere you don’t want to be.

A well-tuned bike will carry the front wheel to almost half track. This is a critical moment, the bars must be straight when the wheel touches down, otherwise the pucker factor goes through the roof. And by the way, how quickly did we cover that 660′? Around 4.60 seconds – that’s just over 2 football fields! Imagine covering a football field in 2.3 seconds. Hello! One other stat – your speed at the eighth mile is approaching 150 mph.

By the time you get to the eighth, you should be “getting small”. Laid down on the backbone, elbows and knees in, tucked as close as you can behind the windscreen. This is no easy task, and seat time is the only way to get comfortable with it. The sensations you experience in that first eighth mile are overwhelming. The g’s are like being shot out of a cannon – other ways to describe it might be having your ass strapped to a cruise missile and hoping you can hang on for 1,320′. Another description might be like hanging on to a 1/4 mile long bungee cord – the acceleration is constant over the entire run.

Keep in mind these pro fuel Harleys are “high gear” bikes – no transmission, just a jack shaft transferring power from the clutch on the left side of the bike to the chain and sprockets on the right side of the bike. Can you imagine the torque to launch these bikes? Regarding the “constant acceleration” – the clutch starts engaging around 3000 RPMs and the idea is to put just enough clutch and tire pressure in the bike to keep the revs around 4000 while the clutch does its work in the first 2.5 seconds of the run. After that, the clutch is locked up 1-to-1 for the rest of the run while the revs climb to around 6000.


Let’s get back to the sensations and our run at half track – the wheel touches down and if you have that right you barely notice it. The sound is deafening, the sight picture is blurred by the vibration. The best way I’ve described this is the scene in the movie “The Right Stuff” when Chuck Yeager is attempting to break the sound barrier in the X-1 and the vibrations are so intense you cannot read the gauges in the panel. It’s that intense on a nitro Harley.

From the eighth to the traps it’s all about being smooth and in the groove. Once crossing the stripe, it’s time to get this missile stopped. Remember, the adrenaline is pumping big time and this is no time to get excited. Get off the throttle as soon as you cross the stripe – these motors don’t like revving over 6000, so pay attention. Pump the rear brake lever to settle the bike and slow down. Stay tucked, DO NOT sit up! Start easing in some front brake – keep in mind the tire is skinny and easy to lock up. Lock it up, chances are good you’re going to wash out and face plant. Once braking is under control and you’re comfortable with making the turn off, you can pull the kill switch tether to shut the motor down, shut off timer and Racepak switches and then reach down to shut the fuel valve. By now, the bike has slowed considerably and you are starting to breathe again.

I recall the first full pass I made on a nitro Harley – after making the turn off, my legs were shaking so badly I couldn’t get off the bike. The first thing that came to mind was a quote from a Clint Eastwood movie – “A man’s got to know his limitations”. At the s was it for me.

Now, three years later we’ve been a top 10 plate holder in the Man Cup series, runner up in the AMRA championship, runner up in the NHRA Harley Davidson Drag Racing Series Championship. People will race a lifetime and never win a Wally. In 2015 we won three – and so far in 2016 we’ve bagged two with 4 races to go.

So what’s next? Stay tuned, but that Top Fuel Harley sure does look like there’s another story just waiting to be written!

Dennis M. Fisher
Owner & Pilot
RocketFish Nitro Harley



  1. Chip
    Chip 28 June, 2016, 09:09

    Great article

    Reply this comment

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