Hello,

I am trying to get better performance from my recently purchaced Honda nx 400 Falcon that I purchased in Santiago, Chile.

It seems to be lacking in power. I have a difficult time maintaining 100 kph except for on the flattest of terrain and it is a real pig when climbing (me 90 kilos, load 30-35 kilos). It feels more like a the 1978 xl 250I owned when I was a kid. The 1979 400 cc Kawasaki LTD I had would easily cruise at 75mph with two people


I am considering lowering the gearing by getting a smaller (1 tooth) front sprocket and am wondering what differnce I can expect this to make as far as overall performance. I am sorry to say that I do not know the size of the front-rear sprockets now so I hoping to get an idea ¨in general.¨ The bike is at the mechanics now, so I can´t run out and count the sproket size. I am having the valves and carb adjusted, but am assuming this will not make too much of a difference. Right now she is at about 5000 rpm at 60 kph. Fifth is only useable on the flats and I am down shifting on the slightest of inclines. She is also a little tall in the first gear for negotiating technical terrain with a load. Can anyone venture an educated guess at how much differnce a smaler front sproket might make? Should I consider two teeth lower?


What else I can do to get a reasonable performance level for a modern 400cc. Possibly K/N filter?

Sorry to be so vage but any info would be appreciated.

BTW, I have found out it´s sprokecks are 15t & 40t.

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India Himal, 3mo,2x; Kazak/Krygyz/Tajik, 3 mo; Kashi-Lhasa, China 219! 6 wk; Nepal, 4 days/trekked 55; Santiago-Ushuia-Cusco, 7 mo; Peru, 3 mo; Chile-Medellin 3 mo; Medillin-Arica, 3 mo

Hi Neal,

I am not real familar witht he 400, I did have a 650 so I thought I would have a stab at the problem.

It looks to me that the gearing you have is wrong, 5000 rpm at 60 kph is about 12 KPH per 1000rpm and you shoud be nearer 18 KPH per 1000 rpm. I think the peak power is around 6500 rpm. At 5000 rpm you should be pulling around 90 kph.

The ratio you are running now 15 / 40 is 2.66 to 1.

1 tooth less is 2.86 to 1 about 7 % increase, 64.2KPH at 5000 rpm

Can you find out what the standard sprockets should be?

I maybe completly wrong about this.

Steve

I could be wrong about the revs versus speed, but I am sure the stock sprokets are 15-40 and I am considering 14-40. It is also speced at 29 hp at honda chile.

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India Himal, 3mo,2x; Kazak/Krygyz/Tajik, 3 mo; Kashi-Lhasa, China 219! 6 wk; Nepal, 4 days/trekked 55; Santiago-Ushuia-Cusco, 7 mo; Peru, 3 mo; Chile-Medellin 3 mo; Medillin-Arica, 3 mo

It could climb any trail .... in 3rd gear! A ton of power.

Good luck,

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Patrick passed Dec 2018. RIP Patrick!

Has it suddenly got worse? Maybe some crap fuel or damage to the exhaust. You don't say what altitude you're riding at, that will have an effect too. What happens if you pull the choke out a bit does it get better? Also check the rubber between the carb and the inlet manifold. If it's cracked there could be air getting in and making it run lean. I'm sorry if you've tried all of these already but I'm thinking aloud. Good luck, nothing worse than a lack of power!

I like the idea of an air leak.

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Patrick passed Dec 2018. RIP Patrick!

If the sprockets are correct and I guess it red lines at 8500 or so, it will have a top speed of around 100 KPH.
if it will not red line in 5th will it in 3rd or 4th if so the smaller sprocket may help but you could end working the engine harder.

Patrick may have a point about the timing not advancing.

But even with all the Bolt on tuning goodies you will strugle to add more than a few extra BHP.

if it is remains the same after the service, you may have to accept it is what it is.

What sort of fuel consumption are you getting?

Steve

The nx4 falcon is based on the xr400 motor. The specs are here¨--

Honda

After a valve and carb adjustment, the bike feels much stronger, though I haven´t had it out of the city yet. I will go for a test ride (loaded) today, but still think I may want to lower the front sproket tooth. It seems a little tall in first gear for riding techincal terrain and I will likely gain access to more up the upper powerband when loaded.

I will check out what I can do with the airbox.

Thanks

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India Himal, 3mo,2x; Kazak/Krygyz/Tajik, 3 mo; Kashi-Lhasa, China 219! 6 wk; Nepal, 4 days/trekked 55; Santiago-Ushuia-Cusco, 7 mo; Peru, 3 mo; Chile-Medellin 3 mo; Medillin-Arica, 3 mo

Removing the snorkle in most cases will be only getting HALF THROTTLE.

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Patrick passed Dec 2018. RIP Patrick!

I got her out on the open road for a while today. It´s a little stronger, but still rather "uninspiring." I openend the airbox and tried that way for a while, no0t much more power, but lots more noise.I think the trick will be a single tooth smaller sprocket, I´m only at 5600 rpm at 100 kph and a 7% boost in revs should´t hurt. Also first is a little long legged for tackling technical terrain with a load. Unfortunately, I have been unable to locate a sproket and must be going. Hopefully in Bariloche.

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India Himal, 3mo,2x; Kazak/Krygyz/Tajik, 3 mo; Kashi-Lhasa, China 219! 6 wk; Nepal, 4 days/trekked 55; Santiago-Ushuia-Cusco, 7 mo; Peru, 3 mo; Chile-Medellin 3 mo; Medillin-Arica, 3 mo

I must say, valves and the like is the first place I look, when a bike is not pulling well. Was the air filter dirty? Is the spark plug looking healthy?

As for the uninspiring ride, the NX400 may be based on the XR, but that is where the similarity ends, i suspect. The NX650 (Dominator) pulled well, but was a more sedate motor than a trail bike equivalent. The NXs are road bikes with off-road styling, so do not expect your engine to pull like an XR: it was not made that way, IMO.

Also there is probably far more body work that it must pull along...
I'm sure it will get you to all the places you want to go though. Only, perhaps not on the back wheel!!

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Adventure: it's an experience, not a style!
(so ride what you like, but ride it somewhere new!)

Hi Neal,

5600 rmpm at 100 kph is as expected, I think this motor is made for the South American market tuned to cope with the low grade fuels.

Tipo Monocilíndrico de 4 tiempos, SOHC, Refrigerado por Agua
Cilindrada (cc) 397,2
Diámetro x Carrera (mm) 85,5 x 70,0
Relación de Compresión 8,8:1
Potencia Máxima 21,6 Kw @ 6.500 rpm
Torque Máximo 33,0 Nm @ 6.000 rpm

The differece between a 14 tooth and 15 tooth sprocket is easy to check for your self. I think the 4 th gear ratio and 5 th gear will be under 10 %. if you know what the ratios are you can work it out.

With a 14 tooth sprocket your speed at 5600 rpm will be 107 kph.
ride in 4 gear and see what the speed is at 5600 rpm and my guess is it will be around the 107 area. See how it rides in forth.
Can you reduce some weight, 35 kilos sounds a lot, that will help.

Steve

My Falcon is now 3 years old, around 15,000 K on it. Yes, the Falcons NX400 and Tornados XR250 manufactured by Honda in Brazil are carbed for low grade fuel, very low, and we both find our bikes perform better on lower grade fuel, very weird.

Like the Transalp, designed for the Alps, the Falcon was designed for South America. It is, in my humble opinion, all the bike anyone would need to tour anywhere in Mexico, Central or South America.

We had an experienced rack man "Pato" a friend of Mariano at Motocare in Buenos Aires, do our custom racks and he even built me a not so small metal pannier for my tools, etc.it fits very nicely below the rack for my soft saddle bags.

The only problem experienced through 5 South American countries and more than 12,000 K, much of it on gravel, was power loss under stress at around 4000 meters altitude and above. And, a needed clutch replacement.

Elisa rides a Honda XR250 Tornado and we both pulled our air filters and were able to lug up the steep grades at Paso de Hama fine. It was just too damn cold to change carb jets.

The NX400 is air cooled NOT water cooled (NO Refrigerado por Agua), I have a top end, one up, fully loaded with gear of 130 K/ hour plus and more without gear.

How is your clutch? About 1000 K ago I replaced mine after noticing loss of get up and go. With the new clutch it just jumps. I didn't start noticing the clutch slipping as I have on other bikes. But, my Faclon was acting a bit like your Falcon. I also replaced spark plugs - there are a variety of plugs available for the Falcon, make sure the ones you have are designed and gapped for your needs...

The NX400 has a quirky little way to check oil, it is in the manual and to check oil requires a warm up and "holding the bike level" for several minutes, until oil drips down, having too much oil, apparently can damage the engine.

I have no complaints with my NX400, nor does Elisa have any complaints with her XR250. She has yet to replace anything except air and oil filters. Both were manufactured in Brazil and purchased new in Buenos Aires.

For those interested, we both cruise, fully loaded between 100 k per hour and 110 k per hour, no problem. We have pleanty left to pass trucks etc...

We have almost exactly the same fuel range just under 300 k Falcon with 15.5 liters and Tornado with 11.5 or so. We each carry a 3.9 liter spare fuel tank for over landing.

Hope checking clutch helps. I am not a mechanic, but rather intuitive. xfiltrate

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your bike sounds like its below average. I'd hold fire on changing gearing till you've solved the problem.

has the problem started recently or got worse and worse?

have you checked the spark plug colour? check it before riding, then do a high speed run for a few kilometres. while at high speed, cut the ignition, pull in the clutch and stop the bike to see if the colour is black/white etc. if black, its too rich. if white, be grateful that you haven't seized the engine - yet! from what you said about opening up the airbox, I'd suspect its either very rich (too big main jet) or the timing is retarded. is the ignitor hot at the end of your high speed run?

Benos Dias from Cos Mala, AR. Problem solved, basically.

As I mentioned, I adjusted the vavles and carb as well as a new plug. Air filter was OK, (I will change it in Ushia). I also had the clutch changed as it was exasperating to hit nuetral when the bike was running. How the previous owner finished a clutch in 7000 km of pavement leaves me bewildered. This resulted in a small increase in power.

The key was changing the 15t front sproket for a 14t. This was just enough to get me some access to higher revs in 5th. Now, instead of always shifting between 4th & 5th for barely perceptable inclines while cruising the flats, I can cruise in 5th and even pull 5th gear up a reasonable little hill. The lower 1st gear is very nice as well for technical terrain when loaded. I haven´t seemed to loose any top speed, and the economy seems to be the same, if not better.

She is perfoming as expected now, if still a little unispiring.

Thanks for all the help.
n

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India Himal, 3mo,2x; Kazak/Krygyz/Tajik, 3 mo; Kashi-Lhasa, China 219! 6 wk; Nepal, 4 days/trekked 55; Santiago-Ushuia-Cusco, 7 mo; Peru, 3 mo; Chile-Medellin 3 mo; Medillin-Arica, 3 mo