1997 Honda CB250 Nighthawk

Summary:

Overall a great, cheap to run, commuter

Faults:

I got the bike at 65000km (about 40000 miles), 9 years old with 9 previous owners. It wasn't in the greatest state, but was in good mechanical condition.

After half a year, and 5000km of hard riding, it was still running nicely. Just had to change its brake pads and tires.

Then I crashed. I put a hole through the crankcase, bent the forks, broke the headlight, indicators, tacho, and headlight. Luckily, with a naked bike, there were no expensive fairings that had to be replaced.

I pulled the bike apart and forgot about it. The engine crankcase was left open for 4 months in a damp carport, during winter, as I waited for parts to be fixed, and for the crankcase to be welded.

Surprisingly, with an engine mainly built from aluminium, there was little corrosion. When I finally put it back together, and it started straight away, no hesitation! Talk about reliable!

Since then, the head gasket has developed a slow, slight leak, which I can't be bothered fixing.

The seal in the front master cylinder has worn out, meaning the brake is really spongy (my version of ABS: it never locks up :) ). Still have to fix it, but its been over a year, and works well.

The engine also needs quite a bit of choke when cold. This may be because of using the wrong oil type, or maybe the engine's a little worn out. It's also starting to burn a little oil, but with 80000km on the clock, and with no real engine work ever performed upon it, this is to be expected. Rings and pistons probably a little worn.

Oh, and most recently, the clutch cable snapped. Again, it was expected, as it's been fraying for months.

General Comments:

Overall, the bike is great. Recently I removed the back plates off the exhaust, and got the carb rekitted. It's now running 15hp (and 16Nm st torque) at the rear wheel and sounds amazing!!!

OK, so it's not the most powerful 250cc made, less so at 80000kms, but it's still great.

The bike has a relatively low centre of gravity, and therefore is really easy to handle (better with flatter handlebars), with incredible low speed maneuverability, allowing for real tight turning circles.

Furthermore, as it is not a sports bike, you can't lean it over too far without scraping something (quite easy to do it). Still, it sticks to the road, and allows you to hang right off the seat. This means you can chuck it into corners with speed with little fear.

The suspension is adequate, a little soft, meaning it absorbs all the bumps without giving you a sore back (like CBR's, spadas, etc). Couple this with an amazing seat, and you got a bike that's great for longer trips. I went on tours the length of this country (New Zealand), and can comfortably ride for 3 hours without a stop.

The brakes are nothing special, they do the job. I own the variant with a front disc and rear drum. Back brake works a charm, but the front hasn't worked properly for a while.

In terms of the engine, I absolutely love it. Sure, it's not a highly tuned machine, but it sure does the job.

Being a parallel twin, the torque comes on early, and is nice and constant with the power all the way through the rev range. This means you can drive around town with low revs gears quite comfortably, using little gas.

Furthermore, a wide torque curve means cruising the highway is a breeze, with no need to continuously change gears when the hills come. It also means you can accelerates quite cleanly from 30km/h to 120km/h in 5th. The engine is also super reliable, with little maintenance.

The gearbox it pretty smooth, but could do with a 6th gear. 1st gear is pretty short, but powerful, meaning uphill starts, or starts in general are easy to perform.

Now, the specifications:

Milage:

town - 25km/l with moderate to heavy handed riding, 30km/l with cool/calm riding.

Highway - 35km/l.

Power:

Hp - 15

Nm - 16.

Top speed:

Maximum ever achieved - 146km/h (Desert Rd - long straight road, carrying 125kgs, passenger and luggage, almost as much as the bike itself (130kg) )

Normal maximum - 120km/h

Normal maximum with headwind - 95-100km/h

Two-up - 110km.

Acceleration:

0-100 - hmmm, about 9 seconds. definately not over 10.

Lastly, the Cons, well, the real singular Con - Power, or lack thereof. 5 more horsepower would be greatly appreciated. The bike is great, and can cruise nicely at highway speeds, however, when hills get a little too steep, or when the wind gets a little strong, the bike struggles. A couple more ponies could make this bike awesome.

Would you buy another motorcycle from this manufacturer? Yes

Review Date: 5th August, 2008

31st Oct 2008, 06:41

Love the reliability and the fuel consumption, but I don't get anywhere near the same sort of power.

Maybe I'll get a bike joint to service it and give the carby a clean/tune.

Oh, yeah, what is it with people crashing into you on a black bike?

13th Apr 2011, 20:40

I am a 30 year old bloke that lives in the state of Tasmania, in Australia. I was quite tired of the ever increasing fuel prices, and just started to work on my life-long dream! To finally become a motorcyclist.

I've had bikes before, but never bothered to get my motorcycle license until now. I had just brought a 1999 model Honda CB250 Nighthawk. I had a good look at the bike, and was quite impressed with its overall design, and it was similar to what I have always wanted to drive.

Anyway, I got the bike home and ran it through all the gears. Gears were all panned out nicely and everything worked well. I found that it wasn't incredibly powerful, but have got to remember that it's only a 250cc bike "with 50,000K's on the clock".

I also found that because these are generally used as learner's bikes, they have been designed and jetted to not be an incredibly racy bike. When there's a will, there's a way. I found the biggest problem by far for the Honda's low power output "and drastically awesome fuel economy" was its carburetor's jetting! These bikes run a 110 main jet and a 35 slow jet. I had changed the jetting to a 120 main jet and a 40 slow jet, rebuilt the carburetor at the same time, and lubed up all the cable links i.e. throttle cam and in the throttle grip. It took only a short time to tube, and had to go out 3/4 of a turn on the pilot jet, and had to wind out the throttle stop screw just slightly. I've also heard this will protect the engine life, because these engines burn incredibly lean at a factory tune.

There is another mod with the carburetor, which will increase throttle response. In the carburetor piston, there is a small air hole. Drill that out to 1/8th for increased throttle response.

Also, these NGK sparkplugs "factory replacement" are terrible at best! We've had nothing but trouble from them in the Automotive industry. I looked up some cross-referencing, and found that you can get Denso Iridium plugs to suit and replace the NGK CR6HSA's. The Denso plug part number is IUF22. They can take some tracking down, but there's plenty of them around on ebay, and that may be the best place to get them from. Running these plugs will give you a much greater efficient fuel burn, increase economy, and they only have to be replaced at around every 100,000K's or so. After these slight performance mods, the bike had picked up dramatically faster, and I was able to easily clock the bike "+140KPH".

The last mod that I had done for the time being was change the sprockets. The drive sprocket I had changed from a 14t to 17t, and the rear sprocket was changed from a 30t to a 28t. You'd think this would slow the bike down considerably, but not so. With the extra HP from the basic mods, the bike was more than capable of going a lot faster "Even from take off" from the best of stock CB250's.

The last mods I'd like to do is track down some kind of performance cam "if possible", bore the engine out & do some mass port work on the cylinder head, as well as plane of a couple of ml off the block surface and head surface to increase compression.

I've written this technical/mod info, as there is such a lack of information to mod out this bike.

Now back to the review part:

Engine is adequate for most riders with an apparent good torque rating. To me, the selling points of the bike is its styling, comfort of riding, great fuel economy, reliability, and good to adequate braking system. Not to mention the ease of maintaining the bike without needing a mechanic to do all your work.

Would I buy another one of these bikes??

Hell yeah!

In reply to 13th Apr 2011, 20:40

26th Nov 2011, 19:28

Hello. I own a 2008 Nighthawk. The size 40 slow jet is only listed as a part for the l986 CB450SC. Its part no. is: 99103-420-0400.

The 38 slow jet is listed: 99103-KR3-0380, but that is listed. Right now my bike bogs in the low end, so it definitely needs re-jetting on the slow jet. I just am not sure if it is a 38 or 40. If it needs one size up from stock, then it seems a 40 will be better with an opened up airbox. (I opened that up, and with the lean jetting, it spat like a mad toddler) Did you open up the exhaust also? Seems like good work. Thanks for a reply. Sincerely, Par3pio2@msn.com Paul Reichle lll.

In reply to 13th Apr 2011, 20:40

13th Dec 2011, 21:33

Hello.

I did what another owner did first, and put in one size bigger jet. 38 and 115. I put two small No. 4 washers on the jet needle. After my ride tonight in cold weather, the Denso Iridium plugs still read lean. I purchased also a 40 and 120 like this post, but the 40 was a different part no. and it is longer than the two other OEM pilot jets. Does this matter that it sticks further down in the carb. bowl?

I am going to add one more washer to the jet needle first, because it seems okay in the idle and low range. This also is why I didn't put on the K&B air filter, and I am glad I didn't. This is the process of trial and error. I was hoping you may have a part no. Honda for the 40 idle jet.

Thanks. Par3pio2@msn.com