hey guys, i just got this 99 nighthawk 250 and so far it runs good until i get up to about 55 mph. then i starts the sputter or misfire every now and again. it did it about 10 times in a 20 mile ride. i was told by honda there is no oil or air filter to change. not sure where teh fuel filter is at if there even is one on the 250. this is my first bike so i dont know all the mech side of motorcycles yet. any ideas of what could be the cause of the sputter?

 

I had the same issue with my Nighthawk, but around 65-70. The best I came up with is the little 22mm carb is starved for fuel at higher speeds since the throttle is cracked open almost all the way 24/7 to maintain speed and the super tiny float bowl runs dry with the quickness. I solved this by periodically closing the throttle all the way for a second or two just to let the bowl fill up completely and then continuing on as normal.

That is of course presuming everything is in working order, so double check your plugs and their gap, and make sure the carb throat is nice and clean.

 

i just put new plugs in them and they were gapped to 0.028 like it said to do for this bike. not sure how to check the carb throat on a bike yet. i have had the bike for about a week and thats all of my motorcycle experiance

 

but it definately sounds like what ur saying is right on the money. it felt like no fuel for a split second and it was only when i was tryin to do the speed limit of 55 out in the cuts. if i backed off to 50 it didnt seem to do it, or atleast not nearly as often

 

also i know honda cars are know for their ability to interchange parts between cars. is there a carb that will bolt onto the 250 that gets better fuel flow?

 

Not to the best of my knowledge, the Nighthawk 250 hasn't really been changed in any way in the past 25+ years so there isn't even a newer carb design to switch to. The bike should do well up to 60+ MPH without any kind of choking so my best advice would be to pull the carb off and clean out the inside + Re-seal it. You'll find a few "How-To" videos on youtube for it and that should get it running just dandy below 75MPH for just a few bucks and a bit of labor.

 

I think you should consult a good mechanic about this problem.may be he can help you out with this.

 

hmm, I had a '94 CB250 and never had this problem. Bought it new in '96 and put like 12,000 miles on it in 9 months I wish I had kept it. Great little commuter bike (if you don't mind going slow).

 

My fiance's Nighthawk 250 does not have this issue either. Carb cleaning would be my first idea.