After a particulary wet day I was riding home when the bike started to lose power and then pick up again. I was riding at about 7500rpm when it would drop suddenly to the point where it would almost cut out but then it surge back up again (never moved the accelarator). This carried on for about 10 mins (2.5 miles) and eventually it did cut out. i tried to start it but it wouldn't so I left it for another minute and it started up fine but then continued to surge and lose power. I thought it might just be the rain getting in somewhere but I left it over night in the garage to dry. Next morning it started up first time but still continued to lose and then regain power after driving ok for about 100 yards. I put a new coil and spark plug on about 2 months ago, is it possible that the air filter might be dirty and need replacing thus its not breathing right?

Stewart featherstone, October 2005

i also own a dna 125 and have had similar problems; my problem was actually the ht lead had snapped near the spark plug, thus causing the loss and gain in power, i shortned the ht lead as the damage was about 4mm from the end but your may need replacing.
mike

mike, July 2006

clean the ht lead which is on the coil and has the ht cap on the end of it also make sure the ht cap fits on the spark plug nice and tight ,dont use wd 40 its a conductive lubricant use holts damp start its an ignition sealer the lead and cap may have been holing some water from the rainy day and causing it ti misfire even days after ok this is definately an electical problem nothing else, the spark to the plug is disappearing which is causing your misfire ,adam

adam, December 2005

Thanks very much for the advice Ben I might just give that a go.
The only thing which concerns me is that when I took it out the next day which was a dry day it still did the same. Is it likely that it got so wet that there is still residue\condensation around the plug ? Would it be worth taking it out and carefully drying it with a cloth?

Stewart, October 2005

you are getting water into/onto your spark plug. this is a common problem with NRGs. somebody surgested i sprayed DW40 around the spark plug to help the water drip away from the spark plug area easier, and it has worked, another way to stop this is just plain and simply dont drive in heavy rain and through big puddles.

ben g, October 2005