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View Full Version : Bogging down in the power band then stopping?



nathan k
10-29-2012, 10:14 AM
Another problem with my Derbi gpr 2003 so I guess I should post here.

Cold rainy morning, I start it up using electric start let it warm up then drive off, 200 meters later it starts bogging down in the power band then about 30 seconds later stops all together.

even a running bump wouldn't start it so gave up and started pushing, 10 mins later I try again and it starts I manage to just get home as started to bog down again in the power band.

Had this problem about 5-6 times now and only seems to happen if it's raining or cold.

My 74cc Italkit has arrived but I don't want to fit it until I sort this problem out first :(

apriliamandan
10-29-2012, 10:30 AM
so as it starts to warm up, it bogs down in the powerband? Only in the cold weather, never in summer?

plug oiling up???

nathan k
10-29-2012, 11:56 AM
Only when it rains to be honest, A good example would be when me and a friend were driving around for about an hour with no problems, on the way home it started to rain and then when it hit the power band the engine would stutter and lurch forward every now and then until it came to a stop then awhile later it started and I managed to just about get home. Checked the plug when it stopped today and seemed normal, I feel like it's the spark i just don't know how the rain is effecting it?

apriliamandan
10-29-2012, 12:37 PM
yeah a weak spark, most likely the cdi is faulty and the cold/rain triggers it to pack up???

nathan k
10-29-2012, 01:21 PM
Well i've tried a couple of different cdi's I've had laying around with no difference, What could effect spark before it gets to the cdi?

chrism15
10-29-2012, 02:19 PM
sounds like a carb issue but if it is only happening when it is raining then it must be drawing in water from somewhere causing it to bog and splutter then ultimatly die

do you have the stock airbox or a open/cone/foam k&n style filter (id advise keeping the stock airbox)

(you can still post this in the tech section even though it isnt a RS50 )

next time it bog splutters and dies and it doesnt re-start just leave it till you get home or to a place you have access to tools, remove the carb and take off the bowl of the carb (taking care to keep the fuel in the bowl) and look into the bowl full of fuel and see if you can see any bubbles or droplets/clear balls sat on the bottom of the carb... this is the water which has seperated from the fuel

nathan k
10-29-2012, 02:51 PM
sounds like a carb issue but if it is only happening when it is raining then it must be drawing in water from somewhere causing it to bog and splutter then ultimatly die

do you have the stock airbox or a open/cone/foam k&n style filter (id advise keeping the stock airbox)

(you can still post this in the tech section even though it isnt a RS50 )

next time it bog splutters and dies and it doesnt re-start just leave it till you get home or to a place you have access to tools, remove the carb and take off the bowl of the carb (taking care to keep the fuel in the bowl) and look into the bowl full of fuel and see if you can see any bubbles or droplets/clear balls sat on the bottom of the carb... this is the water which has seperated from the fuel

Yeah it does have the stock airbox, I'll have a look if it's raining tomorrow but I still think it's spark. (no spark straight after it dies then after a few mins it's orange then after 10 mins it's blue and the bike starts).

chrism15
10-29-2012, 03:04 PM
remove the spark plug and put it in the ht lead like normal, crank it over and see if it sparks

nathan k
10-29-2012, 03:17 PM
Yeah that's how I looked at the spark

nathan k
10-30-2012, 04:22 PM
Bike blew up the other day, crank bearing and piston knackered. No idea why as everything is stock apart from the exhaust but the bike was jetted on a dyno by the previous owner!
Anyway I'll be on the forum a lot till I raise 300-400 to get it fixed
If anyone knows a decent mechanic I could mail the engine off to replace the bearings that'd really help!