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View Full Version : Some seriously confusing problems on my derbi...Need help and fast :(



nathan k
09-25-2012, 02:11 PM
Ok so 2003 Derbi gpr 50 R.

Ran fine until woke up one morning and wouldn't start..had to do a really fast running bump to get it going and then it would smoke (never did before) and die within one minute. If you hold down the throttle it takes around 20 seconds to climb to 10k revs in idle.

Checked:

Fuel (flushed whole system with fresh fuel)
Spark plug (replaced)
Spark (blue)
Carb (jets cleaned)
Cdi (replaced)
Oil pump checked

Note- Problem seemed to have started after I charged the battery...What electrical component could have been damaged from overcharging? If it even is electrical...

There is a slow 2 stroke oil leak coming from somewhere underneath the bike.

Need to solve it quick- Will send a gift through paypal or some AM6 parts for whoever solves it.

chrism15
09-25-2012, 03:22 PM
are you loosing coolant? even slowly, possibly head gaskets blown..

if your leaking 2 stroke oil sounds like a gaskets blown somewhere

jack12
09-25-2012, 04:29 PM
Mine did the same when my head gasket went. fine one day next day it wouldnt start and when it got going it wouldnt idle and smoked really bad. Dont know about the oil though

RS_Roadrage
09-26-2012, 01:12 AM
Whats the compression like? Last time it had new piston or rings? Also take the fairings off and look closely to find where the leak is coming from! Could possibly be the main end bearing getting tired and stiff trying to lock (doubt it ) or even a crank seal!;P

nathan k
09-26-2012, 04:34 AM
Whats the compression like? Last time it had new piston or rings? Also take the fairings off and look closely to find where the leak is coming from! Could possibly be the main end bearing getting tired and stiff trying to lock (doubt it ) or even a crank seal!;P

Engine has covered 4000 miles I guess it could be the head gasket but i've seen no evidence that it's losing coolant or any water on the plug. It seems to be running really rich. I'm gonna check the top end today and I'll post back.

williamr
09-26-2012, 07:05 AM
Ignition system is completely separate from the lighting and starting circuits, so the battery has no effect on it.

Sounds like an air leak - head gasket, carb gaskets or crankshaft seals. Could be a holed piston or partial seizure.

But before you panic, check the air filter. What did you disturb while accessing the battery for charging?

Rob

nathan k
09-26-2012, 09:32 AM
Ignition system is completely separate from the lighting and starting circuits, so the battery has no effect on it.

Sounds like an air leak - head gasket, carb gaskets or crankshaft seals. Could be a holed piston or partial seizure.

But before you panic, check the air filter. What did you disturb while accessing the battery for charging?

Rob

Didn't really touch anything mechanical to access the battery, I supposed an air leak is possibility so I'll check..I've some instant gasket somewhere..

I've tried with an open filter and is exactly the same issue, I get the feeling the choke is stuck on but I've gone through everything related to the choke and it all seems to work fine, however the bike runs bad with or without the choke, it doesn't seem to stop the bike running like before.

chrism15
09-26-2012, 10:02 AM
dont just cover everything in instant gasket if you suspect a air leak..

do a spray test:

get a areosol of flammable contents, be sensible though so dont use somthing like de-icer. USE WD40 or Carb Cleaner spray

i know its hard to keep it running but do your best with a bump start

remove side fairings and get the bike running

spray over joints, seals where you suspect the engine is sucking in air

if the revs go up or down even a little bit when you spray on a area then that is where it is sucking in excess air so it isnt sealed properly. for example inlet manifold, remove it, clean joints lightly with sand paper, new paper gasket and a slither of instant gasket pressed on, bolt it back on and clamp it down tight and level

places to check are between airbox and inlet manifold

if it is a air leak causing your problems then before doing this test just make sure everything is seated correctly and tightend down tight like the airbox rubber, inlet manifold ect.. might just help keep it running.

if you suspect the choke is sticking on then remove airbox and operate the choke lever and see if it moves the plate fully

im going with head gasket for now