Derbi GPR Issues

[MTM281]

Hi Guys,

I'm completely new to biking and I'm having a few problems.
My cousin has just got a new bike and has (very kindly) given me his old derbi gpr 4t.

I was so happy that I had gotten a bike, so i went out and brought all the gear and did some training. However since getting it; i took it to be cleaned and valeted (because its new and i want to keep it all shiny lol) its been really underpowered and jerky.

Say i was in third and gave it some throttle, it would get a bit of power then, sort of, gurgle with no power and then the power would go through, it is also getting stuck at 55mph and no going any further.

Can anybody give me any idea of what's wrong?
I can't take it to a garage at the moment because all my money is going on student fees so i cant afford it.

P.S
I'm also having trouble putting it in neutral, no matter how gently i am with it , it will jump to either 1st or 2nd unless i turn the engine off and turn the ignition on then it slots in easily.

All help appreciated thanks guys.

EDIT: All perfect now! It was just water and it was fine after it was heated up for a while.

[0l0dom0l0]

Hello

Sounds like it could be a dirty carb. Does it do it all the time or just occasionally? Its possible its suffering from carb icing. Also has the bike been sitting atall?

With regards to neutral, it could be down to a number of things. The easiest way to 'fix it' is to go for neutral when you rolling slightly. So you might have gone from second to first coming to a set of lights and just creep up to the lights with the clutch in and try to go for neutral. It normally works.

I'm assuming its the 125 if its the 4t?

If so they are very new bikes and you shouldn't be suffering from problems like that already. Its possible it needs a good service. How many miles has it done?

From here I would, give it a good service. This means: Oil, Oil filter, Plug (which might help the jerkyness btw), Air filter (depending on miles), Chain tightened and lubricated, clutch cable adjusted properly, gear linkage assembly lubricated.

That should sort it and all of that you can do without taking it to a garage. I think it might cost you about £25 for all that?

Hope that helps

[MTM281]

Thanks for the quick reply,

It does it all the time at about 6000 rpm, it hasn't been sitting for that long maybe a week, its done about 1400 miles.
I didn't have this problem before getting it cleaned though.

[fiery tupp]

[bikersupermot...]

id agree with 0l0dom0l0 (had to copy an paste that lol)

also dunno if u got access to a garage thats dry ? ... if u do, id keep the bike in there as much as poss when ur not using it ... coz if it wasnt doing all this before u washed it, its poss water has got into the airfilter/carb and / or the electrics and upset them.

a warm dry garage might help to dry it out.

also, definitely fit a new spark plug - can fix a lot of probs as the plugs burn out or foul up and its also your cheapest option - cpl £.

id also take out the air filter and dry it out if its damp ... even repalce it if its dirty.

good luck an let us know how u get on with it.

nice bike btw
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tinybikes

[0l0dom0l0]

Sounds like its water in something then in that case. Not really sure what to suggest and what part would be causing this problem if it had water in it.

I would still do the service regardless, just don't worry about the air filter. It should help the neutral problem.

[MTM281]

[HD]

Maybe water in the air filter then?

And as for neutral I can't put it straight in. Just rock the bike forward and back a bit and it should slot in
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Rusty '02 Vito Camper + CBR600F3

[cheekythomas]

It shouldn't be airbox related as it's hidden away nicely under the seat unit... They did suffer from some models not having the wiring from the stator sealed, which allowed water to get in and give odd running, normally though they would turn over but not even attempt to fire, but they would bump start within 2cms!! Proper odd!

The carb is electronically heated so shouldn't ice up, try just draining the float bowl incase it's got a little water in it, also might be worth checking the vacuum fuel tap works.

Ah and while I remember, check the ht cap as the first ones used to leak voltage to the engine casing around the sides, fitting a better NGK item is the proper solution, but to test just wrap some insulation rape around the old one and see if it fixes it.

[MTM281]

Ok, i think water is probably the main problem. But seeing as i have no idea where it could be, how could i go about removing the water? Just let the bike get hot, and hope that the water evaporates?
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