dt125x really slow pickup at low - med revs

[bikersupermot...]

hey guys, hoping someones good with 2 strokes here! . got a 2004 dt125x ... has a dep full system on it.

these newer dt's dont hav a rev counter unfort. prob i got is, in town riding, low-medium revs, its just got no go at all. its totally embarassing and im gettin passed by guys on 50cc peds.

but stay in 1st, throttle pinned, revs pick up really slow ... then about top end of medium revs ... i get a tiny splutter an the exhaust note changes ... an suddenly the bike flies ... it'll easily lift the front end....the power comes in hard and violent.

nice maybe on a roads, ... but most of my riding is in town an the lack of accelaration at low revs is dangerous. the revs where the power comes in hard is just too high for a town bike.

im told its likely to be powervalve related. do u guys think the powervalve is broken then? or what cud be wrong?

hope someone can help coz its driving me crazy esp as the weathers so good to be riding but im not gettin on with the bike in the way its riding. thanks.
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tinybikes

[d-bug]

hi i dont know the ins and out of your bike but with what your saying , it does sound like the PV is working as your saying around med to high revs ya bike is taking off , so its opening ! , as they come in around 8000 revs well mine does there some might be a little lower or higher

when u turn the bike on do u get a sound , should be like a electric sound from the motor , u get a sound of 2 turns errrrrrrrrrr , errrrrrrrrrrrrr lol

if you do then its fine and the only thing i can say would be to give the carb a good clean , making sure every think is fine and see if its still the same after that

cheers d-bug

[bikersupermot...]

hey d-bug, thx for yr reply ... yeah i do get that sound when i turn on the ignition an before i start the bike ...

when i bought the bike it already had the dep pipe on it ... do u think it might not be setup right for that pipe?

im not enjoyin riding it at all coz i cant pull away safely at the traffic lights the way it is ... but my old kmx125 pulls like a train or a diesel car at low revs an at 7000, it pulls hard (but not as hard as the dt does when it hits that certain spot) ... so iv gone back to riding the kmx at the mo till i can get this dt sorted!
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tinybikes

[ms51ves3]

It still could be the PV. Just because it works when the ignition is turned on, doesn't necessarily mean it is working when he is riding the bike.

What you need to do is take the pulley cover off, let it do it's little check on the ignition, once the check is complete the PV will be in the fully open position. Start the engine and it should turn to the fully closed position, if it doesn't and it stays in the fully open position, you have found your problem.

[bikersupermot...]

hey there ... thanks for that info ... ill hav a look over the weekend! ... let me get this right, ill take the cover off ...

switch on ignition and the valve shud open.
once the engine starts, the valve shud then close.

shud the valve then re-open at a certain point when the engine is running/revved up?

and is it obvious to see the power valve opeing and closing?
thx for yr help there btw.
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tinybikes

[MaybeGuy]

it could be adjusted wrong
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Blue_SV650S wrote: it was a sh1te wheelie, but it proves that he can get it up in 3rd and can do angles. In summery, mattsprattuk is a gobby little sh1tebag, dopehead tw4t, but sadly for all of us, he probably isn't THAT full of sh1te!!
Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[bikersupermot...]

[ms51ves3]

[bikersupermot...]

ms51 ... thx loads for the pic - thats really helpful to me. ... i really appreciate u posting the pic. ill hav a look at the valve asap. unfort, gotta work tmrw (-
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tinybikes

[eazy rider]

I'm betting the powervalve has been pinned open with the cables unhooked.

I've owned a DT125R a while ago and it was just as you describe, although I did it purposefully as I loved the feeling when it hit the powerband and took off. Was much fun for wheelying.

btw the trick to riding the bike in that state is to keep the revs high both before setting off and when changing up a gear.

[stirlinggaz]

hi,
as above, sound like the powervalve has been pegged open, so your only getting the benefit of it, when you get up into the high revs.
& its running shite low down in the revs.
theres a good step by step guide(with colour pics, wow) to these pv.s over on dtr.net.
cheers,
GAZ

[bikersupermot...]

guys ... thanks for the info an help here ... really really appreciated ... will be lookin at the pv next weekend as iv gotta work today unfort!.

so thanks again big time - i had no idea about the pv but am confident about lookin into it now!.
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tinybikes

[bikersupermot...]

update on the dt125x! ...

well guys, thanks for all your help! ... some of you were totally right! ... round of applause to ya!

the power valve cables had been disconnected and the valve had been pinned open.

so, the cables are back on again and pin removed, the valve turns fine when ignition switched on/off ...

but, the running is only a tiny bit slightly better in town running/low revs ... still gutless.

and at high revs, the bike suddenly pulls hard and very smoothly ...

so with the power valve working, what do i need to do now to sort out the power delivery - more bottom end and maybe a lil less top end wud be great!

thanks once again guys for yr help on this one!
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tinybikes

[tutton]

Id suggest sprocket change next?
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Past: '05 Peugeot XPS '99 Aprillia RS125 '94 FZR600R
Current: '02 ZX636 A1P '51 CCM R30

[bikersupermot...]

hey tutton ... funny thats my next job as the chain has a tight spot ... new c&s kit ....

so wot size sprockets u recommend i go for or wot do u use?
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tinybikes