Derestricted DT Problem.

[DirtBar]

Hello, i been poking at my bike all day (DT125R 1998) to derestrict it, first i took off the exhuast and used the pullys to open the power valve all the way, but with it open all the way i got no power at all till 7000rpm, then it would snap my neck and be out of the power band in a milli second, sounds cool but as soon as you left the power band it would sort of flat line even in 6th as if the bike was not geting enough petro. so ive shut it about 3/4 of the way open, getting good acceleration, but again top end is terrible, i get like 60 tops.
i should also mention that i have disconected the valve servo because it did not seem to operate properly. when you started the bike it would open the valve and then close it, but when giving it some revs it was not opening up the valve (this was in netual) mate asured my that even in netural the valve would still open.

basically i dont know if i need the valve operating on a servo to get better top end, (maybe it need to close a bit for better top speed, at the moment its jammed open)
or mabe i need better Jets to feed more petrol?
phew this is a big one
thanks.....l

[hustler]

Sorry I can't help, but shouldn't this be in the Workshop section?
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As I said to that guy with the crutches and full camouflage gear, you can hide but you can't run.

[DirtBar]

I should also mention that ive jsut done this to a mates older DT without the electric servo, i think its about a 1994 model, jammed valave all the way and its completly different, massive top end and acceleration, got 70 on my road EASILY !!!

[bugsy46]

ok listen up i will tell you, got a pen??? ok here goes

1. first you have to stop what you are doing
2. you have to place an ad in bike mart for a 98 dt125
3. once you have sold it then you must buy a faster bike or if you are old enough pass your DAS and get a proper bike


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Laura - "And where did looks come into this and bugsy leave steven alone. You are not gods gift to women you may think you are but you're not."
Keith - "All the best"

[stinkwheel]

That all sounds perfectly normal to me. I would expect opening the powervalve to give you a razor thin, virtually unuseable powerband and nil acceleration. Variations between normal and that by degrees of opening.

As far as I am aware, the servo does not open the powervalve on ANY UK model DT125 as they are not fitted with a powervalve control box.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Keith]

I've heard that the standard exhausts are heavily restricted, even with the power valve completely open.

Try get your mitts on a full DEP system, try ebay, they are fairly common/cheap on there
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Aprilia RSV Mille R Edwards Replica - Aprilia RS250 - Suzuki GSXR600 Supersport Race Bike

[DirtBar]

just tryed that, was exactly the same apart from it sounded alot cooler

[Frost]

the power vavle must be able to open and close otherwise you are either restricting the top end, or removing all power at low revs shifting the power to high revs.
Forcing it open or closed simply moves the power about the rev range. the power vavle servo needs to be connected to allow it to control the power valve.

[DirtBar]

yeah thought that might be the case, but surely if the valves jammed fully open it would take all power from the bottom end and move it to the top right?
my bike just sticks at 60, my mates 1994 does over 80, just been out on it properly its loads better.
tomorrow i will reconect the servo and ride around with the cover off to see if the valve accually opens up while i am moving.
thanks

[M1ke]

This bike is a complete bitch, we spent all day poking it with pliers and stuff

Basically the powervalve SHOULD do something when revved passed 8000rpm but its not doing anything. I'm think a wire that connects the powervalve to the rev meter is not connected or something.

With the powervalve jammed open I quite liked it however with full throttle the bike was just really stuttery, this I think is down to the petrol flow. I have suggested a bigger jet could be in order.

Are there any other restrictions that could be on the bike? Do they bother restricting the carb? We have tried the bike with a full DEP exhaust system and it still won't go over 62MPH.

[Frost]

The jets will need doing once the powervavle is set up correctly, if jammed open then they would need doing.

[Smoto Bob]

you will need to go up a few jets, and move the needle clip to the 2nd from bottom (ish) would be a good start.

your servo wont function properly, it should do a full sweap on ingnition on from fully closed to fully open, but genrally when running they only open a bit due to the cdi i think
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F'it DO WHAT EVER MAKES YOU HAPPY!!!!! Even if it screws over everyone else :p
Titz wrote: "..and my 3rd accident was when this police car....."

[DirtBar]

oki, i got a guide on how to derestrict and it says this in one part...

“ONLY ON SOME 97 THROUGH 2000 MODELS”

AT THE BOTTOM OF THE TWO STOKE OIL TANK AT THE FRONT YOU WILL FIND A SMALL SILVER/GREY BOX WITH FOUR WIRES COMING OUT OF IT - THESE ARE WIRES SWITCHING THE ORIGINAL CDI UNIT - THE COLOURED WIRES ARE RED, YELLOW, BLUE AND GREEN.

THE RED GOES ON A BROWN OUT OF THE REGULATOR
THE YELLOW GOES TO A RED / WHITE STRIPED - INTO THE IGNITION PULSE COIL UNDER THE LEFT HAND ENGINE CASING.
THE GREEN GOES TO THE RED/WHITE FROM THE CDI
THE BLUE GOES INTO A PLUG FROM WHERE THE YELLOW ONE IS COMING FROM.

NOW FOR THE CHANGES - TAKE THE RED ONE - MARK IT AND ISOLATE IT - DO THE SAME FOR THE BLUE ONE. YELLOW AND GREEN WILL REMAIN, JOIN THEM TOGETHER THEN JOIN THE 2 REMAINING RED/WHITE STRIPED WIRES. MAKE SURE THAT EVERYTHING IS PROPERLY INSULATED AND REASSEMBLED. HOPE YOU GOT ALL THAT !!!!! READ IT A FEW TIMES AND YOU WILL UNDERSTAND IT.
ive attached some pics of a couple of boxes
does anyone know if these boxes are the ones? different colured wires

[DirtBar]

nevermind about that, i manged to find a pic of what the silver/grey box is like and its defiantly not on my bike! its definatly limited somehere though because it dies at about 7000 rpm, and just judders about, anyone know how to check jets / carb?

[Frost]

Meh i just had a poke.
The bike seems to start to splutter and miss at around 7k rpm with eh powervavle 3/4 of the way open.

The plug is fine, the mixture is good, air filter is clean, pletiful fuel supply. the only things we havn't checked or adjusted are the jets and the compression.

I'm out of ideas :<

[Smoto Bob]

power valve has to be fully open!!! i mean absolutly fully or your just goign to be tuning for a very small about of revs, like 3 lol

found my fresco pipe if ya want it, its stupidly powerfull/peeky, you will need to go from 120->150 minimum if you run this ( later dt-s had 150 jets stock, again i would go 170-180 for them? at a guess)

give me a pm and we can sort somethign out if ya want it
____________________
F'it DO WHAT EVER MAKES YOU HAPPY!!!!! Even if it screws over everyone else :p
Titz wrote: "..and my 3rd accident was when this police car....."

[Frost]

Power valve fully open = 0 power throughout the rev range, then the bike hits 6k, wheelies, then hits 7k and revs no higher, then you change gear and repeat this for every gear.

[DirtBar]

i definatly interested in the pipe, but i had a full dep system on it yestuday and it gave me no performance increase what so ever
so i need to sort my rev problems out 1st

dreading taking it to a real mechanic, cost laods

[Keith]

Does it still have the standard air box on?

Also, what does it idle like, maybe the carb just needs fiddling with.
____________________
Aprilia RSV Mille R Edwards Replica - Aprilia RS250 - Suzuki GSXR600 Supersport Race Bike

[DirtBar]

it idles fine at about 1500, im pretty sure it has an original airbox.
i am going to get teh carb looked at a spoze, bottom line is i need it to rev higher, cant see anything else that could be wrong !

[Frost]

Idle is slightly lumpy, but nothing too serious.
It just seems to lack power, or even miss at high revs

[Keith]

I heard myths that some of the DT's have a throttle limiter?
(Could be complete nonsense but the DT's are restricted differently through the years)
____________________
Aprilia RSV Mille R Edwards Replica - Aprilia RS250 - Suzuki GSXR600 Supersport Race Bike

[Trunecka]

Yes DTR's were restricted differently throughout the years.

The 98model N E E D S a powervalve servo motor to get power throughout the revrange - try and find one in a breakers. I have a 99-model DTR servo which might fit, PM me for details.

The DEP system is definitely worth keeping, but you really should fit a bigger jet.

The standard main jet is a 210 size. The best size to fit with a new exhaust system is a 240 size, don't get a 260 because it's simply too big.

Since you'll be getting more fuel, you could probably do with cleaning or replacing your airfilter with a pattern part item. You won't need a freer-flowing one, you just risk wrecking the air intake system, and it's always better to run a two-stroke too rich (mor fuel) than too lean (not enough fuel).
The airfilter's easy to get to under the plastic triangular cover on the left attached by three screws.

I would also suggest looking through some bikereview web sites to find out exactly how the 98model was restricted - some newer ones even had an electrical throttle limiter, but yours might not have.
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"I'm gonna get free, Ride into the sun..."
-The Vines

[DirtBar]

ok, been doing some snooping on the net, i am 99% sure ive found the problem..... but its on a german website !!!! GRRR

www.dt125.de

i have translated a few pages which talk about rev limiters ....

https://translate.google.com/translate?u=http%3A%2F%2Fwww.dt125.de%2Fdt125%2FMainpage%2FTuning%2F6gang%2F6gang.htm&langpair=de%7Cen&hl=en&ie=UTF-8&safe=off&ie=UTF-8&oe=UTF-8&prev=%2Flanguage_tools

https://translate.google.com/translate?u=http%3A%2F%2Fwww.dt125.de%2Fdt125%2FMainpage%2FTuning%2FEdrossel2%2FEdrossel2.html&langpair=de%7Cen&hl=en&ie=UTF-8&safe=off&ie=UTF-8&oe=UTF-8&prev=%2Flanguage_tools

https://translate.google.com/translate?u=http%3A%2F%2Fwww.dt125.de%2Fdt125%2FMainpage%2FTuning%2FEdrossel%2FEdrossel.html&langpair=de%7Cen&hl=en&ie=UTF-8&safe=off&ie=UTF-8&oe=UTF-8&prev=%2Flanguage_tools

if anyone knows how to get thier head around that i will be impressed

thanks for info on jet sizes, local bike shop didnt know !!

[Frost]

Doesnt sound too bad,
Basically it is saying that the powervavle servo is controled by throttle position rather than a black box.
says you need to drain out all transmission oil, take the kickstart etc off, remove transmission cover then fanny about a bit,

Print those instructions off and i shall come have a poke at it tomorrow