another dtr 03

[leedo55]

i have another post about my dtrs problems this one is for my mates as we bought them together to do some greenlaning.

ok his is also an 03 model but his has the servo on the powervalve and where looking to derestrict.

we cut the exhaust open to take out the ring and mesh but it was already done, read that we needed to go in behind the clocks to cut a wire but cant find the right wire to cut as we have read all over google and everyone is saying diffrent things.

also read that we needed to disconnect the reed switch from the clocks, we did as we read unplugged the reed switch from the seat behind the clocks and took of the plastic case and then gaffa taped it up althought even when doing that i couldnt see it making a diffrence and it didint.

so right now the bike flat out does about 50mph and will only pull up hills in 2nd and 3rd gear and will not rev over 6000 even when dropping gears



if there is anyone local around the durham area willing to come and have a look your more than welcome and any advice on how to get this derestricted would be great

[stevo as b4]

I remember a 2001 DT125R I rode in Greece a few years back. If the 03 bike is similar, then I'd say it has to have some form of electronic restriction.

My guess is that it's a speed restriction limiter, and also that apart from the cleaning cycle that the YPVS valve does not move when it's revved to higher speeds.

The 01 I rode felt nice and pokey even two up between 4-6k rpm, but stopped dead just before 7000rpm, and would not exceed 56mph.

Maybe it has a speed limiter that reads off the speedo cable or gearbox sprocket, and or the CDI unit retards the ignition map massively past 6000rpm, in which case a CDI from an earlier uk bike might be a big improvement?

[leedo55]

i think its a wire needs earthed behind the clocks steve but the previous owner has been into it and its a mess, we took out the reed switch from behind the clock and took off the plastic cover and wrapped it in electrical tape like we read on some other forums on google and its a waste of time just like we thought when doing it as it is still working from there and just took out of its seat.

bike will go then totally die at 6000 revs, go into 4th on a hill and its dead, you got to drop to 2nd then back up to 3rd just to stand a chance

[leedo55]

starting to think it may be a powervalve problem after reading this https://www.bikechatforums.com/viewtopic.php?p=1715732 as its exacly the same trouble where having, i sent ghettostan a pm to see if he ever got it sorted then realised that thread is 6 years old ha so probleys no chance of a reply.

seems the previous owner has been into everything on the bike and guessing he has messed up the powervalve as it never kicks in at any point and wont go over 6000rpm.

when i turn the key i can hear the power valve moving and we took of the cap and it is lined up propley with the hole.

is there any way of adjusting the cables to get more revs to make it rev higher than 6000 and get the powervalve to actually kick in

[stevo as b4]

It's not a case of adjusting the powervalve cables though to make the powervalve kick in as you call it.

Is the valve free to turn with the cables disconnected and have you checked that it's fitted the right way around, in case it's possible to fit it 180deg out, if the previous owner has been in there messing about?

Assuming the PV is fitted correctly and not seized, then with the pulley cover off and the cables adjusted to take up the slack, you should see the PV pulley rotate as the engine is revved past around 6000rpm or so?

Don't assume that if the YPVS servo motor and control box is fitted, that the PV works just because it does the ignition on PV open/close sequence, as I'm sure the later DTR's have everything fitted to make the YPVS operate, but something in the electronics/CDI/Speedo sensor etc is stopping it from operating when the engine is running.

[leedo55]

cheers stevo i will check that out in the morning and let you know how i get on

[leedo55]

hello steve, took off the powervalve cables today and the plastic and got behind it and the valve was over to the left i flipped it 180 to the right and seen a small improvment in performance with it like this feels and sounds like its a fanny hair off kicking in the power but it dies at 6000rpm still, flat out 50mph down a hill, when bike is revved the valve turnes to right then eases back down to line up with the hole again where its supposed to go,

mates close to selling it now as where nearly clean out of ideas and to be honest as you can probleys tell where no mechanics.

[leedo55]

also for the few pms i have received it has had a new br9es spark plug fitted

[stevo as b4]

From what your saying it does still sound like an electronics or speed/rev limiter device than any mechanical restriction or the YPVS valve not operating.

You should still get to nearly 8000rpm with the YPVS valve in the down position, but the power would be dropping off by then. Even restricted 12bhp bikes manage around 65mph indicated.

You can try disconnecting the powervalve cables and manually setting the YPVS valve in the up/open position, and then ride the bike to see if the rev limit is still there?

I bet it is though and it's something in the CDI that is triggering a rev limit or massive ignition retard at the speed you mention. Other than the so called reed switch device in the speedo causing it, then I can only assume it's a restricted CDI?

Have you read up on the DT125R forums, as I believe there are differences in the de-restriction process and what things need to be done on 03 and 05-07 models. I'm sure someone will have worked out what needs to be done or replaced to get full power from these model years bike.

[leedo55]

tried taking the pully cables of yesterday steve and setting the valve fully open and your right it made no diffrence.

reed switch it out, taped up and put right away from the speedo, however i just read that if my engine numbers start with 4BL the reed switch is inactive anyway and that his engine numbers.

only other thing i have read is a 4 wire connector block behind the speedo has 4 wires going in and only 3 coming out and i need to earth the wire that doesnt come out the other side but had the headlight off about 4 times now and that block isint there,

could get some pictures of it up if there helpfull.

[leedo55]

ok forget the 4 wire connector block just found out thats for 04 models onward, only restriction on 03 is the reed switch which is out and exhaust which has also been done.

moving onto the carb now to see if its getting starved of fuel, going to check to see if any jets are blocked but at the moment the bike kicks over 1st kick with no choke and ticks over lovley so i dont thinks its that but will check anyway.

does anyone know where the needle should be set in the carb?

[stevo as b4]

It might be worth checking the jetting and what if anything has been done to the carb. I don't think it's your issue though!

But check the Main jet size as I believe the restricted DTR runs about a 210main jet and when it's been fully de-restricted it should use a bigger jet around 240. But you need to re-search the 2003 bike as much as possible, as I know unlike say the KMX125 Yamaha made changes to many things over the production run, and some European bikes are very heavily restricted like the NSR125 for example.

Was your bike an official u.k model?

If you have no luck else where I'd be comparing your CDI to an early 90's DTR125 CDI and see if they are a plug in swap. I think it's fairly likely that your machine has a CDI restriction and trying an early CDI box if compatible might solve your problems?

Good luck all the same!

[leedo55]

cheers stevo

yeah been researching 03 dtrs but it seems there is 2 different models 98/03 03/04 i only know that as i valued my bike online and it asked me which model mine was and i have no idea.

only difference i see between my bike and my mates both 03s is his has the servo and mine doesnt and mine had no restriction behind clocks just in the exhaust.

anyway never managed to get into the carb today ended off messing with the powervalve again and i have now totally sacked the servo and removed it, jammed the powervalve open checking inside the exhaust port and it now wheelies in 1st and 2nd gear with the valve kicking in and sounds a lot beastier, but in 3rd it bogs down again and loses power then stuck at 50mph, at least i got a small improvement out of it today.


i have no idea if the bike is an official uk model hes still waiting on the log book coming through, will it tell us on the log book?

gona sit and spend an hour looking at the cdi on google now steve see what i can find.

[leedo55]

update for anyone reading this with similar problems in the future,
we got it fixed.

put a new carb on and its a rocket, the main jet was wrecked and cross threaded.

[stevo as b4]

A great example of how previous owners messing around and bodges complicated what should have been a much more straightforward procedure.

Glad to hear you got it going as it should though!