De Restricting my DT125R

[Airhead]

thats all you have to do ben

[monster_ben'ergy]

I had a look at my reed switch today and it looks like the two prong bits inside are already touching, i might be wrong as is so small but thats how it looks, also the corner of the glass casing of the reed switch is cracked and has small hole init. I put some more electrical tape onit and tucked it behind a fuse as the wires wouldnt let me stretch it anymore, went out and still only goes 55mph. can i replace it or any other help??

[Wacko paulie]

I have a 56 plate dtx 125, an I raced my mate on his fully deristricted aprillia mx 125 an I'm keeping with him all the time, topped out at 97 mph!!

All it has is a full arrow exhaust system

Speedo grey wire mod on the bk of the clocks (allows it to rev higher)

Sprockets and chain

And main jet was apparently changed to a jet higher before I had the bike

An the plastic bottle on the left-hand side of the air filter box I leave to hang so it breaths better.

[Wacko paulie]

Does anyone now where I can get a vforce 3 reed block and carbon fiber reeds?

[rcirjoescu]

hi guys , i also have a Dt125 r from 2003 ,from what i noticed it goes easy to 7000rmp ,after that goes up a lot slower to 9k or more but very slow. My engine is *4BL-14670--* i suspect the exhaust is the limiting factor. On the exhaust is written YAM. 3RM-00. i would really apreaciate it if u guys could tell me some more about how is this limited and what can i do to improve the preformance.

[baggie00001]

I have a 2007 DT125RE. Ive done most of the mods mentioned in this thread.

I have the power valve set in the fully open position when the ignition is turned on. Not tried to pin it fully open and would be interesting to know if it makes a difference if it is pinned in the fully open position.

Fitted a full DEP pipe and blocked off the catalytic convertor pipe from the Airbox.( I used the nozzle from a standard silicone sealant tube. Wedged it into the hole in the Airbox and put the rubber pipe back on over it)

Blocked off the snorkel that fits into the Airbox. (I used a blank rubber washer and wedged it into the bottle and the refitted the bottle)

I think there are a few people who get confused which bottle that needs blocking off. Its not the one that fits on top of the carb inlet manifold. That one is a boost bottle.

This is the one.

Cut off the rubber restrictor on the carb inlet manifold and chamfered the hole in the rubber.

Like this.

Changed the stock Carb 210 sized jet to a 240. (Ive checked my plug and the 240 jet is bang on. I wouldn't recommend going any higher) The Bike already has great throttle response and runs cooler)

I removed the rev limter by earthing the Green/Black wire that goes into the speedo.

I am trying to get hold of the inlet rubber Airbox manifold from a DT230 lanza.

Like this one.

I did look into fitting some racing reeds. I liked the idea of the dual Boyesen type. I emailed them and this was their reply:- We list Boyesen Power Reeds, part # 666, to fit the ’88-’93 Yamaha DT125/R. Attached is a picture of reed # 666, and the dimensions are: length = 48.1mm and width = 49.1mm. Unfortunately, we do not list reeds to fit the newer Yamaha DT125re.

Anyone know if these will still fit?

The difference in performance is massive to what it was when i got the Bike. It was extremely slow at first and the rev limiter was an awful restriction on these Bikes. The Bike was being held back so much. It was like the Bike was telling you to change gear at 5000rpm.

The most noticeable mods was definately the DEP Pipe and removing the rev limiter.The DEP is definately worth shelling out the coin. Removing the rev limiter costs nothing.

I decided not to cut open my standard exhaust cos i will probably need to fit it back on along with the hotcat catalytic convertor for MOT purposes.

As for the rest of the mods that ive done. I would say each one on their own doesn't really make a huge noticeable difference but when you combine them all together there is a big difference.

The only thing that i'm not too happy about is that the power band is quite high. Easy enough to hit the PB in first and second but you have to thrash it through all the gears to keep the Bike in the PB. Maybe i will try a slightly smaller front sprocket.

[AndyDtr08]

hi guys , i also have a Dt125 r from 2003 ,from what i noticed it goes easy to 7000rmp ,after that goes up a lot slower to 9k or more but very slow. My engine is *4BL-14670--* i suspect the exhaust is the limiting factor. On the exhaust is written YAM. 3RM-00. i would really apreaciate it if u guys could tell me some more about how is this limited and what can i do to improve the preformance.

This sounds more like the rev limiter. You'll find the info on how to remove this with the wire behind the speedo if you have a look through this thread.

[rcirjoescu]

thanks a lot, i will try that

[rcirjoescu]

Hi guys, i just removed my exhaust to see if there is any restrictor there, so the first thing that i saw when i took it down was this addon to the begining of the exhaust. Should this thing be there or is just a restrictor and i should remove it?????

http://imageshack.us.../exhaustql.jpg/

[baggie00001]

Thats odd. Not seen one like that before.They are usually different to that. I still think it is restrictor though.

[Airhead]

Hi guys, i just removed my exhaust to see if there is any restrictor there, so the first thing that i saw when i took it down was this addon to the begining of the exhaust. Should this thing be there or is just a restrictor and i should remove it?????

http://imageshack.us.../exhaustql.jpg/

Thats odd. Not seen one like that before.They are usually different to that. I still think it is restrictor though.

What are you two referring too...I must be missing something here

[rcirjoescu]

i am asking about the small pipe that u can see coming out of the exhaust and is a bit longer than the main exhaust which ends with that ring . That is a small piece of pipe about 5-10cm that goes inside the exhaust pipe and has that part that comes a bit outside.

[Airhead]

Thats not a restricion its part of the way the manifold flange is constructed, see post #1 in this thread

[AndyDtr08]

There is a "small pipe" that is a restriction in that part of the exhaust but I don't remember if it looks like that. It's welded at 3 points into place and can be removed by disc cutting the weld points and it should slide out. If that's not what you are talking about don't start cutting.

There is a site that is something like Dtr. Net that shows photos of it in place and removed. I removed one from my brothers 1989 model but have not seen one since.

[Airhead]

There is a "small pipe" that is a restriction in that part of the exhaust but I don't remember if it looks like that. It's welded at 3 points into place and can be removed by disc cutting the weld points and it should slide out. If that's not what you are talking about don't start cutting.

There is a site that is something like Dtr. Net that shows photos of it in place and removed. I removed one from my brothers 1989 model but have not seen one since.

never mind dtr.net andy, see post #1 here

[AndyDtr08]

Nice one airhead. I'm on my phone at work using the IPB mobile app and could t work out how to get back to the first post. Worked it out now and see you have some nice clearer photos there.

As you say it's the same as yours after the removal so no restriction there.

[rcirjoescu]

ok thanks a lot guys

[rcirjoescu]

oki today i cut it wide open so the only thing that i found inside was this ring that is welded there in 3 or 4 points. That doesn't look to me like a major restrictor. Anyway should i take it out cause on some sites they say that is the restrictor to my type of exhaust 3RM-00.

[AndyDtr08]

Yeah that will be the restrictor. Wait for a few more confirmations but I'm pretty sure that will be restricting it quite alot. According to some who have done it, you get better power from the Yamaha original exhaust once this plate it knocked out compared to fitting a DEP downpipe which costs £150. I think that ring would be disrupting the back pressure of the expansion chamber.

I think it was DeeTeeMX who posted about the exhausts. Up until 1999 the exhaust was only restricted by the cone insert that you looked for in the end of the exhaust. After 1999 the exhausts had 3RM stamped. Their fittings were slighlty different and the restriction was moved to the expansion chamber ( like yours). I presume this was to make it harder to removed or maybe more effective at restricting.

You'll need to be very careful at lining it up when you weld it back together. Might be worth lining it back up now and putting some lines to match up when your ready.

I'm on the look out for an earlier exhaust for my 1998 bike so hopefully will only have to remove the cone in the end.

Keep us updated with photos and results.

[rcirjoescu]

Ok guys , yesturday i put back my exhaust with that thing taken out. First thing that i noticed was the sound, wich was a bit more like a motorcycle not like a scooter anymore, and the response to throtle is more quick, also grows faster in rpm. it still doesn't redline wich i think is because of the switch thing wich i will do the next days. Anyway it was worth all the work and it all cost me about 8 Euro. Later tonight i will share some photos with that ring that was inside the exhaust and with the exhaust after welding it back together. Thanks alot for the support.