DT125R FORUM

@SpookDog I really don't think an o ring will solve your problems. Your problem almost certainly lies within the cooling system. Sticking/seized thermostat, defective water pump or defective pressure cap. You can easily eliminate the water pump by removing the hose and check if it's pumping and the thermostat by removing it and put in a pan of water on the hob and check the water temperature when you see it open.

@Stevie-Wonder the air screw only affects the pilot circuit so not that. You screw it out to allow more air. Check the float needle seat that it's seating correctly and the rubber isn't perished or missing because that would cause fuel to leak out of the overflow. Notice the little rubber tip.
https://www.ebay.co.uk/itm/194220758338?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=dpDE_KyJTQ-&sssrc=2349624&ssuid=7ztfcrwyt6w&var=&widget_ver=artemis&media=COPY

@89dt125nick hi nick, I used to have a 88 model, the early ones didn't have a servo as this was the learner legal restriction. Later ones had working powervalve but restricted elsewhere. If you remove the powervalve cover on the right hand side of the engine you'll see a small metal dowel which locks the valve in place, you can only move it 180 degrees due to the dowel so either fully open or fully closed. In short open for high end power and closed for low end power so each one is a sacrifice of the other. You can easily retro fit a servo for the best if both worlds but for the older models as you have I believe you need the 3 wire servo as opposed to the later 5 wire.

@Scootjockey the 2002 full power European model comes with a 240 main jet as standard, the restricted UK version has a 210. Is yours restricted? Also you seem to have the wrong idea of what a plug chop is. It's performed with a brand new plug. You don't ride around for any length of time, (no more than about 20 seconds) you then remove the plug and put your old one back in for the short ride home, (or push it back) and most importantly, you then take a hacksaw and 'chop' it. This video explains exactly how to do a plug chop. The chop is performed at around 8 minutes but I highly recommend watching the entire video.
https://youtu.be/Zx44uRFKRD8

@Calum I didn't think of that I'm sure they must be raking it as you said but surely in this exceptional case that has affected and touched pretty much the whole world they could do their bit and reduce their commission assuming that is how it works. Apparently he spent 3 years as a POW and he's an ex motorcycle racer. He was in the army endurance racing team and he also set up a motorcycle training school for the army. Visordown did a piece on him I was reading this morning. Captain Tom. What an exceptional man!

@MadGyver I believe the reason for changing reed petals from stainless steel to carbon/ GRP was not for fear of them breaking, though it would be catastrophic I think it's very rare. But more due to them suffering from metal fatigue and flutter.

@tim85 on my bike they are overflow/breather pipes as they connect to nothing, just directed downwards. I think The smaller lower one is for when you drain the float bowl. The carb warming pipes are on the other side and a bit higher. Sort of directly behind the choke linkage, 2 pipes quite close together and pointing upwards My warming pipes have just been removed and looped at the cylinder head by the previous owner. I guess they're only needed if you live in a cold country.

@HOTSHOT-III Calum will obviously advise you better but my belief is, when people upvote your posts and it builds your reputation, you need quite a high reputation to be able to sell bikes on here. Sure I read it somewhere.

@Scootjockey zeeltronic ignition is a direct replacement for the CDI unit and has no effect on the speedo/clocks. You can control the advance/retard of the ignition and the opening and closing of the powervalve. I think I have a spare mph Speedo in my workshop if you're interested.

@shanedalton no you most certainly can not. Use 2 stroke oil to mix with the petrol and make sure that it's compatible for premix as some are specifically designed for autolube/oil injection pump only and they won't break down and mix properly. If in doubt as to the ratio use an online premix calculater. As for the engine/gearbox use either silkolene or putoline light gear oil. It's all very critical as if you get it wrong you'll be looking for an engine rebuild very soon.

@shortstockevs if you are on Facebook join the group 'Frankies French imports'. There's a few guys on there that rebuild DT125LC's who will gladly help you. And you can scroll back through all the posts for lots of pictures during the builds. You may find the help you need on this forum but it is mainly for the later DT125R.

@DTTOLATE electric start was an optional extra from factory only in Europe.

@Scootjockey 37f is dt200lc. Here's another good Yamaha parts supplier.
https://www.bike-parts-yam.com/

@Calum I understand what you're saying about the exhaust wrap, that also came already on the bike, I may take it off. As for the CDI it might have been changed already as it's a 3rm-30 which I'm led to believe is good also quite rare is it not? Also I might add the log book says first registered in the UK 2007 I was told it's a French import.

It has the Athena 170 bore kit, not what I would have chose especially after reading @Calum's opinion on them about port timing etc but it was on it when I bought it. So was the nice shiny new full dep exhaust though not sure how long the front part will stay that shiny as I gather from what I've read on this forum they rust easily. Does anyone here know of anything that can coat/treat it to slow down the rust?
A few things on my to do list eg. Get the powervalve working as the servo is disconnected and it's set fully open, I've bought a battery as it didn't have one so I'll fit that and look at connecting ypvs back up. Also I must look at the jetting as it currently has a 290 which I thought seems a little big? Anybody here used a 290? Any thoughts please? It's a 2000 model.

@Calum sorry my mistake I'm blaming tiredness I meant Speedo and rev counter not throttle cable.

Hello forum, I'm Markus.
I bought my 2000 dt125r back in September last year but still not 'on the road' yet. It's currently stored at my place of work which is on the local port estate so I have ridden it a few times around the private roads inside the estate. All seems good as far as I can tell. It has no lights or clocks but they all came included in a box with the sale except for throttle and rev counter cable which I have since bought for about £6 each brand new. I guess not genuine Yamaha items but I don't suppose that would matter? Will be on the road in the next month so I'll let you all know how that goes and look forward to getting to know you all though I think over the past few months I have read almost every post on here and feel like I know you all quite well already and have learnt so much about the dtr so thought it only fair I introduce myself and say thanks for sharing your knowledge.

@deigo27 it's fine lots of people have done it. They are only needed if you live in a country which is very cold. I'm in UK and most people I know have bypassed them. The idea is to prevent the throttle slide from sticking in extreme cold.

@DTR12503 yes it is meant to cover the outlet for the overflow and it lifts at a certain preset pressure which should be stated on the top of the cap and it could be worn and lifting slightly too soon. Different caps are set for different pressures so make sure you order the correct one.

@DTR12503 you say that the only thing you haven't checked is replace the barrel but you haven't mentioned the radiator pressure cap. Don't overlook the importance of this item as it regulates the pressure in the cooling system and at a certain pressure it opens enough to allow expansion into the expansion bottle but if it opens too soon it would cause the problem that you are having. Too low pressure in the cooling system would cause the water to boil at a lot lower temperature hence the head gasket failing. the idea is water under pressure boils at a much higher temperature and the pressure is regulated by the radiator 'pressure' cap and they can fail.