hello everyone
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Hi guys, I'm adrian from the UK and I own a 1998 dt 125 r (at least that's what the logbook tells me).
Mine is the filthy one in the foreground :) I'm actually trying to sell it now as I have gone to university, and i will be making a post later in the electrics subsection to query its fault that's preventing me from selling it. -
Hi @aragian,
Oh cool, that looks pretty tidy to be fair? That could fetch a nice price, shame you need to sell it for uni and you can't sit on it, as these things are appreciating classics!
hello @Calum, this is an old photo and there are few more things to it than meets the eye lol. I'd rather it go to someone who could make it nice too, as being at uni means I can't spend as much money on it as I'd like to. I'm also looking to upgrade to a 450cc at some point, hopefully this bike will help me achieve that.
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Hi guys, I'm adrian from the UK and I own a 1998 dt 125 r (at least that's what the logbook tells me).
Mine is the filthy one in the foreground :) I'm actually trying to sell it now as I have gone to university, and i will be making a post later in the electrics subsection to query its fault that's preventing me from selling it.@aragian Hi Bud and welcome to the Forum.
Sorry to hear your bike keeps killing CDI units, I owned a couple of 3NC DTRs and never had an issue but one of them, despite being an immaculate, low mileage example ran very badly when I got it and this was eventually traced to a pattern coil (among other things like incorrect jetting etc.). Those cheap pattern coils cause a lot of running problems on DTRs as they sometimes don't have the correct primary and secondary resistances, and in extreme cases this can damage the CDI so it's well worth taking a look at. Signs to look for (besides testing with a multimeter) include an overly long HT lead and being brightly coloured (OEM coils are black). If this is the case and you still have your original, best course of action is to replace the HT lead (explanation copied and pasted below):
Possibly could be the HT lead as they break own on DTRs causing this exact problem. The actual coil is very good quality so it's well worth fitting a new lead; you can cut off the very top of the coil's outer case where the lead pushes in with a junior hacksaw, pull out the old lead and solder the new one to the coil output for a really good connection. Then re-waterproof using Shoe Goo and electrical tape. Looks messy but no-one can see it under the tank, and you should notice a performance increase as the leads deteriorate over time. Much better option than just buying a new pattern coil as these often have different specs to OEM which can cause other issues. Fit a new NGK cap while you're there, try to get the type that's moulded into a single piece of rubber.
I had a high-rpm misfire once, after trying everything else we replaced the HT lead in the manner described above which took around 1 hour on a summer's day so the engine was neither stone cold nor up to operating temperature when I took it for a test ride. It wheelied out of the driveway without me even trying, and I couldn't believe how much better the performance was at all engine speeds. Made a big impression on me as I was 17 at the time and I'd spent practically a weekend trying to fix the bike and getting nowhere.I don't think any other DTR CDI unit can be fitted to a 3NC without serious alterations to or replacing the loom unfortunately (3MB CDIs are similar and appear to give a stronger spark than 3NCs but still have one or two different colour wires so I wouldn't advise it). In fact a company called The Tuning Works who import Zeeltronic ignitions into the UK once told me the stopped selling Zeeltronic CDIs for the DTR because Yamaha changed the electrical platform so many times in its 20+ year production run (although Zeeltronic will sell you one direct if you email them pictures of your existing CDI/loom connectors). I just had a quick Google and was pretty shocked at the 3NC CDI prices on eBay etc. but if it helps you this breaker in Germany appears to have two 3NC CDIs and a loom which might be worth having (it's a 3RM loom which I think = 3NC sold in Germany as the loom appears to have the correct connections for a 3NC CDI):
https://www.ebay.co.uk/itm/146868783391
https://www.ebay.co.uk/itm/157439162265
https://www.ebay.co.uk/itm/146948681784
There are specialists in the UK that mend CDI units, so if you have a few toasted OEM ones it might be worth looking into this by asking around local bike dealers etc.
As I say I don't have any experience of repeated CDI failures but it sounds like something is overloading it, either a pattern coil with resistances too high or something at the stator end. Early DTRs have strange electrical system where the same wire (yellow/red) powers the lights directly with AC (this gives the advantage of being able to run a 100/80W headlight bulb which a lot of bigger bikes can't do, see below) and charges the battery with DC via the regulator/rectifier. The stator has three coils; charging coil (battery), lighting coil and source coil which powers the the CDI (in fact four if you count the pulse coil on the outside of the flywheel which sends the CDI the signal every crank revolution like the crank sensor on a car). Haynes manual has all the numbers enabling you to test all these as well as the ignition coil so it's well worth getting yourself a flywheel puller and a multimeter and going through this; it could be as simple as getting another 3NC stator and bolting it on (Yamaha used to sell the stator coils separately but they're hard to find now and IIRC you have to solder them up yourself).
Understand the attraction of getting a modern 450 but these aren't without their own problems; a lot of people in the MX/Enduro world are utterly fed up with the "four stroke revolution" as they can be complicated and expensive to fix when they blow up. If you persevere with this reach a definitive conclusion/remedy your DTR will be reliable and easy to keep that way for the forseeable future, a usable classic with advantages such as VERY powerful headlight, Autolube (literally mechanical engine management from the 1970s), limitless brand new plastics from Portugal and ease of maintenance due to grease nipples everywhere etc.
Here's a 3NC wiring diagram if you don't already have it, hope this helps:
100/80W Headlight Bulb Explanation:
The stock DTR headlight takes a P45T bulb (similar fitting to H4 but not the same) and has AC lighting (i.e the power for the lights comes straight from the magneto without involving the battery) so you can run a 100/80W halogen bulb without flattening the battery unlike a lot of bigger bikes which run DC. The DTR’s actual light lens/reflector is the same as all Yamaha superbikes of the 80s like the RD500LC and XJ900, but Yamaha cheaped out and fitted a 45/40W candle to the DTR which is why lots of people don’t find it bright enough. 100/80W bulb lights up the roads/trails like a rally car and retains an MOT-friendly beam pattern. Once a year or two ago I met up with a bunch of guys greenlaning on modern KTMs and decided to tag along with them as it was getting dark; they couldn’t believe how much brighter my headlight was. Get this one:
Also MOT stations have a headlight beam board and can set up the headlight perfectly for you in a few minutes but you can get it more or less where it should be by finding a brick wall and measuring the height the centre of the headlight glass comes up to with you sat on the bike. Then sit on the bike about 6 feet from the wall and get the headlight main beam to this level and pointing straight ahead using the adjusters.
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@calum I wish I could say the same about mine, but I think I just got unlucky with the electrics of the bike. Not to say I didn't have some fun on it, at the time it was an amazing bike, but after sitting for so long without use, I feel like its potential is higher with someone else.
@hotshot-iii Thanks for all your advice. Before i went to uni I had had checked over the whole bike for all the points you mentioned. I took a multimeter and checked the HT coil, the end of the lead, for resistance readings, same with behind the flywheel, everywhere where the manual specified for troubleshooting no spark, and they were all within required ranges. I inspected the loom for exposed wiring/shorts but found none, and checking for continuity gave me no anomalies. It's after checking all this I asked on some Facebook groups for advice, and some said there will be a buzzing white box underneath the seat, but my model didn't have that. Some suggested it could be a faulty regulator, and turns out my bike had an aftermarket one on, so I replaced it with an original and ordered another CDI (when you could still find them). Now I will admit the installation of the last one was the reason I think it went; I didn't make sure the CDI was grounded properly and partly blew it. There is a weak spark when I kick the bike over, but not enough to start the bike or keep it running when bumping it. Considering that all other aspects of my electrical circuit seem to be fine, I am inclined to think one last CDI will finally awake the bike again (when grounded properly!). I did see that German one you have linked, and last resort I may get it, I also want to bide my time and see if any will get listed for the prices I used to get them for (70-120).
I would love to keep the bike but its MOT has expired, and unfortunately i don't have a homologated exhaust for it anymore, which I'm sure would be easy to find, but whilst at uni its tough to keep spending money on it, let alone time, so I think I need to part with it so someone with the time and money can give it the tlc it needs. I just don't want to sell it in a non-running state, as advertising it with a blown CDI isn't exactly a great selling point lol.
I have a some mates with 450s, and I have heard their stories about their issues, but it is more of a long-term goal to move up to one for me. Whilst I spend so much time away from home I don't think its practical buying a bike for it to sit, my reasoning behind selling my DT too. Unfortunately i have plenty of parking space but nowhere inside, and cover storing a bike for years doesn't sit right with me.
