C
My Dad did this on his VW Split Screen van so that all the doors used the same keys.
He just spent the time and recoded the barrels on the lock that matched the genuine key.
You'd need to be familiar with how locks work etc, but if the the barrel is dismantleable, or you can find a barrel which fits, then it should be possible.
Hi Andy!
Fab!
My Dad has a DT400B that he's been in the midst of restoring for about 8 years now.
I think he has all the parts, but he's since moved on to a Vespa and Lambretta obsession!
But I'm hoping he'll throw the DT400B back together and talks of passing it on to me 
This is predominantly a DT125R website, so knowledge about early models is very limited.
But of course we're all motorcyclist enthusiasts so we welcome any bike really.
Although, admitably, traffic has plummet in the last 12 months.
If the original ignition coil was faulty, replace it with a 3RM genuine one. I fought this battle when I rebuilt my DTRE and then put it into storage. Years later when I got it out of storage, and everything was new on it, it took me ages to realise it was the non-genuine coil.
I was having neighon similar symptoms. It would run from cold then, after a short ride, wouldn't rev.
I only realised it was the ignition coil when my brother's RD350 was fitted with the same type and the mechanic scoughed at it saying how they basically get saturated with voltage and can never recover. So once they're depleted they provide a weak spark.
So as I say, that would be my first port of call.
Anyone have any idea what’s going on and what I could t try to get the bike going?
I think this is probably your problem. Instead of addressing the issue which caused your bike to fail the first time around, it sounds (going from your description) that all you're interested in is getting it going again, which unfortunately, on a 19 year old bike, probably isn't enough.
Why did it fail the first time round? Once you understand that, you'll be in a better position to address the follow on issues.
What made you think it was a coil? Did you measure the impedance between the primary and secondary coil and it was out of tolerance? What were those measurements? Did you replace with a genuine 3RM coil? Those Chinese aftermarket ones are only worth throwing in the bin, they do not work!
It sounds like there are two issues here, one is sounding ominously electrical, the other clearly mechanical and until you strip the bike down to investigate and eliminate you'll continue to have problems.
The DTRE in stock trim is an incredibly reliable machine, but that said 20k and you'll going to want to do some TLC overhauls.
The engine failed last year and damaged the barrel, well there is no real reason it would do that unless the maintenance schedule wasn't adhered to. Or the oil pump failed. The problem with the latter is throwing a new piston/barrel at the problem doesn't fix anything and is money wasted. If it was just worn rings and you were hammering it then that's just lack of maintenance.
I could throw you a whole raft of potential solutions but sounds like your bike is a bit of a basket case.
Because of this there is likely a whole host of things that your bike could be missing and botched so diagnosing is a bit of a rabbit hole. My advice put the bike back to factory OEM spec and go from there.
Why do the plugs keep failing? Are they black sooty? Has the oil pump failed and just throwing copious amounts of oil at the engine fouling plugs, is it because there is no YPVS and it's thrown the settings off.
But throwing in some simple checks, probably:
I can go on, but really you want to tear the bike down, do a compression check, make sure the engine is healthy, that the airways are clear, exhaust, intake, airbox etc. Carb isn't blocked.
A prime candidate for this could be:
You just want to use 10W-40 Semi-Synthetic Engine Oil, avoid Castrol Magnetec as I had clutch slipping issues using that type of oil.
If you've addressed the above issues and are still having problems then given the cheapness of a clutch rebuild kit I'd just grab EBC Dirt Bike clutch plates and new uprated springs and throw it back together.
@HOTSHOT-III Glad to hear it, your help is invaluable.
Happy New Year
Hope every made the most of 2024 and it's now onwards and upwards for 2025!
Thanks to the contributers over the last 12 months helping those with questions.
I look forward to seeing what 2025 brings us in terms of projects. Although the forum is very quiet, I plan on making a few posts on the DTR related projects I've been working on.
@FloWolF
See below threads which have said:
Its strange but cables going 1 - 2 , 2 -1 .
The right hand side houses the screw that threads the two halves together. There is nothing surprising about that.
Take care when removing as the screw holes can become brittle and are prone to cracking, so just gently pry the sides open.
I mean, two stroke to lubricate in the loosest possible sense. Unburnt two stroke is quite sticky, hence why the powervalve needs cleaning to ungum it up.
Splitting the powervalves can be a little frustrating in order to properly clean the system out.
@ALLE19E04 Hello there and welcome.
That is the Yamaha Energy Induction System (YEIS).
You should also find another one on the carburetor to airbox boot.
On June 30, 1980, Yamaha announced two new energy-saving engine system technologies that it had developed independently: the Yamaha Induction Control System (YICS), a technology for 4-stroke engines, and the Yamaha Energy Induction System (YEIS) for 2-stroke engines.
YICS reduced the amount of fuel consumed by speeding up intake charge to the cylinders, reducing combustion time, and increasing combustion efficiency. This technology made it possible to create energy-efficient, low-cost engines.
the speed of intake charge in the intake manifold to ensure stable intake efficiency, which results in improved output and lower fuel consumption. In testing on actual motorcycles, it was confirmed that fuel was conserved by around 10%. Development focused on 2-stroke engines, but the technology could also be applied to 4-stroke engines. YEIS was first used on the YZ motorcycle in 1980, then on four 2-stroke models in 1981.
The Yamaha DT125LC had these:
@mbmO8 Not according to the parts diagram.
https://www.fowlersparts.co.uk/parts/4159461/dt125r-3rme-1999-060-a/front-wheel
