I'll be keeping a close eye on things, regular compression tests and plug chops to see whats going on.
I think I've done what I wanted with the head for now. I'd say I've given it more of a polish than anything
Its far far from perfect, but also a lot better than what it was 
one of the marks is still fingernail deep, but I'm reluctant to go much further without taking it somewhere knowledgeable with two stroke machining. I'm happy enough to fit and find out for now 
I didn't need to read that, damn it 
Good read.
Little update. After running it in a little and opening it up a bit, I wasn't particularly impressed. It felt worse than before up top. So I did mess with the squish too much I think. Luckily managed to get another 3mb head in a more normal condition for £25 and have just fitted it and compression tested it and its up, so hopefully tomorrow's ride will be an improvement.
Now I have the old head here may as well look into getting it sorted properly at some stage and swapping back later down the line.
So, check the green black wire is grounded and stick a finger in my exhaust is the next port of call?
Cheers for the help btw guys
I'm in the UK.......just see the price, lets hope it's not that
Its not the valve. I took the exhaust off and aligned the valve, unplugged the servo and it was still the same at the top. What should I look at next?
Cool. Its a bit dark out there now, but I'll let you al know how I got on soon 
Thats a real nice refresh of an RS there, fair play
@Calum So there are other heads apart from them two, cool I didn't now
At least the whole top end can be ruled out now, plus ive got a spare head to play with, so not all bad. Just need to get to the bottom of this issue once and for all.
At this rate I'll have a nice stash of spares 
@Calum I'd adjusted the throttle too much so when I fired it idled around 7k I think was the reason. Took it out for 15 gentle miles yesterday and all seemed well, and took to work this morning, so far so good. Just trying to be gentle and keep the revs relatively low for the meanwhile and get some miles under her belt.
Its back together and running. Not ridden yet, but let it get to temp and adjusted idle. Took about twenty kicks to start first, but now its starting first kick. Took a compression reading before I started the engine with the exhaust off
Pretty busy tomorrow, but If I get a moment Ill take it for a spin and see what is what 
@NINJA Yeah I agree. She is a French import, although it was the runt of the litter so to speak, and had expected stuff to go wrong and I guess the mileage is about right for a top end. Just surprised that any plugs I pulled looked fine and it always started first or second kick right up until that incident.
I've run it on super while I've had it, so I guess it must have had some crap French fuel a while back and just managed to hold it together pootling about French lanes until I got my hands on it 
On the upside this may well go to explaining why it wasn't too happy revving over 9k, so if it solves that issue at the same time, I'll be happy. 0.5mm oversize piston, small end and gaskets have been ordered today and the bore and head are at the machinists. Hoping for a quick turnaround 
@NINJA I'll have a little fishing session with some magnets and see if I can find anything left behind.
@Calum What years out of interest had cats?
When you look at it £175 is less than two weeks worth of charges, so it would pay for itself pretty quickly.
There are a few post 2007 strokers available like the KTM's and Huskys, so in theory a two stroke has the possibility of passing.
I'd hate to see cities without the occasional sound of a two stoke reverberating off the buildings and a whiff of two stoke, it would take away some of the character
Alternatively we could just wait, as I believe Historical vehicles (40+ years) are also exempt. Classic Lambrettas and Vespas should be cool.
So, there is that ULEZ zone around London and pre 2007 bikes must pay a £12.50 charge to enter. It doesn't currently cause me problems commuting but it may well do when the area expands in 2021. Other cities will most likely follow suit down the line, so would be nice if we can work out if a DT could pass the test.
It would be handy to pop into town on the bike if I wanted too of course
There seems to be 3 main ways of conforming to the rules.
First and second is to obtain a certificate of conformity or a homologation certificate from the manufacturer to present, some seem to be now charging for this privilege. So, what do you think the chances are of Yamaha having these for a DT?
Thirdly, is to take your bike for an emissions test on a case by case basis, so just because one DT passes does not mean yours will. Currently only 1 place in the whole of London has been authorised to do this, Riverbank Motorcycles, and they want £175 for each test. What they are looking for are the Nox levels and the magic number is 0.15g/km or lower.
Lots of older bikes seem to be passing, albeit I've yet to see a 2 stroke mentioned in any blurb I've read yet.
What do we think? Is this possible for a DT, anyone got any idea of Nox emisons on our bikes?
Oh yeah, did any year DT's come with a cat in the silencer?
I didn't need to read that, damn it
Good read.
@Calum So there are other heads apart from them two, cool I didn't now
At least the whole top end can be ruled out now, plus ive got a spare head to play with, so not all bad. Just need to get to the bottom of this issue once and for all.
At this rate I'll have a nice stash of spares
@NINJA I've been doing plug chops but nothing untoward has been spotted, here is the most recent, was a new plug when the new piston went in
And here is the old head with no casting on top, yet the heads dome defo isnt the restrictive head
And the new fitted
I cant see anything wrong with the plug, but feel free to chime in
It's still basically the same 
Gotta be something else....not much left really, CDI, crankcase seals or clutching at straws for an extremely worn carb?
I've never inspected the reeds and the exhaust is a bit of an unknown, so could both be causing possible issues and shouldn't be overlooked.
Got a second hand CDI winging its way to me to rule that out. I'll do that and go from there....
@Calum It had a few small nicks, but was a whole load better looking than the other. Got it from where I bought the bike, it was the best 3mb he had, got loads of the more restrictive ones though.
Sadly no snaps NINJA, I think maybe it's a slightly older head as it had 3mb and Yamaha embossed on the top of it which the other does not
Little update. After running it in a little and opening it up a bit, I wasn't particularly impressed. It felt worse than before up top. So I did mess with the squish too much I think. Luckily managed to get another 3mb head in a more normal condition for £25 and have just fitted it and compression tested it and its up, so hopefully tomorrow's ride will be an improvement.
Now I have the old head here may as well look into getting it sorted properly at some stage and swapping back later down the line.
@Calum I'd adjusted the throttle too much so when I fired it idled around 7k I think was the reason. Took it out for 15 gentle miles yesterday and all seemed well, and took to work this morning, so far so good. Just trying to be gentle and keep the revs relatively low for the meanwhile and get some miles under her belt.
Its back together and running. Not ridden yet, but let it get to temp and adjusted idle. Took about twenty kicks to start first, but now its starting first kick. Took a compression reading before I started the engine with the exhaust off
Pretty busy tomorrow, but If I get a moment Ill take it for a spin and see what is what
I'll be keeping a close eye on things, regular compression tests and plug chops to see whats going on.
I think I've done what I wanted with the head for now. I'd say I've given it more of a polish than anything
Its far far from perfect, but also a lot better than what it was
one of the marks is still fingernail deep, but I'm reluctant to go much further without taking it somewhere knowledgeable with two stroke machining. I'm happy enough to fit and find out for now
I'm in the UK.......just see the price, lets hope it's not that
So I fitted a new coil. Its a little better but still not quite right. Gets to 9700 now before going flat, but still feels like a little step around 9 where it tails off. I checked the carb and I think someone has previously removed the filter as I cant see one in there. I've got an o-ring coming for the tap so will wait until it comes then check that out too. Then I guess its time for a compression test, but I'm not expecting anything out of the ordinary because it runs sweet everywhere else.
How much is one of these zeeltronic jobbies then?
Should also add that the bike revs freely to the red line when in neutral with no load.
Thats a real nice refresh of an RS there, fair play
All good ideas there thanks
Float level was set when I changed the needle stop as it was pissing out fuel from the carb when I got the bike, but sadly the problem was present before.
Tank cap Is a good shout, Ill take a look at that and the filters once the fuel level gets lower.
Air filter is new and not particularly over oiled, but again its been doing it with this one and the previous filter so can rule them out.
Ordered a new coil, HT and cap anyway. Possible the one on the bike is 25 years old, so cant hurt
Rino Racing or something similar the exhaust is.
So check over the coil next?
Just an aftermarket exhaust and a 240 main jet I stuck in, that's it. So compression test next?
Yeah still going flat in the higher rpms. Maybe the coil is weak. No plug chops yet, but I stuck a new one in a few weeks back ngk 8 i believe. Also along with a new air filter as it just ticked over 24km.....about 15k miles. Snorkel is in. Problem has been there before the service too. Would be nice to get to the bottom of it
Its not the valve. I took the exhaust off and aligned the valve, unplugged the servo and it was still the same at the top. What should I look at next?
Cool. Its a bit dark out there now, but I'll let you al know how I got on soon
So, check the green black wire is grounded and stick a finger in my exhaust is the next port of call?
Cheers for the help btw guys
Can anyone recommend an LED headlight bulb to fit the DT?
Thanks in advance
Thanks.
The bike is from 1993, I think someone has put later decals on, should it have the blue and pink ones, and blue fork gaiters?
see if this works
![alt text](<a data-flickr-embed="true" href="https://www.flickr.com/photos/40448090@N02/41510423080/in/dateposted-public/" title="20180706_121436"><img src="https://farm1.staticflickr.com/842/41510423080_d01c1b7ed0_z.jpg" width="640" height="311" alt="20180706_121436"></a><script async src="//embedr.flickr.com/assets/client-code.js" charset="utf-8"></script>)
[url=https://flic.kr/p/26f8LzE][img]https://farm1.staticflickr.com/842/41510423080_d01c1b7ed0_c.jpg[/img][/url][url=https://flic.kr/p/26f8LzE]20180706_121436[/url] by [url=https://www.flickr.com/photos/40448090@N02/]The Pablo13[/url], on Flickr
 )
My first bike was a DT50 about 22 years ago and I'm back again
Picked this up last weekend, little tatty French whore
Needs a few bits like a rear tyre and an oil seal changing, then she'll be good to register.
Does anyone know what the original colours should be?
