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I was also awake, pottering, turning, thinking and wondering if a decompressor helps navigate a tricky bit of terrain like a rocky drop where much control and finness is desired and a decompressor could help by being able to keep the bike in low gear without having any power on or stalling. So it seems none of us win a warm feeling in the pit of our stomach....haha

Next rime it cuts out ,spray easy start up the carb,,,just to see if its fuel related

Thanks for that, guys. I've eventually managed to get a couple of 32mm seals on ebay from www,scooterandbikes.co.uk. I fitted them this morning and it has then taken the rest of the day to bleed the bugger! In the end I resorted to getting a big syringe and sucking the fluid through the bleed screw, filling the reservoir frequently as the level would drop quite quickly. This got most of the air out and then a bit of conventional bleeding has got the lever nice and tight. Hopefully back on the road tomorrow!

When i first got it running in May it was old version unleaded and ran fairly okay, if a little underpowered at high rpm. Thinking about it it has got a lot worse since using the super so will mess with timing. I was advised not to use new e10 unleaded as not good for the carb etc

might try here https://www.rdlccrazy.co.uk/html/for sale link page.html have you tried Fowlers too?

I know a lot of small capacity bikes for the Asian Market run twin plugs due to poor quality fuel. Firing them at slightly different times ensures a complete burn I think it's the theory. My vtwin rotax engined aprilia has 2 plus per cylinder. But both fire at the same time and you can run with just one without any noticeable performance loss so no idea why they're fitted

I'm sure you've all been there but I had a sleepless night last night, mainly with my brain popping up random thoughts that i couldn't get rid of....and it kept me awake! One of them though was "Why DID early Yams have twin spark plug holes!!?" I came to the conclusion that it was either for 'Performance' or 'Diagnostic'...... "Performance" to make it better or worse! or "Diagnostic" to see what was making it better or worse! yup not the best discussion to have with yourself at 4 am....but.... It also got me thinking about what was available back in the 70's to do either of them...As regards to 'Diagnostic', there was Colortune sparkplugs, which were a popular 'accessory' that found their way into many a christmas stocking for dad who had everything. It was a plug with a glass inspection construction so you could 'see' the colour of your spark!.....oh joy!....come on... it was 4am!! but would Yamaha construct cylinder heads just for this purpose?....unlikely I thought!...unless it was a high performance engine......not your run of the mill Trial bike... it was probably 04.15 by now! Which made me think of 'Performance'. Was there really a need to equip their cylinder heads with dual spark plug holes to run twin plugs? Presumably that would mean twin HT Coils and maybe twin contact breakers? makes you think doesn't it? it was probably at least 04.30 by now! I don't recall my mate who had twin plugs on his AT ever having twin coils, true he had both spark plugs inserted but only one was ever connected at a time. He would change the HT lead over to the other plug if it got too fouled up...but thinking about that today (04.40) the chances are the carbon fouling was probably all over THAT spark plug too!!....but heh we were just 16!...it seemed to be the 'right thing' to do, swapping HT leads.....wow...the performance change...Not!! Anyway, (04.45) I came to the conclusion that dual plug holes was probably related to performance more than anything else......mass produced?...domestic market vs sports market?.......then just blank off the hole that's not in use and make use of the twin holes for the sports related performance. Seemed logical, and probably not untypical of 70's thinking. No I didn't drop off ...I still had Quantum and String theory to discuss with myself along with what am i going to do today?, what I'm going to be ABLE to do today with so little sleep!!.... what's that ringing?...it's the alarm......time to get up! Then I thought "Why don't I google it? " Twin spark plugs on Cylinder heads.... I was right after all....its performance related... https://www.rediff.com/getahead/report/slide-show-1-biking-and-motoring-why-twin-spark-is-superior-to-single-spark-tech/20140104.htm So I just have to answer one final question.... Why didn't i get up at 4am and look it up? ...would have saved myself all that 'deep thinking"! Gee ...i'm tired!!!

Anything must be worth a try if you've tried everything. But i just did a quick google search for timing with unleaded vs leaded, and apparently you retard the timing slightly. One guy writes that for his classic bike engine he normally sets the timing where it "should" be and, providing he gets it going, goes for a ride up a hill, if it pinks he retards it a bit, if it doesn't he advances it until it does pink then winds it back very slightly. Remember it only takes a fraction of adjustment to alter the effect it has. Like I said it might be worth altering it, you can always set it back to 'normal', if it doesn't work. it's only a screw adjustment afterall, but having said that, I'm not so sure I altered my DT for unleaded! .....I may have done , it's so long ago though!.......good luck Phil keep us posted.

Hi Neo thats a good point. It actually has super in it as I was advised not to use the new E10 stuff now at the pumps. I will look to do this at the weekend. Thanks

Why is it so hard to find parts? Can any New old stock be gotten anywhere? Im looking for clocks, handlebar switches, rear mudguard, and centre stand. Can anyone help me please? Sorry. titled mk1 should be RD125LC mk1

if its only done so few miles it won't be a choked exhaust then. However, you say the timing is 1.9. is that for leaded 4 star fuel? which it was designed to run on back in 1984. Now your using unleaded. I'm wondering if you need to advance the ignition timing slightly to compensate.

Decompressors are for big bore singles, [ or diesels ], XT500 had one, the DT400 ha an Automatic decomp, works of the kickstart via a cable,, i blanked it off .made little difference...

I have caustic cleaned and washed out exhaust. I have also replaced packing in silencer. There was some old oil and some carbonisation but not bad. The bike had only done 4033 miles in its first year (1984) and then not run until this year. I really am struggling with this. I have even bypassed wiring on stator direct to coil and makes no difference

Okay, heres another thing to rule out..... What about the exhaust? if its choked it won't run. Try disconnecting the silencer, it will be noisy....but unchoked. 2 strokes rely on a bit of back pressure to run successfully, so you won't be able to ride without it, but it would give you an idea if it's choked up too much. if it doesn't start you know its not that.

The tank was stripped delisted and revealed with POR15 so no bits in it New fuel tap too. The fuel flows well out of pipe with or without the cap on. This has been cleaned and breaths well. But a good shout as i had this issue in a Kawasaki AR many years ago

Might be worth ruling out the petrol cap.... they are vented to stop a vacuum forming inside the tank, which can cause the engine to stop with fuel starvation. Had this happen on my 400/4. Sometimes the seal sticks or the outlet tube on a trial is blocked.... Rule it out by seeing if it will run with the cap unscrewed/off. ....if it still won't start/run you know its not the cap. it's a simple enough test with no cost involved....unless it's the cause!! The seal acts like a one way valve, it lets air in but stops petrol leaking out.

Hi Cynic I have had the carb ultrasonic cleaned as it was basically full of resinous old petrol. The floats are sealed, needle good and jets replaced

Thanks NEO. that DVLA info is very helpful indeed, and that insurance sounds just right.

Thanks for that NEO. I myself can only think there must have been a good reason why the designers would have put in an extra spark plug hole, so it's still a bit of a mystery. For some reason i never ever have ridden a trials bike. I watched them a lot, but that riding never appealed to me, though that tv programme 'Junior Kickstart' presented by Peter Purves was very watchable. It seemed a very different skill, and they had a little lever on the handle bar to decompress, and i suppose the use of it would only be known to a trials bike rider. But maybe even a DT in certain situations could benefit from a decompressor. But I don't know. Doug

Hi, I have a XT125R 2009 and the speedo is in Ntrd speedo setting and I need it in Endr Setting. How do change to the Endr setting? Thanks

Hi Mike, It's just outside of Lichfield. The next "Ride to the Wall" is on 1st October 2022, but I'm sure there's no issue in driving there, if its not practical to go on a bike. I didn't really serve - I was "in the RAF" at Biggin Hill for 10 days going through the selection process for a Pilot Officer Training sponsorship for University (I wanted to be a fighter jet pilot), but was invalided out due to my hip issues. They couldn't risk me wearing a G suit, as my leg would likely freeze when the suit pressurised my lower body, and I'd be in agony....and probably just crash. At the time I turned down the chance to be a "transport" pilot or ground crew. But, I have an affinity to anyone who served, they deserve our support. Here's a couple of links, one to RTTW and one to the Arboretum. https://www.rttw.org/ https://www.thenma.org.uk/

Have you checked for floaters in the fuel. They can randomly block pathways in the carb and then clear. Causing your symptoms.

and oddly enough...I answered a similiar post a few years ago on the very same subject. I also gave the process of how I got mine reclassed as HISTORIC. Have a gander, it may help.... P.s. I have a multibike insurance with CIA for my two classic bikes DT and Honda, limited to 2000k miles per year. It was £120 fully comp this year for both.

Nope, that isn't a typing error in the title! I've just found a Thunderace for sale with less than 200 miles on it!!! https://www.gumtree.com/p/cars-vans-motorbikes/1996-yamaha-yzf1000r-thunderace-thunderace-sports-tourer-petrol-manual/1418957595?utm_source=newsnow.co.uk It's not pristine, hasn't been dropped, but has some damage on it (I assume from being leaned against stuff). Not that I have £3,500 spare, but I'm curious..: 1/ Would you be looking at a full engine strip? 2/ Other than all the rubbers replacing, what other problems would you expect from a bike that has basically never run for 25 years? 3/ Why do people buy bikes and then hardly ever use them??? P.S. Same colour as my Ace!

Hi Cynic, Thanks v.much for the reply. This is what I was dreading, having not undertaken a complete engine strip down before. I have the Haynes in front of me and have found some useful info on Youtube (Millyard). The actual parts are pretty cheap but I can see that I'll need a few additional tools. This is a low mileage bike (5800) so I'm guessing the bearings will be good. Out of interest, PJ Motorcycle Engineers indicating £200 for a crank rebuild.