Cynic

Yep 2h500 carb, looks like a gianelli pipe (common replacement for rotten stock pipe) with the generic tailpipe. The leaky airbox isn't good but not neccesarily the cause. All of it looks ok enough, unless you were spanking it at high rpm? Possible crank seal issue. Ig can also play a part but it doesent go off much on DT's. It needs to be absolutely cock on but if it hasn't been messed with it wont go awol. The people rebuilding the motor, are they doing a full build or just the top end?

He's going old skool on us. Its what the old coach builders used to do to fill welds and such on bodywork its a lead/zink blend i believe.. Some call it silver soldering (very similar to plumbing soldering), only used on older car radiators now i think and really expensive car restorations. My ol man could do it if i'm understanding it right.

The airboxes changed with the oil tank and if its filling the right hand side then it will be the earlier 1979 type. The main jet being a 160 with that airbox shouldn't have blitzed the motor, its 30points too big it should run like a dog. There is info your not telling here. Has the bike got, Std exhaust and tailpipe? Effective std or equivalent filter? Gas tight inlet and exhaust joints? The biggy, properly sealed oil connection at the carb? How does it run generally, high tick over, bad starting? Gearbox oil level? The bike won't be 'just' lean, i doubt the carb settings are the problem. Is there a tag on the carb that gives you the 501 carb id.

How would Blackcurrant Juice help........? Detox.....

Nothing wrong with DID looked after that chain should be good for 10-15000mls, badly adjusted and left dry you will be lucky to get 1000mls

Its good practice to do a bit of an intro on here. There are no silly start up screens and protocols but its generally accepted you pop a few words in the new members bit. Your piston issue, 41mm is the stock size for that bike, has been for the dt 50 since i was riding em in 86. The 0.5 on the piston denotes the oversize, ie it has been rebored and a piston .5mm bigger diameter has been fitted. If you want to replace it then you will need the next oversize up probably 1.0mm The bigbore, who knows. If you can't find out who made it to get replacement parts it may well be junk.

Where are those numbers coming from? The 2h500 carb does exist but not with that needle id, although it does have a 130 main. that would be for the earlier bike though. The 2H501 is an unknown for me? To be sure all you need is which side the oil tank is on, if its on the right of the bike( when your sitting on it) then you have the later airbox/cdi needing a 160 main, if its on the left you have earlier filter/cdi and the 130main will do. ............................ Early.... late type..................... vm24ss.... vm24ss id......................... 2h500.... 3u500 main jet............... 130.... 160 jet needle............ 4j13.... 4j6 clip pos frm top.... 3rd.... 3rd Needle jet............ 0-2.... 0-8 Thr cutaway........ 2.0.... 1.5 Pilot jet................ 25.... 20 Idle speed........... 13-1400.... 1500+/- 50 TBH so long as the main jet and the needle jet is right the rest is down to how fussy you are as you really won't notice all that much. The 1980 125mx is pretty much identical to the 175 save for obviously the cc, the carb and the clutch which is slightly bigger with an extra plate. And the fact the 125 needs spanking like a politition to get it going, wheras the 175 has a lot more plodability but doesent like revs. 8k is about as high as you want to go unless its for short blats.

Don't know if this helps, its from a write up from 1974 Cycle magazine. The engine's ability to generate enough power to get the rear wheel churning away starts at 2500 rpm. The rate at which you accelerate is directly related to the amount of throttle applied. The DT360A's muscular engine takes most of the hassle out of dirt riding. It doesn't have to be wound up tight in order to pull the bike over a snag or out of quagmire. The block-pattern tires, tractionless terrain or tall street gearing are the only limits to the engine's pulling potential. Because of ease of riding gained with this extra low-speed power, it's certainly worth the additional investment to get the larger 360cc engine in place of a smaller displacement machine. Attempting to spin the engine above 6000 rpm for more power is futile, but staying below this rev limit still gives the rider a 3500 rpm power range, and that's more than enough to overcome the broad gear spacing. Riding in the rough, for expert and novice alike, is made enjoyably easy by this wide power spread. Gear shifting doesn't have to become a preoccupation. When you want to accelerate, rolling open the throttle another notch generally brings the speed up. The engine doesn't have to be spun like a buzz saw and is seldom worked hard. It's entirely possible that this engine would last an entire enduro season without appreciably wearing engine internals, because of low crankshaft speeds and moderate work loads placed on them. It quotes peak power at 6k and peak torque at 6.5. The full write up is here. http://www.motorcyclespecs.co.za/model/yamaha/yamaha_dt360%2074.htm

Think your going a bit overboard there, dilema's on legality are, is this exhaust too loud? Can i use these headlights? No L plates is a given, its not something only a traffic cop will know. You would even have beat bobbies walking past nicking you for that one. They are there for your safety too, it 'should' allow you a little give to make mistakes on the road. Ryan hardly jumped on you, you are aware of the irony reading your post? he was only voicing his opinion.

Don't do it, 24 years ago i did exactly the same. It was 2 points and 30quid it cost me then so relatively its a lot cheaper to be a bit dim these days.

Not too warm, oh i wish. Its 5 or 6deg and blowing its preverbials off around me at the moment. The not too sure element is pretty standard for a 70's 2 stroke, i actually ride with a finger covering the clutch lever. A carry over from my teens riding some pretty ropey stuff round my cousins field, most of that siezed without any real warning. Ideally DT's run better when they are a touch rich in my experience if you are riding at higher speeds for a while, they are aimed at trails and commute i suppose all low rpm stuff. Ultimately for mine i ended up putting a slightly smaller jet in and lifting the needle 2 points, makes her a bit faffy round town but she's safe to thrash, i mean ride with gusto on faster roads.

Nah, i bet its one of them sliding paper things.

3 very important words to help. Vehicle wiring products Have to admit when i rebuilt my loom i cheated, and where they were perfectly servicable i kept the multiplugs. A lot of the stuff in the headlight for example is usually mot all that bad. It was the stuff exposed to heat and road crud that suffered and there i used connectors i felt were practical. An example being the mag multiplug, on the dt it sits near the exhaust under the tank. Not any more. Lay the loom out on a big bit of board with pins/ nails in it to locate stuff, long enough and wide enough to lay it out properly, with any tape on it for now. Peg all the legs out and highlight what they do. Mag, brake sw's etc. picture it like your bike squashed flat in an old MGM cartoon. Then take the tape off, nasty shitty job. Now (dull bit) do yourself a drawing, better done in sections or it gets too confusing of all the wires and note all the colours. There WILL be more than in the manual, check the lengths and order as required as well as connectors etc. Now get another board and duplicate the peg/pins and the various locations on that, like 'headlight', 'mag' etc. Then build up the new loom referencing the old, double check then once your happy add the connectors as required (you may want to use modern stuff unless your after factory anorak spec) then remove from the board after a token tape up to make it protable. Shape it on the bike so it fits the frame properly, check it all works then give it the good news and tape it properly. Easy eh HTH

Think they were Kev's (up yours) first words?

So do you worry about it when your out and it rains? Don't be so daft.

Your only changing the profile not the actual size of the tyre, it will affect the gearing and will damage the on road handling but they will fit fine, providing there are no current clearance issues. An 80/90 tyre is a tyre that has an 80mm tread area and the tyre height is 90% of the width of the tread ie 72mm. Your replacement will be the same width but 80mm tall, 8mm doesent sound much but you will feel it. The rear will be more, a 88mm high going to 110mm. That will affect performance to the point that it may be worth considering a gearing change to keep the bike lively performance wise. Think of the rear wheel as the last big gear in the transmission and your making it bigger by 20%. Could be worth a tooth off the front to compensate, possibly more when you allow for the extra drag of dirt bias tyres and loss of top speed. Of course it will affect insurance too, esp if handling can be pointed to as the cause of any incident.

Have you checked the plain metal plates, they don't need to be out by much to ruin a clutches performance. Happened to me on my old 350, followed the same route you have turned out to be the plain plates being warped slightly caused by heat due to the slipping of the worn friction plates.

2012 here,

Don't swap in another one, that may be no better. Float valve seats last for years and don't fail all of a sudden. They get blamed for overflowing unfairly, people accuse that then adjust the floats when they fit the new one and magically its fixed the problem. After a rebuild there is more likely a tiny bit of rubbish in there or the tang on floats need a tweak. I had to do my TDR a while back as that started to weep from the left carb. One last thing, if the bike has a jack up kit its highly likely for it to leak due to the stand being short, mine is terrible for it.

There could be some truth in that with the etanol they are adding to fuel so its cleaner, modern fancy pants electronics have all sorts of sensors to correct the mixture to a finite degree. Our little DT's don't, so you may well have a valid point.

Paul the Belgradia easily qualifies as rocking horse shit rare. They were a special edition in their day and many got used for racing thanks to the upgraded running gear, forks, wheels etc. You will have to hunt high and low for parts as save engine and wiring there are lots of unique to the model parts, the sw arm being one of them.

Welcome to the forum. Your in a good position, if you can't fix the bike then you will get your money back advertising it on the TDR 250 forum as the running gear, forks wheels etc are a dead easy swap to moto the TDR. That said i'd sooner help you get her going, TZR's are great little rockets.

Thats my summer sport, there are several roads near my village that would give you an arse spanking to rival miss whiplash on a rag day if you were riding a racer. My TDR eats them, it excells on point, brake, blast it roads. They end up stood on the back wheel on the big stuff or bogging in the wrong gear on the 4/6oo's. They never figure the dirty worn bike gears means riding A LOT more than they do Bring it on.....

Yes..

So has the bloke that mot's my bike and he still needs me to tell him how to turn on the lights on my DT cos he can never figure it out. It has an on/ off switch on the bars AND an on/off setting on the ig sw. Go figure.......