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Hi there, The trouble is with many DIY ultra sonic cleaners is their small size. You can get bigger ones but You'll need one to fit at least one carb if you want the internals cleaned properly so you would be looking at at least a 1 litre one. Having said that you might want to consider looking up ultrasonic cleaning services for motorbike carbs (often seen on ebay as a service). These guys can strip it down and reset them etc,I appreciate it won't be cheap but an industrial one will beat any home purchase one hands down. As drewpy says it's likely the internals which are blocked and often no amount of blowing with an airline will clear them. Petrol if left standing evaporates leaving behind a shelac like varnish which is unbelivably rock hard!!

Good to hear you're up and running Brett, Nice one. As regards to the output at the headlamp, Here's a little tip for you especially if you don't understand electronics etc. Batteries produce DC wheres a Generator will produce AC. (I know some bright spark may pipe up and say about Invertors and Commutators, which are generally expensive devices to get AC from a Battery and DC from a generator BUT you wont find these on a little DT motorbike!!!) As you're working in the headlamp shell you will find both AC and DC. However, only the headlamp bulb is fed from the generator so it's the only one which is AC. All the other wires will supply DC from the Battery. And to supply the headlamp with AC the generator needs to be running. Turn off the engine and the AC stops....the headlamp goes out! Hope it helps, Well Done mate!

And here's the same circuit with the modification. Note nothing else has been touched.

Brett it may be useful for you to locate a DT175MX 1978~1982 wiring diagram and compare the layout to yours. However, the headlamp is run from the generator on an MX bike (1978) There are no circuit breakers or resistors or control boxes etc. it's a very simply wiring circuit/diagram. The ignition switch controls the circuit. Positon OFF : Engine off. Light circuits OFF position I : Engine running . switched lights only (indicators horns brake light) no headlamp. positon II : Engine running . All switched lights above plus HEADLIGHT AND TAIL LIGHT ON (today this would be called daytime running also) position III : Engine off. Tail light and parking bulb in headlamp ON ( Key can be removed from ignition bike left with minimum lights on for parking up at night) Here it is: once again colours are for a 1978 175 MX UK bike. the Ignition switch internal contacts are the black bars and dots. in position II the red wire from the battery is connected(by internal contacts) to the brown and red/blue strip lights/indicators etc. Whilst at the same time the yellow wire from the generator lighting coil goes to the yellow/purple of the headlamp and also to the regulator which 'clips' it preventing overvoltage to the lamp (a 6v regulator will clip it to 6v for a 6v headlight whereas a 12v regulator 'clips' it to 12v when a 12v bulb is used.) Also the generator white wire goes to the rectifier which in turn goes to the battery and charges the battery. It is noted that the white wire also goes to the switch but in postion II it is not connected. (In position I it helps prevent overvoltage to the battery.

I can't stress this enough but the colours and procedure is for the DT175MX range for the late 70's and early 80s models. Its unlikely that the colours used on the MX are an exact match to colours of another wiring diagram even if its built by the same company! so bearing that in mind, The C90 regulator uses three wires and an earth (dont forget the earth, the body was earthed to the frame on a MX bike, the C90 body is not earthed from inside, it uses the terminal) The C90 is wired using the two wires which went to the rectifier (red and white on 1978 MX) to one side. The other side has the earth and what ever wire connected to the regulator on the other side.( yellow on a 1978 MX, yours may be a different colour!) I don't have your circuit diagram in front of me but if you're saying the yellow/white wire went to the regulator then that's the wire which goes to the C90 combined reg/rect. The wiring colours below are those of a 1978 DT175MX....yours maybe different.

Hi Brett, welcome to the club, nice to hear the 'ol 12v conversion is still being read. The write up was aimed of course at MX models 10 years earlier than yours! so it may not entirely apply as the wiring is likely to be a little different. However, I guess if you've got so far you've taken that into consideration. if it was an MX I'd be thinking...... Is the 6.4v at idle without the effect of the regulator/rectifier in the circuit? This would be expected as shown in the 3rd post on the first page of this topic it would then go up as you rev the engine. As explained the purpose of the 6v regulator was to clip the voltage to 6v regardless of the output. Fitting a 12v one in essence clips the voltage to 12v instead of letting it get to 14v etc... if you're saying its 6.4v regardless of the revs then I also might be thinking you've got the 6v reg still in the circuit or the one you bought is a 6v one or faulty. Having said that, all this applies to the MX wiring circuit and may not apply to later models. Earlier models of DT have fancy things called avalanche resisitors and whatnot! (as mentioned by Cynic and Airhead in earlier posts) so it's not unreasonable to think you may have other accessories in the wiring which might effect the results. You also mention the tail-light lights up without the engine running, Well that is the same as the DTMX as its only the headlamp and charging circuit which runs off the generator. Everything else: indicators,brake light,tail light and horn all run off the battery. This may be of some help to you but equally just proceed with caution. Good luck

This has an air of familiarity for sure!....I certainly had a similar issue, I could rev mine over 5K + when its not under load, ie on tick over then whacking up the throttle and it run fine, however.....go for a ride with it under load and it didnt like going above 5K. Mine (although I wouldn't consider it at the time) was my exhaust pipe. ie the end can. I was given and fitted an original tail pipe, I was told it had been 'decoked' and I too cleaned it out with so called exhaust cleaner, and for a short time it did seem to be ok, but then the 5K problem started, it wouldn't run well at speed and top speed was only about 40~45 before it would play up, something was wrong but I carried on , but it didn't get better. After doing many things including new plug, carb, aircleaner, I eventually put back my rather noisey aftermarket can, and suddenly everything was back to normal, top speed and running all back to as it should be. Might be of some help?

the new rectifier/regulator..... Pattern part ? or Genuine?

What did you do in the end then Alex? did you hear back from Yamaha?

There's an interesting video on you tube from a fellow Oz suggesting the manual is wrong, i assume you've seen it? https://www.youtube.com/watch?v=l3q6wbct6-I

Hi Jonross, Might be worth looking at the parts lists for the R6 which may help you https://www.cmsnl.com/yamaha-yzf-r6_model16903/

I dated an imported bike once........from france if I recall.....boy was she rough!??

Nice, ....especially the brown carpet!?

Hi Emmert The three drain plugs are indeed one for the crankcase drain https://www.cmsnl.com/yamaha-ya6-1966-usa_model8299/partslist/A-05.html item no 17 is the drain plug and its corresponding filler top plug is item no 18. and the other for the transmission/clutch with item 15 being the drain plug and the filler cap being item 20 https://www.cmsnl.com/yamaha-ya6-1966-usa_model8299/partslist/A-06.html The third drain plug you mention is the actual drain FILTER plug, (item no 16) and is a seperate plug just with a drain screen fitted. The YA6 (like most motorcycles) is a wet clutch model, potentialy there can be 'bits' floating about from clutch wear. Back in 65 Yamaha thought it worthwhile to incorporate a drain plug to empty the crankcase and another for a filter screen, today it would be just one plug. Yamaparts provide a free pdf for personal use of the YA6 engine service manual, just click on the book image and it will download. You need to go to yamaparts.com / 2013 /01 /engine service manual its a bit dated but it might be of some help. I didn't know this but the YA6 was the first model to feature the Yamaha's dramatic new AUTOLUBE system!. You learn something new everyday. (Autolube was the separation of the two stroke oil into it's own little tank.) Member DirtyDT used to have one of these so he might be able to tell you what oil and capacities it uses but he doesn't often post these days.

Certainly drain and put in fresh petrol, Old petrol goes stale after about a year or so and loses it's 'ginger' ...it's ignitability! Equally if it's been sitting in the carbs it may well have evaporated by now leaving a rock hard shellac like deposit in the float chamber and in the jets! and disturbing the dry seals to inspect it will result in them requiring replacement too. The spark plug may well be okay, but for the sake of the few minutes to remove it and clean it all up helps elimante any problems starting it, ie "well I've checked and reset the spark plug" I left my 400/4 for a number of years and then set about getting it back on the road, like you it had been sitting in the shed for several years and all what you are doing is practically the same as i went through, having said that i was surprised how 'damp' the whole lot was even though its a dry shed, I'd recommend leaving it out in this sunny hot weather and get a free heat penetrating dry out, it will certainly help when it comes to starting her up. New battery fully charged, I moved over to the yellow gel battery and never looked back, well worth the slight extra compared to topping it up with water/acid etc. keep us all updated on your progress.

You don't mention whether you are looking for the round tube or square tube.( Earlier swing arms were round) but heres a square tube one on a frame, which you could buy and sell on the unwanted frame to someone else. Either way its an option? https://www.ebay.co.uk/itm/YAMAHA-DT-50-MX-FRAME-for-restoration-project-spares-or-repair-/153052149817

Hi there theres one for sale on ebay.... https://www.ebay.co.uk/itm/Yamaha-DT50-MX-Swinging-Arm-Spares-Or-Repair/312162229308?hash=item48ae519c3c:g:IyAAAOSwbsRa4C42 might be what you're looking for.

What a team eh?

The part number you need is 2N4-22141-00 and is common to over 323 machines. Just a case of looking for one for another model https://www.cmsnl.com/yamaha-mx175-1980-a-usa_model8746/shaftpivot_2n42214100/ i think you have to log in to see the full list. https://www.bike-parts-yam.com/yamaha-motorcycle/assignment_spare_parts/2N4-22141-00 this also gives a list of other bikes it fits hope this helps.

Yambits sell the kit https://yambits.co.uk/dt175mx-swing-arm-repair-kit-p-3002.html not a bad price at all, under £30.

Rick , I think you'll find it very difficult to cut that bolt out with the engine in place. As you can see, the amount of space available will make the job so much easier.

Hi Rick Yes, my mistake I was indeed thinking it was the swing arm pivot bolt which is just as difficult to get out! You're referring to the lower swing arm bolt (as you said in your first post!!) arrowed here! I assume you've taken the engine out to gain better access???

Hi Rick I did a thread to this on my own MX a few years ago https://yamahaclub.com/forums/topic/28370-dt175mx-refurbishing-the-swinging-arm having cut mine off, I used the socket and bolt to 'push' out the remains in the vice and also having re-read the post I even made a new swinging arm pivot bolt from an M10 stainless bolt and put a hole in the side for the split pin. it was a PERFECT fit and it's still there today working fine! The socket was used to 'receive' the bolt remains whilst the shiney bolt there was used to drive the remains into the awaiting socket. The vice was tightened up and up until there was a loud 'bang' as the remains of the shaft gave up! then it just had to be pushed out. I remember it well, such a sense of achievement!!

Well for those that have been following this topic, I've just had to 're-tax' my HONDA 400/4 which was declared an HISTORIC VEHICLE on the V5c the fee being £0.00. I received the V11 reminder which states the fee of £0 but also states "This vehicle needs an appropriate MOT test certificate" so I went to the GOV.uk website, put in the 16 digit reference number which stated the details of the £0 and then It stated "This vehicle was constructed over 40 years ago and may be exempt from MOT. To which you have a choice of selecting a declaration that the vehicle had not been radically altered from its design and thereby declaring it exempt from MOT, If you select otherwise the you then have to organise an MOT). i selected the declaration and the next step was saying no fee to pay for next 12 months. it would appear that every year you have to declare its exemption and your no tax, which is not transferrable. You still have the option to declare SORN. Well there you go, a relatively painless process from someone who's actually done it. ((you can now ignore any other stories you may have heard!!)) Nice one.

Yes, that's correct! The "failure" over-rides the rest of the MOT. Regardless of the amount of time remaining. That's the drawback should it fail. The advantage is of course if it passes, as you explained, it continues for 13 months.