NE0

Faulty engine kill switch?, Presumably it has one on the handlebars? Also worth checking the wire that goes to it too, if it's grounding before it gets to the switch, it won't matter how good the switch is if the cable has lost its sheath and the wire is grounding enroute. (I had something similar happen to me with my 400/4 one Christmas Eve!, unbeknown at the time, the cold weather had made a cable brittle and had exposed the wire which was grounding next to the steering head, just wouldn't start.... long push home for something so simple!)

You say you wouldn't be able to test the Regulator, but the regulator might actually be ok!, ...it relies on the metal body being in contact with the frame to complete the circuit, so in the first instance clean up the 'Earth connection' and check that the wire to the regulator is intact from the Ignition/light switch. We already know the wire from the magneto to the light switch is intact. (because the excess volts is blowing your bulbs!) but within the ignition/lightswitch, there are internal contacts which diverts the excess voltage via the yellow/white wire to the regulator. Disconnect the regulator and test the yellow/white wire which goes to it. You should get tha same rising voltage you see from the magneto, BEFORE it gets clipped by the regulator. This test would prove that the voltage is at least getting to the regulator! If it is getting as far as the regulator, clean up the earth connection, by removing the body and taking the frame back to bright metal to make sure of a good earth connection. If it isn't, (no volts at the wire) you need to check the wire for breaks all the way back to the Ignition/light switch. If the wire is intact (and still no voltage) then check the ignition/light switch, the internal contacts might be preventing those volts going to the regulator!! It might turn out to be new ignition switch is needed! P.S, if you've not got a Test meter, use a 12volt bulb instead, at least it will give you a visual indicator that the volts are getting there! (just don't rev the bike to over 4000v otherwise that bulb will blow too!)

Hi Doug, Yes it certainly points to the regulator not working. If you disconnect the yellow wire from the magneto and put a Meter on the end of it you'll get results like this... With the engine running and the generator disconnected from the rest of the bike, the output is as follows: Read the scale of the meter for AC volts. Yellow wire (lighting circuit) 2000 revs = 6v 4000 revs = 11.5v 5000 revs = 14v 6000 revs= 16.5v (This is my DT175MX lighting coil your result may be different) but the principle is the same.....now you can see why your 6v bulbs blow!!! the purpose of the regulator is to 'clip' back the ever rising output to a steady 6volts to run the lights. The regulator will get hot as it 'soaks up' the excess voltage, which is why it has the cooling fins on it. As you can see at 6000 revs it's soaking up over 10 volts! just to keep the output at the steady 6volts. You'll need a 6 volt regulator, presumably your bike is a DT175 1G1 model?

hi there, the output of the flywheel/magneto is AC...but....if it's not running...then you will only be able to test the output when you kick it over, don't expect a constant reading as the Flywheel will only spin a few revolutions. What model is it DT125 ?E ?F ?1F9. You mention "compensator" . In the UK it's referred to as a condensor, so is this a US or UK or another Icelandic bike?

So over a month on, have you now got it working? what was the problem.?

Hey Doug, There's a new old stock 1974 magneto on ebay Uk, Not cheap, but.... https://www.ebay.co.uk/itm/324829629386?hash=item4ba15acbca:g:yikAAOSw~35hZsJ1 you could make him an offer? Check it's the same one as yours of course.

You're welcome Doug, Think you're going to struggle to get one other than ebay or similar. You might have to think laterally , and instead of searching for a magneto.....search for another engine......just for the spare parts it will have.... to keep yours going. Doesn't matter even if it's seized ...if its got a magneto it will be worth buying. You won't need reminding that you're searching for 47 year old parts!...in a few years time it will be 50 years old!! and the bad news is ....I can remember being at school in 1974....and it doesn't seem that long ago!......gee life's short!!

I'm now convinced the part you're describing is indeed the advance and retard arm as you mention there is a sleeve which spins on the rotor body. For those that might be interested, this is the advance and retard mechanism for this bike. Typical of early car engines the timing cam was directly driven from the crankshaft. which meant the faster the engine went, the faster the timing shaft would spin. If the contact breakers (points) were fixed in one position and opened & closed accordingly, as the engine speed increased, the engine would not run properly as it would'nt be able to 'keep up' with the speed of the shaft. It was discovered that if the points were 'moveable' then they could be adjusted to open at a different position relative to the position of the cam. On a points based ignition system, the timing of points opening relies on moving mechanical parts to contol the opening and closing of the points. In an early 1970's car with an early LUCAS distributor, the points are attached to a moveable plate which is moved by centrifugal forces and is also attached to the vacuum of the carb. The faster the engine went the forces would move the plate altering the position that the points open. With a motorbike from the same era, there is not enough room to fit all these moving parts, so they created a system which moved the position of the engine cam instead. Here on the Yamaha DT of 1974, the points are mounted in a fixed position on the backplate. Unlike a car the backplate is not adjustable with this setup. Yamaha subsequently came up with the idea to advance and retard the opening and closing of the points by altering the position of the engine cam. In this case a sleeve which can be moved on the magneto body. Centrifugal forces makes the free moving sleeve spin faster, the arm and spring hold it in check, but in essence the position of the cam, when spinning faster, will cause the points to open sooner or later (depending on engine speed) Which hopefully answers your concern from your first post Doug:- No it can't be in a 'fixed position' otherwise it wouldn't be able to alter the timing. It's designed to move... but not by much. Hope this helps. NE0

Or Doug.... Having just re-read your post... I think you're referring to the Advance and retard arm which is fitted INSIDE the magneto unit. I looked on ebay and found a 1974 Magneto unit and there was a close up photo of the inside. Unfortunately, the part in question is part of the rotor assembly and does not have its own part number. You would need to source a replacement rotor (magneto unit) to obtain the part you are seeking. NB. For many of you who might be reading this :- Generator, magneto, rotor, flywheel are all (rightly or wrongly) terms used by owners worldwide for the same thing!

Hi Doug Initially i thought you were referring to the lubricating sleeve arm. As it's a points based flywheel (Not CDI). There is an arm which screws onto the backplate which is the carrier for the little pad which is soaked in oil, to lubricate the cam. Go to cmsnl website and find DT175 parts list and under flywheel magneto image you will find .... Part 11 and 12 in the above diagram refer to the pad and retaining screw, its not clear from this diagram whether the pad comes attached to the arm as a replaceble part. The photo appears to be a replacement pad only.

Hi Richsteer Welcome to the site, and to the world of biking ( XJ550 nice first bike) There are various websites which sell parts for Yamahas One which will be helpful will be this site https://www.cmsnl.com/yamaha-xj550_model16827/ Once you get used to navigating around you can find which other bikes (if any) share the parts. Unfortunately it would appear that the carbs only fit the XJ500 (Europe model). Assume you are in UK? or USA? Nonethless, new carbs won't be cheap and bear in mind a 1981 bike is already forty years old!! Most suppliers don't often keep new original unsold parts on the shelf for so long. You may be able to get 'pattern parts'. remade carbs but its questionable whether it was popular enough and has enough of a following for a company to invest in making them. (bear in mind the carbs don't appear to fit anything else). Which leaves you with the second hand market of ebay and other such sites. Then its all down to luck and whether someone has a set of four to sell. You might have better luck on looking "worldwide" instead of your local country. There's none available (only pattern repair parts) in the UK, I've just looked for you. Unfortunately theres also none available "worldwide" either...but thats just today. Looking at the 'completed sales'....there hasn't been any either recently. However, there has been a couple of 'barn find' XJ550s which were purchased both selling for under £500. So there is a chance of getting something for spares. Which might be useful if you've got one. I must say that I might have wondered why a bike was being sold WITHOUT its carbs? it may be the previous owner was having the same difficulty. just my thoughts. Anyway i wish you well in your search...keep us informed. Good Luck ..

Hello there MG, welcome to the group. Lots of big boys there MG! all over a litre!, i remember a time when it seemed like only the Electra Glide was over 1000. Where abouts are you in Kent?(general location only) Son has recently moved to "HawkyHinges!" so getting to know the area slowly. I'm along the SouthCoast near Sunny Brighton, not a cloud in the sky at the moment!! look forward to seeing your fleet.

It reminds me of the R1 video from 10 years ago!! complete with music from the Matrix.............I wonder if this guy is still alive?

I see the graphics on this latest game are approaching being rather realistic!! The give away being no spray from the tyres and nobody can ride that fast in the wet without taking a spill.!! Enjoy...

Is this a UK bike? Road legal? or a dirt bike used elsewhere? Presumably you've not had it long otherwise you'd know where the switch was.? if there's no switches on the other handle bar, have you considered asking the previous owner if there was one?

What would be ideal for you is a headless bushing adapter. Unfortunately I can't find one big enough!! M14 to M10 seems to the biggest. Although thinking about it 17mm to 19mm is only 2mm difference thick, so its going to be thin! which may be the reason they don't exist. The guys who could probably answer this in detail would be a custom bike maker, where everything is built practically from scratch! I'd err on the side of opening the hole even larger, welding in some solid rod and redrilling that and taping a new hole.

Hi Lotty, As Telly Savalis once sung a song!!....A picture paints a thousand words.....sing??? He practically talked his way through the song!....anyway.....I've re read your previous posts about your DT, it seems you successfully managed to upload photos via photobucket before... You could try again using Flickr as photobucket no longer works. There is an excellent step by step guide by drewpy here:- https://yamahaclub.com/forums/topic/45201-uploading-photos/ Your uploads attempt seem to be done with Outlook and its linked to your hotmail account. (hovering over the broken photo link gives the world this information).

Why's that then bud? Are you restoring it to concours and just showing it? Not being funny mate but I've been down the concours route and it's not worth it. It's very expensive to keep it "showroom", especially for a classic motorbike, where everything has to be 'perfect' to win prizes. It can consume you.

I re-embedded them this morning, they appeared again, but now they've disappeared again.. I did the same with Chrome and the same thing happened. They appear for a few minutes, but the link fails. Must be a Dropbox related problem, I'd recommend re-uploading them into Flickr as recommended by YOC.

mmmm....Photos seemed to have gone from my posts! They were there....honest! the link I embedded was this https://uce17a2cfdf4e8e825edb6623891.previews.dropboxusercontent.com/p/thumb/ABN7d9ZsZFaOqQXwa1BIFDSUcIziY8akLAn1PAFh-Y5WMlm_esdYM2E0N7VRNn65efT-Fwu11sZuLdmhptEZ4j6R9nZCjIKCd-44UPjMFOXsaz1-yWtbjac9xLGaQhrSo02bUs6ndNm4oUMjc8HivAGfwiSPviyDSZN46GJ4aR2LuIZk1fMKHAAV88f9PrRxWPPT9NmWCTd7taxZKqkK3W3dH1DYZy1vtE9FXf4rBqdzo9WFAemHyjThmoGVC2AMWYljBJh9YuFUe92fzouxoTZ_axJEYsgpQOjmyDTla_0pvz4oC0WxvIZyBRst308kfC5RlSO36zlRQh2M8oD9MQftp57dWFPk8nn0VdsyGZ5noKmN_77o5hAaFxpwQvtkM6bAXYY0Pal0X5Ln24HO8eIQ/p.jpeg?fv_content=true&size_mode=5 whereas it seems to have been truncated and ended up as p.jpeg?fv_content=true&size_mode=5 which is the last part of the link....

Welcome Justin, nice intro, well done for taking the time and effort to write one. Nice bike you got there, I like the 3 into one exhaust, not disimilar to my Honda 400/4 with 4 its snake pipes into one. I guess being a 77 its one of the first bikes to see mag Wheels as it was probably around that time they were introduced. My 75 is wire spoked and i don't recall seeing mag wheels anytime before 77. A lot of the members (the regular ones who respond) are all UK based and I assume CO and GA are in the US? At present the forum is a quiet place compared to a few years ago when it certainly was a lot more active. Nonetheless, welcome to the forum, hope you enjoy the place.

How odd!, I can see them in mine and in your reply post Snake. Yet if i click on the actual photo of my post I get a Dropbox410 error. Not sure what a 410 is,! same as a 404 I guess I'm using Firefox if that makes any difference.? Its even more perplexing as they have now disappeared from mine too!!!....I wonder if Dropbox are offline?

Try that? You're probably wondering how i did that? I hacked the Main frame using a Trace program after I went down the rabbit hole......hang on!.....back to the Real World.....it wasn't as exciting as that!!..... I initially clicked on the dropbox link which took me to the dropbox photos then right clicking over the image I picked "Copy image link" from the menu and inserted that link into my post and the photo came up within my post. Hope that helps.

That's the most sensible answer I've seen for a long time, Excellent.. I like the way you think! Although in his case, he mentioned it's already snapped. So as Finnerz says:- just buy one with a rivet link.

That is a very nice little project for someone. Appears to be all there, easy strip down. Being small and compact would be great even for a small workshop/shed. E Reg 1987/88...based on the current 40year exemption that will be Tax and MOT free in 7 years time. Might not be something that will be ridden around much once restored but would make a excellent 'showpiece' for someone.