JimR

That is non Yamaha ..... looks like a Honda one !

Welcome to the Yamaha Owners forum :welcome:I just guess you have not got everything connected don't forget all circuits need to wired in .... my Divi did 3 years in a shed (and without the removal of the fairing) fired up no problem .. but perhaps check the fuses and insure that the battery 'really' is good enough .. perhaps just run a car battery in series but without more info this will be difficult to solve

Ok ... sounds like you have the older SOHC bike rather than the newer DOHC bike .... 1983 was about the time the design switched (in the UK) and shops could hold older stock and have the title a year or so later than manufacture. Assuming the earlier bike (from your recognition of the images) you have many things to check ... which have to be checked in the right order (if you do not check in the right order you may have a miss diagnosis) This may sound silly but do the following :- 1) Battery Voltage =< 12 volts but >13 volts 2) Valve Clearances 3) Compression test (Wet & Dry) over 100 kpa but less than 10% difference between the figures 4) Vacuum pipes from the fuel tap & fuel tap itself 5) Carbs Cleaned 6) Wiring from the CB points to the rest of the ignition circut but in real terms check electrics,carbs & compression if you have all of these it should run .... but I guess new bike owners tend to over complex the problem .... let us know how you get on

Look at the diagram supplied ... if you have melted the 3 white wires from the generator it does sort of point to a problem with the VR if it has been wired up incorrectly, but I guess that worked all of last year so it should be wired sound.As you have only changed the rear light before the problem occured (correct me if wrong) is there a chance you have taken a live feed from the wrong side of the VR ? From the photo's shown I can not quite way up how you are rectifing and regulating the voltage supply does the car part have a regulator & rectifer built in or have you just guessed ? This may do the job if the car unit is just a regulator .... given time I could produce a full loom design for you .. all you will need to do is follow the instructions .... but bear in mind it would be UK spec

does the bike look like this one ? or like this one if it looks more like the top image you may need to get one of these

The wire that is frying appears to be the power supply from the generator ... I also only have knowledge of UK spec which may be slightly different ... could you have soldered 2 wrong wires at the fuse box ? what you describe appears to be the charge from the generator going to the wrong place, but to be fair (& looking at the photos of the wiring) I would suggest you do a total rewire this may be some use you will notice the yellow is totally unused when using a simplified wiring loom. given this starter diagram you could easy add extra live feeds from the ignition switch to run indicator lights, horn, dip/main beam etc. Given a little time you could design & build a loom to run what you need. if you look at the old loom ... the brown wires tend to power switches etc so you could work from that on your design

are we talking a dohc XS400 twin or something else ... if it is the twin .. check the fuses first then go for the CDI box

38k the old girl should be a bit loud (with out a strip) mind you if you strip a girl with 38k on her she is a) thankful & loud

I would change the jets ... as the oily mixture would require a slightly larger main jet .. I would guess you have done the obvious .. ignition timing & decoke to ensure the rest of the motor is running ok ... but also if you have not blanked of the oil intake into the carb for sure the motor will run weak

If you are going to change the clutch basket & primary driven gear make sure the primary drive gear has the same letter etched into it .... if you do not everything will work fine but you will have some noise from the primary drive ... but at 38k I would guess this noise will be lost in the overall mechanical noise of the motor

The white & red wires also run up to the ignition switch & light switch which in turn may give you false readings via a multimeter depending on how the lights on/off & ignition switch are set .. it is possible to have a good circuit between the wires until you toggle a switch ... then when load is applied to the charging circuit direct voltage is applied to the bulbs as the broken wire allows mag output to them rather than running through the charging circuit. Look at the wiring loom running below the bottom yoke .. if the plastic section is cracked (or maybe repaired) there does stand a chance of a broken wire .... with the cost of bulbs (as they go bang, but a with a brill white light) I would investigate it .... Other things to look at are the ignition switch .. has it gone a bit ape ... so going O/S when you turn it to 'lights on' position the same is true of the lights on switch (if fitted) on the left hand switch gear

Sounds like a broken white wire to me .... cut the loom back where the plastic bit joins the tape (below the head stock) it was a very common fault with the RS series

Glad you know what model we are talking about .. there appears to be no notification to that ... so what is confusing ... my reply or the thread ?

Ok RS125 .. no problem as I can not see the original problem can you tell me what has gone wrong ?

it would have been good to know which model the OP asked about. After looking at the bikes owned I guess this to be an RXS100, which in really is an RS100/125 with CDI & YEIS .. so therefore it runs the 353 unit with also a soak diode in the wiring loom .. which was badly placed ( just under the bottom yoke). With the introduction of CDI there should be a single wire VR supplied from the loom via a yellow wire with a black trace, but from memory the loom did not do that and the original issues with the RS100/125 loom would still apply. but I'm old .. and may be wrong .... let the youngsters who have read the books prove me wrong

I would try balancing the carbs ... you could also try checking the valve clearences and checking the cam chain tensioner is in good nick

it well depends on the type of rectifier you are looking at... a good old 6 volt one is simple basically a zenier diode as the 70's evolved some of the 12v rectifiers also served the purpose of voltage regulation, which then added more diodes to the unit to turn the AC output from the generator to DC .. I.E cutting the wave form in half, then passing the resultant current to another diode which managed the supply to the battery (this diode went O/C if too much current was applied and stopped battery charging). 6V systems just tended to boil the battery (hence the phrase rectum fryer as most batteries were placed under the saddle), but later 6V systems added extra diode to make sure the battery did not boil

I guess you need to set the ignition timing .. if the condenser is giving problems .. the motor will run but misfire if you add load to the mag (switch the lights on) but if you want to test a condenser just test to 22 microfards across the unit then charge it up & then discharge ... But another thing YB100 suffered with was 'loads of carbon' you may find that the rings have stuck or the bore has been 'glazed' with carbon and your problem is lack of compression. Don't forget if you remove the mag you must set the ignition timing

Not with the YB the disc valve will be in such a position that will not to allow not allow the fuel evaporate

Welcome to the forum Max ! just a thought why do you not want an OEM tank ? ... as they tend to do the job that the designer designed it for. you could run the bike without a fuel tank ... a bottle will do, but I guess that after 10 years in a barn the bike (Carb etc) may have other issues and a fuel tank maybe the last thing you need .... I think a better idea would be to get the motor running again then look at the aesthetic requirements of the bike Regards Jim

Well the carbs are off an XJ but without some venturi sizes I can only guess they originate from a 550 !!

Hi & Welcome to the forum adding new bulbs may be problematic without checking the wattage of the relay. back in the day there was a 'fix' for the indicators not flashing at the correct rate :- fitting lower wattage bulbs & relay. So if you fit 10w bulbs & have an 8w flasher can, they will not flash (just stay on). To test a relay :- 1) Ensure the battery is well charged 2) Remove the relay from it's rubber band 3) Turn the indicators on 4) if they stay on tap the relay .. if they flash when you tap the relay then replace the relay & ensure the bulbs match the wattage of the new can - job done else you have earth problems which may stem from either the bulb holders or naff wiring on the earth to each indicator. Headlight problem sounds like a badly fitted bulb or someone has plugged a blue wire into a yellow or vice versa Regards Jim

sounds like the clutch has siezed up .. give this a go :- start the engine (making sure the rear wheel is off the ground) zip tie the clutch lever to the handle bar then engage first adjust the tick over up to about 3k press the rear brake pedal if the engine stalls the clutch needs freeing off if does not everything is fine if the engine stalls just let the engine run in gear and the clutch lever zip tied up, at some point the clutch will free up (you can test this by pressing the brake pedal from time to time). If you don't want to do this strip the clutch plates out of the basket, allow to dry & refit

Hi you still have a carb issue, I would guess, but the motor may also lack compression ..... can you give me an idea on how long the motor has run after it's 10 year lay off this will help on which problem you have

a pee wee will run fine with any engine noise .. remember the engine is just an MA50/QT50 engine (road moped) The only engine noise to be aware of is if it sounds like the crankshaft is going to exit crankcase This motor did suffer from noise from the automatic clutch, which gave the impression of the motor being worn when it was just that dam silly clutch gone wrong Being harder to start would indicate a few problems 1) Pulse coil on it's way out 2) exhaust blocked (this also can make an engine noise) 3) the silly start switch !!! 4) blocked carb you need to work out where the problem lies .... if when the bike is running it goes fine discount mechanical failure and look at the other points