YPVS TONE

It sounds like the rear brake light switch .

Yes, this should set the piston at TDC but make sure when you rock the flywheel just before and after this position that the valves Don't move. If they do, turn the flywheel another 360 degrees so when you turn the flywheel just before and after this position that the valves Don't move. This will put the engine in the correct positon i.e TDC on the Compression Stroke to set the valves and camchain.

The camchain and valve clearance have to be set cold with the engine at TDC on the Compression stroke. If you remove the gear lever and the LH side engine cover you should see a T mark on the flywheel which you align with a timing mark / pointer on the crankcase at about the 11oclock position. When you have these lined up rotate the flyheel back and forth a bit while watching the valves. If both valves move you are on the wrong stroke and you need to turn the flywheel 360 degrees. As DirtyDT has said the pushrod inside the adjuster should be flush with the end of the adjuster with the engine still set in the above position. If it's whining it sounds like you have the camchain too tight. Once set start the engine and with the adjuster cap off make sure you can see a bit of movement on the tensioner pushrod .If not loosen the adjuster off a bit until you see the pushrod move slightly in and out. Tony

Looking at the manual the forks look pretty conventional with the only tool you need is to hold the damper rod while you undo the bolt at the bottom of the forks. Tony

What freeplay have you got at the clutch lever? You should have 10-15mm measured at the end of the lever or 2-3mm measured between the clutch lever and the clutch lever holder before you feel resistance. As DirtyDT has mentioned there should be an adjuster at the engine end incorporated in the outer of the cable and one at the handlebar end where the cable goes into the clutch lever holder. If it is a pattern cable it may not have the adjuster in the outer cable. Tony

THE 1979 DT125MX I had defineately had a rectagular swinging arm and from what I remember as Airhead say's the oil tank was on the right hand side and the airbox on the left.

Just had a look on the parts cataloque for the XT550J and XT550K and noticed on the J model there are three screws that hold on the front sprocket cover with one screw boss to the right of the sprocket. Just wondering if at some time the chain has jumped the sprocket and broken off the boss hence the repair ?. On the the later K model there looks like only two screws that hold on the cover both to the left of the sprocket. How many screw holes do you have in your front sprocket cover and if three would the one on the right be inline with the "Hole" you've found. Just an thought as I can't see any bungs shown on parts list. Tony

Think you will find the Red/White and Green/White wires from the pulser coil and the charge coil wires go to the CDI unit. Can you look at the wires on the CDI unit and see what colour wires come from it. They should be colour coded so it should be a case of matching them up. I remember when I worked for a Yamaha dealer back in the 80's a chap brought in an IT125 that ran backwards and it turned out that he had taken the engine out and wrongly connected two wires to the CDI unit.

As Airhead has said if the mirror hits something when you're moving forward they are supposed to unscrew rather then shear off and ruin the mounting.

He's been watching Jamie Whitham ride.

Does it look like this RT180 ? http://www.cmsnl.com/rt180-motocross_model16785/info/ The 500cm3 marking sounds like the gearbox oil capacity if it's by the transmission oil filler. Is the 178cm marked on the cylinder ? Tony

Done a search and the 5x5 prefix seems to refer to a 1982 YZ250J motocrosser. The UK DT125LC MK1's were 12W (Restricted) or 10V (Unrestricted).

Isn't there a main light switch on the RH switch assembly just above the start button you have to turn on first ?

As Cynic has said chain maintenance on a bike is pretty basic stuff but it always makes me wonder when you see how many people get it wrong, even Dealers. Remember a few years ago my Brothers mate took his new Triumph in to an Official Triumph Dealer for it's first service and noticed on the ride home there was an annoying whine from the rear. When he got home he noticed there was no freeplay in the chain at all and it was as tight as a bow string. Needless to say he never took it back there for a service if they couldn't even do that right !! Makes me smile when you go to local bike meets and you see all these latest superbikes with all the latest end cans on to get an extra few BHP, then you look at the chain and it's nearly draggin on the ground with no lube and the sprockets all hooked.

Yes it should last longer then that but as mentioned depends how well it is mantained. If you are using the platinum lube this should be ideal as it is Yamaha's own brand and is what I use and found it one of the best as it stays on the chain well. The only thing is you mentioned that the dealer adjusted it to very little play in it then this will drastically reduce the life of the chain and sprockets. In the manual in say's you should have between 20-30mm of freeplay measured in the middle of the bottom chain run with the bike on the centre stand. Any less and it won't take long before they are worn out. Maybe you should have a go at doing it yourself. Providing you follow the book and make sure everything is tightened / torqued up afterwards you should be ok, then you know it is done right.

As mervin has said it shouldn't have worn out out in that time providing that it has been adjusted correctly and kept lubricated. The dealer sounds like he was on about the sprocket carrier bearing but if the chain has been overtightened this will cause it to fail as well as putting strain on the rear wheel bearings and also the front spocket output shaft bearing. What free play have you got in the chain at the middle of the bottom run ? What kind of chain lube are you using ? Again as mervin has said check your receipt which should have the mileage on it when the work was done and provided they used Genuine Parts which they should have done at that price ask about the warranty on the parts. Tony

You should have three wires going to the rear light, a Yellow that does the brake light, a Blue/ Red that does the tail light and a Black that is the earth. Are these connected to the corespnding wires in the loom .Check mailnly the rear light is earthed ok. Tony

Just had a look on the parts list here http://www.yamaha-mo...L_R5_(R5_-_1970) and it shows a seperate wire thats held on to the indicator stud that provides the earth which should plug into a plain black in the harness. Tony Just clicked on link and it doesn't go straight to it but if you select : Step 1 Motorcycle Step 2 1970 Step 3 R5 Step 4 Turnsignal you will see item 9 which is the seperate earth wire Tony

Check to make sure the wiring connectors to the indicators and relay are tight and not corroded and also the bulb sockets are clean. If the brake light flashes as well sounds like you have something wired wrong or a bad earth ( Plain Black wire on Yamaha's).

Put the two bulbs marked 6v 17w in the front and back of the right hand side and put the indicator switch to the right and see if that works. You say the battery is fully charged but do the indicators come on without the engine running?

Does the new relay match the wattage of the indicator bulbs ? On the relay it should say something like for example 6V 10w x 2, so you need to make sure the indicator bulbs are all 6V 10w.

You are right in that there should be two wires going to each indicator. Dark green is the feed to the RH side indicators with a plain black being the common earth on Yamaha's and Dark Brown is the feed to the LH side indicators with again a plain black for the earth You should have a Dark Brown and a Dark Green in the headlamp shell unless someome has cut these as well. hope this helps. Tony

There is usually an "O" ring fitted around the end of the starter motor where it goes into the crankcase.

Do you know when the valve clearances were last checked. My brother had this on his FZR1000 EXUP he once had and found some of clearances had closed up and it was a pain to start from cold. Once it had warmed up it was ok.

Hava a look here, looks like it's a 6N7. 5-5A : http://www.ydsparts.com/yds3ym1chassis.htm Hope this helps. Tony