Speedshop

You mean like this: I don't like to just chop off the back of the frame, looks a bits crap in my opinion. This is my remodelled SR 500 frame. You can play spot the differences for hours between the start and finished pictures! You won't find any angle grinder marks or obvious signs on the the remaining tubes where the old brackets where removed from. The idea is to get it so it looks like it left the factory like this.

Check the wiring in the headlamp. Also the fuse box....I've had the contacts (where the fuse clips in) fall to bits before on the XS650 causing intermitant faults. Take all the fuses out to check if you haven't all ready. And check all the fuses with a meter, I've had dodgy fuses before, the glass tube type being the worst for this.

If your chain has come off once thats a big hint you need to change both chain and sprockets. Even if you never adjusted the chain so it became loose it will tend to stay on the sprockets if it is not worn. Its only when the chain and sprockets are very badly worn the chain comes off (generally, there are limits as to how loose you can let a chain get) . Riding a bike round with a worn chain just bloody dangerous and stupid. The chain can snap and come flying off the bike rearwards if not arrested by the chain guard. Or it can become entangled in the wheel, locking it solid causing you to loose control, or possibly it can jam the front sprocket and smash a hole through the engine case. Been there and got the T shirt, I thought I couldn't afford to replace a chain when I was younger - a new engine due to the crank case being smashed beyond use as the chain tore through it was even less affordable.

The timing is controlled by the cam shaft, not the heads. If the direction of rotation of engine is the same on both bikes, the cam shafts will be set to work in the right sequence. The timing of the valves might be different though. If there are differences I'd check very carefully what they all are. Yamaha may have changed the number of teeth on the drive sprockets, for example - hours of fun if you put the wrong cam drive with the wrong crank drive ratio. They have done this on numerous occasions in the past with different models. You are going to need to build up the engine and use a DTI to measure the actual movement of the valves and compare them to the spec sheet for your engine. Good Luck!

The TCI shouldn't be affected by the resitor in the cap. Its purpose is for radio intereference, but you get a better spark with a resistor cap as the voltage builds up to a higher level before discharging across the resistor to the plug

I believe the xs400 is TCI and not cdi, which is why 3 ohm coils work ok.

My 650 ones did this, in answer to your question no you can't use a gasket sealer. The rubber washers under the taps will have chunks missing so will need replacing. The remaining seals will want looking at to why they should b leaking, but you shouldn't need goop to keep the fuel leaking out.

Try looking for ecu or fuel injection plugs. Thats not a Yamaha only item, cost them too much to design and develop a one-off plug.

No real way of doing a meaningful test on a cdi box with a multimeter, You come across diodes and transistors very soon in the circuit. I think if you do a google search you'd be able to find the resistance valves of the pickups. then do a thorough check of the wiring to see if the side stand and any other cut outs are good, working reliably and in correct sense. Once you've done that you have to think along the lines of you have power, signals from the generator and the coil is good............not much left in the system is there.

Why - this method does not acually remove the rust, just converts it - google it. Also if you cut the tank in half, you'd see it had missed areas - put selant on top of that and it'll be coming off again very fast as the rust lifts it.

I'd use the existing wiring to control the relay and run new power feed direct from the battery (with a fuse to protect the circuit). Doing this on its own may actually improve the lights by a noticeable amount. You'd have to delve in and see the best way to do this. Its unlikely there will be masses of power spare. You could use HID lamps that consume far less power then standard bulbs, or change all the bulbs (except the head lamp)that are on when you turn the lights on for LEDs - this may free up an amp or 2.

I say no as I assembled many new ones out of the crate and test rode so many of the damn things I bored myself to death with them. They were one of the least inspiring bikes, for me, to ride (second only to a Hardly which at least sounds good). I don't doubt the XV fills a gap in the market, they certainly are popular but I just don't get them, bland, middle weight, average are the only words I can think to descibe them! The Ford Escort 1.1L (in pale blue or grey)of the bike world.

Good job, I had nothing to do at work while it was down

basically you can't test it without specialist equipment. As I manufacture CDi units I have this gear, I can test units but swapping for known good items is usually easier. The DT box is very common.

Petrol

Forget the washing soda and electricity. it doesn't work inside a tank. Been there got the tee shirt. I even made special electrodes to go right inside the tank. It only really works 'line of sight'. Any curves or bends mask the effect. Cement mixer and blankets - totally barking bonkers mad - an English man on acid in the mid day sun mad! What you want is deox c from bilt hamber. Commonly used to regulate the ph of swimming pools. Mix with water, fill the tank, leave 24 hours, drain, inspect the shiny metal. Unlike the complicated, downright dangerous electric method the acid actually removes the rust. the washing soda method does not. Fact. Deox C leaves the metal bright and clean, does not effect the paint and no risk of blowing your garage. After i would coat the inside of the tank with an etch primer and leave it at that. Don't what ever you do use a tank sealant like 'pet seal'. you'll find this in your carb once it starts breaking away. Etch primer clings tenaciously to the metal and is thin so doesn't break away but protects the metal under.

I must admit this is a tricky one. If you are getting the battery voltage at the windings and appearing on the earth side of the regulator thats got to be OK. 11.87 volts from a new battery is very low (13.8 is more like it) , can you get access to another battery? Does the terminal voltage jump up when you disconnect it from the bike's electrics? A car battery slaved in place of the bike battery would do. Very unscientific, but with the ignition on will the generator just about have enough magnetism to hold a 10mm spanner against the case? Lets stand back and have a cup of tea (of coffee). The items in the system are: the regulator/rectifier unit. The field windings. The output windings. The wiring. The battery. The fault lies with one of these! Sherlock Holmes said rule out the impossible, then you must consider the unlikely. If the generator windings bell out OK these must be good. You've inspected the wiring. So really we need to look at the unlikely - the battery and the possibility you have two duff regulator/rectifier units. I have known good spare XS650 regulator/rectifiers that could be slaved in and would work the same way as the 400 one.

Never a truer word spoken. I've always had twins and single, but the more miles I put on the Beemer the more pissed off with putting tyres on it and stopping for fuel i became. And those damn indicator switches, 3 fcuking buttons to operate one system, OFFS! Handles well for such a heavy lump tho. want to go for something lighter with more range from the tank and less heavy on tyres/ brakes etc.

Not sure what they mean here. The regulator EARTHS the field winding. It should get the full battery voltage on the windings via the brown wire. If the windings are not even getting full battery voltage there's a fault in the wiring. If you shorted the green wire to earth then you'd effectively be calling for full power from the alternator. Be careful, alternators are 100% rated so will run quite happily supplying an extremely high current also running it unregulated will very soon burn it out. Shorting the green to earth will put the system in a dangerous state. I take it the regulator is earthed? (black wire should do this)

Diodes work or they don't 99.9% of the time. I found my Haynes book of myths for this bike! Brings back memories! It looks like you are in for an oily mess. The starter drive is in here and the starter motor is sealed as well.

Buy one - after a day out riding with a guy who had one,(on the Poker run in Sussex) I want a Kawasaki Versys to replace my 4 tonne extra girthy BMW R1150R

NO I don't care what arguments for and against - its a XV535 that SHOULD be enough reason not to want one.

There's your problem - that field voltage is all over the place. Check the wiring very carefully between the regulator and the generator (i think i read you changed the regulator). I've pointed out that these used to wear through the generator wiring at the gear lever so if you haven't already checked - please do so. My old black SE did exactly this and I saw several other 400s that did the same. The generator readings are low, they are normally much higher direct off the generator say about 20 volts rising to 50. The meter needs to be on AC. These readings would be low if there was a fault with the field. Which is I think what you are looking at. You need to see full battery voltage on the field with just the ignition on. For it to drop to 8.8 volts I'd want to be seeing 14.5 or higher across the battery. Can you confirm you have a solid state regulator and you've tried different ones? If its vibrating contacts, run some 1200 grade through the contacts and re-check. Its been 20 years since I last owned a 400, can't remember if the generator sits in oil, but there will be a gasket to seal the cover to the engine either way. My XS650 stopped charging last year, the field winding should have been 5 ohms, but measured 3.5, it was the field windings that was the cause - very common on the 650, I'd check for a wiring fault on the 400 first.

one tip, use a plummer's heat mat to wrap round the baffle first, then pack the baffle with fibre glass - lasts much longer like that.

most yamaha speedos run at 2:1 so it should be accurate. You only get problems if you change wheel diameter