81 Yamaha Maxim problems help plz....

[gjewison]

Hello everyone just joined this site and like the lay out so i thought i would give it a shot.....Well...

My problem so far:

I bought a 81 yamaha maxim 650 and have been having problems getting it to start. I dont know how long it sat before i got it but i have tested some already problems.

1. compression tested and is good
2. pulled spark plug to test there is no spark
3. gas is getting to cylinders but is not firing can tell because plugs have gas on them.
4. checked wiring replaced all the fuses

when i first bought the bike there was a spark but but only the first time i hit the start button every time, then it would crank over and there was nothing after that. I just put a new battery in and now there is no spark! The battery is good and turns it over very well. I have search all over to find info on the web and bought a repair manual but will take a while to get and want to get this fixed. Does anyone know of a good way to troubleshoot this problem? I have read all over that it says to test the coils, rotor and contacts, and other wiring...but it dont tell me how to actually do it? Is there a selonid or fuse that i would be missing for the ignition?

Any help would be greatly appreciated! TIA

gjewison

[Easy Rider]

Originally Posted by gjewison

...... bought a repair manual but will take a while to get and want to get this fixed. Does anyone know of a good way to troubleshoot this problem?

If it has the "classic" points/condensor type of ignition, I'd change points, condensor, plugs and maybe rotor and cap first (standard tune-up). You can start looking for the parts while waiting for the manual to arrive, 'cause you'll need the book for the proceedure to set the points and timing.

Good luck!

[omegajim]

Let's start with what I'm pretty certain of and go on down the list from there

1) didn't happen to overlook the kill switch did you? I have nearly pulled my hair out only to find I bumped the kill switch. Which is why I almost never use it, because I will forget by the next time I start the bike.

2) this bike is an '81 and although it is a 650, I'm reasonably certain that it has electronic ignition which rules out points as it won't have them.

good luck

[gjewison]

i check the kill switch and if its off engine dont turn over or nothing when its on it works and turns over fine....dont think thats the problem. It does have electronic ignition and coils. wires and ignition coils are the same unit and have to buy all together and are rather expensive and would prefer to troubleshoot and leave those as a last result. i check everything i can think of is there a selenoid that im missing for ignition fuses are new and so are plugs....please help thanks!

[GregR1]

there's likely a way to check if you're even getting a voltage spike to the coil in the first place. the controller side of the coil is low voltage, so you should be able to find a probe / light / analog needle voltmeter that will indicate if you get "spark" spike from the ignition control parts. if you don't get a "spark" spike, then you gotta work your way back through the distributor and controller box until you do get 'spark'.

[gjewison]

not sure what you mean i understand that there is surges everytime the ignition coils will fire the plugs but i dont have the first clue on how to actually do it or to find out what its suppose to be? I have read on the net here that you need to test the ohms that are going to the coils and when it spikes is when it should be firing but cant find out what the ohms are suppose to read and where your suppose to test them on the coils??

my iginition setup included to "points" that are magnetic it seems that a rotor passes by for the firing sequence....which then sends a signal to i dont know where... which is suppose to tell the coils to fire the plugs. behind the cover on the left side of the bike is an ignition module or something and the bike actually came with an extra one and replaced it and still is nothing i would doubt that both those are bad so i dont think its that.....any help is great

thanks!

[GregR1]

you sort of coulr check the coil's primary ohms but there's not enough wire turns to make it terribly accurate. you can do it on the plug side, though, since the coil has way more turns of wire out there.

ok, the coil (either one central one before the distributor, or one-per-cylinder) is gonna have 3 wires - the ground connection, the low-voltage end that goes to the controller, and the 50kV that goes to the spark plugs. the ground is easy to figure out since it will lead to the chassis somewhere. the 50kV line is also easy since it'll have that thick wire on it. the last wire is the one that goes to the controller.




ah, bugger it for now. anyone got an exploded view of the coils on that bike? would be easier to explain the system from that....

[gjewison]

i might be able to get a picture on here have to check....theres 2 coils each coil runs 2 plugs there is 2 wires that go into the front of each coil and 1 ground for both of them. where do i hook up the meter to test though and how will i be able to notice a flux in power is it going to be very noticable?

[GregR1]

ah, ok. that's what i recall from a similar thing a while ago. hmm, those two wires are low-voltage, so you COULD hook up an analog (needle) voltmeter between one pin and ground. the spark will be fairly quick, so the needle might not jump far, but it SHOULD move (might have to set the voltmeter to a lower range).

if you don't have one, find a cheap $5 or $10 analog (needle) voltmeter. they're stupidly handy for a bunch of things.

[gjewison]

when i got the bike the cover for the ignition points and rotor area was loose and not tightened and also needs a new gasket but inside i noticed that one of the contacts was missing a little bolt that was suppose to be holding it in place better....i did replace that but its a little dirty in there also is there a good way to clean that up at all? i dont think that it would affect it that much for spark its not greasy and all just dust and dirty and i wiped some stuff down. i have carb cleaner could i spray that area?

[GregR1]

best thing to use is (electrical) contact cleaner. not sure if carb cleaner has the right stuff inside to clean off the contacts without leaving a film. you could use a bit of very fine grit sandpaper to clean the contacts, but be very gentle. i'd stick with 800 wet or higher.

hmm, does it look like a regular (but small) distributor? one wiper in the middle rotating, and 4 contacts around the edges? is that wiper put on right? it might be angled / set wrong, so the engine is trying to fire the plugs when the wiper is not aligned with one of the 4 contacts.

[gjewison]

there is only 2 contacts im assuming 2 with 2 coils one fires each one...im not sure what to do with it and what the problem is its so damn frustrating...haha i just dont know what would be safe to use to clean them since there is rubber around the contacts except the little metal for contact. i was thinking maybe steel wool??

[gjewison]

not sure if its set right but i believe so it does stop at the timing needle right on the mark of the rotor or wiper.

[GregR1]

ya know, it might be best to wait for the service manual to arrive and check their electrical diagram. if ya were close to where i am, i'd offer to swing by and help, but MN is a bit of a long ride.

i'll see if i can find an electrical diagram online somewhere....

[GregR1]

found this. not sure if you already located it or not. sort of a service manual. i'll read it over and see what i can pick out, but you might as well poke through it as well if you haven't done so yet.

XS650 Service Manual

[Aussie Steve]

Just remember in order to fire you need low voltage in and high out. So in order to find the low...12VDC in.... follow the wires from the wiring loom to the coils. These will trigger a low VDC in the primary windings of your coils. it doesn't matter which stroke you are on because it sounds like the lost spark system to me.....ie one cylinder is firing and the other (fed by the same coil) is on the exhausts stroke so a spark does no harm. You must get a reading of 12VDC across the terminals of the coils with the red probe of a multi meter on the terminal and the black probe to an earth. Once you establish power to the coils ...or not as the case may be... you can then check your HT voltage output. It is a very good idea to use a digital meter they are cheap, easy to read and some have a "hold" button. To check your HT voltage simply red probe the plug cap and black probe to earth. Make sure you set the voltage selector on the meter to 45K VDC + so you don't blow its fuse. If you want to test the coil output itself try and remove the HT lead...sometimes they are glued in and are impossible to remove without destroying them. Then simply red probe to where the lead came out and black to an earth. (Needless to say while checking all of these things the motor needs to be spun over.) so why did I say it????

If you do not get primary voltage of 12VDC at the coil/s you will need to trace back from the coils to the triggering device. If all ok there then from there back to the supply side....battery, ignition switch etc..... If you do not get HT voltage suspect the coils, leads, caps. The final test is the plugs... in cap sparkplug to cylinder head. No spark = check the plugs.

Hope this helps and please post if not. I will try to help or someone else will surely do so!

S

[artistic_gore]

You can find info for this bike at XJBikes.com › News and by signing up for the mailing list at the XJ Owners Group, the latter was a very active community when I was a part of it, between these two places you should be able to find all the info you could ever want on this bike.

In the maxim's ignitions system you have primary coils (up top) and pick up coils (under the left side engine cover), You're going to have to get a manual, I would mail you some but I gave them with my bike. Anyway you need to check the low and high voltage of your coils (I can't remember the numbers off the top of my head) but you need to check the high side (spark plug side) with the caps removed, corrosion in the caps or in the wires where the caps screw in can cause increased resistance. corrosion in the low side connections can be an issue to.


Gore

[Aussie Steve]

Just a short note on how the coils/ignition systems work.

I don't want to sound presumtious but all too often people jump to about ten conclusions before sitting down and thinking the problems through and trying to logicaly work it out. So here it is.

An engine needs a "fat hot" spark to ignite the fuel at the right time this is produced in exactly the same way today on all these fancy motors we run as it was all those years ago on any "old" engine other than a diesel.

A coil is in fact two windings...one, the primary windings, of a few heavy copper coils, on the outside and two the secondary windings, a lot of lighter copper coils, inside the primary coil. A bar of iron is inside the secondary windings. A small voltage (12VDC) is introduced to the primary windings via the ignition circuit from the battery causing a magnetic field to build up in the iron bar.

When the motor is spun by the starter the triggering device (used to be points on old motors) interupts this voltage supply at the correct time for ignition causing the magnetic field in the iron bar to collapse this induces a voltage in the secondary windings. Because there are many more windings in this coil the voltage is stepped up considerably

This voltage (around 30,000VDC +) leaves the coil via the HT lead connecting it to the plug and jumps the air gap between the points of the plug causing the mixture to explode. This method is no different from the simple points/advance/retard system of yesterday to the complex black box controlled electonic triggers of today.

Simple.... yes.... Trouble is if you think of all the other systems that make up our bikes and cars it then becomes difficult to get your head around. I have found over the years, and I'm sure others have too, that it is far easier to break each machine (read motorcycle) down to its systems. Then from there break each system down to its sub systems This makes everthing so much easier. Sorry for the dubious lesson folks don't mean to be a bore!

S

[gjewison]

well im going to check to see if i can get the electrical to it tested tonight and get back to you guys thanks for all the help so far!