Need help identifying components of a 1983 Maxim engine exterior

So I took a look in the manual and online and couldn't find a good description of the more technical portions of a motorcycle exterior. Was just wondering if someone can help identify the portion that I have labelled with letters....such as where the carbs are, transmission, crankshaft (crankcase), pistons, cylinders, camshaft, alternator, and the various wires closeby. I think I have an idea where some of it is but just want to confirm in the event I ever take the engine apart sometime for inspection. Any help would be much appreciated!

First pic

A = Engine mount (attached to the cylinder head)

B = Cylinder head (camshaft cover where the cams and valves are)

C & D = Carburetor, C is the diaphragm and D the body with of course the bottom being the float bowl.

You have two things marked E but the one on the left is the cylinder and the round thing is the stator cover (generator).

F = Side cover with timing marks and pickup coils

G = Clutch rod cover and sprocket reside under here

H = Starter

Second pic

A = Carb

B= Cam cover (intake cam inside)

C = Cylinder bore

D = Crankcase breather tube

E Clutch cover (clutch plates are under there)

wow thanks for helping illuminate these components. What exactly does the generator do? And the timing marks/pickup coils? And the cylinder bore?

And so would the transmission reside in G as well?

The generator is not exactly the right terminology. A generator generates DC voltage. The unit in your bike is an alternator, it creates AC voltage then convets it to DC.
The timing marks are used to tell if the ignition timing is correct.
The ignition uses a TCI or Transisater Controlled Ignition uses the pick ups to determine engine position and rpms. It uses this info to determine when the coils spark.
The cylinder bore is where the pistons reside.
I think you should study a repair manual. The manual tells you most of these things.
Googling four stroke engines will help explain how an engine works.
Leo

Just had a few last questions on these ones...


For the wires, A would be the vacuum correct? It connects to the petcock from the crankcase?

And B...not sure what that is and where it goes to or connects too. Something with the clutch plates/sprockets?

C...this is a wire that runs from the battery to the ignition coils?


And for the second diagram, really not sure what these different components do or how they help with the carburetor so labelled them as well. Does this assist with the float bowls somehow?

Ok on the left picture, A is indeed the vacuum line. It connects the petcock to the carburetor boot, this is the black rubber boot (you have one on either side, the vacuum line connects to the left one) which connects the carburetor body to the cylinder. Through this boot, the cylinder sucks in the fuel mixture produced in the carburetor.

B is your clutch cable. So yes, something with the clutch plates. Not so much to do with the sprocket.

C is an electrical wire which provides power to your starter.

Second picture there are a few things indicated but I don't think its very clear what you mean. The cable indicated with D is your throttle cable. When you turn your throttle, this makes the rod at B turn which makes your carbs open internally to provide more gas/air mixture towards your cylinders. Check this, you'll see how it works. The screw on the left end of the picture (the one with the spring on it) is the idle screw, this controls the amount of throttle when you let go of your throttle handle. If your engine tends to stall at very low revs, you might need to adjust this.

Under C there is a sealed hole in your rubber carb boot. This hole is used when you're measuring the strength of the vacuum you're pulling in your cylinder. You need this when adjusting your carbs (synchronizing, or syncing your carbs). But for now it should be closed, as it is in your picture.

My best guess with part A is that it seems to be your choke (fuel mixture enrichener). On my bike this looks totally different (DOHC, later model XS400). The way to check if I'm right is to see what happens when you pull out your little choke lever on your handlebar. You need choke to start your engine when it's cold (which you probably already know), leave it on for a minute or so after you start and then put it back. Leaving it on could drown your engine in fuel, putting it back too soon could make your engine get too little fuel and stop as well.

The float bowl is basically a little bowl of fuel in the bottom of the carbs, which has a little straw in it. The height of the fuel stays constant, this is controlled by the floats (which are basically just air-filled plastic bits, made to float on top of the fuel). When the floats reached the right level, they lift up the float needle, which cuts off the fuel inflow from the petcock. When the floats lower (because you take fuel out of the bowl) the needle lowers again and the bowl is filled up. The throttle doesn't really do anything within the float bowls itself, but it adjusts how much fuel is sucked out through the straw in the fuel bowl (the jet). But how that works is more than you will need to know for now, and more than I can explain because I'm not 100% on it yet either.

Thanks for getting back to me on this stuff. How does the vacuum regulate the fuel leaving the gas tank going through the petcock exactly? And is the sprocket located somewhere with the clutch plates? I hear a lot about this but not quite sure how it relates to the gear system.

As for the clutch cable, does this connect directly to the clutch on the handlebar? And does the electrical wire going to the starter come back from the start button?
Thanks for clarifying the throttle cable contraption, I'll take a look at it next time I'm in neutral.

Hmm I do know how a choke works on older cars but as far as I can tell my bike doesn't have a choke - there's just a clutch switch on the left handlebar and the regular lights and kill switch.

That's interesting about syncing the carbs, would this be done after cleaning them? Or in which scenario should I sync them? Suppose you wouldn't know of a link on the site with directions to do this would you?

Carb syncing is fine tuning one does after everything else is done.

http://www.xs400.com/forum/showthread.php?t=10009

chrisd1984 said:

Thanks for getting back to me on this stuff. How does the vacuum regulate the fuel leaving the gas tank going through the petcock exactly?

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No problem. You can have a look yourself, just disconnect the fuel line (the one with the filter) when the petcock is in ON or RES position. A little bit of fuel should drip out, but no more than was in the fuel line itself. Then try to start the bike (of course this won't work) and when the engine turns over, fuel should start pouring out of your fuel line. How this works exactly is hard to explain in words, there's a membrane in your petcock that regulates this. Keep in mind that the petcock doesn't really regulate the amount of fuel flowing, it's just flowing or not flowing. The amount of fuel sent to the cylinder is determined within the carbs.

chrisd1984 said:

And is the sprocket located somewhere with the clutch plates? I hear a lot about this but not quite sure how it relates to the gear system.

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They're in the same area of the engine (the one you indicated in a previous post). The clutch connects or disconnects the front sprocket (which, of course, drives your chain) with the turning parts in your engine. When you take the sprocket panel off you can see the sprocket, but the clutch is somewhere on the inside of your engine.

chrisd1984 said:

As for the clutch cable, does this connect directly to the clutch on the handlebar? And does the electrical wire going to the starter come back from the start button?
Thanks for clarifying the throttle cable contraption, I'll take a look at it next time I'm in neutral.

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Yes, it connects directly to the clutch on the handlebar. The electrical wire connects to a few things, but ultimately to the main fuse, the battery and of course the start button. Check your wiring diagram for this. The throttle cable you can also check when the bike is off, it's just a cable which you pull when turning the throttle.

chrisd1984 said:

Hmm I do know how a choke works on older cars but as far as I can tell my bike doesn't have a choke - there's just a clutch switch on the left handlebar and the regular lights and kill switch.

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That would be strange. I think all our bikes have or have had a choke, I honestly can't live without it since without it my bike just won't start. Maybe someone who has your model can shed some light on this. Or you could take a picture of your carbs on the right side of the bike showing the rest of the carbs, it should be somewhere on the top of your carbs or maybe a bit more on the left, maybe it'll just be there somewhere and I can identify it

chrisd1984 said:

That's interesting about syncing the carbs, would this be done after cleaning them? Or in which scenario should I sync them? Suppose you wouldn't know of a link on the site with directions to do this would you?

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As Mark said, you do it once in a while. Definitely always after checking and adjusting your valve clearance, but also when you feel the bike could run a little bit better. This is sort of a fine-tuning thing, a last step in making your bike run smoothly. There is a screw in the middle between your carbs (hard to see when theyre on, it usually also has a spring on it like your idle screw) which is the one that you would turn in the process. If you've accidentally turned this when you took your carbs off for cleaning (like I did the first time around), you'll have to do it.

Thanks again for the informative reply. So to sync the carbs after doing a valve check I just turn this spring screw? How would I know if I've set it correctly? And I realize it may be hard to explain in words but what exactly does this do internally for the carbs? Hmm might be getting confused but isn't the idle screw also located near the carbs on the right-hand side of the bike with a spring on it and this helps switch gears from neutral to first if the bike is stalling a lot?

Hi chrisd1984,

If I may suggest you get 1983 Yamaha XS400 J/RJ :Factory Service/Repair Manual, you can get it on ebay.
It's very informative and explains almost everything.
Also you can go to Boats.net and look up your bike, they show parts diagrams and part numbers.
Good luck.

Ok I'll take a look for that thanks

chrisd1984 said:

Thanks again for the informative reply. So to sync the carbs after doing a valve check I just turn this spring screw? How would I know if I've set it correctly? And I realize it may be hard to explain in words but what exactly does this do internally for the carbs? Hmm might be getting confused but isn't the idle screw also located near the carbs on the right-hand side of the bike with a spring on it and this helps switch gears from neutral to first if the bike is stalling a lot?

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Happy to help. Have a look at the thread about syncing carbs, there's a little bit more to it than just turning the screw. The objective of syncing carbs is that you make both cylinders pull the same amount of vacuum, so they get equal amounts of fuel to fire on. This way, they work together in a most efficient way to turn the engine. Internally, it sets your butterfly valves on the insides of your carbs relative to each other.

There are two "idle screws", the idle mixture screw (the one without a spring on it) which adjust richness of your fuel mixture, and the idle throttle screw (the one with a spring) which adjust your revs at idle, basically how much throttle is the minimum amount (when you let go of your throttle handle). If your bike tends to bog down in low revs and stall because the revs get too low, it helps to turn the idle throttle screw. If your engine is running too rich or too lean, the idle mixture screw needs adjustment (or your carbs need cleaning, or re-jetting, there are a number of causes for that problem, you usually leave the idle mixture screw alone)

I see. So would the idle screw be the one with the spring in this photo?

Also tried locating a choke and couldn't find one anywhere on the bike. I attached a closer up image of the side but still couldn't find one...

Hmm also can't still figure out that rear brake light issue. I attached a photo of the under the seat switch which I tried adjusting and still didn't turn the light off...

Also attached a photo of the front handlebar...I searched under everything there and I really don't think my model has a switch there.

Yes, that's the idle speed adjustment screw. The sync screw is between the carbs.
You won't find a choke because there isn't one. It uses an enrichener.
A choke cuts off or chokes the air flow through the carb thus making the richer mix needed to start.
An enrichener open to add more fuel to make the richer mix.
Leo

On the rear brake switch As you step on the pedal it pulls on the spring. This pulls the switch closed to turn on the brake light.
To adjust the switch you turn the nut so the body of the switch moves down towrd the spring. Turn it untill there is slack in the spring.
Another thing you can do is folow the wires to where they plug into the harness. Unplug them, does the brake light go off? If so the switch needs adjusting or the swithc is bad.
Adjust the switch.
On the front brake master cylinder take a pic straight on from the front.
Leo

Hey took a photo of the front brake head-on, couldn't find a rear brake switch there anyway.

Also took a photo of the brake switch under the seat again. So I would turn the switch circled in red downwards? I've turned it up and down and still no luck. Can't seem to get any slack with it.

Hmm would the fastener holding the wires to the rear brake light be under the seat? Or would I unscrew the rear light to find it?