help needed with testing my motor for the first time.

[Mitchell_p]

when i bought this '75 motor and frame it hadnt been run in a long long time.
Shifts through gears alright and the kick arm goes through nice. Just wondering if i can
start her up with just a battery and coils to see if it runs or will i need the reg/rec connected just to test the motor. Im trying not to spend anything more than what i already have until i see how well the motor goes.

heres a pic of my set up, please excuse the shit heap messed workspace.

 

[azman857]

Change the oil. Clean the filters. Plugs out run the new oil around by pumping the kickstarter or electric foot. Gap new plugs and install. Get carb kits and do a full soaking carb cleaning followed with a can carb cleaning. Use new o-rings/gaskets. Cam chain adjust. Valve adjustment. Lube the ATM and gap and static time the points. Now apply the power to points and ground and give it a crank. You do have an exhaust hooked up, right?

 

[Mitchell_p]

Yeah exhaust is on there now, old photo.

Soak and clean the carbs - this is done without taking them apart?

I have never rebuilt carbs so im abit nervous, so many tiny parts. I do have a manual though.

 

[azman857]

Read the carb guide here under the Tech tab up top. Read and Heed. Yes, you have to disassemble the carbs and remove all the old 0-rings. The parts aren't that small. Be brave. It's not that hard. Read first. Repeat. Then grab tools. We're here to help if you get stuck.

 

[Mitchell_p]

Thanks heaps, I'll let you know how it goes.

 

[gggGary]

Don't worry about charging, coils is all you need for a "test pop off". I am with you, I will dribble a little gas or (GASP) use some ether to see if she'll pop and run for second or two before I go further. AZMAN is right though, a full carb overhaul is the ONLY way to assure a decent runner. Two common issues with "sitters" are stuck rings and rusted or "gunked" valve stems. One valve has been sitting open for all this time and a sticking valve has been the demise of more than one recently revived XS650. A piston is not a good tool to loosen a stuck valve. I like a bit of PB blaster in the plug holes overnight.

 

[hotrdd]

I was nervous the first time I rebuilt my carbs, and even the second time because I didn’t follow the guide perfect. Test the carbs for any leaks and make sure you get every passage extremely clean and the float bowl height set properly. I suggest only taking apart one carb at a time so that if you forget something you have one to reference. If you have some basic skills you can do this.

 

[Mitchell_p]

ok so ive just tried connecting the battery to the coils to the plugs/points.
Theres no fuel connected so i sprayed some fuel in with a spray bottle. Tried kicking it over and nothing. Pistons arent stuck cause its sucking in air and you can hear everything sounds ok. Battery was charged. The coils actually got pretty hot after a while of being connected to the battery - is this normal?

Took the plugs out and sprayed abit of fuel in just incase it wasnt making it through he carbs. Still nothing.

Any ideas?

Also on my cb360 you can hear the kind of ratchet noise when you draw the kick pedal back up. theres no noise like this on the xs650, not sure if thats how its meant to be?

 

[sgallaty]

xs650 uses a bendix, not ratcheted teeth so you won't hear that. Same with the starter, much to our neverending dismay.

You probably need a remote fuel can to run the bike with. Spraying fuel in never works for me. You can fabricate up a remote fuel can pretty easy - it doesn't have to be big.

Start by measuring your compression. If you're getting anything close to 120 dry or 150 wet, your mechanical is probably ok in that arena. There are 3 systems involved in making the bike run - so don't put too much into spraying fuel in and it not kicking over.

In order of complexity, expense and difficulty to correct, in the engine you have :
The mechanical system of intake, compression, exhaust and lubrication.
The fuel system of carburetion and fuel delivery
The electrical system of ignition ( and secondarily charging )

Any one of those not doing what it is supposed to do will stop the bike from running. You need to test each one starting with the mechanical and being methodical and thorough through each one. Pretty much, if your mechanical systems are sound everything else is comparably trivial.

I'm just saying this because I don't want you to get disheartened by trying a test that has too many variables. You could have a great engine in mechanical shape that happens to have carbs with tar and crap in the idle circuit that will never start.

 

[XSLeo]

I might sugest getting a repair manual if you don't have one.
Next check and set the can chain tension.
Next adjust the valves.
Next set the points gap and timing, right side, thats the upper set first then the left, lower set.
Your coils got hot because thats what happens when power is applied without it running. A switch between the battery and points is a good idea, a fuse might not hurt too.
Now with the plugs out, fresh plugs hooked to the plug wires check that with power on the plugs spark when you kick it over. Turn off power.
If plugs spark and you followed the repair manual to set the points. Use your squirt bottle to put some gas right in the plug holes. A teaspoon ful or so. Put in the plugs. Turn on power and kick over the engine it should start and run a few seconds.
Leo

 

[azman857]

I did give you one bad piece of advice/info. It's not power to the points, it's to the coils. My mistake. The electric power goes thru the coils, thru the points to ground. For plugs to fire, when the cam opens the points, the magnetic field of the coils collapes and the plugs spark.

 

[sgallaty]

I did give you one bad piece of advice/info. It's not power to the points, it's to the coils. My mistake. The electric power goes thru the coils, thru the points to ground. For plugs to fire, when the cam opens the points, the magnetic field of the coils collapes and the plugs spark.

sort of.

What actually happens is that the coils are an exaggerated step-up transformer that relies on inductive kickback to drive the secondary.

It's basically a high voltage transformer that uses the collapsing field of the primary to convert that to a high voltage using a secondary coil with a large number of windings. The primary coil is 12v with a high amperage spike (as the magnetic field collapses) and the secondary coil is a high voltage with low amperage.

The primary circuit at the very simplest is +V to ignition switch to primary windings to points to ground..

the secondary circuit is output side of coil to spark plug anode -> air gap -> plug cathode -> ground (Or in some cases, return side of coil)

 

[Mitchell_p]

thanks for all the help guys, ill let you know how i go. i plan on ordering a carb kit as soon as possible and rebuilding them so i have no doubts about them. then ill try starting again and go from there.
Cheers.