Get the motor running

[Oldtramp53]

My stepson had the heads rebuilt and has not been able to get the old xs to fire since seems like it should be a timing issue to me.Any ideas this is my first go on these xs's

 

[Brassneck]

OK, I'll take a stab at it...and I'm 99% confident this is your issue: It's either fuel, spark, timing or compression. LOL.

No, seriously though, it's probably one or more of these...but it's hard to tell with the info provided. I'd start with checking the easy stuff first. Also might help to know what year, what mods, etc...

Lots of help on this site... but I think we're going to need more info.

Good luck!

 

[gggGary]

Is it backfiring at all? Points ignition? Try swapping the coil leads at the condenser junction under the tank. If that lets it run the " real" fix is that the advance rod is mounted 180 off, very easy to do, and to change back.

 

[gggGary]

Welcome to the forum old tramp! Pics, we need to see pics of the bike!

 

[uncle meat]

Recently had my top end rebuilt and when I got it back it wouldn't start, only pop every 5th kick or so. Talked to the mechanic and he knew right away that the timing was 180 out. Readjusted, and it's good to go. Hope yours it that simple.

 

[Oldtramp53]

I'll have to post some pics.At this time no pops spits nada .I told him I thought 180 out he said he tried changing no difference.Guess it's time for the old man to start fooling with it.
Thanks gggary

 

[Oldtramp53]

I'm gonna have to look at it myself ,any luck 180 out.

 

[5twins]

You should probably back up one more step and assure the motor was assembled correctly, that the cam was timed to the crank right. Here's an easy method without having to tear it down again .....

http://www.650motorcycles.com/CamTiming2.html

Then you can go about verifying the external timing settings. On the advance rod that runs through the cam, there are locating pins on each end for the points cam and the little disc that ties into the advance unit. These should be aligned, pointing in the same direction. It's possible to install them with the pins set 180° to one another, and that's what throws the timing off 180°......

 

[Oldtramp53]

You should probably back up one more step and assure the motor was assembled correctly, that the cam was timed to the crank right. Here's an easy method without having to tear it down again .....

http://www.650motorcycles.com/CamTiming2.html

Then you can go about verifying the external timing settings. On the advance rod that runs through the cam, there are locating pins on each end for the points cam and the little disc that ties into the advance unit. These should be aligned, pointing in the same direction. It's possible to install them with the pins set 180° to one another, and that's what throws the timing off 180°......

Thanks for the info I'll be looking into that right away

 

[XSLeo]

Who assembled the engine? It's not hard to install the cam 90 degrees out.
Easy to check. Turn engine so the timing marks line up at TDC. Remove the round cover on the right side of engine. Look at the end of the cam. There is a pin that aligns the advancer unit to the cam. With the timing marks at TDC this pin should point straight up or down. If the pin points anywhere else the cam needs to be line up right.
This will require pulling the engine. Lifting the rocker box off. Loosen the cam chain adjuster, even pull the adjuster screw out. This will give you the most slack you can get.
Now lift one end of the cam, slide the bearings off the cam. Do the same on the other side. Now you can lift the chain of the sprocket and move it around the cam so it lines up right.
On the left side of the boss the sprocket is up against there is a notch. This notch must point straight up with timing marks at TDC. On the right side of the sprocket out by the teeth is a dot or dimple. This must line up with the sealing surface of the head.
A few folks have misread the repair manual and lined up this dot at the top instead of at the sealing surface.
Doing it this way you don't have to cut the cam chain.
Leo

 

[Oldtramp53]

Thanks for the input Leo ,you all have given me a couple of good starting points to trouble shoot this thing,greatly appreciated.If I can get this one going I'll call the boy and he can pick it up ,then I can start on the project bike

 

[grizld1]

Oh, for cryin' out loud! Didn't anybody think to ask if the plugs spark at all? If the spark is weak to nonexistent, condenser ground is one of the first things to check; a favorite amateur hour trick is to paint over the contact point on the frame. Also, have you inspected the point gaps and timing? Refer to the factory service manual for specs and procedures--it's a free download at http://www.biker.net.

Are you getting power to the ignition coils? Check with a volt meter. If it shows voltage at the coils 1/2 volt or more lower than voltage at the battery, you have some work to do on connectors, switches, and/or wiring.

This business of checking if the advance rod is in phase can be done with a fast and direct inspection. Just pull the left cylinder exhaust valve cover and observe which points open when the valve is closed (tappet loose). There is no voodoo involved here; the breaker point ignition should spark leading into the power stroke, not the exhaust stroke, and that occurs when the points open.

 

[Oldtramp53]

Oh, for cryin' out loud! Didn't anybody think to ask if the plugs spark at all? If the spark is weak to nonexistent, condenser ground is one of the first things to check; a favorite amateur hour trick is to paint over the contact point on the frame. Also, have you inspected the point gaps and timing? Refer to the factory service manual for specs and procedures--it's a free download at http://www.biker.net.

Are you getting power to the ignition coils? Check with a volt meter. If it shows voltage at the coils 1/2 volt or more lower than voltage at the battery, you have some work to do on connectors, switches, and/or wiring.

This business of checking if the advance rod is in phase can be done with a fast and direct inspection. Just pull the left cylinder exhaust valve cover and observe which points open when the valve is closed (tappet loose). There is no voodoo involved here; the breaker point ignition should spark leading into the power stroke, not the exhaust stroke, and that occurs when the points open.

Thanks grzld1,I haven't taken a look at this myself yet,I'll be checking elec power spark etc.as soon as I get out there and charge batt.I just wanted to get a starting point ,s .Still like 16 degrees out there no heat I garage .