Points setting and correct timing? It just wont start - but have spark?

[Stabler]

Hi gang.

This is getting frustrating. On my CB750 this went painless, but on my XS400 I can't get it to start, after changing my head gasket.

My problem:
It wont start. I get an occasional cough out of it and one or two back fires.

What I've done:
Had the engine out, the top end of, changed out the leaking head gasket, set the valve timing and valve gap according to my shop manual, cleaned up my points - set their gap to specs, used my voltmeter to set the points plate according to specs. (I might have fubbed up any of these settings).

So. The points are supposed to open at the low dead mark on the alternator plate yes? (Pardon my lousy english, I'm from Sweden). I get my voltmeter to go silent at this exact mark. I also did the 45 degrees counter turn to prevent any slack in the timing chain - and rechecked this. The points still open att this mark.
The spark look ok outside the motor. (New spark plugs).

I'va had the carbs off and got new main jets in those as well. They were cleaned last season and looked clean now as well.

Any ideas to what might be causing it not to start? Anyone with any usefull ninja-tricks to get it to run again? I need it in working order by friday..

Oh - and where do I connect the ground wire running up to the battery? The one coming out of the motor is obvious, but the other one? I cant frekkin remember..

Thanks in advance, Stabler.

 

[drewpy]

there's only one main ground from back of engine to battery, the other is the starter lead to solenoid.

I suggest you connect those properly before trying to start it

 

[Stabler]

I wasn't all clear in my writings before. The one coming of the starter goes to the solenoid, but where on the back of the motor do I connect the ground?

Thanks again.

 

[drewpy]

I wasn't all clear in my writings before. The one coming of the starter goes to the solenoid, but where on the back of the motor do I connect the ground?

Thanks again.

one of the 8mm bolts at the back of the engine

 

[Stabler]

Ok. Then I've already done that right. Still wont run..

 

[drewpy]

have you got the timing out?

I recently replace the duff electronic ignition with points and got the points cam out 180'

ensure the piston is on compression stroke ie hold thumb over sparkplug hole and feel the compression. check it all lines up on the pointers.

Make sure the points open at the correct gap and then approximate the timing.

finish off use a strobe light when the bike is running.

if you done the ignition, try squirting easy start in the carbs when turning over to see if it starts on that.

 

[Stabler]

Oh - crap. That would be so typical me. By points cam you mean that little "sleeve" that goes on the end of the cam shaft, the one that opens the points yes? The one that goes on before the points plate goes on?

Today I got a set of new points and set them correctly according to the shop manual. But if I get what you write, I might be 180 degrees off?

With easy start I got it to cough and back fire through the left carb. Nothing through the right one. Comparing to my CB750 it behaved the same way until I switched my coil signal leads. That didn't work on my XS400 though.

So, is this sleeve what you mean? If so I'll get right on that.

Thanks again man.

 

[drewpy]

yep try it, takes 5 mins to check/do

 

[Stabler]

I will. Thanks for your input man.

 

[Stabler]

Ha. Insane. I did what you said and it started right up.
Thanks drew!

 

[mattg666]

ok, im having a similar problem as far as the occasional backfire and cough, but i dont know how to adjust these "points". meaning, i take off the cover, and i dont have points, it appears to be magnetic im assuming? it has a big black plastic cover that doesnt seem to be detachable....need serious help with this...i have new tci, new volt reg., new rectifier, rewired completely( and yes, its done right, i triple checked it). the carbs are cleaned...so from what ive read its either the points, or the coils backwards...but i cant seems to adjust the points...or even see them, as soon as you open the cover, its just a hunk of black plastic with no way to take it off. please help.

 

[xschris]

There are no adjustment for a tci bike. Have you set the valves and synced the carbs?

 

[mattg666]

Gotcha! Yeah it dawned on me right after I posted that, to try and switch the coils and it fired right up... But! How do I make sure both cylinders are firing? Or is that just it with a tci... They are either both firing or not? And also... How do I go about doing the valves and syncing the carbs?

 

[xschris]

With a tci bike either it works or it don't. Do a search on the forum for valves and carb sync. There are lots of them Make sure you down load the manual it will answer most of your questions.