Just Finished Rebuilding, few things still wrong. Need Help.

[pablohoney]

Finally got the old xs back together. It runs pretty well but the problem is that the plugs look way too lean and it dies as soon as the choke is pulled. Starts right up with no choke and dies just a fast when it is pulled in. Also yesterday it gave a nice pop when I turned it off. The ignition timing and the valve lash are both spot on. Know what it could be. I figure it is the carbs, but I thought that it would run better with the choke on if it were just lean. It also won't really accelerate over 60, it just kinda gives short weak bursts. I don't know, Thanks

 

[pablohoney]

I just cleaned the carbs really well, and checked all the specs on the carbs and no change. Still dies with the choke engaged.

Also the RPMs drop really slow when I rev it. Please help me.

 

[Travis]

More information would probably help.. Things like which carbs you're using, jetting, what ignition, pods or air box, what exhaust...

What makes you think it's lean?

 

[Hairyblackdude]

From tuning quads & 2 strokes over the years, every symptom you are describing sounds like a lean condition to me..

Slow for the revs to drop, popping, flat spots etc... Especially if thats how the plugs are reading..

 

[gentlemanjim]

I had similar issues and it was a leaking diaphram. Got the pop and and hop. Adding choke can camoflouge or creat a whole set of incorrect symtoms

 

[pablohoney]

Yeah, the plugs were totally white. Definitely lean. The carbs, airbox, jets, exhaust is all stock. I have the pamco electronic ignition and coil in.

I remember now that I when took apart the carbs to clean them a few months ago, I took out the jet needle, maybe I didn't put it back together on the right clip. I'll check it out.

 

[pablohoney]

Checked the clip position and it was spot on. I didn't screw that up. Now, what did I screw up?

 

[Pandorasglocks]

Check for air leaks? Could be getting lean off a leak.

 

[pablohoney]

I'll check for air leaks, But I also just saw on Mike's Tech Tips that the intake valve clearance for the 1979 is 0.075mm. My manual said that it should be .06mm. I set it to the latter. So,
A.) Which is correct?
B.) Does .015mm even matter? If Mike is correct, could my setting cause problems?

 

[KevC]

0.15mm = 0.0006" and will make no difference at all
Inlet valve clearance depends on model
my manual states
inlet
XS650(UK) XS650D(US).......................................0.05mm (0.002")
XS650E and SE(US)............................................0.10mm (0.004")
XS650SE(UK), XS650F,G,H,SF,2F,SG,SH,SJ,SK(US)...0.06mm (0.0024")
exhaust
......................................................................0.15mm (.006")

 

[pablohoney]

Glad to hear about the valve clearing.
Checked for air leaks, didn't seem to be any. Arrgghh.

 

[pablohoney]

One thing that I do find odd, that might help is that I had to take the engine out after rebuilding it a few times and on the time before last I didn't get the valve timing correct it was to advanced. But when I rode it then the plugs were a heathy brown. This last time, I took it out, and corrected the valve timing, with the round mark on the back of the camshaft flush with the cylinder head, I readjusted the valve lash and now it is lean. I didn't touch the carbs at all. Maybe not a carb problem? It is the choke part that is throwing me off.

 

[pamcopete]

Well, just as a sanity check, check the free "snap back" of your advance rod, like in this video:

 

[pablohoney]

Did that when I installed the new springs and clips a few days ago. It is all good. Thanks

 

[yamaman]

Pablo, please confirm your valve clearance. 0.06mm or 0.075mm is too tight for your inlet.
Go for either 0.1mm or 0.004" inlet & 0.15mm or 0.006" exhaust.

 

[cheftay]

Valve clearance need to be checked at top dead center on the compression stroke right? Or can you just wind the kick start until the rocker has play in it...?

 

[pablohoney]

Top dead center on the compression stroke.

 

[pablohoney]

I have been thinking and I think that if anyone can answer this question, I will be able to fix this bike. Why would an engine with white plugs die when the choke is applied?

 

[pablohoney]

Maybe this will help. I just took the bike around the block and checked the plugs, they were white. I then put the choke on and reved it to keep it running and the plugs looked like this:

 

[Travis]

You might try checking the timing with a strobe light to double check it, advance and all.

Other than that, you could try getting another set of good carbs just to throw on the bike to find out if they are the problem or not.

I have had many later year xs650's and have a set of clean carbs always on the shelf to use as a test set. When I bring home a non running bike that I suspect carb problems, I'll use the test set to get it going and tuned up, then clean the carbs that came on the bike when I have time. If I get it running good with the test carbs, then put the original cleaned carbs back on and have problems, I know I missed something with the carb cleaning. I have a test TCI box and regulator/rectifier for the same purpose.