1 Cylinder not firing

[XS650Cafe]

So apparently i bought a large pile of shit last year , i already made a thread about it, so i've done some maintenance to it

- Changed Oil and filters (sump and secondary)
- Rebuilt Carburetors
- Changed Air Filters
- Changed Fuel Filters
- Changed spark plugs, spark plug wires, resistor caps
- Changed Ignition Coils
- Replaced Contact Points

And still one cylinder is not firing and is fouling plugs with fluffy carbon as the book puts it.

Because i'm on the verge of taking this p.o.s to dead horse point and pushing it off the edge while i cheer.

Thanks in advance.

 

[jayel]

what is the compression on that cylinder? a leak down test will tell you valves or rings if it's got good compression look at the carb again or weak spark on that side

 

[xjwmx]

Does it fire before the plug fouls? Since it has fluffy carbon on it, it had to fire to get that way. If it was wet with oil instead on the other hand...

Could be someone... tinkered with the carb on that side...

 

[inxs]

And still one cylinder is not firing and is fouling plugs with fluffy carbon as the book puts it.

- overly rich fuel mixture?
- weak spark?
- stuck choke?
- heavy or misadjusted carb float?
- leaky needle valve?
- low coil output?
- high resistance in the plug wires?

 

[XS650Cafe]

well what happens is the bike starts and runs, but I have no idea what happens because only the one side (left side) gets hot and the right side stays cold to the touch. If revved up a bit it backfires like crazy, and it was blowing some black smoke on occasion. The spark plugs are good, tested both of them for a spark, checked the valves and they both were moving with ease, not stuck open.

 

[cheftay]

You might check the carb diaphragm for any small holes... I had the same problem on mine and tried coils and plugs and finally found a tiny like poke in the diaphragm and I replaced the assembly and it fixed the problem.

 

[donmillerx]

I'm having the same issue, ever get yours worked out?

 

[Gordon]

Ok, you still didn't mention compression one the engine, both cylinders. Second, check that the wire from the points to the right coil is good, making a circut. Third, check that the same coil is getting battery voltage with the key on or running. Forth, check the coil resistance, make sure that it's good. Probably in the wire from the set of points that fire that cylinder. I don't know which set fires what cylinder, but should be in the manual. The spark plugs get messed up easy on these too.

 

[gentlemanjim]

Is it not running becasue 1. there is no spark to the plug or because 2. iti is not getting fuel? Determine this first and then procede in the right direction. Pull the plug and lay it against the block when you crank or run the engine is the dead clyinder getting spark? If not its the points, coil, plug wires or plug. Swap the plug wires does the other cylinder now not fire?

 

[XS650Cafe]

I'm having the same issue, ever get yours worked out?

no sorry, haven't figured it out yet

and as for compression i can't check it because i don't have a tester, i did a finger test with my friend where he put his finger over the hole and i kicked it, he said the side that's not firing felt weaker than the side that is, but its obviously not a very accurate test.

 

[XS650Cafe]

Is it not running becasue 1. there is no spark to the plug or because 2. iti is not getting fuel? Determine this first and then procede in the right direction. Pull the plug and lay it against the block when you crank or run the engine is the dead clyinder getting spark? If not its the points, coil, plug wires or plug. Swap the plug wires does the other cylinder now not fire?

it is getting a spark because i did that test and both plugs are sparking

 

[matt81xs]

thats really not a good way to check compression....even 10psi will feel strong when its shooting out of a plug hole.....buy a cheap compression tester off harbor freight....

 

[gggGary]

Sounds to me like the bad cylinder is flooded with gas. shut off the petcock and see if she clears out and runs just before it runs out of gas.

 

[evans_search]

Your situation sounds very similar to mine and I have done several of the same things you have to try and fix the problem. I was finally able to get a hold of a compression tester and it was way off. Although I didnt test with the throttle open all the way. Let me know what you find. Do the plugs have a more dry our wet appearance to them?

 

[gofastcrazy]

hello, i hate to bring this thread back after so long , but i am having this issue now. comp:is 130 psi on both cylinders, i have switched the coil hots , rotated the ignition plate 180 deg:,awitcged the plug wires, everything i can think to do..... i have spark at the plug but i can not get #1 cyclinder to fir. i am out of ideas , and would love some input.

 

[HooliganCycles]

Have you verified you are getting fuel? Spray a little carb cleaner in the sparkplug hole and see if it fires...the other day mine would only fire on one cylinder and I pulled the pilot jet and it had some crud in it, blew it out and fired right up

 

[fredintoon]

hello, i hate to bring this thread back after so long , but i am having this issue now. comp:is 130 psi on both cylinders, i have switched the coil hots , rotated the ignition plate 180 deg:,awitcged the plug wires, everything i can think to do..... i have spark at the plug but i can not get #1 cylinder to fire. i am out of ideas , and would love some input.

Hi gofast and welcome,
did you buy the bike like that or was it running on two and then only on one?
When was the last time you cleaned the carbs?
No matter, do it again.

 

[ippytattoo]

When you clean the carbs pay extra close attention to the jet sizes.

 

[CDNTX650]

And float heights.

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[gofastcrazy]

carbs are cleaned and cleaned again. she is getting fuel and still nothing. i bought it as a bike that has not ran in 3 years. the guy had it stored proper, and ran all the gass out of the carbs and cut the petcocks off. i am not getting a good spark on number one no matter what i do.