Strange miss

[XS1100 Newbie]

Let me start at the beginning. The other day the bike was sitting in the drivewayn, and it started leaking fuel after i turned the pitcocks on I turned them off and waited for about two hours. Checked the oil for gas, pulled air cleaner. turned the fuel back on, and started it. No leaks. I thought i had something get through and hung up a float. I had to pull the carbs to set the floats at a different level, and in doing so, did not find anything wrong. I reassembled along with my oil filter conversion, and an auto tensioner, with new oil. When i started it and synched it, everything seemed fin. I still could not get it all the way to red line, but it was better. The other morning i started it, and immediately on start, it sounded like i had a cylinder miss. I turned the choke down, but it continued. I looked for leaks, none, i rode it to my bike night, and it seemed fine at above 2000 rpm's, but was not idling well. It didn't die though. The next day i pulled the plugs to look at them, they looked just like they always do. I am in Vegas now, but when i get back tomorrow, i will check my pickup coils. Any other thoughts to guide me to the problem would be helpful. I figure i will have to pull the carbs again as well. Thanks for listening.

[DGXSER]

Does the miss get worse or better when you hit the throttle below say 3k RPM? Does the miss go away after you ride a few miles? or stay the same? Get worse?

I recently worked on a fellow XSives ride that had a stumble and miss at low end. The more you give it gas, the worse the sputter and miss, until you got to about 3k or more in the RPMs. It sounded like the miss was gone or going away. Ended up being bad coils. My theory is that above 3k the alternator puts out just enough more juice to let the coils give a little better spark. Or at the increased RPM the engine just seemed to smooth out.

[XS1100 Newbie]

Doesn't seem to be sluggish at all, and it really never goes away, it just sort of smoothes out. I thought about the coils too.

[motoman]

Does the miss get worse or better when you hit the throttle below say 3k RPM? Does the miss go away after you ride a few miles? or stay the same? Get worse?

I recently worked on a fellow XSives ride that had a stumble and miss at low end. The more you give it gas, the worse the sputter and miss, until you got to about 3k or more in the RPMs. It sounded like the miss was gone or going away. Ended up being bad coils. My theory is that above 3k the alternator puts out just enough more juice to let the coils give a little better spark. Or at the increased RPM the engine just seemed to smooth out.

+1.......had been 'arguing' with mine for some four yrs. on and off and would just park it since I have the other bike to ride. Had solved the low primary voltage issue, but was still not it self in the lower rpm range. Decided to put my original coils back on as I had put another set of original coils in to make sure they were operational as I do not do any bench testing since under heavy heat, that all goes out the window anyways. That was four yrs. ago as I left them in. That came back to bite until I finially decided a couple weeks ago to put the bikes original coils back on. Cept for needing a mixture re-set and re-sync, the motor is happier again down at the lower rpms.

[DGXSER]

The other key identifier that led me away from carbs was that I could run the bike in the miss range for a mile or so, and all four pipes were equally hot. So that kind of nixed the carb being an issue as it was not one cylinder missing.

[XS1100 Newbie]

I am thinking i will take my temp gun and ride and check those pipes.

[DGXSER]

Ride the bike for about a mile with keeping it below 2k if you can. That being your miss range. Then park it and check the plugs. You can also park it and just let it idle for a few minutes with it missing. Then check the plugs as well.

Do also check the header pipes, I just spray a little water to see how they sizzle. If one is colder than the others, you will see the water start dripping from it faster or more so rather than all of it turning to steam.

[hamjam]

I had a strange miss in my car..............it led to a divorce ;-)

[DGXSER]

I had a strange miss in my car..............it led to a divorce ;-)

That funny right there...I dont care who you are, that's funny.

[XS1100 Newbie]

I agree, that thar is funnnnny! Now on to the problem. I started the bike today, and imediately started feeling the pipes. #1 stayed cold as 2,3,and 4 warmed up. I started testing, first for spark: OK, second for the plug: OK, next i checked the compression: OOPS! DOWN TO 60 POUNDS! I check #4 for comparison: it was 120lbs. I pulled the valve cover to check the valves. #1 was loose on the intake, and tight on the exhaust. I ran the rack, and found all but the intake on #3 needed changed. I am hoping that it was the exhaust valve being held open a little, or the intake not opening enough, or a combination of both. let me know what you think.

[DGXSER]

You mentioned changing out the cam chain tensioner. Did you do that on the centerstand? Did you make sure to put the timing mark on the C before removing and replacing the tensioner? If you did, then it may just be needing re-shimmed, If not, you may have a bent valve sticking it open.

A fellow XSive ran into some really bad luck a few years back. He had his motor eat a valve, dropped off the stem into the engine while running. BAD things happened to the head, and the piston. Soo...replacment motor was located. Well, the replacement motor had some "issues". One was that it blew the vacuum cap off the nipple on one carb. So, pulled the head, and one intake valve was bent.

[XS1100 Newbie]

I did follow all procedures in putting the tensioner on. I double checked the marks before install, so i doubt the problem is the tensioner. You never know though. I did check the marks on the cam with the mark aligned, and they matched up to their marks.

[crazy steve]

Valve lash can make a big difference; my XJ project had numbers from 60 all the way up to 160 before adjustment. After, they were 180/180/180/160 (the last one was the 60 lb one). And I think even that one will come up after running it a bit...

[XS1100 Newbie]

That is what i am hoping for too Steve. Just need to find me 4 shims.

[Barnfresh]

Assuming your compression is ok - I had a similar problem with new NKG spark plug... Switched to AC and the problem went away. New plug was not firing across the gap.