Hello all, I’m having a bit of trouble with my bike. I posted this on another forum without a single suggestion so I’m going to try here. I’m copying from that post to this one:


2000 ultra classic 80k on the bike, 15k on the 103 kit


I just rode my bike 600 miles to the beach for vacation. I let it sit overnight and went to start it this morning to go grab some food and it immediately started clattering and died. It sounded like a rod turned loose in the tone of it. I thought my starter Jack leg got hung or something so I tried again. Same thing. Did it again and it finally started and the clattering stopped, but it’s only running on one cylinder and backfiring pretty bad. Oil pressure is right on the money, no more noise, spark plugs are fairly new. I swapped the plug wires to see if it would make a difference, and it made it not run at all. Pulled the plug wires and the oil cap to see if air from the cylinder was going through the case, it wasnt. I’m going to run a compression check and electrical diagnosis if the compression is there. But I’m shocked. It ran perfectly fine all the way down here, was shut off several times along the way and started right back up just fine. No hiccups, spitting, sputtering, etc. never had an issue with this bike. Any ideas? Bad coil? Bent valves? Bad crank sensor?


I was able to start it the following day after I posted, and it ran like it was firing both cylinders at the same time or something and won’t idle without cracking the throttle a little. I went out and got a few things to do tests at the condo and the compression was 125psi in the front and 90psi in the rear. That threw me way off. Added oil to the rear cylinder, no change in psi. Did a leak down test on both, 4 hours each. Neither one dropped a single psi. I’m back home now, I had to trailer it 600+ miles home. I tore into the bike today, rockers, pushrods, lifters, etc look good. I haven’t pulled the heads (last resort). Primary cover was pulled, all looks well no snapped/worn tensioner, compensator was tight. Drained the oil, no metal shavings in it or on the plug, pulled the crank sensor, no metal shavings stuck to it. I’m pulling my hair out. At this point, I’m leaning towards overheated cylinder(s). The noise is constant, idling, accelerating, decelerating (although it sounds a bit louder of a tapping when letting off the throttle), etc. it’s not progressed worse, but it’s definitely not better. I don’t think it’s a bent valve due to the leak down tests. But this was a solid 13 hour straight ride, half or more of that time was in the 105 degree Georgia and Florida heat. Any suggestions??? I do have a video of it running on hand and you can clearly hear the noise. Any help is appreciated. Thank you!

 

I know it may seem like the noise is from the shifter/linkage but I can assure you it most definitely is not.

 

Sorry about your issues...

I was going to guess maybe a collapsed lifter or an adjustable pushrod (if you uesd them with the 103 kit) got loose... but you checked those...

I read your post 3 times, sorry if I misunderstood or missed this info.... but I have a few questions:

You posted the results of the compression test, 125 front/90 rear.... The rear cylinder is way out of spec and should be within 10% of the front.... What were the results of the leak down test....?? Did they both hold at that psi, or are you losing air from the intake, exhaust, or breathers?

You mentioned the "rockers, pushrods, lifters, etc look good". What are the etc? Did you open the cam chest? Are the spring cam tensioners both OK? Are the inner cam bearings, or cam plate bearings for that matter, all good too....?? Did you update the cam plate/inner cam bearings when you went to the 103...?

 

Cam chain tensioners or loose pushrod nut.

 

yes, both cylinders held said psi for several hours without losing any pressure, which is why I was in shock since the rear is only 90 psi. As for the “etc”- the valve springs, breathers, and play were all good. I haven’t cracked anything in the bottom end open yet, I ran out of time yesterday, but will do that today after work. The cams were swapped to SE when the SE jug kit was installed and with new bearings. I’ll check these things this evening and get back with you. Let’s say that explains the knock, but What about the rear cylinder compression? Unless it’s not letting the cam turn like it should, letting enough air in on lift. Correct?

 

Maybe find a bore scope and take look inside the cylinders.

 

You describe to a 'T' what happened to my bike (also '00 FLT,) after a 600 mile round trip to Maggie Valley and back in 90 plus degree temps 7 years ago. The bike ran like a champ but the next morning dropped to one cylinder when I tried to start it. My issue turned out to be a bent valve, although I can't explain your leak down numbers. I bought a set of used heads and a gasket kit and it's been good since. Good luck,,,

 

yeah see that’s one reason why I’m stumped, I’m not sure how it could happen overnight unless it bent or messed something up when I turned it over. I’m trying to keep from pulling the heads and jugs unless it’s a last resort, so I’ll see if I can get a bore scope on the way home.

 

My 15 street glide did this, and the MAF sensor plug was loosley connected and was nto getting a good connection.... started to haeva slight miss, then it evolved over the next 24 hours of treavel...to full blown backfireing, bucking, dieing etc.

 

I got to talking to a friend of mine at work and he thinks it’s got a bent valve. He explained he’s seen where the cylinder builds just enough compression to push the valve closed once it gets to the catch area or the “bend” in it. So since it’s bent, it sticks until there’s enough pressure to push it past that bent and until it seals, causing the low amount of compression and keeping it from leaking down. Which sounds like it would make sense, given that there’s a racket going on in the meantime and no metal in the oils or cracks in any rockers or anything.