Engine skip or "Bucks"

[NCBILL]

Lobo1, first off, I would suggest copy / paste to your documents the above list that Jeff supplied, can come in handy. Keep a copy in your saddlebag, in a zip-lock freezer bag for protection, and quick access to whenever you're out on the bike. Next.......I'm just tossing up another suggestion, if your "new to you" Twin Cam is a 2006 or older. Has the bike been serviced, ever, in relation to changing out the original style cam tensioners? If not, or if you don't know for sure, next oil change drain the spent oil through some white cheesecloth, and look for yellowish or orange particles, that will be an indication the cam tensioners are failing. Unfortunately, all the ones I've run across are the inner tensioner, which is really hard to see. IF that is, in fact, what's happening, I can imagine the oil galley is beginning to clog, hence, the reason for bucking at lower rpm's. At higher rpm's, the oil is just barely being forced past the trash from the failing tensioner particles. I may be stretching my theory a bit, but realistically I can see that happening.

 

[Lobo1]

@NCBILL when I bought the bike back in March, I did my usual when I buy anything used. I pulled a compression test, changed oil, filter, primary lube, transmission lube, plugs, checked brake pad linings etc. That was before I even rode it other than test driving it. Brought it home on my trailer.
After about the first 3 weeks I read about the cam chain tensioner issue and how they should be changed at around the 30,000 mile mark. I removed the exhaust and opened up the cam chest to inspect the tensioner. When I saw the outer one I knew I didn't need to go any further. The front one was about 25% worn and was starting to pit. Luckily I still had the oil filter that I took off when I changed the oil so I cut it in half. I couldn't see any sign of any plastic nor anything the orangish color of the tensioner. I took it to a very reputable motorcycle shop here locally and had the hydraulic upgrade kit installed. That includes new chains, new hydraulic tensioners, new cam support plate, new oil pump, pushrods & cam bearings. Plus seals and gaskets etc. Hopefully there is no oil circulation problems. I have 35 PSI on a hot engine at cruising speeds and 25 PSI at idle since the new pump was put in. The pressure was also checked with a mechanical gauge.
I also found the front exhaust stud broken off on the front head. Broken off flush. Someone had tried to weld another bolt to the stud to remove it or something because the area around the head was messed up pretty bad. I had him to put a like new "take off" front head on it too.

Oh yeah, it is a 2005 model. And I like your idea about keeping a copy of the procedure listed by Jeff in my saddlebag. Will do that for sure.

 

[NCBILL]

Oh yeah, it is a 2005 model. And I like your idea about keeping a copy of the procedure listed by Jeff in my saddlebag. Will do that for sure.

Good, good. I'm happy to hear you've already addressed that cam tensioner issue. You'd be surprised how many "riders" don't even have a clue as to that issue. Those "yuppie" types, add gas, crank it up, go. They never take the time to "know their machine". Those are the same ones paying $80.00 hr. for HD shop labor rates, serves'em right, lol.

 

[Jeff Klarich]

Lobo1, After rereading all the post I have a question or 2.
Did you notice this issue before you had the work done?
If not i'd be more inclined to look at what was taken apart that could cause such a problem.
I would take a closer look for a air leak around the intake and a closer look at the wires on the injectors, they are prone to cracking and can give you intermittent cycles of no power to an injector.

 

[Lobo1]

Good, good. I'm happy to hear you've already addressed that cam tensioner issue. You'd be surprised how many "riders" don't even have a clue as to that issue. Those "yuppie" types, add gas, crank it up, go. They never take the time to "know their machine". Those are the same ones paying $80.00 hr. for HD shop labor rates, serves'em right, lol.

yeah. I do most of my own service, repairs, etc. Especially with Evos. But Twin Cams I'm not all that familiar with but I will and shall learn. I ordered the service manual from the stealer ship the day after I bought the bike. Learned a lot from it already.

Lobo1, After rereading all the post I have a question or 2.
Did you notice this issue before you had the work done?
If not i'd be more inclined to look at what was taken apart that could cause such a problem.
I would take a closer look for a air leak around the intake and a closer look at the wires on the injectors, they are prone to cracking and can give you intermittent cycles of no power to an injector.

I did not notice this issue before the cam tension upgrade and front head was replaced. ( both done at the same time). It started exactly one week after I picked it up. Picked it up two weeks ago today. Problem began last Wednesday. I keep thinking about the fact the intake had to come off to change the head. Can't swear a new o-ring / gasket was installed. As far as the fuel injector wires, I'm glad you brought that up. I haven't thought about tha. Will definetly add that to my list for this weekend. I am Determined to find the problem and fix it right this weekend.

 

[Harttoo]

Symptom sure sounds like an intake leak.No code.Problem occurs when engine hot.Bucking when slow or turning corners.Make sure You check for intake leak when engine is hot.

 

[flusher]

Don't think I am crazy, but, have you checked the liner in your gas tank to make sure it is not peeling.

 

[Lobo1]

No. Haven't thought of that yet. Been concentrating on possibilities related to the work that was done just before this problem came up. That will be easy enough to check though and it will be a good thing to check anyway. Will do. Thanks.

 

[Fisherking]

No. Haven't thought of that yet. Been concentrating on possibilities related to the work that was done just before this problem came up. That will be easy enough to check though and it will be a good thing to check anyway. Will do. Thanks.

What about a crank posistioning sencer? . Has it been out and cleaned?

F.K.

 

[Lobo1]

What about a crank posistioning sencer? . Has it been out and cleaned?

F.K.

Yeah, actually the guy I bought it from had a new crankshaft position sensor in the saddlebag still in the original packaging. I checked all the wiring going to it for chafing etc. changed the sensor out after doing that. No change though.