Looks like a scooter, sounds like a Harley By dhull (Read 1,267 times)

[dhull]

Big Red has decided it's time to wake up the neighbors.

Over the past few weeks I have noticed a noise coming from my MC-54-250B (16,200 miles so far). When the engine is under load I could hear a very slight tfff-tfff-tfff... sound, which sounded like an innocent exhaust leak. Last night while riding I noticed that Big Red was starting to roar and my ride got progressively louder as I went to work. After work I started him up and wanted to ask who had replaced my mild-mannered scoot with a fire-breathing Harley.

What was a simple tfff-tfff was now a full-on rumble, complete with the occasional backfire on deceleration. It was so loud that I felt the need to coast into my neighborhood to keep the peace with my neighbors.

I plan on checking it out this afternoon when I get home, but I'd like to have an opinion on where the problem is. My guess is that the little metal ring gasket between the engine exhaust outlet and the muffler pipe has worked its way out and is no longer with me. Is there somewhere else that I should check?

Here's a small backstory that might shed some light. A few months ago (February 6), I was taking a right-hand turn and hit a pile of dried road salt, which took the bike out from under me and laid it on its right side for a 15-20 foot skid. Since that is the side with the muffler, which took the brunt of the road contact, I'm wondering if that didn't flex that joint and cause it to loosen and possibly damage the gasket, which gradually worked its way out.

[Alleyoop]

I think you nailed it, amazing nothing else broke loose.

[cyborg]

Alleys is probably correct as usual,,,but a few variables may have occurred ,,,pipe cracked or the flange may have cracked at the pipe joint,,,could have pulled a stud or both or worse case senario broke part of the exhaust port boss off the head,,,in any case i hope it's a gasket and call it a deal ,,

[cyborg]

Oh as a side note,,,you ok?? Fu(k the bike ,thats just a pile of parts that can be replaced

[dhull]

Wow, you're gonna make me admit this. I was really stupid because it was the first warm and dry day after temperatures in the teens, so I was wearing a pair of shorts instead of my usual riding pants. When the bike came out from under me, I went off on the right side and my right knee made contact with the pavement. I immediately flipped over onto my back and slid a couple of feet on my jacket's back armor.

I ended up with a road-rashed knee scrape almost the size of a baseball. I'll spare you the photo I took. I manned up, though, and went on to my night-shift job where I was headed, which requires about 5 miles of walking. It really didn't hurt until the next day, but I learned to keep it covered and moist with antibiotic cream.

That was three months ago, and the scar is now just a dark brown tan (road rash is technically a burn) about the size of a chicken egg.

[skunkhome]

My vote would be the donut seal determination caused by a bent flange or crushing. 

[cyborg]

Pull a few panels on the exhaust side and lets see what's going on,,,post a few pics please

[dhull]

Okay, repairs are done and here's the update. I wish the situation was a bit more exotic and i didn't look quite so stupid, but the truth is that when I got down under the bike, I found the the exhaust pipe had completely disconnected from the exhaust port. The nuts had worked their way off and the pipe was just hanging there.

Of course the donut gasket was gone, so did a little searching and decided to follow Alleyoop's steps on how to make your own exhaust gasket from wire. A trip to Lowes and $3.00 later I had a couple of feet of 6 gauge copper wire and two 8M nuts and lock-washers The gasket fix worked perfectly and I'm back on the road.

The only way I can make this story really intriguing is what I think caused the exhaust nuts to loosen and fall off. My guess is that the February 6 laydown started the process and jolted them loose, but another factor probably contributed. In April I was riding to work when the bike just bogged down and died. On the side of the road I tried the started and it fired back up, but the throttle gave me no power to the wheels. After 15,800 miles I had finally broken the belt. Fortunately, a new belt had been on my Christmas list last year and Santa had come through, so I had the replacement hanging on the garage wall.

I pushed Big Red into the driveway of an abandoned house that was for sale, got my tools and began taking the CVT cover off. A few bruised knuckles later, this is what I found:





The belt hadn't just broken. It had exploded into a thousand bits and the remaining radial cord had wound itself around the clutch. When it blew, it took out several of the teeth on the variator fan as well. I extracted the cord, reset the variator, installed the new belt and got back on the road.

When I was done, I was amazed at how smooth the acceleration and ride had become. It made me realize that the bike had been shuddering on take off for quite a while and I had just gotten used to it. Apparently the belt had been trying to warn me for some time but I wasn't paying attention. My guess is that the excessive shuddering helped to work the nuts completely loose from the exhaust port and contributed to that problem.

The belt replacement was my first dive into the CVT, and it inspired me to do an upgrade. I've ordered a set of 14g Dr. Pulley slider weights which should be waiting for me when I get home, so this afternoon I plan on doing a quick install and we'll see what kind of performance/speed/MPG changes they bring.

[cyborg]

GREAT!!!!! glad you got it sorted out,,,and i'm also glad it was just the nuts came off the studs instead of the head cracking or the studs pulling out,,,yeah baby