Death rattle

[gasman]

Before the race started this past weekend, I thought my motor sounded a little more "clattery" than usual. I told myself it was valve clatter and that I should have checked lash beforehand. It kinda sounded like it was getting louder until I got stuck in the mud at about the 40 minute mark. I had it pinned to get unstuck, and when I got out it was a pretty loud knocking rattle. It sounds like a couple marbles rattling around in the cases. It's not in-time with the valvetrain (1/2 RPM), it's more in-time with the actual RPM's. I ended up just putting out of the woods and back to my truck. It starts and runs fine, no coughing or hiccups, revs fine, seems OK except for the rattle. Sounds like the bottom end, maybe even toward the left side. This thing has had a weird clunking sound when starting it and especially when shutting it off for the whole two years I've had it. Is it possible it might be the starter clutch, even though the starter still engages and seems to work OK? I haven't even pulled it off the trailer yet, so I haven't drained the oil yet either to see if there's anything weird in there.

FYI, if you haven't seen my post in the pics section yet, this is an FST 446 stroker. Not that that makes any real difference.

 

[boxhead]

I'm willing to bet it is. It's possible a couple of the metal pieces came apart on it. Seems like everyone has had to replace that on theirs lately... It might also be the bearings on the gears in there, I've heard that case with someone lately. I imagine the gears would rattle on there if so.

 

[gasman]

Thanks. Keeping my fingers crossed, thinking positive thoughts. lol I need this to be simple and relatively cheap, as I'm in the middle of a points battle and if it's something major the $$$ might put me out of the running.

 

[91warrior]

yea i would drain the oil and see whats in it. before mine blew up when the cam bearing went out, if i just would have changed the oil when i was supposed to, i think i would have notices something was wrong and took it apart, but i ran it till pieces broke. i would check her out really good to find out what it is.

i dont know if you could maybe post a video of it running, that might help a little for other people to chim in and help ya.

 

[boxhead]

Hopefully that's the issue, anything else in the case can be a very bad thing. It probably is if it has been clunking/slapping while you turn it over at startup.

 

[gasman]

Found it.

Big end of the connecting rod. Can't imagine what that's gonna cost on my stroker crank.....

 

[91warrior]

what happened? did the connecting rod bearing on the crankshaft fail? that sucks man.

 

[boxhead]

I don't like death rattles....

 

[gasman]

There were shavings in the oil drain plug, just enough to fill the plug. The rod moves up and down on the journal about 1/16". I'm really hoping that just the needles took a ****, and it didn't tear into the rod bore or the journal. That rod journal is just a press-fit pin between the two crank halves, right? So it would be replaceable without trashing my whole stroker crank? And is that a stock Yamaha rod on my FST stroker? The guy that does my bore work (2 miles down the road) said he can also do my crank, as long as the parts are common and readily available. If all the planets align just right, I could get out of this a lot cheaper than I first thought.

 

[gasman]

Nevermind, I just went to bikebandit.com and answered my own questions. Looks like I can get the rod, crank pin, rod bearing, and thrust washers all for maybe $140 or so. I can probably do better than that with the cute parts chicky at my dealer. lol

edit:
I just found the whole rod kit, including the rod, pin, bearing, and washers, on eBay for $66.50 shipped. And I've bought from that seller many times. It's looking better all the time!