TroyBrock Posted March 29, 2014 Report Share Posted March 29, 2014 As many of you know I've been stricken by this wonderful knocking sound which lead me to tear into the top end. To my surprised the pistons barely had any play in them 1/16-1/8 of play back and forth and the rod bearings are tight on each end. I still have no idea what this knocking is. My dad is coming this weekend to look everything over. I'm still considering to have the jugs sent off to be bored and honed just to put a fresh top end in it seeing it appears to be the top end they put into it in 1987. Quote Link to comment Share on other sites More sharing options...
Nieskes Posted March 29, 2014 Report Share Posted March 29, 2014 Take the motor apart, and look at Everything!!! Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 29, 2014 Author Report Share Posted March 29, 2014 The sound is coming from the top end. It doesn't change when holding in the clutch or putting it in gear or both. Whatever is making the sound is attached to the crank and the crank feels tight, so I think it's either piston slap or something on the clutch side, but the sound is the same on both sides. Quote Link to comment Share on other sites More sharing options...
Zillaguy Posted March 29, 2014 Report Share Posted March 29, 2014 Sounds like a main bearing... Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 29, 2014 Author Report Share Posted March 29, 2014 If one of the crank bearings broke wouldn't there be other signs? Quote Link to comment Share on other sites More sharing options...
WINDYCITYJOHN400 Posted March 29, 2014 Report Share Posted March 29, 2014 If one of the crank bearings broke wouldn't there be other signs? Eventually. ....but by then the damage will be sever. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 29, 2014 Author Report Share Posted March 29, 2014 It's had this sound since I got it and I've put at least 5 hours on it. I don't know how long it had this sound before I bought it though, but it's probably been a while. I'll double check it but everything felt tight. Anyway I could really test it? Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 29, 2014 Author Report Share Posted March 29, 2014 Had my dad over today to take a look at my jugs. He said, left side jug is fine just needs a hone but right side is in need of a bore and hone and is most likely the cause of the knocking. He also said the pistons are shot, which is expecting with a 27 year old engine. I'm sending the jugs off monday to be bored and honed so I should have everything back together 2 weekends from now Quote Link to comment Share on other sites More sharing options...
Starwriter Posted March 29, 2014 Report Share Posted March 29, 2014 I would still split the cases and check out the crank. Would suck if a 27 year old crank let loose and took out your brand new top end. Also, since I doubt you did a leakdown test before you tore it apart, who knows what shape the crank seals are in. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 30, 2014 Author Report Share Posted March 30, 2014 I didn't do one but the way the gaskets were it would have leaked either way. I'm gonna have to be a bit of a dumbass and not listen to what everyone is saying about splitting the cases. I want to buy new cases anyway cause mine suffered from the chain breaking so I'm gonna hold off on splitting the cases til next winter and cross my fingers. Quote Link to comment Share on other sites More sharing options...
Starwriter Posted March 30, 2014 Report Share Posted March 30, 2014 If that's a 27 year old unwelded stock crank, it should have blown up about 22 years ago. It's gonna take a lot more than crossed fingers to keep that motor together. Total catastrophic destruction in 5,4,3, BOOM!!! Be sure to post carnage pics. You get a gold star if the rod punches out the bottom and a poston is jammed sideways in the bore. Quote Link to comment Share on other sites More sharing options...
TroyBrock Posted March 30, 2014 Author Report Share Posted March 30, 2014 I will sharpy "I'm a dumbass" on my forehead if it lets go before next winter. Quote Link to comment Share on other sites More sharing options...
sheerider11 Posted March 30, 2014 Report Share Posted March 30, 2014 I'll pay you if you make it a twingle Quote Link to comment Share on other sites More sharing options...
RagunCajun Posted March 30, 2014 Report Share Posted March 30, 2014 OP i been there. It's very intimidating to tear apart the bottom end of the engine. Get a clymers manual and start turning wrenches. It's a very easy case to split. The best thing to do is to take the entire thing apart. After you find the problem, there may be other signs of wear or things about to fail. Freshen the whole engine up. That way you will have worry free fun once it's back together. Do it right the first time. You are looking for an easy way out. split them cases sir. wash the bike well before you do that though. Quote Link to comment Share on other sites More sharing options...
gonecheenin Posted March 30, 2014 Report Share Posted March 30, 2014 Is it bored out with a shaved head? I had a Banshee bored to .080" with a .025" shaved head and the pistons were actually hitting the spuish area of the stock chambered head. Needed to send the head out to be cut larger for it all to work correctly together. Quote Link to comment Share on other sites More sharing options...
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