Piston Slap? Only when hot

[Ekins]

Looking for some help with my XB12R ('04) I thought I was chasing a lifter issue . but after replacing the lifters, pushrods and then the cylinder head with a known good head ( because the original had some marks where it looked like valve Contact from a screwed up guide or similar issue) . The new /used cylinder head made the bike run smoother in general but didn't solve the initial issue . I have a metallic sound from that cylinder that starts to creep up and then gets loud right around the time the bike hits top of it's heat range ( where the fan kicks on ) . I'm thinking piston slap but it is odd I don't hear it until the engine really heats up . Once the noise starts the cylinder will start acting erractic and try to stall the bike. Once the bike has cooled it is back to normal and will run fine until it reaches fan temp again. With my stethoscope I haven't heard any telltale knocks from the crank . Any suggestions greatly appreciated . thanks in advance J.ekins

 

[Theycallmecrash]

Goodluck with your noise, cause the engine makes a ton of noise like what you described. Trouble shooting your performance issue when hot might be more beneficial, piston slap when hot doesnt sound likely. Possibly engine knock, due to an intake air leak? When it starts running poorly, vent some propane towards the intake manifold, if no change then down the intake. Note engine performance change. If better, air leak or lack of fuel, if bogs or stumbles probably mechanical.

 

[Red93stang]

They do make a lot of noises. But a more common issue with these engines are crank pin problems. Research that and see if its your issue. Tons of info and threads on this common failure.

 

[squidbuellie]

When you pulled the heads, you didn't check the crank play? It's sounds like as soon as the oil thins out your getting a rod knock.

There was a high milage bike I bought off a fourm member a year ago or so. It sounded like it needed a top end (scoped it) but it ended up being a bad crank.
If I find time between football ill load up a video of the crank after I pulled it out.

 

[Ekins]

Thanks Guys , No intake or exhaust leaks present . I only pulled the front head because the rear wasn't making any of these noises to my ear or with my stethoscope ( auto style). The original had valve contact damage that scored parts parts of the combustion chamber near the end of the intake valves travel which is why i switched out the head along with the lifters and pushrods. the piston crown looked to be in good shape with no contact markings and had no excess play in the bore . Here is a video I took of the hot engine at it's worst . This is the original head but the replacement yielded the same results once the engine hit the same temp , THanks J. ekins

http://www.youtube.com/watch?v=A-4Jz8DVljU&feature=youtu.be

 

[thuren67]

Does it run fine? Mine makes lots of noises but runs good lol

 

[squidbuellie]

It sucks to do youtube noise diagnoses, but to make it simple.....i dont think there is going to be a easy quick fix. it will need to come back apart.
Also it sounds like a rod knock. The front rod is the one that goes.
One thing you can check is, use one of those magnet on a rod tools and stick it in the bottom of the oil bag to see if their are medal shavings or see if you have shinny flakes in the oil.
I've seen wrist pin slide out and sound like that too.
Also a stupid question...you did make sure the cams where all lined up?
When you take the motor out you can just pull the front head and jug, then pull the spark plug out of the rear and rotate the the crank to the top of the stroke and then check it for play. Tiny side to side is ok...but up and down is all bad.

 

[garyphantom222]

I can get on my bike like I did yesterday and it ran without much noise at all,but the next time I ride it the engine will be as noisy as heck,it's all good with mine though,like squidbuellie said it may a knocking rod or a bad crank.

 

[Ekins]

Thanks Guys . I think squidbuelle is right about the con rod .I'm thinking there is probably just enough slop in the crank or the rod ( big and/or little end ) that it doesn't act up until the piston get's hotter and tightens up in the bore and asks more from the rod to move it. It is so weird that the bike will run beautifully for miles until the engine hits that temp mark ,usually idling in my driveway at the end of a ride or at a stoplight. Thanks a ton for all your input guys . Gonna figure out my next move since splittin the cases is in the bike's future. Thanks J Ekins