Piston slap and Oil?

[XS1100_OEM4ME]

Finaly got my 1979 XS1100 Special almost done (taking off after market parts and going OEM) and now that I can hear what the motor is doing, I have piston slap sound. (poor power and knocking from 1000-3000 rpm under load) I tried 25w60 Drag Spec. oil with some Lucas add, didn't help knock but shifts great now but has a new noise at idle, sounds like a hamster wheel (LOL) I only have about 50 miles on oil and I am going to change now, any help on what will best help piston slap noise? Bought GN4 Honda 20w50 per dealer recomend. Any help would be great, Lon

[cywelchjr]

That sounds more like a rod knock to me. However, does it get louder under load or quieter? An automotive stethoscope might help you determine if it's in the top or bottom end, which would tell you what you have. I know when I had a rod going out, it still had power, and with the piston slap I'm 90% sure I have now it's still got good power, and it's not very loud either.

My knock is from about 3k to about 4500 and pretty much goes away under load (actually it's only there from light to medium load), and only when warmed up, as soon as it cools down it's gone.

[XS1100_OEM4ME]

piston slap

Thanks for the getting back. First when i looked on here under "search" for "piston slap" I found a post with a yamaha tech bulletin that discribed your exact problem as a timming advance problem for 1980+ XS1100's. I hope it might help your bike, sounds like an easy fix. I looked in my Climmer man. for my noise and rpm under load for my bike and it said most likely cause was piston slap. Must be very commion on this bike to make the trobble shotting pages. It clears up at 3000 rpm and I dont hear it without a load, nothing at idle where most rod bearings love to knock, thanks though, Lon

[XSokieSPECIAL]

I hate to be the bearer of bad news but that is exactly what my engine did when I had a main bearing go out just recently.

I had a knock under power mostly in the higher gears coming from the left side of the engine.

Sound familiar?

[XS1100_OEM4ME]

piston slap

Thanks, but mine dosent sound like a crank related knock and the I am the secound owner and the first, a friend of mine, was an old guy like me and road like an old man, never even ben ridden in the rain! 17000 miles on her and changed oil every 2500 with yamalube. Only thing he did wrong IMO is put an after market exaust on it, and from what I have learned if you dont re-jet, you can overheat the cylinders and cause poor fitting piston problem that can cause the piston slap. I know the best fix would be to tear down and re-bore but the sound is slight (most would not notice but I am a nut when it comes to any noise. I was hoping someone had had good results with a grade/ weight oil to calm her down. When I was an auto mech for years I found a big differance in motor noise and brand/ weight, Thanks, Lon

[mro]

least XSpensive way to fix ...
Parts bike, 50 to $100.00

swap cylinders and pistons.
Of course, it helps if the donor is good.

mro

[petejw]

have you syncd the carbs yet,
if there out of sync that can create
a knocking sound.
also check your cam chain and valve clearances.

[XS1100_OEM4ME]

Thanks, Photo's

I guess I will try the GN4 oil as it cant hurt. The noise is lame and I will just live with it. What happened to adding photo's? Cant find any other members or add my own?

[bikerphil]

Don't think anyone mentioned it yet, is the ignition timing correct? Is the mechanical advance working correctly? JAT

OEM, follow instructions in this thread if you want to post pics....

http://www.xs11.com/forum/showthread...ht=photobucket

[XS1100_OEM4ME]

Pic link

Here is a link to my bike pic if anyon is interested



http://us.mg2.mail.yahoo.com/ya/down...ean=0&inline=1

[XS1100_OEM4ME]

Fixed!

Took out the 25w60 Drag Spec. oil (only ran it less the 20 min.) , didnt like the way it acted/sounded). Put in the honda 20w50, runs and sounds great! No chatter or squeek. Runs smooth and excel. is great. The shifting improved dramaticly from the Lucas I added to the 25w60 and still is the best shifting XS I have ridden, even with the oil change with no more Lucas added. Who would have thought oil could make that BIG of a diff?

[prometheus578]

Who would have thought oil could make that BIG of a diff?

Uhm.. actually...quite a few of us here.
See here was your problem with the 25w60 Drag Spec oil....
""Meets all warranty performance criteria for Harley-Davidson® engines""
well DUH! No wonder it started shakin' and rattlin'.

Now, I know your name says, "OEM for me", but a lot of us run Castrol GTX 20w50. A lot also run Shell Rotella oil. Some run other brands. For a variety of reasons (problems), it's not advisable to run synthetics.

(Now, let's not start an OIL THREAD war. When I said "it's not advisable", I meant, me, myself, I would not advise it.)

[XS1100_OEM4ME]

Hd

LOL, shakes and rattels like a HD, Next, if I want to be an HD owner I will need a pick up truck to get it home when I go riding, and then a wife to drive the truck (LOL) Much cheaper to ride a YAMAHA with the right OIL. I did the Drag Spec oil as a test (IE, only in the bike for a few mim.) From the (Guru's) and it did help me learn what was going on in my motor, (no piston slap and no bearing prob, like someone here thought. And it flushed out some ugly stuff that might have sat in the case forever. The short time the Lucas was in there did make it shift like a John Deer instead of a russian tractor and still shifts the same. Worth every dime, or dollar in this case!!!!

[XS1100_OEM4ME]

Noise returning

OK, the 25w60 hd oil did calm down the rattel but now back to 20w50 and it has returned! Here is the best way i can discrib, "slight" sputter at take off then runs great through the gears. Get to speed and OK under no or slight load. Give it gass when around 3000 rpm and a rattel sound, more gas and goes away. Over 4000rpm and smooth and runs like a scalded dog. Did timming chain adj to clymer spec, carbs rebuilt, new kits and floats set with a mic. New plugs,ngk, this bike starts first time every time and need little warm up. All lines, gas, vac are oem hook up including octy rebuilt. I have heard ing. advance and or carb sinc can be causing this, bench sinc and works great otherwise and adv works when vac applied?

[Ken Talbot]

I only did a quick look back through this thread, but did you mention anywhere about being sure the vacuum line for the advance is hooked to the nipple on the body of carb #2, and not to one of the nipples on the intake manifolds?