Hey guys like I said it’s a noise that only happens under load and it’s almost like piston slap. It sounds deep inside the motor like around the carb area. It only happens after I get on it maybe 1/2 throttle closer to 3/4 throttle.

It kept happening until the head gasket started blowing out the compression and most of oil all over my right leg. The bike still runs but you have to run it light and slow. I’m not running it anymore until I change the head gasket but I want to know what that noise is. As I don’t want to change the hg just for it to happen again and mess up the new hg.

Notice when I took off the rocker cover the two head bolts on the exhaust side were LOOSE and the leak was on the exhaust side (by exhaust side I mean right side where the exhaust is routed.)I tightened those bolts up put the cover back on and the oil leaking got a little better. But eventually came back. Can this be a timing problem? Can being a tooth off timing make that noise and blow a hg? Any help from the xt gurus would be greatly appreciated. Just waiting for some insight before replacing the hg.

Also when I’m idling and I give it a quick blip of throttle it makes this horrid metal noise just as soon as I crack the throttle like piston slap. Only happens when I give it a good blip does not happen when I roll on the throttle more smoothly.

try to load a youtube video where you can hear the issue, MIGHT help, but could be so many things.


if the bike has been ok before, not a chance that cam jumped a tooth.


only thing to check easily is the crankshaft nut on the right, sometimes it gets loose. if its not that, then its top end off to find the cause

It’s always done that noise since I bought it a couple months back. I just didn’t hear it because it wouldn’t get that high in rpm until I fixed the carb issue. I’m thinking piston slap or pre detonation.

Is it normal for a blown hg to leak oil or do I have blow by?

I’ll try to upload a better video of the sound as this is just the sound of the blown hg.

https://youtu.be/oCnMZZghnfA

Wow that`s a leak.

So you need to do the head gasket for sure, as for your other "knock" check out THIS post i made several years ago.

Mezo.

I’m definitely changing the hg tomorrow actually I just didn’t want it to go bad again. I’ll see if once I change the hg it keeps doing the knock. I’ll get a vid of it. I saw the post you mentioned and it’s not that. The knock is so strange. At first I thought it was the front fender rubbing against the tire, then I thought it was the butterfly o the carb flapping away because it would go over 180 degrees at wot. That wasn’t it either. I’m honestly stumped. We’ll see tomorrow if it keeps making the noise.


Little update
Took off the cylinder head to change hg and found 2 bolts had helicoils but they were stripped. Put new ones in new head gasket in torqued down to 20 ft lbs and low and behold same issue. It’s leaking the compression through right side hg. It’s tons better than before and i don’t think it’s leaking oil yet...

I made sure to clean the mating surfaces well but looks like I will have to resurface them as it looks to have had some warpage on the right side. Hopefully it will hold up a bit longer until I can do everything properly with time but I need the bike running as it’s my only means on transport.

Anywho this thing runs no matter what. I love the old reliable steel steed. Here are some pics.

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Does anyone know what the hose on top of the rocker cover does? It this a vent tube for the oil tank?

For some reason I have oil leaking from there. I follow that hose back to the upper part of the oil tank.