wilmar13
Husqvarna
AA Class
OK, so I noticed I had dirty coolant a couple days ago... checked the radiator from a cold start and while I couldn't see bubbles, the level rose until I shut it off and then went back down... DAMN!
So this afternoon I tore it down and removed the head. Looks like a minor leak had developed with migration starting in a couple other places. Bike had ran lean when I shorted a wire on my Autotune setup so for all I know that brief overheating is the root cause. I do have the 530 big bore kit on and with 100mm bore there is 1.5mm less to the water jacket so it makes sense it will be more prone to leaking.
My question is about whether I need to remove the studs and scrape the heads. Where the leak was occurring there is a slight bit of corrosion that you can just make out with your fingernail. I have tried cleaning it with a rag and acetone but it seems to have no effect. It is very slight, but I don't have a good idea if the gasket will seal it. I am thinking that it is so minor I am more likely to cause more harm than good trying to scrape the heads, but I don't have much experience building engines so I am looking for opinions/experience.
Here are some photos showing the damage on the cylinder face, note that it is mostly on the side opposite the cam chain.
It seems like there should be one more fastener on that side since the water channel it large and to offset any asymmetrical clamp force the 8mm bolts near the cam chain may contribute.
And here it is on the head a bit worse, same place:
Keep in mind I have cleaned it with a terry cloth and acetone, no abrasives, but the carbon deposits are gone... the discolored area can be felt with a finger nail, like it is slightly rough.
Here is the gasket:
And some closeups... note the bubbles everywhere the water jacket was... is this indicative of overheating, or normal? Also why are the holes in the gasket so much smaller than the channels in both the head and cylinder? Seems like it would make it more likely to leak.
And in the FWIW category the gasket was not stamped perfect to the bore. With the guide pins locating the gasket, the bore hole was not quite perfect (about .020" shifted, but I could definitely tell when I was looking closely. If the replacement is the same way I will probably try to open up the holes in a way so that worse case it stays there, best case it is perfect.
So long post, but any advice or hints to make it less likely for this to happen are appreciated.
So this afternoon I tore it down and removed the head. Looks like a minor leak had developed with migration starting in a couple other places. Bike had ran lean when I shorted a wire on my Autotune setup so for all I know that brief overheating is the root cause. I do have the 530 big bore kit on and with 100mm bore there is 1.5mm less to the water jacket so it makes sense it will be more prone to leaking.
My question is about whether I need to remove the studs and scrape the heads. Where the leak was occurring there is a slight bit of corrosion that you can just make out with your fingernail. I have tried cleaning it with a rag and acetone but it seems to have no effect. It is very slight, but I don't have a good idea if the gasket will seal it. I am thinking that it is so minor I am more likely to cause more harm than good trying to scrape the heads, but I don't have much experience building engines so I am looking for opinions/experience.
Here are some photos showing the damage on the cylinder face, note that it is mostly on the side opposite the cam chain.
It seems like there should be one more fastener on that side since the water channel it large and to offset any asymmetrical clamp force the 8mm bolts near the cam chain may contribute.
And here it is on the head a bit worse, same place:
Keep in mind I have cleaned it with a terry cloth and acetone, no abrasives, but the carbon deposits are gone... the discolored area can be felt with a finger nail, like it is slightly rough.
Here is the gasket:
And some closeups... note the bubbles everywhere the water jacket was... is this indicative of overheating, or normal? Also why are the holes in the gasket so much smaller than the channels in both the head and cylinder? Seems like it would make it more likely to leak.
And in the FWIW category the gasket was not stamped perfect to the bore. With the guide pins locating the gasket, the bore hole was not quite perfect (about .020" shifted, but I could definitely tell when I was looking closely. If the replacement is the same way I will probably try to open up the holes in a way so that worse case it stays there, best case it is perfect.
So long post, but any advice or hints to make it less likely for this to happen are appreciated.