I think I have a blown head gasket on my M8

[NGOT8R]

I'm right at about 4300 miles on my 2018 SGS and it appears that I might have a blown head gasket. What drew my attention to a possible problem was the way the bike acted when I went to start it up after it sat for about a month and a half. It idled high (3500 rpm) for about 6 seconds and then dropped down to a normal idle. I took it out for a short ride and it sounded like it has an exhaust leak. The bike sat for a couple of weeks and when I started it up, it idled high again for about 3 seconds and died. I began looking around the front and rear heads with an LED light and noticed that there is carbon on the edge of the head gasket in the front center. Damn! I'm aware that some M8s have encountered blown head gaskets, but I was hoping I wouldn't become one of them. The pic is sideways for some crazy reason, but you can see the carbon that I am speaking of. The rest of the gasket edges (front and rear cylinders) are rust colored.

 

[hulkss]

Maybe an intake manifold leak? That can cause erratic idle and poor running. The stock plastic manifolds have had issues.

 

[NGOT8R]

Thanks Hulk. I'll take a look at the intake as well. What are your thoughts on the black soot that appears to be carbon on the edge of the front head gasket? This problem is so weird, in that it just popped up all of a sudden. I'm going to investigate things more thoroughly once I finish up with my Sportster build.

 

[hulkss]

I guess you could do a cranking compression check or a cylinder leakdown test.

 

[NGOT8R]

I guess you could do a cranking compression check or a cylinder leakdown test.

I do plan to perform a leakdown test, just as soon as I can pick up a tester.

 

[Mojo]

I have a friend that just had rear head gasket blown/ 2017 FLHXS - 24,000 miles. Out of warranty, Dealer fixed it no charge.

 

[NGOT8R]

I have a friend that just had rear head gasket blown/ 2017 FLHXS - 24,000 miles. Out of warranty, Dealer fixed it no charge.

I'm probably on my own if the head gasket is blown Mojo. I installed an S&S cam and tuner a year ago.

 

[baldman]

I had an Evo motor on a chopper that used to blow head gaskets every year or so. You should be able to hear it and feel it - you'll hear the "pfft pfft pfft" of compression leaking and feel the blow by at the leak.

 

[TomA]

I'm probably on my own if the head gasket is blown Mojo. I installed an S&S cam and tuner a year ago.

Sound's like your up for another build of course if your taking the head off why not have them worked on just a little bit. You have t replace the second one just for peace of mind right. That Zipper's kit Michael had installed looked like fun.