I have SE 204 cams in my TC96 2010 Ultra and was thinking about installing a 103 big bore kit. what's the highest compression I should go with the 204 cams and still have it drivable in the summer without pinging issues?

 

Keep it under 10:1 and you should be fine. Use the HD cast flat top pistons and a standard Harley head gasket (0.045" thick) and you'll be in good shape. I think this puts you at a static compression ration of around 9.7:1.

I would recommend putting in some manual compression releases if you don't have them already. By brother has this exact same set up in his 07 Street Bob and has some hot start issues. He's putting in compression releases this winter.

He doesn't have any pinging issues. It's a nice running set up.

Good luck. It's a nice, proven build.

 

You can go to 10.5:1 if you back the timing off in cruise area from 2750 to 3500 to no more than 38 degrees and richen it up in that area also about 5%. The stock timing is way to high for any cam with over 10 to 1 in that area.

 

I would just do the SE cast 10-1 pistons and a .030 gasket. 10/10.2 is fine with 204s. 10.5 is pushing it but can work with proper tune. Of course, 10.5 and some more cam is always better... especially with headwork.

 

Thanks for the feed back. The mechanic suggested setting the compression at 10:1 so that is what I will be going with. I like the 204's but if I were to change cams what would be a good cam to go with in a 103 with 10:1 compression?

 

I'm running Andrews 54s at 10-1 without headwork with good results but 57s would be my pick now without headwork. Woods 555s/S&S 570 are a good ones too but like 54s they would really like headwork too.

 

I was just reading about the 57H's do they like 10-1 compression?

 

I think they'll love it.

 

10:1 will be just fine.

 

I went with 10:1 Pistons, .030 Cometic gaskets, Woods 555's with head work. No ping ever with just a few V tune runs. I'm pleased.