I got into a discussion on another site about what "bolt in" means. I always thought the stock heads(valve springs) were good for 510 lift. I was told that the newer bikes can run up to 600 lift? Is this true? I'm pretty sure my 88 inch can only safely handle the 510's and that why all the manufacturers make 510's and sell them as stock bolt ins. What gives?

 

Later models can accept about .600" lift.
Early T/C's, as well as Evo's, were limited to .510".
Scott

 

Thanks Scott for the info.
Dan

 

Beehives were introduced in '05 but I believe some late production '04s have them as well. Plenty of guys running stock beehives up to .570" lift; myself included.

 

Is there a mark or stamp or part number so you can tell if you hve the beehives? Either on your late 04 or if you were to buy a set of used heads off craigslist/eBay?

 

Just look for '06 or newer heads. "Beehive" is a type of valve spring which has a reduced coil diameter near the top.

 

Any heads produced from 2005 forward will have beehive springs. If you are buying heads off Ebay and don't plan to port them, buy a set of the '06 or later heads as they flow better. If you intend to port them, it doesn't matter what year you buy and you can replace the stock springs with beehives if you want.

If you want '06 heads, just look for a set with the -06 suffix at the end of the PN. The '06 and later heads have a 1.808" intake valve vs 1.800" in the '05s and 1.615" exhaust valve vs 1.575" in the 05s and the exhaust track and port were reworked for improved flow. If you so go with the later model heads you will need the later model intake flanges to install; they are cheap.

You can easily distinguish bee hive springs, they taper toward the top instead of having the same diameter from bottm to top.