I made a bold decission today. I'm going to take the time and energy to modify my frame to allow head removal in-frame. I've modified the engine to 836cc, added a big cam, ported the heads, added after market exhaust, K&N's - all to get the bike I wanted. The time and effort it will take to completely strip this bike down just to lay it down on a table and remove the engine so six $3 rubber seals can be glued in-place is not the way I want to do it. I'd rather spend that time engineering, carefully cutting with a Portaband, and machining barstock on a lathe to fit bolt-in frame tubes. Two of my new/modern bikes have bolt-in frame tubes for engine removal. It's practical, it can be done correctly, and it can be made safe.
I posted this here for input, please. Who has done it, what are your impressions afterwards, and what would you do different?
Today I rode over to my local speed shop to show the guys (father/son) the bike they did the head porting and 836cc bore work on for me. I showed them my leaks and they laughed - 30 minute job "at most". Obviously I'm not believing it - until I'm shown their 2 drag bikes. Both CB750 SOHC models. One is a 900cc and the other is something over 1,000cc. Both are sleeved, ported, extensive valve work, super-lift cams, and open headers - all for drag racing and heavy launches with big tires and wheelie bars.
Both bikes had the two horizontal frame tubes removed from the steering head to the front of the seat. These are the 2 that run just over the head cover. They don't run anything, just the single back-bone. I will not try that although they've done it for many years and thousands of passes down the strip.
I plan to cut those 2 tubes carefully, deburr the ends, have perfect-fit barstock inserts machined to fit into the 4 tube openings left after cutting. I'll take the removed pieces to a machine shop and have 1 side clam-shelled so it can be bolted onto the original frame in 4 locations and fit over the 4 barstock inserts. I've looked and the bolt heads will clear the tank and there is plenty of room for the locknuts to the inside. Even the trangulated center piece can be "tabbed" so that too can be drilled and stainless bolts used to "tie" it all into a stock configuration and retain high strength. I figure this will add 1/2 pound and the very most and I'll have a fully removable frame section that will allow head removal in-frame.
Honda would/should have done this back then. But, we know they were trying to hold pricing for their "new" superbike to those of the British 750's back in 1968 when the CB750 was launched.
Comments and photos please - I promise the same. I'll have this done at a friend's machine shop then powdercoat before adding the stainless hardware that will hold it together. All of this will absolutely invisible when the stock tank is in-place. The barstock inserts fit into the bike's frame and the removable tubes are bolted "onto" the inserts and then through-bolted for complete rigidity. I think it can be done - it should be done!
I don't really see the long-term potential of my modified K4 going up in value, so purist - give me a break ! I wouldn't dare do this to a K0, Z1, or an H2. This is "my" bike and meant to be ridden, enjoyed, modified more, played with, modified some more. What better way to enjoy a solid engine than with the option of easy head and cylinder removal ??
Regards,
Gordon
