TOPIC:

Whew! Thanks for all the advice and info guys! sorry I was away for the weekend. A lot to consider here.
I want to up my performance a bit more (nothing too insane) but I still want some decent reliability as I ride quite often. I think I may settle on rebuilding and getting a port job from larry on a regular J head (cheaper and easier to find anyways) and dropping in the .410 lift cams along with some pistons to up the compression. Im not gonna up the displacement much so I don't think I really need the Bathtub heads and the extra CFM. The port will get me what I need from what I understand.
Jay you say the .410 is good with SOT. Is that like you probably wont throw a shim? or you've never heard of it happening with the K410 at all? everywhere I've read up on it thats right on the limit of risky business and I really don't want to have to deal with that happening.
Plus I'd really love to keep my SOT just for the ease of maintenance like old_kaw said... and to save myself some $$$.
Still doing research before I pull the trigger on any big decisions! Found a good J head I think I'm gonna get tomorrow just to start tearing into. I'll make sure to start a build thread for it so everyone can see my progress if they're interested!

It is my understanding that the "bathtub" head has different valve angles then the regular J head. Jay would know for sure. If that's the case, then you will need to be careful with the piston to valve clearance. Not sure of the difference as to what the angles are but with the bigger cams, it might not take much. Something to check on...

racer54 wrote: It is my understanding that the "bathtub" head has different valve angles then the regular J head. Jay would know for sure. If that's the case, then you will need to be careful with the piston to valve clearance. Not sure of the difference as to what the angles are but with the bigger cams, it might not take much. Something to check on...

It's only the exhaust valve which is 1 degree steeper to allow for the bigger valves used.
Inlet is same angle as the J etc.
Combustion chamber is also same volume as the 'J' at 39.9cc.

Good to know. Thought it was both valves and angle would be steeper but really didn't know other than I read they were different. Do you know how much different the angles are compared to a KZ head valve angle?

racer54 wrote: Good to know. Thought it was both valves and angle would be steeper but really didn't know other than I read they were different. Do you know how much different the angles are compared to a KZ head valve angle?

It's the same difference compared to all KZ's.
Valve angle is the same in all KZ 900 through to J and GPZ1100 plain hemi heads.
Just the bathtub head which has a steeper exhaust.
'J' type /early GPZ heads got away with just having the valves set deeper in the larger/higher combustion chamber to accommodate the bigger but shorter valves .

Hardgun wrote: Whew! Thanks for all the advice and info guys! sorry I was away for the weekend. A lot to consider here.
I want to up my performance a bit more (nothing too insane) but I still want some decent reliability as I ride quite often. I think I may settle on rebuilding and getting a port job from larry on a regular J head (cheaper and easier to find anyways) and dropping in the .410 lift cams along with some pistons to up the compression. Im not gonna up the displacement much so I don't think I really need the Bathtub heads and the extra CFM. The port will get me what I need from what I understand.
Jay you say the .410 is good with SOT. Is that like you probably wont throw a shim? or you've never heard of it happening with the K410 at all? everywhere I've read up on it thats right on the limit of risky business and I really don't want to have to deal with that happening.
Plus I'd really love to keep my SOT just for the ease of maintenance like old_kaw said... and to save myself some $$$.
Still doing research before I pull the trigger on any big decisions! Found a good J head I think I'm gonna get tomorrow just to start tearing into. I'll make sure to start a build thread for it so everyone can see my progress if they're interested!

We have never heard of one of our 410s throwing a shim and we have sold that cam for over 30 years.