Gonna be getting some new parts for the ST. I originally wanted to just open up my cam cover and check how things looked in there. But now I want to upgrade everything, minus increasing the bore size.
Currently it has a star racing 30-30 .485 lift cam, s&s plate and pump, s&s lifters and pushrods.
I have about 125 horse and 136 tq.
Want to not make any typical DIY-er mistakes this time around... For instance, I did not check crank runout when I installed the first cam. Better late than never - got the dark horse runout tool and will check it this time. I plan on checking everything inside to the best of my ability.
Anyways here's what I plan on:
1. FM level "AX" heads, with george bryce's springs rated for 0.640 lift, and feuling head breathers
2. cam: moving up to a star racing F35A cam (0.572 lift, 35 degrees close). Some pre-emptive tranny work might get done also, as I heard of bikes suddenly losing their 3rd gear.
2a. also while i'm in there i'm going to inspect my own work... lifters, lifter bores, etc. I'm installing some s&s piston cooling jets in there as well.
3. trask power plate, barnett clutch basket, star racing billet comp ramp.
4. trask checkm8 as well
5. May replace the s&s precision tappets with feuling race lifters.
6. NO bore work - stock 117 displacement. No intention to do anything beyond the heads.
7. currently has 5.5g/s bosch injectors and a 55mm intake manifodl from s&s. Not sure if I should increase intake manifold size at this point?

I don't get to ride this bike much, but when I do I love to ride it in the higher RPMs. I did take this bike on a couple long trips, but I decided to just get a bagger down the line for that kind of riding. This bike, I'm going to throw a high rpm cam in it, and see how fun that is. The main thing I'm just concerned about is increased wear on the bike from riding it hard all the time. I have heard these m8's like to rev high - be that as it may, I'm pretty sure harley never intended my m8 to put out (potentially) 135+ horsepower. So I just want any advice on things I should replace/ check on.

 

Well your starting down a rabbit hole and you have to ask yourself how deep do you want to go! The new parts you are listing are not going to make much of a change from what you already have for the cost of them. If you want to see a real performance increase, you need to increase the compression ratio from the OEM level and since your planning to remove the heads its not much more work. Then if you decide that's what you want to do, how many miles are on the parts now as it might be cheaper to buy a piston cylinder kit so its all new.

 

Thank you Steve - not many miles on the bike its pretty much brand new. Do you have a favorite piston manufacturer?

 

If your sticking with the same size just make sure you get a forged piston that must have skirt coating applied and top coating is a good option. Really the SE piston cylinder kits are a great value and they come in various sizes and they also have just forged piston kits alone.

https://www.harley-davidson.com/us/e...ter=2020-FLHXS

The above link gets you to the HD site and you can take a look to get some ideas.

 

Assuming I steer clear of a big bore kit and just get nicer pistons. How much more compression would that get me, if any? Thanks for your insight.

 

Your current setup is 10.2:1 advertised. You can use a .010" base gasket and .030" head gasket (Cometic Gasket C10166-HB-030), and raise the static compression ratio to 11.1:1, which will help with that cam. IMO, you'll also need the 64mm throttle body and ported manifold (along with a great tune) to help with your HP goals.

 

Wow, big difference with thinner gaskets. Thanks for that

 

If what your after is a nice street bike that can run all around without issues I would say keep the compression around 11:1, and since I see your listed as CA the fuel we can buy along with the amount of traffic and heat we get it will be a nice combination. The 30 - 30 cam you list is a mid range to high RPM camshaft design so it will run best above 2800 RPM if that's what your looking for. Changing to the F35a is just going to move that up higher in the RPM range to more like 3200 and up. The more RPM you run the engine the faster the wear on it is going to be, so pick your poison and know what your getting into.

 

It will be my first true hot rod so I gotta find out for myself. The 30-30 has been good to me, it still runs pretty good with no lugging down to 1900 rpm. If the f35a ends up being too hot I'm thinking no big deal, I'll just swap it down to an m28 and retune it. It's really hard to say right now. Think I just want an excuse to open my bike up.

 

The problem is the fuel that is in CA doesn't allow for the engines to be opened up to much. Go east and they can buy 91 or 93 with NO ethanol all over and in CA your stuck with summer blend and winter blends that change and your limited to 91 with ethanol and sometime you cannot even get that. That why I said pick your poison.............