I've been building this Firebolt for a while, for a friend. I've been meaning to make a build log but with the new baby and relocating my Dad, just no time. So consider this the build log of sorts. Still not done, but getting closer. Hoping to start it up in the next day or two.
Here's an Imgur album of the photos, feel free to ask any questions.
-Bored cases -08 XB12 crank pro plugged and balanced by Darkhorse -07 oil pump -bronze drive gear -NRHS CAT4 .590 lift cams modified for XB use -S&S lifters and cylinder studs -Axtell/NRHS 90" kit with 15* reverse dome pistons -NRHS chromoly pushrods -883 heads with 4 new valve seats, porting and other mods by me -AV&V 1.980" intake, 1.610" exhaust 7mm stem valves, AV&V manganese guides, S&S 650 beehive springs -XB12 manifold ported and modified by me -60 lb/hr injectors -08 XB12 primary gearing -Energy One clutch pack with Barnett +25% diaphragm spring -easy clutch leverage extender -XB12 header and race muffler ceramic coated, header interior flow coated -57 psi fuel regulator, new filter and screen -1125 forks and trees, top tree modded for risers and Fatbar setup -ZTL2 caliper and MC -powdercoated wheels -04 pulleys powdercoated and CNC cut by Free Spirits -Falcon SPC drive belt -Free Spirits pulley cover -Free Spirits belt tensioner -Braking front and rear rotors -2010 LED taillight -Ballistic 12 cell Lithium battery -American Sport Bike left and right carbon fiber air scoops -Knight design drop pegs -billet timing cover -polished clutch and chain inspecrion covers
I'm sure I'm forgetting stuff, and there's still more to come.
The wheels are actually a dark orange, a dead ringer for the decals, though they have a little bit of metal flake. The dimples are to create a smaller boundary layer for better flow, similar to a golf ball. The manifold is similarly dimpled after I ported it.
I did the dimples on my little race bike to try and squeeze every single bit of power I could get out of it. Did make a big difference in jetting. Went so far as to dimple the valves too. Will eventually look for the poor flow spots on the piston and dimple those as well. Takes a boat load of time, but seems to be worth it.
Mine were a dremel by hand with little spherical cutters. I found some cheap diamond ones on amazon that had longer shafts and this proved useful. The diamonds also worked a lot better on the valves (not the seat or seating area!!!). It's a tedious task but seems to pay benefits in making power. Do some internet searching on "dimple intake" or derivatives, there are some interesting explanations of the benefits. Not sure how much is real and how much is voodoo, but I did see my jetting go incredibly rich between no dimples and dimples, just like some of the better articles explain will happen. Something about the boundary layer keeping the fuel atomized better which of course leads to a better burn. Some also say that they needed to retard the ignition a little to get the best power due to the better burn, making more power because of the better burn and not doing the negative work from lighting the fire as the piston is still moving upwards in compression. Not sure about that yet, haven't built my dyno yet to find out. And retarding ignition on my little race bike requires moving the trigger or flywheel.
Thanks for the explanation guys. I've never heard of that procedure. Read about all kinds of laminar air flow and intakes but no dimples. I'll look that up as I'm going to be stripping a road king motor soon.
A friend of mine uses what he calls, "Surface Turbulence." There are a couple of mods he does but the main one is cutting a stair step on the back of the valves causing an air bearing. The air in the step spins as air rushes by and makes a circular roller to increase flow. Sort of like a pickup will really get better mileage with the tailgate up rather than down.
Posted on Wednesday, February 01, 2017 - 10:31 am:
I looked for some pics but could not find any. You basically put the valve in a lathe and cut roughly 1/32" steps on the radius and then grooves once it flattens out on the back side of the valve. I checked their website but they don't show it. Their engines run cooler and more efficient. I remember seeing a head where they used surface turbulence on two cylinders and left the other two stock. The "ST" was burning clean where the other two showed much more carbon.
Retirement has been great. Finally getting all those projects done that I put off for years! I still have a long way to go though! I have to take a few trips along the way, I mean all work and no play...
I actually had to pull the whole top end off after running it a little bit last week; I found an unfortunate base gasket leak. Worked out for good, as I found the valve pockets were just slightly getting nicked by the intake valves. I checked the valves and heads and they are good, but I'll have to make those pockets even bigger.
I'm waiting to hear the end result and see the dyno #'s. At some point, I'll be looking to do some engine work to my SS or Roadster, and am looking into solutions for combinations that actually work well for the street.
I clayed the pistons and valves when I assembled the motor, and there was over .100" clearance in most every valve to piston critical zone, but I suspect the clay moved and didn't properly interpret the side of the valve to pocket clearance. The motor turned over fine. I revved it quite a bit in the heat cycling to get a feel for the fuel and timing settings, because they are a shot in the dark until I can tune them in. The valve only touched very slightly in some of the higher revs, and never enough to hear it touch. About a .005" nick.
The 883 heads were used as a cost offset measure. The heads got welding and 4 new valve seats, which XB heads would have also gotten, so the finished product and cost of work was indifferent to base heads. Thus the XB heads were sold and replaced with 883 heads as a cost saving measure. It essentially turned $1300 headwork into $1100 headwork.
Some new additions btw, Spiegler brake lines (orange with blue fittings), Brembo P32 2 piston rear caliper, hidden caliper bracket, Lightning clutch cable, Uly throttle cables, and ROX offset risers, to move the handlebars further back to clear the fairing lock to lock.