Our Shop Mule '94 Sportster 1200 w/our draw-thru turbo setup on 9psi on an otherwise stock engine. Needs more valve spring! Couldn't continue any further due to how bad the valve float was. The pulls were done in 4th gear, add +5% for 5th gear numbers. I believe with only a set of beehive's it will put down at least 90/90 and pull all the way to 7k even with the stock D cam. We're going back to the dyno after we get some new springs put in, and then after that were going to be testing a healthy set of cams. This bike has been turbocharged for 14,000 miles, who knows how many pulls I've put this thing through. I'm looking forward to retiring it from daily riding duties; I sold my car 2 years ago after I finished building this bike and it's what I use to get around everywhere

 

The more I looked at the graph, the less the valve float theory made sense. When you lose control of the valvetrain, you don't get it back. So the power coming in and out kind of rules out valve float, especially after looking at run 003 and seeing the dips at the top end. So what would cause the bike to misfire, mostly at high RPM, and only under high load?

Spark Blowout! Spark blowout is a bit of a misnomer; it's the spark plug's inability to jump the gap due to cylinder pressure. I was running the as-delivered .035" gap on the plugs....apparently I totally forgot to gap them down when I swapped them out at the last oil change. So a new dyno test is in order with the gap closed up to .024". I think at least 90whp is in the cards on 9psi with no other changes....with the D cam and stock '95 1200 heads!

We're breaking 100whp on the next dyno test. I'm going to be putting a manual boost controller on the bike and I'll do a run or two on 9psi, and when we have the numbers for that, the boost is going up to 12-13psi. It's going to be on c12 race gas this time

 

67,000 Mile, Turbo Buell PSiclone on 9psi boost, pump 91 - 106whp! Wasn't even a full dyno tune session, just a few pulls with 1 minor adjustment. There's 10whp left in the tuneup without a doubt, on the same boost level. As a reminder - 1998 Buell M2's did NOT have Thunderstorm heads, M2's didn't get them until 1999. The M2's also still had D cams; other than a smaller 62cc combustion chamber, the heads are the same as every other 90's sportster 1200. They are 10:1 vs. 9:1 compression, but that has to be offset by running a more gentle ignition curve on pump gas, so it ends up being a wash IMO.

If you look closely, you can see there's a stumble around 5,500 - it was the adjustable power jet we are using adding too much fuel - the AFR's went into the low 10's, and settled at mid to high 10's, which is obviously wayyy too rich. This is why the power takes a dive at that point. We were testing an alternate Powerjet supplied by a company that said there's was better than the one on our sportster kit; that was not the case. This bike will be getting the better powerjet installed, which will cure this really fat spot - and probably have it crest 110-115whp......on what is essentially a 90's sportster motor!

 

Here is my aging dyno sheet. For my bought new '13 Custom. ...Hammer work done in '13. I had an odd mix of parts, where maybe I could of done better for improved numbers.
But its very strong as is. NRHS Stage I heads 10.2:1 compression (stock pistons), N4 cams, Hammer intake, Patriot Defender exhaust which IMO make the whole thing work well. Well regarded header. Heads are key too.
Couldn't quite get to 100 hp and the stock clutch is worn & losing grab atm. Its does run like a champ though ...right now. ;-)
I shoulda gone all Hammer, but it was early in my knowledge base.
Looking maybe to up the power again...