Wow, can't believe I haven't seen this thread. Excellent thread and kudos for having the stones to really get into the engine. I did cams last summer, and, even with a whole bunch of things not going quite right, the satisfaction of doing it was immense. Reading this thread has me wanting to go further. Congratulations on your rebuild. Again excellent thread!!!!!

 

Tarik, not sure I could wait as long as you have to lay into it... great thread.

I second cggorman about the breathers. I recently put a HSR42 on mine and did external venting in the process. Definitely smell that venting at stoplights.

-G

 

So, here's a little bit of delayed wrap-up to this thread... My bike's previous owner had the motor built in a couple of versions between '01 and '03, and I have those dyno sheets. The later build was 95", headwork, 10.5:1 (I think), Andrews TW60 cams, Mikuni 42, Cycle Shack M pipes, and SE selectable ignition. Here's that sheet:




Eleven of twelve years later, the bike definitely wasn't making this power anymore, although it ran reliably. It really wasn't a quest for more power that brought on my build, it was really triggered by some pinging that I couldn't get rid of (even with less advance) - likely brought on by carbon deposits, and some increasing oil leaks from the lower rockers. But naturally, if I was going in there I was hoping for more... Quick summary of my build: 97", a little bit more porting (by the same person), 10.5 or 10.8:1 (we talked about head gaskets and shaving, and I don't remember right now what we settled on), S&S 585 cams, RR3, same carb and ignition. Not radically different, but I was hoping for about 110/110. A couple of weeks ago, I trekked out to McNews Automotive in Dillsburg, PA. They were recommended by my motor guy, and they were super knowledgeable and nice to work with. I was a little disappointed with my results initially: 105/108. But I've now spent a lot of time looking at the curves and riding the bike, and it really does work well. Here's the chart:



The red run file is my completely untuned motor, as I built it. I was impressed that ten HP were found in jetting and two more degrees of overall advance! My Mikuni ended up with a 98 needle and a 162 main. I do think there's still some room for improvement... At a very basic level, the old run was done in November, and my new run was done with a 97 degree ambient temperature... That may be a few horses right there. They also had some trouble with some rich spots, brought on by the fact that I'm missing the screw that sets the accelerator pump closure (I'll be ordering a new one). I decided I needed to analyze the two charts together, so I made a little graph in Excel... It's not super detailed, but it's helpful to me. I plotted HP and TQ at 250 RPM increments. The graph just draws straight lines between those increments. I also had to draw (by computer) more incremental lines on the new dyno chart to be able to see what was what accurately. Here's my graph (blue is the new run, green from 2003):



I'm now much meatier in the 3000 - 4000 range, where torque is now over 100 the whole time, and was hardly there at all before. As much as this torque curve is nice, I'm not adverse to RPM and I like HP. I'm wondering whether a Mikuni HSR 45 might not be a better idea than my 42. I'm even a little curious as to what S&S 625s would do in place of the 585s. But this is a very useable power curve (but the TW60s really seemed to come on strong upstairs!).

I think I'll take another shot at it in the fall, with cooler temperatures. I'll have the accelerator pump sorted out, and I've been thinking about a 3.25 air cleaner from R&R Cycle. They make a backing plate for the Mikuni, which would eliminate the disruptive, clunky adapter that's currently behind my old SE setup.

We'll see...

 

Looking at the overlayed graph you made, looks like you made some noticeable improvements. There might be more in it for upper RPM power, but that low/midrange torque curve looks real nice.

 

Yes... As I said, it really runs well and is very nice to ride. After tuning, it also starts and idles better. I used to have to leave the richener on for a mile or so, and now it can usually come off before pulling away from a cold start. It actually feels very flat if I inadvertently ask for anything below 2500, but by three grand all is great.

I am curious how much of that torque curve would go away if I went up in carb size. I'll spend the next month riding it, and think about things more once I really feel that I'm using it properly.

 

The Excel overlay really helps put things in perspective. I do the same thing for comparisons, tho for me it's usually been frequency response or lighting output comparisons. Regardless, it's a good skill/tool to have.

I'll have to check into the R&R filters. I hate that Mikuni adapter.

I'll also be REALLY curious to see how the curve is effected with any future changes you make. I've also wondered about the HSR45. I like how Mikunis tune. It's familiar...similar to Rochesters (without the hateful vacuum secondaries.)

 

T, do you happen to have any video of your bike after the chain issue was sorted and she was all broke in?

My build plan is tracking very closely to yours so far and I'm curious how you would describe the way your engine runs... Idle, throttle response, tq/hp curve "feel", etc. The general character of the engine.

 

Unfortunately, the only recent running video I have is of both bikes taking there final gulps of Sta-Bil before winter. You can hear the Dyna on a fast idle (enrichener on), but it's a little mixed up with the Triumph exhaust. The twin Arrows cans are internally modified a little for a "raspier" sound (one layer of packing removed, and a thin sheet of aluminum wrapped tightly around each perforated tube). But even though, you can kind of hear what the Harley sounds like. While it retains the expected rumble, it has a little bit more treble to it than before. Kind of like a rapid double-bass drum with a raspy staccato overlaid:


As far as overall "character" goes, I would describe it as eager and ready to go from about 2800 rpm up. HP takes over nicely as TQ starts to decline, so it feels pretty seamless from 3000-6000. I've never owned this bike with a stock engine, so I can't really compare it to such. But I would describe it's personality as similar to a SBC with comparable compression, if you know what I mean. You know... That satisfying midrange pull of a good normally aspirated V8 on it's way to redline?

Although I'm not disappointed at all, I continue to think about a bit more carb and cam... But I'm staying focused on the chassis for this round of spending (time and money).

All this is a little intangible, so I hope it's still helpful.

 

No, that's good. Thanks! It may seem odd, but it's the intangible I'm more interested in. I really couldn't care less what my displacement or power numbers end up being. The stock power is actually pretty decent for me. I wish it had maybe 25% more top end power and a choppier idle.

You feel like the engine is "on the cam" at highway speeds?

Sounds like it's pretty eager to rev. Is that fair to say? I'm wanting to keep the short stroke in hopes of creating a higher revving engine. I grew up with short stroke, big bore V8s so that's what seems right to me.

I'm leaning heavily toward a HSR45 but I can't seem to find anybody with a strong opinion or experience. Fair bit of scratch for 3mm...but, like you, can't shake the idea that a bit more carb (and intake manifold) would be a benefit at the top end.

I've started a dialog with Vee-Twin Performance about what he would recommend for me. We'll see what he comes back with.

 

I also prefer bore to stroke, when given the option... Even though low-end tractor torque can be fun, I always prefer something eager to climb the tach. My engine is definitely happy to rev. As far as being "on the cam" goes, I would say yes... But actually the TW60 may have felt a little "cammier" at fast highway speeds. The 585s do exactly what they're supposed to... Fat midrange curve, eager to pull, but not really a "dramatic" cam (if that makes sense). Hence the little voice in the back of my head... But I'm sure I would need more carb if I had more cam. Which would also mean a new manifold, and mine has been port matched. and a new R&R back plate, which aren't cheap...

Also, my gut feeling is that a lot of the personality of my motor (which sounds similar to what you're after) comes from compression as much as cam...