I'm doing cams in my 03 Ultra this spring and I've narrowed it down to these 2. I've seen lots of posts recommending these but very little about what the real world difference is. The numbers are quite different for cams that basically have the same stated goal.

I put in new Cyco tensioner shoes, bearings and a Daytona pump last spring. I'm running a stock headpipe, stage 1 breather and Khrome Werks slip ons with a PV. I have a base map from Dynojet for the 509 but I'm sure they'd have one for the 21 as well.

Hypothetically, if I ran these back to back, what would I see/feel/hear?

 

We prefer the 21's here, as our go-to plug/play in 88"ers.
They work very well indeed.
Have never taken the much needed time, to perform back/back same day testing/tuning of those 2.
Scott

 

Thanks. I know you build a lot of these and have used both. What makes you recommend the 21 over the 509, noise, longevity, easy starting, heat, fuel economy, area under the curve or some combination of these?

I'm just really curious about how they each make power. Everyone always says that an early intake close makes quick torque, which should give the win to the 509 but other than the 551 I've never seen an intake close that early. Everyone who has either of these seems to like them but they just look so radically different, on paper, that I feel like I'm missing something.

 

I have the Andrews 21 and like it. The power comes in early where you need it on a bagger. Here are the #'s for both, pretty close really

ANDREWS 21 10 30 40 8 220 228 100 106 0.498 0.498 0.134 0.121

S&S 509 18 18 46 11 216 237 90 107.5 0.500 0.500 0.156 0.133

 

Is the 21 suitable for a 95-98" build down the road as long as compression is kept in check?

 

Yes, but if head work is part of the plan, there are many more suitable choices.

 

+1

 

I like the 509 for two up riding and the 21 for solo. It's been a while since I rode a bike with the 21 cam installed but I definitely remember how much better the engine ran over stock. I installed a set of 509 cams in my friends heritage last year because his riding style is mostly two up on back roads, hills and mountains. He is very happy with the results but to be honest I tried to get him to go all out to a 98" with head work and a 37 cam but he didn't bite. Both are great choices.

 

Question: Hypothetically, if I ran these back to back, what would I see/feel/hear? I think the 21 cams carry a little better to the right when accelerating but I only installed and them in a fatboy, night train and soft tail standard.

 

We're usually 2up, mostly back roads, 50 to 60 mph. There are some higher speed highway runs up to around 80mph. I find that at slower speeds the bike is ok but pulling out to pass, uphill stretches and merging, especially on one uphill ramp we have near the house, the bike just doesn't have enough power to get the job done. Passing on 2 lane roads definitely requires careful planning.