Here's the deal in a nutshell
2009 FLTR
96"/PM Super Gas A/C, Andrews 37 cams, SE Pro Tuner, OEM head pipes and Kerker Slip ons with glass packing removed, tapered tips.

I had this bike tuned and tweaked once afterwards, by someone I consider a rather competent tuner/mechanic. It ran GREAT, until the cam install. Since then it has 'hesitated' from launch, sort of a lull before the throttle picks up. Had it back and tweaked once, seemed a little better but not where I think it ought to be. When you release the clutch, it 'stumbles' up to 2200, then comes alive. The dyno sheet reveals no cut off or valley anywhere.
What I want to know , before I throw good money after bad, is:
1.Change exhaust , maybe 2 into 1?(the slip ons I have are good but have back pressure designed for a basically stock engine)
2. Maybe I have the wrong cams for my riding style ( I am a low rpm cruiser/highway rider) I really want some power in the 1000 to 2500 range
3. Maybe the tune is just not right? Seems like more of a throttle problem than a running issue (I am no expert!)...
For those of you that say exhaust, D&D is probably NOT an option for me, they are way too loud for my taste. I am really looking for some direction here, but all responses are welcomed!

 

My guess would be in the tune. I had the 37's in my last bike with Rinehart tru duals, V&H Dresser Duals w/ Supertrapp mufflers and finally with a D&D Fatcat. I never had a stumble, always ran smooth. TTS MasterTune.

I did dump the cams because they came on later than I wanted, somewhere around 2500/2700 rpms. Pulled like a sumbeach from 3000.

 

Unfortunately there is probably not one single component you can point to. It's most likely a combination of the cams, pipes, and tune.

The 37's are a good cam, but not known for off idle power like some earlier closing cams are. You could have some reversion issues that are beyond your tuners capability to be tuned out.

If your going to swap parts given your riding description, I would say a set of either SE255's or maybe something like the Headquarters 525 and a good 2-1. Supertrapp is probably going to give you the quietest power.

Couple those changes with a good tune and you should be much happier.

JMO
Zach

 

Mike the 37 cam is a good cam but needs a little more comp to bring it on like gain busters in the bottom range, but with that said a good tune will work wonders, I put in 204's in my 2010 FLHX and they have great bottom end but they had to tweak the tune, 204's have a 34 intake closing to 38 on the 37's, my freind has a 07 flhx with 37's and we hit it off and I pulled him quiet a bit going through the gears, he has rineharts tru duals and I have the V&H's power duals with the 4.5" twin slash ovals, these pipes have the power chamber in them and seem to be pretty good, I made 90hp and 101tq, like I said though a good tuner should be able to get the stumble out of the bike but lugging it want help the issue but I ride in the 2000 to 3000 rpm range, if it does good there and gets decent gas mileage then I'm happy.

 

I would think it could be the slip on's and the tune. How much time was spent working the lower throttle positions? Here is some 37' in an 88" with the fatcat. Fat cat definately helped on the bottom but you have good gearing and 96". The lower throttle positions on this took a long time but customer is happy with how it pulls.

 

By "stumbles to 2200" do you mean that it feels like there is nothing there and then takes off? Kinda sounds like its hitting the rev limiter and then lets go?

If thats the case its REALLY lean 1700-2200, either have the wrong cal for the cam or the tuner just didnt get it roght in that RPM range.

If your set on wanting to lug the Hell out of it (1000-2500) then Zach is right about the 255/525 cams, better choice than the 37's for you.

 

Thanks for your response. I don't lug the engine, I am talking specifically about launch from a dead stop. If you do not rev the bike to 2000~2500 coming off a stop, it chugs and hesitates. I am wondering if I got the cam, pipes or both wrong. When it was Stage I and tuned, before the cam and retune, you could release the clutch while applying throttle and ease away. Cannot do that anymore, its all or nothing.

 

OK that was giving you some crap but what about these two descriptions?

 

OK maybe 'stumbles' is a bad descriptive word. I realize it is impossible to diagnose a problem like this without actually seeing and riding the bike. Best I can describe it is like when you're at a stop. Idle is fine, if you begin to release the clutch without enough throttle, it will stall . If you give it a little throttle, it will launch but hesitate until it reaches about 2200, then it pulls fine. If you rev it to 2200~2500 and release, it takes off...Maybe I am riding it wrong for the cam? If that it the case, this is definitely the WRONG cam for me. It is almost impossible to ride at slow speeds without giving it throttle.

 

That sounds like its LEAN in the 1700- 2200 range. Ive come across that a few times on various cams that are more intended for high RPM, it takes a ton of fuel in that area to get past it then the demand drops way off at 2500.