Cam Questions

[Mighty Horse]

I've been doing a lot of reading and trying to understand how to pick the right cam for my bike (2007 FLHPI 103" with fishtails). I understand the the first consideration is, what you want to accomplish. For me, I want to make my bike "quicker", better acceleration especially from a stop. But, i dont want to run out of power in the passing range (3200 - 4000). I would like to have enough passing power on the highway to just roll the throttle and not need to downshift. My typical cruising RPM is about 2800-3200 RPM and usually "Potty mouth" gears around 3200. I rarely see 5000+ RPMS. I ride with buddies who have big CI conversions on their softails. I realize my big touring bike with fishtails will never be able to hang with them, especially up top, but I'd like to be able to give them a run for their money off the line and down low. Quick acceleration up to about 80 or 90 MPH would be ideal.

I've read a post/article called "What you need to know about cams". It outlines several cam specs and the ideal range of each to produce good low end/mid range torque. I've spent weeks comparing cam specs, reading reviews and dyno sheets and trying to understand how each spec effects performance. I've even developed an Excel spreadsheet that allows me to compare each cam side by side. There are a few questions that I can't seem to find a good answer to or get straight in my head.

1) Not all cam manufacturers list the RPM range of their cams. I understand that the Intake Valve closing angle is what determines the RPM when the powerband will start. Is there a way to actually calculate the RPM (bottom and top) range for a Cam?

2) I understand that the cam timing can be advanced or retarded which will shift the powerband up or down by 200-300 RPM per degree. Could I expect to lower the RPM range by 800-1200 RPM with a 4 degree advance? Secondly, how do you know when you need to, or should, advance/retard a Cam? Is it done only to move the RPM powerband?

3) Based on the "ideal" ranges quoted in the post/article "What you need to know about cams", I have found only 2 cams that meet that criteria. The Andrews 21H and the Redshift 527-HS. I've also read that the 21H is considered a baby or mouse cam because of the low lift. I've also read about the mouse cam on stilts which made me question the possibility of using increased rocker arm ratios to increase the lift of a cam. I have stock heads and realize that they are limited on how much they will flow. When should changing rocker arms be considered?

4) I have used the following criteria to drill down to the 2 cams mentioned above. This is also the order of importance that I have been using.
- Intake Close (30-38 deg)
- Intake Duration (220-235 deg)
- Overlap (<30 deg)
- LSA (98-103 deg)
- Intake Open (<25 deg)
- Exhaust Open (40-43 deg)
- Exhaust Close (8-12 deg)
- Intake Lobe Centerline (~98 deg)
- Exhaust Lobe Centerline (~112 deg)

My question is, are these the correct "ideal" ranges to use and is this the correct order of importance?

5) I've read a little on changing drive sprockets to gain better acceleration. Should this be a consideration to help if I were to use more of a mid range Cam?

It seems that most people have a favorite cam or know a buddy that's used a cam and really liked it. I would prefer to know what it is about the cam that makes it better than all the others....what is the cam spec that makes it "best" and why? Maybe I'm being too black and white about making a choice, but I feel that engine building is somewhat of a science and certain specs and/or combination of specs will produce and expected outcome. Thank you in advance for your input.

[K4FXD]

The andrews 48 should fit you to a T. Will pull off idle and will pull to the rev limiter.

There are a few others also.

There is no "magic" cam. There is no one spec that makes one better than another.
Some specs are not published like where the lift is at piston 45 degrees ect..

I like Andrews cams, they have the HD's figured out. The Cycle Rama cams are damn good also. I like good running quiet cams.

[Hybredhog]

  Your going into untold hundreds of suggestions, mine being a 48h or S&S 570, the later valve springs give you more lift options, use them. But I do feel that a 21 is probably no better than what you have, and the fish tails aren't helping either. You didn't say if you ride double or "heavy", but your gearing choice makes better use of a 6 speed.

[Mighty Horse]

I read a lot of good reviews on the 48H. I've also been playing with the TW-222 with +4 advance. That seems to bring more of the points into the ideal range. Anyone have experience with the 222 and a +4?

Other cams that I've considered, but don't meet all of the "ideal" range criteria are the TTS 100, S&S 551. Any opinions on these?

[Barrett]

I read a lot of good reviews on the 48H. I've also been playing with the TW-222 with +4 advance. That seems to bring more of the points into the ideal range. Anyone have experience with the 222 and a +4?

Other cams that I've considered, but don't meet all of the "ideal" range criteria are the TTS 100, S&S 551. Any opinions on these?

The Cycle Rama CR570 would be worth lookin at. Check the dyno section.

[Ohio HD]

I also like the 48's they're a good all around set of cams for no head work. A good tune of course brings out the best of any set of cams you do use. I've run the 48's in two different 96" motors, they're really decent. This link is to my '09 that I put them in last summer, and had tuned at Roeder Racing in northern Ohio. They're about 7 hours north of you. J&B Performance is only about 5 hours south of you, they also do excellent work.


http://harleytechtalk.com/htt/index.php?topic=98936.0


https://www.facebook.com/jandbperformance/


https://www.facebook.com/Roeder-Racing-Page-1123744250983143/

[FXDBI]

Brother has a 08 Fat Bob with a 103 and he rides same kind of rpm has you do.  He put in some S&S 583 easy starts and is tickled pink with the results but he doesn't rev past 5000 very often. Lots of cams out there but those fishtails are going to mess the mixture. Maybe one of the tuners can chime in with a cam that works with them. You haven't said which tuner your using or planning on using. Something to also think about because it will need a proper tune.  Has for using a +/- key on a cam you need to look at TDC lift and consider that when doing so or you might have contact problems. If you search the posts here and read you will see a mixed review on changing rocker arm ratios. Go play with the calculator at Big Boyz    http://www.bigboyzheadporting.com/TwinCamComp.htm   this will let you see how they effect the running compression. It will allow you to see what a +/- key does in the mix to ccp. In the calculator section is a cam compare chart that let you look at 3 cams at a time. Bob

[rigidthumper]

Typically, a power band is 2500-3000 RPM wide- so look at torque peak, and go +/- 1250-1500 RPM from that to determine if the cam does what you want when you want it done. If you shift at 4K, don't pay for performance at 5K.
Earlier close cams tend to make torque peak at an earlier RPM, but that can be greatly affected by pipe choice.
Advancing a cam yields ~75-100 RPM shift per degree-so a +4° advance typically shifts the TQ peak ~300-400 RPM sooner- partly due to closing the intake valve 4 degrees sooner, partly by opening the exhaust valve 4° sooner, bleeding off piston pressure, reducing horsepower.
Look at dyno sheets from bikes with cams like: stock Rushmore, TTS100, SE255, CR570, RS525, S&S 551, etc- all of these have an early torque peak, and see which one fits your riding style the closest.

Which fishtails? There's a huge power difference between Samson dual fishtails, Vance and Hines Big Shot Duals Fishtails, and some stock headpipe combo with fishtail style slip-on mufflers.


2007 had the tallest overall gear combo of all the touring models, so that's an acceleration issue- easily fixed by using the drive pulley off of a trike, and the wheel pulley off of a softail, keeping your original belt. You will need to use a flash tuner to correct speedo, and tune the ECM to the new components.

[HD/Wrench]

551 is a great cam .

+4 makes it seem ok for intake but i also moves the ex side sooooo that does not always work out great . Myself not a fan of the woods 222 Heck i would buy a 50 dollar 255 before that as the end results are just too close to say one is FAR better than the next . Andrews 48 is another that is very close to the 255 in power..  having done the back to back testing I can say the andrews 48 does out perform it by a slim margin .

But you are only a  few posts away from being told the 255 is a school bus cam..

In short you take all the cams listed and a few more . Install all of them in that 103 tune and over lay the graphs and the end result is one thick line of runs with not one being a " much better cam " than the others ..

Steve Cole did just that tested our cam Andrews t-man  woods  and a bunch of others the margin between them is all slim . Dont feel that you have the wrong cam and need the right one .  yes you are over thinking it ..  its going to move the power a bit one way or the other . Myself not a +/- 4 degree fan . Time consuming to test and end result may be nothing or a little one way or the other .. 

Just like the rockers i did testing on several cams with stock vs 1.7 rockers  some changed a little others nothing in one case we lost a few.. Riding the bike seat of the pants nothing was better or worse as  increase or decrease was too little to feel. 

Sure you could take this and test each one and add the +4 re test on to the next cam with YOUR set up and find one that makes a touch  more .. If its not +8 lbs of tq you are never going to feel it and more like 10 is the change point in my opinion to where it can be readily felt seat in the pants o-meter..

[Gerry Smith]

My 2 cents worth would be the new Cycle Rama 570 + cam. Derwood could give you some input on these cams.

[Ohio HD]

551 is a great cam .

+4 makes it seem ok for intake but i also moves the ex side sooooo that does not always work out great . Myself not a fan of the woods 222 Heck i would buy a 50 dollar 255 before that as the end results are just too close to say one is FAR better than the next . Andrews 48 is another that is very close to the 255 in power..  having done the back to back testing I can say the andrews 48 does out perform it by a slim margin .

But you are only a  few posts away from being told the 255 is a school bus cam..

In short you take all the cams listed and a few more . Install all of them in that 103 tune and over lay the graphs and the end result is one thick line of runs with not one being a " much better cam " than the others ..

Steve Cole did just that tested our cam Andrews t-man  woods  and a bunch of others the margin between them is all slim . Dont feel that you have the wrong cam and need the right one . yes you are over thinking it ..  its going to move the power a bit one way or the other . Myself not a +/- 4 degree fan . Time consuming to test and end result may be nothing or a little one way or the other .. 

Just like the rockers i did testing on several cams with stock vs 1.7 rockers  some changed a little others nothing in one case we lost a few.. Riding the bike seat of the pants nothing was better or worse as  increase or decrease was too little to feel. 

Sure you could take this and test each one and add the +4 re test on to the next cam with YOUR set up and find one that makes a touch  more .. If its not +8 lbs of tq you are never going to feel it and more like 10 is the change point in my opinion to where it can be readily felt seat in the pants o-meter..

This may be the truest statement there is. There are a lot of good cams for an application like this. All will give satisfactory results. Go with something that isn't high dollar, and that is readily available. As I said, the tune is what goes a long way to make the bike right.

[Mighty Horse]

I ride solo 99% of the time.

Thundermax ECM
Factory47 45" fishtails (Yeah, they're long!).

[Mighty Horse]

I've seen a lot of discussion on the CR-570 II....but it looks really strange when I plug it into my spreadsheet.

Exhaust Open at 0deg BBDC???
Exhaust Close at 50deg ATDC???
64deg of Overlap???
Exhaust Centerline at 65deg BTDC???

Am I reading something wrong or does this combo just work for some strange reason?

[Durwood]

I've seen a lot of discussion on the CR-570 II....but it looks really strange when I plug it into my spreadsheet.

Exhaust Open at 0deg BBDC???
Exhaust Close at 50deg ATDC???
64deg of Overlap???
Exhaust Centerline at 65deg BTDC???

Am I reading something wrong or does this combo just work for some strange reason?

Your posted specs are incorrect, here is the spec list from Cycle-Rama.
[attach=0]

[rigidthumper]

From a tuning standpoint, it may be beneficial to look at the base maps available for your ECM from T-Max- ie; they have a base map for 103/RS525/slip-ons, 103/RS527/slip-ons, 103/RS577/slip-ons, 103/SE255/slip-ons, etc.
Might make the selection easier. 

[Mighty Horse]

Thanks Durwood...looks like the specs I got off the Fuelmoto site were wrong.

[Mighty Horse]

When looking at dyno charts, how much difference should I expect between a Rushmore motor and my 07 103"?

[PoorUB]

The only difference is a few points of compression, maybe 5 HP/5 ftlbs. Which, if you do your heads, makes no difference.

[HD/Wrench]

cam changed in the 14-16 bikes ...but if I where to give you a avg number 85/105

[Hillside Motorcycle]

I've been doing a lot of reading and trying to understand how to pick the right cam for my bike (2007 FLHPI 103" with fishtails). I understand the the first consideration is, what you want to accomplish. For me, I want to make my bike "quicker", better acceleration especially from a stop. But, i dont want to run out of power in the passing range (3200 - 4000). I would like to have enough passing power on the highway to just roll the throttle and not need to downshift. My typical cruising RPM is about 2800-3200 RPM and usually "Potty mouth" gears around 3200. I rarely see 5000+ RPMS. I ride with buddies who have big CI conversions on their softails. I realize my big touring bike with fishtails will never be able to hang with them, especially up top, but I'd like to be able to give them a run for their money off the line and down low. Quick acceleration up to about 80 or 90 MPH would be ideal.

I've read a post/article called "What you need to know about cams". It outlines several cam specs and the ideal range of each to produce good low end/mid range torque. I've spent weeks comparing cam specs, reading reviews and dyno sheets and trying to understand how each spec effects performance. I've even developed an Excel spreadsheet that allows me to compare each cam side by side. There are a few questions that I can't seem to find a good answer to or get straight in my head.

1) Not all cam manufacturers list the RPM range of their cams. I understand that the Intake Valve closing angle is what determines the RPM when the powerband will start. Is there a way to actually calculate the RPM (bottom and top) range for a Cam?

2) I understand that the cam timing can be advanced or retarded which will shift the powerband up or down by 200-300 RPM per degree. Could I expect to lower the RPM range by 800-1200 RPM with a 4 degree advance? Secondly, how do you know when you need to, or should, advance/retard a Cam? Is it done only to move the RPM powerband?

3) Based on the "ideal" ranges quoted in the post/article "What you need to know about cams", I have found only 2 cams that meet that criteria. The Andrews 21H and the Redshift 527-HS. I've also read that the 21H is considered a baby or mouse cam because of the low lift. I've also read about the mouse cam on stilts which made me question the possibility of using increased rocker arm ratios to increase the lift of a cam. I have stock heads and realize that they are limited on how much they will flow. When should changing rocker arms be considered?

4) I have used the following criteria to drill down to the 2 cams mentioned above. This is also the order of importance that I have been using.
- Intake Close (30-38 deg)
- Intake Duration (220-235 deg)
- Overlap (<30 deg)
- LSA (98-103 deg)
- Intake Open (<25 deg)
- Exhaust Open (40-43 deg)
- Exhaust Close (8-12 deg)
- Intake Lobe Centerline (~98 deg)
- Exhaust Lobe Centerline (~112 deg)

My question is, are these the correct "ideal" ranges to use and is this the correct order of importance?

5) I've read a little on changing drive sprockets to gain better acceleration. Should this be a consideration to help if I were to use more of a mid range Cam?

It seems that most people have a favorite cam or know a buddy that's used a cam and really liked it. I would prefer to know what it is about the cam that makes it better than all the others....what is the cam spec that makes it "best" and why? Maybe I'm being too black and white about making a choice, but I feel that engine building is somewhat of a science and certain specs and/or combination of specs will produce and expected outcome. Thank you in advance for your input.

Andrews 48, as already mentioned, will work very well.

[TorQuePimp]

easy answer.....and not to pile on

andrews 48H

$225-$250 shipped

go get it professionally tuned

[Mighty Horse]

Typically, a power band is 2500-3000 RPM wide- so look at torque peak, and go +/- 1250-1500 RPM from that to determine if the cam does what you want when you want it done. If you shift at 4K, don't pay for performance at 5K.
Earlier close cams tend to make torque peak at an earlier RPM, but that can be greatly affected by pipe choice.
Advancing a cam yields ~75-100 RPM shift per degree-so a +4° advance typically shifts the TQ peak ~300-400 RPM sooner- partly due to closing the intake valve 4 degrees sooner, partly by opening the exhaust valve 4° sooner, bleeding off piston pressure, reducing horsepower.
Look at dyno sheets from bikes with cams like: stock Rushmore, TTS100, SE255, CR570, RS525, S&S 551, etc- all of these have an early torque peak, and see which one fits your riding style the closest.

Which fishtails? There's a huge power difference between Samson dual fishtails, Vance and Hines Big Shot Duals Fishtails, and some stock headpipe combo with fishtail style slip-on mufflers.


2007 had the tallest overall gear combo of all the touring models, so that's an acceleration issue- easily fixed by using the drive pulley off of a trike, and the wheel pulley off of a softail, keeping your original belt. You will need to use a flash tuner to correct speedo, and tune the ECM to the new components.

This sounds very interesting. I'm not good with gear ratios, but I assume this would give a lower gear ratio resulting in a feeling of more torque and quicker acceleration. How would this affect RPM's? And should I consider the new RPM range when selecting a cam?

[rigidthumper]

Overall gearing on an 07 is 2.79:1, so you're turning ~2750 RPM @ 75 MPH. With the gearing I suggested, overall gearing goes to 3.067:1, so you're turning ~3000 RPM @ 75 MPH. 3000/2750 = 1.09, or a 9% gearing change- which results in getting through the rev range a little faster- not quite the full 9%, but definitely quicker. 
Here is a gear ratio tool. http://bigboyzheadporting.com/Gearratio.htm
Trans pulley for a trike is 30 tooth, and rear pulley for an 07 softail is 68.

[Mighty Horse]

Thank you for the explination Rigidthumper! This seems like a nice addition to changing cams.

[sfmichael]

replies #7 - rigidthumper and #8 - GMR ...pretty much sum it all up  (2 very smart and experienced guys that do this for a living)

lots of good cams out there that will do what you want - the exhaust choice and the tuning will ultimately have a huge influence on your end result

I don't think he tunes Thundermax but Durwood / Sheffer Performance is 2 hrs from you and can help you immensely. Definitely worth a phone call and/or a visit