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Ironhead Cam Performance Opinion

36K views 65 replies 14 participants last post by  Jtw79 
#1 · (Edited)
I have done quite a bit of dyno experimentation using many different cams,carbs,exhaust on my stock 900 and my 4&5/8" stroked 900 as well as others but I will only touch on the above 2 bikes here.

(I have zero stock 1000 experience, but can only assume the same info applies to a stock 1000.)

Let me emphasize all this info is for stock 900's, bigger engines are a different story.

I have come to realize the guys at the factory knew their shiet,
and long before computer technology and digital dyno setups.

I used to think of the stock P cams as just that, stock P cams.
I think it has alot to do w/ the catalogs w/ lists of aftermarket cams, there must be a better, higher performance cam for my bike right? In some performance applications yes I agree.
But think back to days before govt mandates and emissions, what would be the reason for the engine designers, builders to use a sub par camshaft... and these were the days before the screaming chicken (HD performance brand)
I have not tested all the aftermarket cams of course but as of yet I have not found a bolt in cam that performs as well as the stock P in a stock engine.
I will clue you in if I do.....

To elaborate some on the "performance increases" guys feel once a different cam grind (or other performance change) is installed.
This is not meant to point fingers or call anyone a liar of course, just to mention a phenomenon I have felt myself as well.
I have bounced this off of a couple very experienced performance guys as well, they feel the same way.

I am begining to realize this situation; that is when guys install a so called hotrod cam
and the engine now runs with a "different" characteristic or rides with a "different" feeling.
This feeling immediately tells the rider... WoW this is a definite improvement.
But just because it feels different does not alway mean better performance.

Some times also when a cam or exhaust or whatever is changed, in effect they are often (not always) losing power in certain critical crusing rpm.
So your crusing around with less power, but when you twist the throttle to say pass a car, you feel that rush that the "on cam" power gives you.
Any guys that have ridden 2 stroke dirtbikes, know what the "on pipe" feeling is, and this situation of the hotrod cam feels much the same.
It's a total false sence of power that is induced from the flat spot you were crusing around in, even when your bike is tuned as best a DIY'er can.
I have a sneaking suspicion that most all performance cams give this false sence of power, in a 900 that is.

Dont get me wrong, I know there are many improvements that can be made and these are true genuine improvements even w/o a dyno graph, but on these 900's they were close to optimal from the factory.
If you do not have a a before dyno run or ET, and a after to compare them to then do yourself a favor and stick w/ the P cams, because I have the graphs and so far have found no extra power in swapping cams.

Exhaust has been by far the best opportunity I have found for increasing power and torque.

Just what I have learned so far on these dinosaurs if anyone cares.
How many of you think im CRAZY ?????

900 thread: http://xlforum.net/vbportal/forums/showthread.php?t=1222275

Stroker thread: http://xlforum.net/vbportal/forums/showthread.php?t=1265958

2:1 thread: http://xlforum.net/vbportal/forums/showthread.php?t=1367025
 
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#2 ·
No, you are not crazy. Even though I do not do dyno work, i do build a bike or two and a lot of 900's have been through my shop, not to mention my own personal collection. You can make them faster, but a increase in cid is necessary, short of a quarter horse here and there. Pipes, are a better hp booster than carbs or cams. Even a sprocket swap can get you closer to what you desire. Remember, these bikes were built to compete with the british twins that were kicking the K's ass. So they built them to run, and run good. When the big twin guys mess with me, i say, i can beat them to the beer store. They say they can go to California much more comfortable than me. I tell them, how often do you go toCalifornia? And, how many times do you go for beer? Sportsters are fast, in the HD world.
 
#18 ·
Im not so sure any cam will perform better than the P's on my small stroker either.

Check the stroker thread I posted.
You will see the P's are better than the PB+'s, that goes for both the stroker and the stocker.
I have yet to do alot of cam swaps on the stroker.
I ran some Andrews X cams and they did not perform well either (although I never posted runs), too much duration.

My stroker is also only 3' bore, I believe the larger bores of the 1000 may change things some.
 
#9 ·
And makes it able to kick over.
 
#13 ·
Just what I have learned so far on these dinosaurs if anyone cares.
How many of you think im CRAZY ?????
Not Crazy at all Chevelle, you are a street rider that also has Dyno access, the info you are gathering is very interesting, looking forward to the Sifton 'H' cam reveiw..
I had changed my stock P Cams with Harley PB cams and you are correct, it changed the WoW factor (for a 55"er anyway) to further up the scale... an around Town stoplight to stoplite Sportster may be better served with the P .400 cams but dedicate funds on improving head flow with a good Porter..
Hey I remember buying a Lake Injector Carb when I was 21 thinking it's the new best hot setup.. we are all quick to search for the magic bullet only to find that there there are very few..
Monte
 
G
#17 ·
.....Dyno Runs.....

Had the Buell at Daytona Bike Week a few years ago...

Alot of the portable Dyno's was in attendance....

Did a run at Carl's Speed shop...Showed great numbers on the chart....

Same night a few hours later went down to Gilly's Pub in New Symera and did another run....Shoot the number's was higher by 12 Horses .....

Pretty cool, I thought going 20 miles down the road and finding more Horse Power....



.....The Air was Heavy down there......

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#19 ·
So after reading all your findings on XL forum with Dyno graphs I am reluctant to change my cams, but more interested in stroking the motor. Already built a 2-1 with Supertrapp discs in a megaphone pipe. Wish I lived near you so I could see what my motor is doing or not doing on the Dyno. Really like all the info you are posting, keep it up.
 
#22 ·
I set up my stock heads to run some Sifton H cams.
Its back together, but won't be able to run it until tomorrow.
I will let you know what the outcome is.
Cross your fingers.

Hopefully this post won't be deleted.
My last few threads/ posts have disapeared.
 
#21 ·
I have never understood why anyone would want a hot cam in any harley. To me, the entire point of an HD engine, is instant off-idle torque, in an engine that's main attribute, is that it's much happier at lower rpms. To trade one foot pound of that torque, for additional horsepower in a higher rpm range, isn't something I would ever want. I've ridden lots of dirt bikes, and built high winding small block chevys. If you want lots of high rpm horsepower, why would you ever want a harley in the first place. If you like down shifting, get a sport bike.

So no, you're not crazy. I couldn't agree more. If anyone ever issued cams for evo sportsters which created more low-end torque, even at the expense of power over 4.500 rpm, I'd be the first in line to order them. I'd much rather have more torque that's useful where I spend 99 percent of my time in the rpm range.
 
#23 ·
I have never understood why anyone would want a hot cam in any harley. To me, the entire point of an HD engine, is instant off-idle torque, in an engine that's main attribute, is that it's much happier at lower rpms. To trade one foot pound of that torque, for additional horsepower in a higher rpm range, isn't something I would ever want. I've ridden lots of dirt bikes, and built high winding small block chevys. If you want lots of high rpm horsepower, why would you ever want a harley in the first place. If you like down shifting, get a sport bike.

So no, you're not crazy. I couldn't agree more. If anyone ever issued cams for evo sportsters which created more low-end torque, even at the expense of power over 4.500 rpm, I'd be the first in line to order them. I'd much rather have more torque that's useful where I spend 99 percent of my time in the rpm range.
I agree.

High RPM performance cams and drag pipes are for the strip and Bonneville. I want all my power from idle to below 5,000 where I do all my riding. I'm willing to bet I've never spun one of my Sportsters over 5,000 RPM and if I have, it was only for 3 seconds and it was probably because I missed a shift. I want a cam, more precisely, that gives me the power and torque from idle to 3,500 and an exhaust system that helps the engine develop and apply that power all at the low to mid range. To me that means a muffler system. Every dyno graph I've seen with drag pipes has a huge hole somewhere in the off idle to 3,500 range.

With these big cams and drag pipes it just seems that your average street rider is spending money to lose power and torque and gas mileage.
 
#25 ·
I have never understood why anyone would want a hot cam in any harley. To me, the entire point of an HD engine, is instant off-idle torque, in an engine that's main attribute, is that it's much happier at lower rpms. To trade one foot pound of that torque, for additional horsepower in a higher rpm range, isn't something I would ever want. I've ridden lots of dirt bikes, and built high winding small block chevys. If you want lots of high rpm horsepower, why would you ever want a harley in the first place. If you like down shifting, get a sport bike.

So no, you're not crazy. I couldn't agree more. If anyone ever issued cams for evo sportsters which created more low-end torque, even at the expense of power over 4.500 rpm, I'd be the first in line to order them. I'd much rather have more torque that's useful where I spend 99 percent of my time in the rpm range.
Did you look at the dyno results for the exhaust testing he did here? Very interesting.

2:1 thread: http://xlforum.net/vbportal/forums/s....php?t=1367025
 
#24 ·
I just looked through your links. Lots of great info, thanks for posting it.

The most interesting part I thought was the stroker exhaust tests. The 2 into 1 test you did was very impressive. I'd love to see the difference in your 2 into 1 setup and a set of drag pipes. After gaining so much with the 2/1 and the change in the power band, I'm gonna take a serious look at a 2/1 system.
 
#26 ·
I just looked through your links. Lots of great info, thanks for posting it.

The most interesting part I thought was the stroker exhaust tests. The 2 into 1 test you did was very impressive. I'd love to see the difference in your 2 into 1 setup and a set of drag pipes. After gaining so much with the 2/1 and the change in the power band, I'm gonna take a serious look at a 2/1 system.
Glad you enjoyed the info, I will update as I can.
Im w/ you guys, if I can get additional power in the 2000-4000 range, thats what its all about for me.

The 1st 2:1 test I did was on my 4&5/8" stroker w/o muffler.
The 2nd 2:1 test was on my stock 900 w/ 22" supertrapp.
So it seems to work equally well on either bike.
I borrowed the supertrapp from another bike, once I get a dedicated muffler I am going to be doing more some more research and fine tune it.
 
#28 ·
I dont have any dyno results, but when I put this homemade 2-1 with a baffled reverse cone on my 74, along with Andrews R5 cams it really came alive. My heads have big valves, 1.75 and 1.92, and a Branch port job. I look forward to seein how it runs with dual plugs and the roller rockers.
 
#29 ·
Chevelle, could not agree more about P cams.

My story: year 1975, 1969 xlch, 77 cu. in ( 3 1//4 x 4 5/8) , branch heads. very light street bike. no slick, no wheelie bar.

Originally put together w/ Sifton minus -minus cams : et 12.19

sold by andrews on idea for more cam -v9 (i think) felt very fast ,big "hit" @ about 4,000 to 7,000 :et 13.05

go back to basics, stock P cams for a base line. et 11.49

Yes they do work. Learned my lesson about total gross HP vs. peak HP.
 
#31 ·
I don't know if anyone is claiming that Ironheads are great performers, just that the original P cams do exactly what they were supposed to do originally and all the claims about the aftermarket cams fall flat or over cam your Ironhead to the point of being pointless on the street.

Someone made replacement Ironheads years ago but I haven't seen any since and I don't think there's a market for them. The Ironhead heads don't crack and they seem to last forever...plus it's just a girls bike anyway, a stepping stone to a real man's bike. ;)

I also remember someone making late Ironhead aftermarket cases but not anymore.
 
#35 ·
"one guy on here somewhere claimed they could own a Hayabusa"

How was that negative? Because I didn't include all the preconditions?
Sorry for the incomplete reporting, but it simply wasn't the main thrust of my question, which was about repop IH motors.

...and if Jesse doesn't know, they're not out there.
 
G
#36 ·
.

...and if Jesse doesn't know, they're not out there.
Who.....Me...????

==========================================

Guys.... This talk is about cams.

What is best suited for your state of motor build....AND what YOU are after from it...

How are you going to be riding the bike, what rpm are to going to want the most to happen...
A Road Race cam wouldn't be right for a 1/4 drag bike. Or the other way around....

......Choice are many.......

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