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Discussion Starter · #1 ·
Hi Kidz,

Okay, I just made a couple runs at the dyno with me thruxton, now fitted with early 790 cams...nark, d&d pipes, stock carbs (148 mains, 1- 0.020" shim, 42 pilots). Sorry the attached needs to be rotated to view...

The blue run is the 865 cams w/ procom ignitor (last fall)

The red run is the 790 cams w/ procom ignitor (today)

The purple run is 790 cams w/ pieman modified ignitor (today)

On the runs, ignore the stuff below 3000 or 3500 rpms, since Scott the dyno man figured out that the CV carbs like to be whacked open instead of rolled on like he did for the first (red) run....

So...the end result of adding just early 790 cams amounted to an extra 4 ft. lbs of torque down low, no more severe of a torque dip in the middle, and a nice 5 hp jump up top.

The pieman ignitor mod adds a solid 2 hp from 5,700 until 7,300 - at which point it makes 1 hp more until redline. It also appears to add about a 2 ft-lb boost down low. The latter is probably due to being able to retain the TPS/low rpm ignitor map, which the procom doesn't offer...

67 rwhp / 55 ft-lbs and counting. I know there is a bit more power hiding in the jetting since Scott the dyno man said the bike was a tad rich on the needle (mains were spot on), but that will have to wait for another lifetime.

Fitting the CR carbs I have waiting in the wings is next...

Cheers,

--Rich
 

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Discussion Starter · #3 ·
cool! That's similar to what I picked up with the 790 cams.
What floors me is that I not only picked up HP up top, but ft-lbs down low...totally contrary to what I expected on the torque curve at the low end.

To say it has transformed the bike is an understatement...
 

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What floors me is that I not only picked up HP up top, but ft-lbs down low...totally contrary to what I expected on the torque curve at the low end.

To say it has transformed the bike is an understatement...
oh yeah, the 790 cams just work better. I could really tell a difference and it made the bike much more enjoyable to ride. Some people might scoff at 5hp, but that's almost 10% gain on a 60hp bike!
 

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Discussion Starter · #6 ·
Nice one Rich, some good figures there. I bet she's a joy to ride.
She is. I'm not real anxious to fiddle any more with the motor for a bit and want to just enjoy her new personality for a time. Well, I may try a slimmer / no shim on the needle since I'm a bit rich in the midrange, but nothing else. I need to get her suspension tuned first, though, since I've added emulators up front & haven't gotten them quite where I want them yet...

Your ignitor reprogram did the trick to the tune of 1-2 HP / 2 extra ft-lbs and is a excellent compliment to the other modifications. Thanks Mike.

Cheers,

--Rich
 

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Is there any long-term danger to the engine due to the 790 cams? Why are the new cams so weak? Emission regulations?
 

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Decker-

i am in no way an expert on the topic, but from what i have learning from the pros on this site is over the years triumph has been putting in wearker and weaker cam profiles, mostly due to stricter emissions regulations.

in another three months i will be getting the first half of a sign-on bonus for a new job i started recently, and have seriously been considering pulling the trigger on some TPUSA cams and FCR's. will most likely do the FCR's first, then drop in the cams later.

definately cool to see that the 790 cams are legit. just wondering how they compare to the TPUSA cams...
 

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Discussion Starter · #9 ·
Is there any long-term danger to the engine due to the 790 cams? Why are the new cams so weak? Emission regulations?
No danger...there's 790 motors with over 100K miles on them that run these and plenty of folks have gone to them to wake up their 865s...

And, yes, emissions is the likely reason for the mild 865 cam...
 

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Discussion Starter · #10 ·
definately cool to see that the 790 cams are legit. just wondering how they compare to the TPUSA cams...
Sweat is planning on doing back to back runs using the 813 cams vs. the 790 cams he currently has in his motor. *That* will be some useful data...

--Rich
 

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i just spoke to carlos at TPUSA, and was told that i would gain 5hp at the rear wheel with the 813 cams, and another 5hp at the rear wheel with the FCR's. that's quite a jump in hp from the 64-65hp i get now. he told me that i just need to hold on with that set up because the front wheel will definately come off the ground!
 

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Great info Rich, nicely presented, and great job!

Sbpark - you KNOW you want those. You got a new job - now go get the reward! :D
 

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i just spoke to carlos at TPUSA, and was told that i would gain 5hp at the rear wheel with the 813 cams, and another 5hp at the rear wheel with the FCR's. that's quite a jump in hp from the 64-65hp i get now. he told me that i just need to hold on with that set up because the front wheel will definately come off the ground!
DO it!! Hey, sb... I hear you can get about 9hp (over stock) with the D&D 2 into 1 race setup. Man... you're gonna need wheely bars!

AFAIK, the D&D 2/1 only comes in black...someone correct me if I'm wrong. I'd go for a chrome setup for that much extra power. Of course, it's comparing to stock restrictive mufflers.

If you already have more open canisters on stock headers, I would "only" expect about a 5 hp increase at redline. Here's a link to their dyno test, and note the peak rpm:

http://www.bellacorse.com/bce066.htm

If they put some bigger carbs on that test bike and ran it to 8000-8200 rpm I think that HP line would keep climbing and not flatten out like it does. Looks like it could approach ~80 rwhp on 865cc's. A 904 kit would add some extra hp too...

Hmmm, how much are those cams anyway...and why are they called 813's?

Cheers!
BLIGHT
 

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i am not a fan of the way the 2 into 1 set-ups look. i am into my predators too much!
 

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I found out that the 813 cams are bad ass in the upper rpm range last sat.I been being kinda easy on the new 904 motor .It felt pretty good up to the 7500 rpms i had been trying to hold it to till i got some miles on it.I had to see what it would do upstairs in the rpms.I turned it loose at 4000 rpm wot the tach went out of sight I pulled 2nd gear wot .Thats when i got the suprise it didnt just pick the wheel up it held it up allmost all the way through 2nd gear.I was like wow a 904 shouldnt do that.It hits the procom rev limit like you turned off a switch it was still pulling hard.The 790 cams pull good alittle past 8000 rpm .I bet these cams will go close to 9000 rpm.
cams mean alot in these motors as we are all learning.
beemerrich thats some good numbers man .
 

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nice.
From that, I assume your a convert.
Carlos, is a nice guy and TPUSA really does got the good dope.
Straight and uncut.

glad it's woking for you cause you done been there and done that way too much. :)
 

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Discussion Starter · #19 ·
"beemerrich thats some good numbers man ."

Mike...that means a lot coming from a guy with the credentials. I'm pleased as punch with the torque the cam made...I really was expecting to lose some down low to get the HP up top. I'm shelving the 17 tooth sprocket for now & keeping my 18 tooth in place...

Overall, the 790 seems like a pretty good cam for the 865 crew who are running stock pistons & carbs...the 813 may do it a bit better, though, but I'll have to wait for another rider to step up with that information. For now, I just need to ride this thing...spring was too long in coming.

Cheers,

--Rich
 

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Thanks Rich for the report.
I need to get me some cams. :)
Ride safe and Congrats,
George

PS: Rich...quick question please. Do you feel fitting the more aggressive 790 cams warrants a change in A/F ratio...i.e. richer jetting? Thanks.
 
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