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Discussion Starter #1
I was curious what a safe high RPM would be for a stock internals 2011 103 CID engine?
 

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How long do you want to run it there, in what gear and what conditions. Trust me you will not be able to kill a stock 103 in sixth gear, it doesn't have enough power.

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Discussion Starter #4
How long do you want to run it there, in what gear and what conditions. Trust me you will not be able to kill a stock 103 in sixth gear, it doesn't have enough power.

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I have a Power Vision tuner and I reset it to 5800. There has been times when I have hit the rev limiter going through the gears. The bike has a Heavy Breather intake, catless header and Klock Werks WFB slip ons. I have done 3 auto tunes and reflashed the ECM so it runs pretty good. I have a Dragula header coming and I was just wanting to know what was a safe high RPM. Hate to scramble the rotating assembly. :D
 

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I have a Power Vision tuner and I reset it to 5800. There has been times when I have hit the rev limiter going through the gears. The bike has a Heavy Breather intake, catless header and Klock Werks WFB slip ons. I have done 3 auto tunes and reflashed the ECM so it runs pretty good. I have a Dragula header coming and I was just wanting to know what was a safe high RPM. Hate to scramble the rotating assembly. :D
HD stage one download to the stock ECM increases the limit to 6200, since it doesn't do much good to go beyond that I'd say that's a good number. I have a Tmax that allows about anything, have it set at 6100, I think.
 

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Discussion Starter #6
I just did set the high RPM to 5800 today. When I was hitting the rev limiter it was at the factory 5200 or 5400, whichever it was. Eventually I am going to do cams and head work. Don't know if I am ever going to go beyond the 103 displacement but was just concerned with the lower end. I appreciate the information.
 

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mine set at 6200 that's when the 254 cams drop out so no need to set it more.I only bump it a few times like to grab the next gear at 5500 if I am getting with it.
 

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I don't see much point in going past 4500rpm. Doesn't make that much more power. Maybe if I was on it hard I might hit 4800. I think you'd have to rev the bag off of it to get it to pop. I never really looked how fast I was going.

Anyone know how fast you're going at 4500rpm in sixth gear?
 

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Discussion Starter #9
I don't see much point in going past 4500rpm. Doesn't make that much more power. Maybe if I was on it hard I might hit 4800. I think you'd have to rev the bag off of it to get it to pop. I never really looked how fast I was going.

Anyone know how fast you're going at 4500rpm in sixth gear?
I think I was doing around 4000 in 6th at 105.
 

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I rarely twist it that hard and shift around 3500. Probily 4500 if I'm being an ass or racing a buddy. I rode a CBR1000 before the RGU it would do 70mph in 1st and rev up to 11500rpm. So the big old RGU is just a tad different maybe I'm still being nice to it. Haven't hit the rev limiter yet.
 

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Crank it up till it blows.......and then don't don't that again.

Really, 6200 is fine. i wouldn't run it there all day, but fine when running through the gears.
 

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In theory, max reliable piston speed on a properly built engine is about 4500 fps.

4.375 x 2 x 6200 /12 = 4520 fps

So banging the rev limiter with a stock 96", 103" or 110" should be considered as the hairy edge of safe... Certainly wouldn't want to sustain it.

That's math... I've 30k on my 4 5/8 stroker evo and it's banged 7k a few times. That's about 5400 fps... so it should have blown apart. But it still runs like a top. My buddy wildman used to bang the 8k rev limiter every single time he raced anyone, and that was pretty much always... Gotta love the Screachin Beagle ignition modules of days gone past. The math, 5666 fps. At 65k the bike is burning some oil. So it took it's toll. But he rarely lost a race.

Moral of the story, I would worry about a ton of other shit over banging a 6200 rpm limiter.

"I'd rather blow my motor than lose"- wildman
Here's to ya brother. (RIP) <clink>
 

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6200 here with breather decat and 555 cam. Great power, pulling away up to 6200 with no problem. Gotta love cranking it up.
 

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When I was building my 95" in my '02 FLHRCI I had several engine builders and parts suppliers tell me HD cast pistons are reliable to 5500 rpm. If you want to spin a twin cam north of that you should put in forged pistons.

I'm no expert, just passing on what I was told and what worked for me.

The FM107 kit in my 2010 FLHTCU has forged pistons. I noticed Jamie at FM tuned it to 6200 RPM. This may be where the cam is done and / or how much power the pistons can take.

Hope this helps. Good luck.
 

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When I was building my 95" in my '02 FLHRCI I had several engine builders and parts suppliers tell me HD cast pistons are reliable to 5500 rpm. If you want to spin a twin cam north of that you should put in forged pistons.

I'm no expert, just passing on what I was told and what worked for me.

The FM107 kit in my 2010 FLHTCU has forged pistons. I noticed Jamie at FM tuned it to 6200 RPM. This may be where the cam is done and / or how much power the pistons can take.

Hope this helps. Good luck.
Yeah not claiming to an expert neither. I used to spin my TC95" to 7k plenty and over that a few times. I take my stroked evo 4 5/8" (more than current TCs) to 7k without fear. My buddy Wildman HIT the 8k rev limiter. All three of these are running cast pistons. Not recommending doing it, as it's your $$... but the evo was a 4.25 stroke vs a TC88 with 4.00 stroke so should be much more tolerant of high rpm, mathematically speaking.

Everyone sets the default "SE" rev limiter of 6200 unless it's a B motor. I'd guess Jamies set up will easily rev further if you want to. 6200 is the 'safe' max but if you have heads and pipes that flow you can keep makin horsepower well past that. Stock heads will drop off and it's somewhat of a waste of RPM.

Just my opinion as someone who is not afraid to spin these tractor motors.
 

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I have hit the rev limiter on my glide more times than I can count and it still runs like a raped ape
 

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Just like others have said, in reality, with stock cams the "sweet band" of the RPM range is already over before 5400 gets there anyway so go ahead and shift even sooner (most of the time).

The stocker can handle several 100 more RPM if that's what you want... but why? Agreed, sometimes we can be in a situation where we'd rather push her farther without shifting at the true "sweet spot" (when true HP starts dropping off lower that what it would be if we went ahead and shifted). That's cool - don't sweat it. For sure don't sweat it with stock rev-limiter setting.
 
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