PCIII - can you detune to reduce HP? - Wrist Twisters
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post #1 of 19 Old 08-07-2017, 07:52 AM Thread Starter
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Question PCIII - can you detune to reduce HP?

I have what might be a dumb question, so bear with me. I have a 2007 Honda 919 with a PCIII. I had it dyno tuned years ago for optimum setup.

Now, I have never considered the 919 a starter bike, despite many arguments on here over the years to the contrary. Yes, it's light and handy, but I think it's just too much for a beginner, power wise.

Along comes my son, who now at 20, is really pushing hard to get into motorcycling. (Much to his mother's chagrin, but that's a topic for another thread.) You could see the disappointment on his face when I told him that there's now way your jumping on my 919 to start with!

BUT - what if I could tune way 30 horses - now it starts looking more like a beginner bike.

Is that even possible without injury to the engine?

year? Rickman 125 moto-Xer (Junked)
1974 Yamaha RD350 (sold )
1984 Honda VF500F (sold)
---19 years out of the saddle---
2007 Honda 919
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post #2 of 19 Old 08-07-2017, 08:07 AM
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Yes you can detune the 919 via pc3. But only to a degree. You won't be able to drop 30 horses though.

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post #3 of 19 Old 08-07-2017, 08:25 AM
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You could put on one of those throttle lock things that only let you open the throttle a certain amount.

Your story reminds me of when I started on my fathers 919

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post #4 of 19 Old 08-07-2017, 08:29 AM Thread Starter
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Originally Posted by Pvster View Post
Yes you can detube the 919 via pc3. But only to a degree. You won't be able to drop 30 horses though.
IS there a rev limit function on the PCIII?

year? Rickman 125 moto-Xer (Junked)
1974 Yamaha RD350 (sold )
1984 Honda VF500F (sold)
---19 years out of the saddle---
2007 Honda 919
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post #5 of 19 Old 08-07-2017, 08:32 AM Thread Starter
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Originally Posted by nathanktm View Post
You could put on one of those throttle lock things that only let you open the throttle a certain amount.

Your story reminds me of when I started on my fathers 919
Don't even try talking me out of my position!!

year? Rickman 125 moto-Xer (Junked)
1974 Yamaha RD350 (sold )
1984 Honda VF500F (sold)
---19 years out of the saddle---
2007 Honda 919
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post #6 of 19 Old 08-07-2017, 09:33 AM
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The 919 is pretty easy to handle and control when it comes to power, but I don't think power is really what you should be worried about. Even a 250 is capable of excessive speed for scenarios you would encounter during riding. You can just as easily blow a turn on a 250 vs. a 919 or pretty much most bikes out there. Not even riding on the modest 125cc Honda Grom makes you immune from crashing:

https://youtu.be/-PxCQOoos74

Lightweight, used, and cheap - that's the common advice given and for good reason. I think that all of us have dropped our bikes at some point because we're learning how to balance a 400+ lb machine. Do you want dents and rashes on your 919 or would you rather your son learn the ropes on his own bike that was cheap to purchase, cheap to fix, and lighter weight to help practice?

You're not going to be able to stop him from riding, but why not tell him to buy his own bike? When I was in my early 20's and started riding, my parents sure as hell were against it, but I never looked to them to buy a bike for me. I would love to be able to go riding with my kiddo in the future too and will probably look into kid size dirt riding, but they're going to need to do their own legwork when it comes to the first street bike.

2012 Yamaha Super Tenere
2001 Honda Blackbird
2007 Honda 919



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post #7 of 19 Old 08-07-2017, 09:53 AM
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I'm not sure if the Ignition Module device includes a rev limiter cutoff.
If it does, you could use that to limit the revs.
The PCIIIusb would need an intermediary "Hub" to allow for an Ignition Module to be patched in.
The sequence would be PCIIIusb/Hub/Ignition Module.
All of it would easily fit under the seat.
The Hub and Ignition Module are also DynoJet products designed to expand the Power Commander capabilities.

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post #8 of 19 Old 08-07-2017, 10:07 AM
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Also.
Within the confines of a PCIIIusb you can not properly and safely soften power.
All you can do is excessively lean out or enrichen.
Both cause engine trouble, and too lean will ruin an engine.
Worse yet, for your son that is, all that too lean or too rich does, is make the torque band bumpy and uneven, in other words the bike will be likely very badly jetted carb'ed bike of old with really bad throttle control.
You want the smoothest throttle control for your son, not the worst.
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post #9 of 19 Old 08-07-2017, 10:12 PM
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They make a variable throttle cam thing that smooths out the throttle. I wonder how hard it would be to reduce the travel of the cable. IDK where it hooks into the throttle bodies, but, if you could extend that, you'd make it so that 1/4 turn = 1/8th turn.

In other words, when you twist 1/4, the cable move the throttle plates a certain amount, if you extend that connection point, you'd slow down the response.

I remember when I was riding the 700S, I had to adjust my grip in the twisties because I had to wring it out more. The wrist only moves so much.

The other idea is any rev limiter if the PCIII doesn't have one.

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post #10 of 19 Old 08-08-2017, 12:56 PM
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Quote:
Originally Posted by KarlJay View Post
They make a variable throttle cam thing that smooths out the throttle. I wonder how hard it would be to reduce the travel of the cable. IDK where it hooks into the throttle bodies, but, if you could extend that, you'd make it so that 1/4 turn = 1/8th turn.

In other words, when you twist 1/4, the cable move the throttle plates a certain amount, if you extend that connection point, you'd slow down the response.

I remember when I was riding the 700S, I had to adjust my grip in the twisties because I had to wring it out more. The wrist only moves so much.

The other idea is any rev limiter if the PCIII doesn't have one.
Have one of these for the race bike... Motion pro throttle... Sure takes some getting used to going from nothing to full throttle in a quarter turn... lol
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post #11 of 19 Old 08-08-2017, 01:16 PM
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Just remove a couple spark plugs and turn it into a twin...
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post #12 of 19 Old 08-08-2017, 01:44 PM
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Quote:
Originally Posted by badmoon692008 View Post
Have one of these for the race bike... Motion pro throttle... Sure takes some getting used to going from nothing to full throttle in a quarter turn... lol
I've gotten used to feathering the clutch on take off, but it would be nice to have something that's adjustable for the jumpy start.

I built a 428CJ for a truck, everything was setup for low end and it was a bear to drive on the street. I'd start off in 2nd and it would just jump as soon as you tapped the gas. I had to change the carb to make it drivable.

I saw the motion pro, but I think that you could simply add a bit to the lever where the cable attaches, but the motion pro could have one device that you can change just by moving the cams in side. Basically, it's just a cable on a cam, you can make a custom cam profile by changing shims or something.

Custom car throttles have adjustable length ball attachments, it wouldn't be that hard to have that on a bike.

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post #13 of 19 Old 08-09-2017, 07:50 AM
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Quote:
Originally Posted by KarlJay View Post
I've gotten used to feathering the clutch on take off, but it would be nice to have something that's adjustable for the jumpy start.

I built a 428CJ for a truck, everything was setup for low end and it was a bear to drive on the street. I'd start off in 2nd and it would just jump as soon as you tapped the gas. I had to change the carb to make it drivable.

I saw the motion pro, but I think that you could simply add a bit to the lever where the cable attaches, but the motion pro could have one device that you can change just by moving the cams in side. Basically, it's just a cable on a cam, you can make a custom cam profile by changing shims or something.

Custom car throttles have adjustable length ball attachments, it wouldn't be that hard to have that on a bike.
Yea, the motion pro has like 7 different "reels" some of constant diameter, and then a couple that are progressive so the initial turn is slow (relative to the larger reels) but progressively becomes faster as the throttle is turned, the idea being that you get smooth initial throttle application while still being able to quickly get to full throttle.

I think the easiest way to implement this on a 919 would be to buy the motion pro throttle kit, and then either modify one of the reels to be smaller, or create your own (which wouldn't be super difficult) you could theoretically make it so you'd have to spin the throttle 350 ish degrees to get full throttle, which would be basically impossible, effectively limiting power output. Similarly, you could add an adjustable stop with some minor modifications to completely lock out the higher throttle applications.

Love is the feeling you get when you like something as much as your motorcycle - Hunter S. Thompson
I just mı̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̸̨ade you wipe your screen.
-2009 Suzuki GSX-R 750 Race Bike
-2007 Honda 919
-1995 Nighthawk 750 (Tboned)
-1983 KZ 440 (Sold)
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post #14 of 19 Old 08-09-2017, 09:04 AM
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Quote:
Originally Posted by badmoon692008 View Post
Yea, the motion pro has like 7 different "reels" some of constant diameter, and then a couple that are progressive so the initial turn is slow (relative to the larger reels) but progressively becomes faster as the throttle is turned, the idea being that you get smooth initial throttle application while still being able to quickly get to full throttle.

I think the easiest way to implement this on a 919 would be to buy the motion pro throttle kit, and then either modify one of the reels to be smaller, or create your own (which wouldn't be super difficult) you could theoretically make it so you'd have to spin the throttle 350 ish degrees to get full throttle, which would be basically impossible, effectively limiting power output. Similarly, you could add an adjustable stop with some minor modifications to completely lock out the higher throttle applications.
That sounds like the best plan. It's a known product that works.

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post #15 of 19 Old 08-09-2017, 10:41 AM
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Or.........................
Put a mechanical stop on the pull to open run of cable.
So the stop butts up against the mounting tube end down near the bale on the TP assembly.
Take a small nut and bolt.
Slot the bolt threaded portion just enough for the cable to be able to slip into it.
(One could easily do the slotting with a hacksaw)
Fit on the nut.
Slide along the cable to where you want a throttle stop to be.
Nip up the nut, enough to hold it but not so much as to ruin the cable.
Voila!
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post #16 of 19 Old 08-09-2017, 03:14 PM
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I think mcromo' s approach is better, other than a different bike. The last thing you want to do is muck with throttle cam changes that teaches bad habits and little to no throttle control to a new rider. Not to mention is something goes wrong with the cam custom modifications, a new rider wouldn't know something was wrong and needed to manually close the throttle. That is a bad combination to have.

Don't teach a new rider bad throttle control habits for the next bike. Throttle stop or a different bike.

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post #17 of 19 Old 08-09-2017, 04:12 PM
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You could just swap the front and rear sprockets
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post #18 of 19 Old 08-10-2017, 09:02 AM
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Quote:
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You could just swap the front and rear sprockets
I Love it. But the fun factor would drop significantly lol.

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post #19 of 19 Old 08-10-2017, 10:25 AM
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Quote:
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I Love it. But the fun factor would drop significantly lol.
If you get enough of a running start... Just think about the top speed. We could get one of those high speed vacuum chamber things...

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