octane and advance curves - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 9 (permalink) Old 05-07-2011, 09:53 PM Thread Starter
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octane and advance curves

So now that I have this fancy Ignitech ignition module that lets me set the advance curve I got to thinking....which sometimes leads to trouble.....but anyway, I was wondering if I can squeeze more power out of the Vulcan using higher octane fuel and changing the advance curve?
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post #2 of 9 (permalink) Old 05-08-2011, 04:20 AM
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In theory you should get more torque and power by advancing the ignition, but I suspect that the improvement is not much. And it is hard to verify with just the 'butt' sensor.

But if you are willing to experiment, I'm sure we all are interested to hear the results. Just keep in mind that if you have too much advance, the engine will knock.
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post #3 of 9 (permalink) Old 05-08-2011, 07:48 AM
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Quote:
Originally Posted by dariv View Post
So now that I have this fancy Ignitech ignition module that lets me set the advance curve I got to thinking....which sometimes leads to trouble.....but anyway, I was wondering if I can squeeze more power out of the Vulcan using higher octane fuel and changing the advance curve?
Don't mess with Ma Kaw. Stock bike is pretty good. LOL

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post #4 of 9 (permalink) Old 05-08-2011, 09:33 AM
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I haven't sprung for the TCPI4 yet, but I can give you some indication from doing a crude advance on the pickup coils. I used the same technique as setting them closer, filing not only the lateral but the vertical edges of the mounting holes. Moving the timing just 3 degrees will get you into trouble off-idle and up to about 1500 rpms. By that I mean it immediately requires premium to prevent serious knock. There is no increase in torque, but, the engine comes alive much sooner, around 5500 instead of 6500, and it pulls significantly better above 7500. Looking at the curves for other bikes with similar strokes and cam timings, my guess would be there's a little more to be gained if you advance 2-3 more degrees beyond that between 7500-9000 (yes, Veronica, the VN will spin there easily). But I would be very cautious of bringing in any more than 4 degrees advance below 5000. And yes, rejet.
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post #5 of 9 (permalink) Old 05-08-2011, 11:41 AM Thread Starter
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The TCIP4 comes with an advance curve like this:



It starts out at 10deg. and tops out at 35deg. The bike seems a bit "boggy" so I went looking on the internet and found a DYNA2000 ignition unit that show the stock Vulcan 750 advance curve should look like this:



This curve starts out at 5deg. and tops out at 30deg. I've reprogrammed the TCIP4 with this curve and am going to go out and do some testing. I have a full tank of 87 octane (10% eth.) once it's gone I'm going to try one of the more aggressive curves from the DYNA2000 website with premium gas and see what happens.
The bike has been re-jetted when I did the ear shave and V&H cruzers. I recently installed baffles from Smartpartz and *I think* the added back pressure may be part of the "boggy" feeling.
Your thoughts/suggestions??
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post #6 of 9 (permalink) Old 05-08-2011, 05:37 PM
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It's pretty clear that the a) the "as shipped" curve of the TCPI4 is pretty lazy. Undoubtedly they don't want people detonating engines right out of the box. b) the stock Kaw curve isn't exactly as graphed...I've put mine on a 'scope and inductive light, and if I were to try and graph it, would look more like two straight lines with an intermediate point at around 6000 or so. But, you'll notice that the as shipped TCPI4 curve is about 3 degrees more advanced when full in. What I would shoot for is a) set the initial advance about 3 degrees advance from the stock VN, b) set an intermediate of 25 degrees @ 2000-2200 c)set another intermediate @ 30 degrees around 3200-3500 d) set another intermediate of 34 degrees around 4500 and d) set an "all in" advance fo about 37 degrees @5500. What you should experience is a far more consistent pull without any loss in the bottom end. If there is a bog right off idle, like trying to do a torque pull from dead stop, then back off the initial advance. After that, it's all about trial and error. Personally, before I started any of this, I'd drain the tank and carbs and use the fuel in my lawnmower...start with all things consistent as possible.
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post #7 of 9 (permalink) Old 05-08-2011, 09:21 PM Thread Starter
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post #8 of 9 (permalink) Old 05-08-2011, 09:38 PM
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There is an old tuners saying that goes .. "There is no replacement for displacement" .

Even a 10% increase in hp on this bike is only 6-7 hp more over stock. No offense, just seems like a waste of time and money.

On the other hand, Pour some money into a VTX and you can feel the difference even if your ass is numb. ( seat of the pants dynos)

Most major changes to the Vulcan other that jetting air intake and exhaust to find more power just make a less dependable ride IMHO.

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post #9 of 9 (permalink) Old 05-09-2011, 12:58 PM Thread Starter
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Quote:
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...No offense, just seems like a waste of time and money...
KM
None taken......... I just need an excuse to tinker with the TCIP4
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