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Old 31st December 2010, 21:10   #31
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Default Re: Harley knocking - Help needed

Sorry to bump up an old thread, but didnt feel like creating a new one.

Never did get any reply from HD, and I'm not holding my breath anymore.

After several trips with jerry cans of Speed97 stinking up the car, and octane boosters not really working as desired, I have finally found a solution to my knocking problem.

After the introduction of BSIV in metros, I doubt any Harley owner in metros are facing this problem. But for Tier II and smaller towns, this problem still exists.

The solution? Reliance Petrol.

Due to the fact that Reliance has only one source of Petrol for all their retailers, Reliance pumps even in small towns are selling BSIV fuel.

Ever since I started using Reliance fuel, the knocking seems to have gone away. I have switched back to Speed93 just to experiment, and sure enough, the knocking comes back.

I thought I would share this bit of information to any/all HD or SBK riders in smaller towns who might have been facing this problem.

@Mods, you can edit title and/or close the thread as I have found a solution.
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Old 1st January 2011, 11:04   #32
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Default Re: Harley knocking - Help needed

Knocking is very, very, bad and you need to fix this. Presuming that the engine is not overheating, it is either not enough fuel or crappy fuel. BTW you need to fit an oil cooler and run fully synthetic oil to deal with the heat issue but that is another subject.

The compression ratio numbers being kicked around are static and it is the dynamic ratios (DCR) that determines the fuel octane requirement. To calculate this you will need to know valve timing. Here is a simple way:
Wallace Racing: Dynamic Compression Ratio Calculator

Once you know your DCR, then calculate the octane requirement by:
10 (multiplier) - DCR = X
X + 10 = Y
Y x DCR = Octane requirement in RON

Seemingly yours is a too low octane problem, however the other possibility is that the engine is not getting sufficient fuel. This could be a result of running too lean in order to pass emission requirements, or you have changed the aircleaner or exhaust resulting in a lean mixture. Contrary to what you are told, the factory ECU is calibrated to meet strict emission requirements with the stock filter and exhaust. Changing one/both of these items results in a lean condition for which the factory ECU cannot compensate, while delivering any measure of performance. There is no way around this problem and once you start on the road to a better intake and exhaust you must buy the ECU a the same time.

Do not waste your money on the factory ECU solutions and go straight to the aftermarket. While a PC is a popular choice is is not necessarily the only choice, and you may want to look at something like Zippers Thundermax with Autotune. Whatever ECU you choose, be sure that it has an autotune function and knock sensor, that can dynamically remap the ignition curve in relation to load, fuel quality, state of tune, and rider input.
This autotune function will get you around the need to dyno tune the engine as it will dynamically alter the fuel and ignition curves to optimize performance. Sure a dyno is nice but you (and I) do not have that luxury so this is the best way around the problem.
Needless to say, fuel consumption comes secondary to peformance and you cannot have both.

There are similar ignition only, boxes with auto tune and a knowck sensor for carbed bikes and I have been using the S&S "Intelligent Ingition" box for several years.

One additional advantage of the autotune type, non-HD ECU is that it can adjust as you change intake, exhaust, cams, compression, fuel, altitude etc. No more dyno runs every time you change something.

The plug suggestions to cure the knocking are uninformed, however you should see a 1 Hp increase using an Iridium plug - I like the NGK's
Index the gap facing the intake valve.

There are larger Sportster tanks from either HD or the aftermarket, and most riders end up buying one as the small tank is far too small and leaves a lot to be desired.
Remember that the expensive bike you just bought is only a starter kit and now you have the opportunity to spend even more money to make it perform like the factory could not.

I am also a Bullet owner, and have owned, ridden, raced, and wrenched HD's for 40 years. Please PM me if you have any other questions as I am happy to help in any way that I can.
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Old 2nd January 2011, 05:25   #33
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Default Re: Harley knocking - Help needed

Hey HogHead,

Thanks for your reply. I was also under the impression that I would need an ECM remap or aftermarket box like the PC to fix my problem, but I am really surprised myself at the way the bike has been responding to Reliance petrol.

I have only added the SE air filter as an upgrade for now, and havent yet gone the whole "hog" as far as performance upgrades are concerned.

My main concern is the lack of support and spares. Its not like I can run to the nearest bike shop in the middle of an upgrade to get some missing parts and/or replace something I might break in the process.

A Zippers Thundermax for the Sportster costs like $900 (without shipping), and to be honest, I dont know if its worth the cost at this stage.

I really do appreciate the offer, and might take you up on it when I get to that stage. I am waiting for the SBK market in India to mature as well so that performance mods can be more accessible to all.

Fingers crossed, but for now the bike is running good, and is fast enough for the roads in my neck of the woods. When the urge for more speed arises, I just jump on the Honda CB1KR and go!!

Ride Safe.
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Old 3rd January 2011, 12:15   #34
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Default Re: Harley knocking - Help needed

Hi, glad to see your problem is solved - but jsut for my reference - what exactly is this knocking sound that your bike?

Many times ppl have a tendency to LUG the engine and call it as knocking.
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Old 13th January 2011, 00:59   #35
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Default Re: Harley knocking - Help needed

Dear GTO/ Gurus,

Did you got any reply from HD India, as i also plan to buy a Iron & will take it for long drives. I too will face this same situation espacially when the tank is only 13.3 lts.
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Old 2nd August 2011, 23:18   #36
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Default Re: Harley knocking - Help needed

Note from the Team-BHP Support Staff : Please use the Private Messaging feature for 1x1 discussions with any member.

Last edited by n_aditya : 3rd August 2011 at 09:24.
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