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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
ATD Advance Timing Curve?
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<blockquote data-quote="Martyn Goodwin" data-source="post: 51659" data-attributes="member: 2433"><p>Chanky is NOT correct in regard to jetting and he has incorrectly made this assertion a few times in the past. </p><p></p><p>At first lean running was suspected as the cause of my piston failure but the root cause was eventually and correctly diagnosed as detonation caused by way too much ignition advance.</p><p></p><p>Since the rebuild my bike has covered over 3,000 miles with leaner (not richer as asserted by Chanky) jetting than when the piston failed - BUT The ignition advance has been reduced from 38 BTDC down to 31 BTDC. For a short time I actually ran with 28 BTDC then started gradually advancing the ignition to the point where I could JUST detect pinking/detonation when under load hauling uphill then I backed it off 2 degrees to settle on the 31 BTDC that I now use</p><p></p><p>For the record, before the piston failure I was running a 210 main and a 106 needle jet. Today I am running a 210 main and a 105 needle jet in my Amal Mk1 Premier 30mm carb. CP 7.2:1 piston and a K&N air filter. I use ONLY 98 RON fuel.</p><p></p><p>This information has also been entered into the other threads by myself.</p><p></p><p>In the last 3 days my Comet set up as described, with me aboard, has covered in excess of 600 miles at an average speed of 56 MPH - with absolutely no issues.</p></blockquote><p></p>
[QUOTE="Martyn Goodwin, post: 51659, member: 2433"] Chanky is NOT correct in regard to jetting and he has incorrectly made this assertion a few times in the past. At first lean running was suspected as the cause of my piston failure but the root cause was eventually and correctly diagnosed as detonation caused by way too much ignition advance. Since the rebuild my bike has covered over 3,000 miles with leaner (not richer as asserted by Chanky) jetting than when the piston failed - BUT The ignition advance has been reduced from 38 BTDC down to 31 BTDC. For a short time I actually ran with 28 BTDC then started gradually advancing the ignition to the point where I could JUST detect pinking/detonation when under load hauling uphill then I backed it off 2 degrees to settle on the 31 BTDC that I now use For the record, before the piston failure I was running a 210 main and a 106 needle jet. Today I am running a 210 main and a 105 needle jet in my Amal Mk1 Premier 30mm carb. CP 7.2:1 piston and a K&N air filter. I use ONLY 98 RON fuel. This information has also been entered into the other threads by myself. In the last 3 days my Comet set up as described, with me aboard, has covered in excess of 600 miles at an average speed of 56 MPH - with absolutely no issues. [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
ATD Advance Timing Curve?
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