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Aftermarket Engine/Parts
Honda Nice
Nice 110 Jetting Baseline for Keihin PE20
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<blockquote data-quote="theraymondguy" data-source="post: 117505" data-attributes="member: 5318"><p>Yes, raise the clip to lean out the mix 1/4 to 3/4 throttle. You may note a subtle change in your pilot circuit as well. </p><p></p><p></p><p>I would not think of the Nice carb as 'being lean' on it's own. As RacerX mentioned, it was asthmatic based on "It was calibrated on the lean side, whilst inhaling through a restrictive airbox, exhaling through a somewhat restrictive exhaust and on straight gasoline, as was widely available 10-15 years ago. Don't know what jets were used, not even the series. And jet needle height was fixed, i.e. non-adjustable.". </p><p></p><p>The same carb could easily be made 'rich' simply by changing the main jet. It was jetted to provide a lean mixture based on the intended engines' flow characteristics operating with the remaining components in the system.</p><p></p><p>Carburetors do not determine rich or lean: air speed and volume (adjusted by the throttle valve and engine rpm, limited by airbox and air filter) drawing on the jets trying to pull fuel out of the bowl - metered by the jet diameter, needle thickness / clip position and then fuel quality - will equate to a rich or lean condition.</p><p></p><p></p><p>This Keihin PD17 was a NOS piece for a 1985 CB125s until some clown bolted it onto a TB 108cc kit.</p><p></p><p>[ATTACH]20701[/ATTACH]</p><p></p><p>The CB125s is a slow revving, heavy flywheel, small valved pushrod, whereas the 108 is a free revving big valved SOHC monster. </p><p></p><p>Tuning this thing was a beast. Swapping jets and adjusting clip height just did not cut it. I nearly abandoned it until it was suggested to make a radical change on the needle, which immediately dialed the mixture in to the 108's flow characteristics.</p></blockquote><p></p>
[QUOTE="theraymondguy, post: 117505, member: 5318"] Yes, raise the clip to lean out the mix 1/4 to 3/4 throttle. You may note a subtle change in your pilot circuit as well. I would not think of the Nice carb as 'being lean' on it's own. As RacerX mentioned, it was asthmatic based on "It was calibrated on the lean side, whilst inhaling through a restrictive airbox, exhaling through a somewhat restrictive exhaust and on straight gasoline, as was widely available 10-15 years ago. Don't know what jets were used, not even the series. And jet needle height was fixed, i.e. non-adjustable.". The same carb could easily be made 'rich' simply by changing the main jet. It was jetted to provide a lean mixture based on the intended engines' flow characteristics operating with the remaining components in the system. Carburetors do not determine rich or lean: air speed and volume (adjusted by the throttle valve and engine rpm, limited by airbox and air filter) drawing on the jets trying to pull fuel out of the bowl - metered by the jet diameter, needle thickness / clip position and then fuel quality - will equate to a rich or lean condition. This Keihin PD17 was a NOS piece for a 1985 CB125s until some clown bolted it onto a TB 108cc kit. [ATTACH]20701.vB[/ATTACH] The CB125s is a slow revving, heavy flywheel, small valved pushrod, whereas the 108 is a free revving big valved SOHC monster. Tuning this thing was a beast. Swapping jets and adjusting clip height just did not cut it. I nearly abandoned it until it was suggested to make a radical change on the needle, which immediately dialed the mixture in to the 108's flow characteristics. [/QUOTE]
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Honda Nice
Nice 110 Jetting Baseline for Keihin PE20
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