SB50 Intake Mod for Spree

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SB50 Intake Mod for Spree

Post by noiseguy » Thu Aug 31, 2006 12:14 am

Thanks to a tip, found a good bolt-up mod for the Spree.

Turns out the SB50 intake and reed valves are MUCH larger flow than the NQ50 (Spree) stock parts. The SB50 intake has a better transition at the carb end, and a larger opening at the reeds. The SB50 reeds are also larger cross-section. Best thing is that that part will bolt up to a stock Spree, and have been reported to help top end. The SB50 intake is painted red in the following pictures.

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Note the larger transition at the carb. If anyone was wondering how the intake mod should look, this is it.

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Here's the Spree for reference. You can see the choke point here. Note that the Spree intake interface is 17mm diam, whereas the SB50's is 18-19mm (oval shaped). The Spree decoupler will work in this arrangement, a new SB50 decoupler is only $4 from Honda, and shows available:

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Here's a top view of the reeds. Note that the insert to case is identical:

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Only problem I see is that there's no oil port for the Spree's oiler system. Here are your options:
- You could oil through the vaccum port, and convert the petcock to always flowing. Many have done accidentally by breaking the diaphram with compressed air; this requires you to cap off the lower vacuum connection on the petcock.
- You could also run pre-mix, removing the teeth from the oil pump.
- You can run down a SB50 carb; having looked at these they don't appear to be any different from the Spree, except for the oil injection tube at the manifold.
- You could add an oil injection port to the manifold and press it in ala the Spree manifold.

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