Project Honda Ruckus Part 5, Engine Bottom End

MotoIQ's project honda ruckus 

 Project Honda Ruckus: Part 5 – Engine Bottom End

by Jeff Naeyaert

In the previous installment of Project Honda Ruckus, we worked with Dan Paramore of DPR racing to go where no one else had gone before by carefully porting the head of the Honda GET engine to maximize flow, improve combustion and raise the compression ratio.

stock honda ruckus head vs DPR qench head
The radical combustion chamber with the large quench pads is the most obvious difference when you compare the stock (left) vs the DPR head (right).

Now it was time to get into the engine's bottom end and do some magic. In order to raise our displacement and to get a tougher piston that could hold up to high RPM abuse and possible detonation from our high compression, we turned to Chanito Motors for one of their big bore high compression pistons. The Chanito Motors piston kit comes with a Wiseco piston that is 3mm larger in bore diameter than stock which increases the displacement from 49cc to 58cc. The compression ratio is also bumped up from the stock 11.9:1 to 12.5:1.

Chanito Motors Honda Ruckus big bore piston vs stock
9cc more displacement and 0.6 of a ratio more compression with toughness and strength are the advantages of the Chanito piston on the left compared to stock on the right.

The Chanito piston kit comes with a big bore, coated steel, thin head gasket and all of the other genuine Honda gaskets and seals needed to rebuild the engine. The head gasket is very thin, 0.009″ thick which is good for reducing the quench volume which works well with our DPR quench head with the Singh grooves. The reduced volume helps the quench area produce detonation reducing turbulence for more complete combustion.

Chanito big bore head gasket for honda ruckus
The Chanito single layer big bore head gasket is great for performance but unforgiving for deck warp.

Using a thin single layer metal head gasket requires a lot of attention paid to making sure that the block deck and cylinder head sealing surfaces are absolutely smooth. This is especially important since the GET engine is prone to warp its deck surfaces with age. We hand lapped the cylinder and head on a surface plate with honing oil and 400 grit wet/dry sandpaper to get our surfaces absolutely smooth and flat. If you don’t have the ability to get the decks perfectly flat, then Chanito also has a 3 layer thicker gasket which is more forgiving, although you probably lose about half a point of compression and a lot of the advantages of quench with this gasket.

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