The M8 is a great engine. But this is America and bigger is better. It’s long been tradition to build up Harley engines for more power. The one thing that holds many riders back, though, is they don’t want to make any major mods to their bike. Once machining gets involved, things get serious and real pros are needed.
The answer is drop-in power. S&S Cycle has long been in the business of building up American V-Twins and the M8 is no different. The S&S 129” and 132” Big Bore cylinder kits are the perfect answer for riders who want to add big power without needing to make any structural mods. These kits simply bolt on and produce big power.
The 129” kit bolts on to your stock 107” and the 132” to your 114” M8. They are completely bolt-on with no machining of the case required. The kits also use the stock heads. Then engine doesn’t even need to be pulled from the bike. The 4.32” bore is combined with an 11:1 compression ratio. That means you get huge power, yet you can still use pump gas in your bike. That’s convenient power.
The S&S cylinders used in these big bore kits are the same height as the stock cylinders. They are also meticulously finished with a wrinkle black powder coat to match the factory finish and will fit seamlessly with the stock heads and case. The original serial numbers are even retained on your M8. All that leads to your bike becoming a serious sleeper. Casual onlookers will be none the wiser until you pull away from everyone else.
When installing these big bore kits, it’s also important to retune your fuel map. Aftermarket tuners are a great start to getting the proper tune. You can also take your machine to a shop to get it professionally tuned.
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