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Curtis’s 385 4-Mil Engine Build

Curtis’s 385 4-Mil Engine Build

Curtis has trusted us with his Banshee before, bringing it in for maintenance and tuning to keep it running its best. After another solid season of riding, he ran into a shifting problem that left the transmission stuck in 3rd gear. Virgil suspected the shift shaft needed repaired or replaced.

Since the engine was already coming into Re-Do Banshee's shop for repairs, Curtis decided it was the perfect opportunity to add some horsepower. He stepped up to a 385cc +4-mil engine build that would gave his Banshee a noticeable boost in performance while keeping it reliable and pump-gas friendly.

For this build, the cylinders were sent to Redline Racing for a dune port by Cameron. Combined with a new long rod crankshaft, new Wiseco pistons, new domes, and Curtis's existing Cool Head setup, the result is a strong, responsive engine package built for years of trail and dune riding. The dune port really helped bring this combination to life, delivering a healthy increase in power without sacrificing reliability.

For more info on Curtis's build: 

  • Watch the video. 👀 
  • Scroll down ⬇️ for the link to watch the build's whole playlist on Youtube. 
  • Keep scrolling down ⬇️ to see the build specs below the video.

 

Parts 2 and later are scheduled to post!

Q- Have questions about selecting parts or getting help with your build? 
A- You can call 📞📱 or message us at 541-419-6054. 

We are flexible and will work with you. We can: 

  • Help you select the parts for your DIY build and ship them to you. - OR -
  • Build your engine and ship it to you to install. - OR -
  • Complete the whole build for you and install in your Banshee.

Curtis's Engine Specs

  • BUILD NAME:  Curtis’s 385 4-Mil Build
  • EXPECTED RIDING CONDITIONS:  Recreational dune & trail riding
  • DISPLACEMENT:  385 cc
  • ENGINE CASES (CASE HALVES):  Stock Cases
  • CYLINDERS:  Stock - Bored to 65 mm
  • PORTED:  Dune Port from Redline Racing
  • PISTONS: Wiseco 65 mm - 795 Long Rod
  • CYLINDER HEAD: Pro Design
  • DOMES:  22 cc Modquad
  • CRANKSHAFT: HotRods 58 mm long rod (4 mm over stock), trued and welded
  • COMPRESSION:  150 psi (determines fuel recommendation)
  • TRANSMISSION:  Billet Pro-Mod Transmission
  • REEDS / CAGE:  Moto Tassinari VForce4 Reed Valve System
  • CARBS:  Stock Mikuni 
  • CARB JETTING:  330 mains, 27.5 pilots (when it left the shop)
  • NEEDLES:  5N7U needles for Stock Mikuni. 
  • AIR SCREW ADJUSTMENT:  3/4 turn out
  • FUEL RECOMMENDATION: Premium Non-Ethanol (91-94 Octane) for 125-150 psi
  • WATER PUMP IMPELLER:  Stock
  • CLUTCH: Stock Clutch
  • CLUTCH SPRINGS:  3 Stock & 3 Heavy Duty Springs
  • CLUTCH LEVER:  Aftermarket
  • EXHAUST: Toomey T5 Pipes
  • STATOR:  Stock with Used Aftermarket Timing Plate, Cast Aluminum
  • TIMING: Set to 4 degrees advanced

 

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References:

  • We calculate engine displacement based on the bore in the engine's cylinders and the stroke length of the crankshaft. Click here for more explanation in our Banshee Engine Displacement blog article. 
  • Click here for information about Banshee engine break-in procedures. This includes our recommendations for Fuel to Oil Ratios and Selecting the Correct Fuel.

About the Authors:

This project article was written by Janel with plenty of help from Virgil. Virgil is the Banshee mechanic, and I am the website mechanic. I do own and ride a Banshee, which helps. 

The Re-Do crew hopes sharing our project info and specs may help some with their own projects, or that you find it interesting. I want our technical info to be accurate and helpful.

Please do let us know if you like our project articles, or if you think I need to correct something. You can send an email to info@redo-parts.com - and your comments will be passed along to me. 

Thanks ~Janel 😉👌

Email to: info@redo-parts.com