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Specialized tunnel porting of crankcase, rotary valve cover or reed boxes, cylinder port matching and exhaust port polishing. Increased airflow capability allows performance modifications in other areas realize their maximum potential. Power gains as high as 18hp.
  • reshape and balance transfers for maximum flow.
  • reshape intake tract & match cylinders to crankcase.
  • match, adjust exhaust and transfer port timing.
  • match intake & exhaust manifolds.
 
Maximum squish velocity is achieved by controlling the burn to prevent detonation while employing maximum compression ratio applicable to available fuel type.

Wow, that's a mouth full, how about this.
After we adjust squish angles and clearances followed by polishing the head to spec, you get lots more power and you get it from pump gas.

These mods work great combined with tunnel porting.
 
With every complete engine job we repair & true crankshafts to within .001 inch runout. There are many benefits to this service.
       
  • Less crankshaft vibration
  • Less wear at high RPM
  • Reduced carb vibration
  • Reduced clutch wear
  • Increased belt life
  • Increased bearing life
  • Smoother overall operation
 
We offer BIG BORE kits for lined cylinders. Our resleeving services include:
  • Sleeve replacement
  • Precision boring
  • Surface preparation
  • Port matching
 
If you have a creation in mind that you want brought to life, Doctor Don will be glad to assist with part or all of your project.
 
* Also available: Big Bore kits for engines with lined cylinders.
BIG BORE KITS 900 & 925cc
Our kits include extensive engine modifications & re-assembly with the attention to detail you expect.
  • Cylinder and crankcase porting
  • Nikasil cylinder plating
  • Head modifications
  • Carb and clutch recalibration
  • Technical support
NIKASIL APPLICATION
Re-plates cylinders with a high tech electrodeposit of nickel and ceramic coating for increased resistance to abrasion and wear. Improves cooling by approximately 40% over cast iron sleeve cylinders.
 
These modifications are necessary in conjunction with crankcase mod's that alter the intake air flow.
The rotary valve cover is modified to match the crankcase then polished to ensure a smooth intake flow.