RPM Manufacturing & Racing Services

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Athena Big Bore kits
CR Big Bore
KTM Big Bore
KX/KDX Big Bore
RM Big Bore
YZ Big Bore
CRF Big Bore
KTM-F Big Bore
KXF Big Bore
RMZ Big Bore
YZF Big Bore
 
     

Yamaha 2-stroke Big Bore kits

Sleeved & Bored Big Bore kits - Bored & Nikasiled Big Bore kits - Do it yourself Big Bore parts kits


Your top end is needed for Big Bore kit installation, unless otherwise specified our big bore kits do not include the cylinder & head

The prices listed in the drop down menu's for Nikasil or Sleeving include all coating, machining & installation charges

The prices listed in the Do it yourself drop down menu is parts only (your responsible for getting the machining done)


(See packaging details & shipping address below)


"Payment details"
All major credit cards accepted
PayPal is hosting all payment transactions and you don't need to have a PayPal account to purchase.
Your paying on a secure and protected site when you use PayPal 

 

YZ80 Big Bore kits


 

 

   Check out the YZ112 Supermini on our Big Bore Stroker page!


YZ85 Big Bore kits


 

 

   Check out the YZ112 Supermini on our Big Bore Stroker page!


YZ125 Big Bore kits


 

 

   Check out our Big Bore Stroker page!


YZ250 Big Bore kits


 

 

   Check out the YZ280 & 290 on our Big Bore Stroker page!

Sleeved Big Bore kit - Parts & Installation info:

 

  


The Sleeved big bore kit consist of a cylinder sleeve, forged piston kit, top end Big Bore gasket kit & top rod pin bearing.

 

Your Cylinder gets machined for the sleeve to a precise dimension smaller than the sleeve, next the cylinder gets heated in an oven to a temperature hot enough to expand the cylinder so the sleeve can be placed & aligned to the ports. After cooling down the cylinder gets bored to the piston to proper piston manufactures clearances. The top of the cylinder gets machined to blend the sleeve to the cylinder.

 

Your Cylinder Head gets machined to the new bore size, the proper squish area is set along with a double angle squish band.

 

If your cylinder has a Power valve it will get clearanced for the sleeve and big bore piston, then cleaned and re-assembled into your cylinder.

 

Note:

If you purchase the do it yourself parts kit, be sure to have a reputable shop do the machining & installation for you.

 


Nikasiled Big Bore kit - Parts & Installation info:

 


The Nikasil big bore kit consist of a forged piston kit, top end Big Bore gasket kit & top rod pin bearing.

 

Your Cylinder gets bored for the piston to a precise dimension larger than the piston for proper nikasil coating thickness, the cylinder gets built up with the hardcoat process, then honed to the proper piston manufactures clearances. The cylinder gets sent out for this process and comes back ready to install the pv components.

 

Your Cylinder Head gets machined to the new bore size, the proper squish area is set along with a double angle squish band.

 

If your cylinder has a Power valve it will get clearanced for the sleeve and big bore piston, then cleaned and re-assembled into your cylinder.

 


Do it yourself Big Bore - Parts only kit:

 


The Do it yourself big bore parts only kit, consist of a cylinder sleeve, forged piston kit, top end Big Bore gasket kit & top rod pin bearing. (your responsible for getting the machining done)

 


1-2-3  Packaging & shipping details:


(Step 1)

Unless otherwise specified all Big Bore kit purchases require you to send us your cylinder, head & power valve. Please remove any cylinder covers, intake manifold, reed block & exhaust flange. These items are not needed for the kit installation. The cylinder head studs also need to be removed and somtimes are very hard to get out, we will remove them if you don't have the means of removing them, but will replace & charge you for any stuborn studs that get damaged from the removall process.

 

(Step 2)

When packaging up your top end try to use the smallest box that will fit everything, and if possible use a double thick cardboard box or add a cardboard liner. Use newspaper or bubble wrap to protect your parts. The most important thing about preparing your package is you don't want your parts moving around inside the box while in tansit or you will have nicks and dings and possibly something broken. We are not responsable for poorly packaged shipping damages. Before sealing the box see step 3.

 

(Step 3)

Make a copy of your purchased kit reciept with proper return shipping address, and a copy of any email that may have specific information for your order, please write your model year on the paper work. Add these copys in with your top end and seal the box good with 2 inch wide packing tape. Make sure your parts can't move around freely inside the box. Our ship to address is listed below.

 

RPM Mfg. & Racing Services

26 Aspen street

Ware,  MA  01082