Product Details

 -860 / 870 Big Bore kit for 2008-2016 800cfi and 800HO AXYS engines. The Top kit on the market for the top riders! 

No other kit is built like the Terra Alps kit. We gained 40 hp (30% increase) with stock pipe over a stock 800 with this kit. Our kit has the most extensive cylinder and cnc case porting of any kit which is needed to get over 20 hp gain. Our kit works on all years from 2008-2018 800s, no strength loss in the 2008's and 09's, we make them stronger. Don't be fooled by big advertisements to sell a kit.

Independent dyno showed a 34% increase in HP (45+hp) over stock, and 18% (26+hp) more then a slp pipe, porting, head kit, with our 860 with twin pipes on pump gas.

Kit includes pistons, rings, pins, (lighter then stock for quicker acceleration), designed similiar to our fix kits for the 800's for more reliablilty, (with taller pistons, not shorter for less reliability) billet head with interchangable domes set up for pump gas or race fuel or any application. Cylinders are machined and ported, cases cnc machined and ported, exhaust valves machined and matched to exhaust ports, base gaskets, shim plate and stronger bolts. 

Send in your cylinder, top case half and exhaust valves. If needed we can supply you with all the parts. Or send in whole engine, we can disassemble and assemble it ready to go.

860-870 kit $2995 cdn. ($2100 us approx.)

PCV fuel and timing controller needed $749.95cdn.  includes maps. for 2011-2015 models

PCV fuel adder $589 cdn for 2008 to 2010 models

Terra Alps Single pipe big volume with high flow Y pipe modification $895 cdn.

send in your Y pipe for modification.


840 STROKER! Turn your 800 into an accelerating monster,  this is how the Polaris 800 should come from factory.  Well something we said a few years ago and Yes Poalris came out with the same engine , the new 2019' 850! 

Send in your crankshaft, cases, cylinder and exhaust valves complete. Crankshaft is stroked from 70 mm to 74 mm.

Cylinder and cases are ported, comes with piston kit, billet head with interchangable domes for pump gas, exhaust valves are machined. $3495 cdn. or 2450 us approx.

 If you have a burnt rod bearing on your crank this is a good time to do this engine work.


909 STROKER BIGBORE! The king of Polaris big bores and performance! Up to 190 hp The top big bore in the industry combined with our Stroker crankshaft! $4495 cdn. or $3250 us approx.



- PISTON FIX KIT                                                 MUST READ!


* Terra Alps piston kit for the Polaris 800 cfi consist of the best set of cast reliable pistons on the market with the best rings. High silicone content for strength and heat resistance. Best suited for EFI sleds. Better dimensional design with less chance of rocking in the cylinder, proper piston clearance and proper squish clearance.   Dont settle for anything less. 


* We have seen some other brand so called fix kits come in thru the shop, Scary stuff. We seen cheap chinese pistons and forged pistons, some with poor dimensions. Another problem is the shim plate that is not the right thickness to keep proper squish clearance and velocity. This will loose hp and acceleration, also some plates are not flat so they have a chance to leak. Poor products and cheaply made by some that try to put anything together. Also some pistons in these kits are 2mm shorter then stock to try and raise the ports to make a peaky gain in hp which the pipe is not designed for and looses power all thru the rpm range. Someones crazy ideas. This piston also wears faster which rocks harder and cracks cylinder skirts. Some will say they are the only one to have lower piston support with a shorter piston, haha now thats funny. Piston support comes from a taller piston with tighter clearances and less rocking. Pistons with poor dimensions like the stock OEM same as Axys pistons, people thinking there different, the pistons rock hard in the cylinder and collaspe. Which is what happens to the copied forged pistons that are up to .010" clearance within 500 miles. Yes I have measured every other piston kit that comes thru our shop. Wondering why do people buy this crap. Buyer beware!


* Some feel there is a need to change out the rods to longer rods. Well this is not the issue with the Polaris engine. The rod ratio is still in spec to standards on todays 2 stroke engines. A better ratio then the Skidoo 800s and you dont see them willing to change the rods on that engine. But someone has to make money on the Polaris's. Some of these long rod kits are using a cheap off shore piston and rod kit, then welding up the lower portion of the cylinder to try and reinforce the cylinder??? This is just blocking off the airflow to the transfer ports and flowing less airflow making less HP then stock. Wow wouldnt that suck, spend all that money for cheap parts and less HP! When the issue is a piston with poor dimensions in the first place, but set up for a production engine with a lean fuel map. So thats what the manufacture has to do to get sleds close to warranty dates.  

So the real fix is to install good pistons and add some fuel.


* Now if you want to increase the acceleration or top end power of your engine, we have kits that can change the port timing in our kit to better suite the mtn guys and turbo kits, and those riding lower elevations. This kit comes with cast reliable pistons, Terra Alps billet head, base gaskets, and all necessary hardware. The Terra Alps billet head has proper cooling dynamics and dome design to make max power with proper squish velocity. We will set you up for pump gas at your riding area.


- PISTON KIT and shim only, uses stock head $749.95cdn. ($540us approx.)

#TARP818  2011-2016 Axys Polaris 800

#TARP819  2008-2010 Polaris 800

#TARP816  Piston kit with billet head $1299.95 cdn. ($980us approx.)

 Independent dyno made 171.6 HP with Terra Alps Billet head, piston and shim kit with thermostat kit, using vipec management, stock pipe, muffler and reeds.(2015 Polaris RMK 800 cfi2, stock made 146hp on that dyno)


- THERMOSTAT kit a MUST! #TAR156 for 08-2015 Polaris 800 cfi sleds, keeps sleds running cooler makes more HP!, flows 3 times more coolant then stock thermostat keeping engine temperatures more consistant, less chance of overheating, less chance of cylinder warpage, removes poor stock thermostat, kit includes billet housing, thermostat, bypass hose, tee and clamps. Total kit $289.95cdn. ($200us approx.)

Availible for AXYS 800HO with Terra Alps billet head.


- BILLET HEAD with interchangable domes, for Polaris 800cc cfi 2008-1015 and 2015-2016 AXYS 800HO with applications set up for pump gas, race fuel, turbos and STROKERS.

Our dome design creates noticable arm pulling power and provides more efficient performance with less chance of detonation with cooling as good as stock if not better. Dynoed on stock 2015 800cfi Terra Alps billet head made 6 hp gain over par head. (both were 13-1)

12T, 12, 13, 13.5, 14, 15.5 race, compression ratios, can make any design for your application. 

2008-2015 800 cfi $549.95 cdn. ($420us. approx.)

2015-2016 AXYS 800HO $599.95cdn. ($460 us.)

Thermostat extra $95.95 cdn. ($69 us.)


DYNO test results

2015 RMK Stock head 12-1 135 hp 8200 rpm

par head 13-1 136 hp 8200 rpm

Terra Alps head 13-1 142 hp 8200 rpm

Terra Alps 860 kit with stock exhaust 171 hp


-The Polaris updated heads for 2008-2010 800's and the 2011-2016 800 are 12-1 compression, low for high elevation riders. Install a Terra Alps head add 7+ hp and get the advantage over your competition. Add our porting package and take it to the next level.


* For more top end power with stock pistons for 2011-2015 800 cfi engines is our billet head with shim kit. We can adjust the port timing also add some compression for the high elevation riders. ADD 10 HP $499.95 cdn.

($375us approx.)

This kit outperformed the slp kit by 5 lengths in a up hill drag race. 


- CNC machined Crank work for quicker acceleration, 2.5 lbs less rotational mass. 

2008-2015 800 cfi and 870 big bores $995 cdn. 


- Porting cylinder $600 - $1250 cdn. call for info.

  case porting $200 cdn.


-TWIN PIPES!  gain up to 18 hp $1499 cdn.  ($1090 us approx.)

Offset steering post required, send in your post to be modified $200 cdn.

Fuel adder needed

-SINGLE PRO pipe gain 8 hp, no mid loss  $699 cdn. ($530 us approx.)

-Y PIPE modification $199 cdn. works with our single pipe, a must for Improvers, bigbores and strokers.


Gauge holders for afr gauges $19.95

Dynojet PCV fuel controller with maps $599.95 cdn.

Dynojet PCV fuel and timing $649.95 cdn.

V force Reeds  $399.99 cdn.


Vents kits availible

2011-2015 RMK

- Side panel vents 2 piece $77.95

- Hood vents 6 piece $94.95

- Air Box mod 2011-2015 $16.95


Clutching kits availible

- Weights assorted 44gram to 86 gram $129.95 (3)

- Team Helix's $149.95

- Primary springs $34.95

-Secondary springs $39.95


Call or email for your application


Videos on Youtube under "Terra Alps Racing"


We have complete performance and race packages for your Polaris! Engine, Pipes, clutching, exhaust, venting, chassis...