KTM BIG BORE KIT (450/520+)

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KTM BIG BORE KIT (450/520+)

520sx/exc/mxc (2000-2002)

450exc/mxc (2003-2007)

525sx/exc/mxc/xc/xcw (2003-2007) big bore kits

Starting at $470.00

Product Code: ROUGHHOUSE_BIG_BORE_KIT_520

KIT SIZE

ADD CAMS ?

ADD JET KIT ?

ADD PISTON COATING ?

ADD STROKER CRANK ?

ADD INSTALLATION VIDEO ?

ADD INSTALLATION TOOL ?

ENTER BIKE MODEL & YEAR

Qty:

Description

The RFS motor is great and very durable off road motor. The handling and over all package has developed into a bike that is way better than anything we have seen from KTM in the past. We started testing on the original 520 RFS motors and came up with the many different motor configurations for the rider that just wants more. We can go from a basic 540 kit all the way up to a fire breathing 600cc monster. Starting with the 540, 550 (13:1 compression only) and 570 kits.

For a nice power boost the 540 gives more every where. The 570 is the next jump up and both give great bottom to mid power gains. For reliability we have left the compression stock at 11:1 unless otherwise noted. You can safely run 12.5:1 compression on premium pump gas as long as you are installing a stage one or greater cam at the same time. Our 13:1+ compression kits require high octane race fuel and make more power than the lower compression kits.

A KTM stroker crank can be added to any of our kits which will turn the 540 kit into a 576cc motor, the 550 kit into a 588cc motor, and the 570 kit into a 600cc easy to ride fire breathing monster. The factory stroker crank tends to give the RFS motors a heavy feeling. We have found a way to eliminate this by lightening and rebalancing the crank. The addition of the stroker crank should be discussed with us before ordering. Weight removal depends on the type of riding you do and should be discussed as well with one of our highly skilled engine designers. If you are “going big” please give our tech department a call to find which kit and combinations best fits your riding needs.

Features

Your stock cylinders must be sent in for boring and renikasil plating. For any kit over 97mm a sleeve is required. We use an aluminum liner and renikasil each cylinder for maximum life and reliability.
Each cylinder is honed to exact tolerances for the best fit and finish possible. We do have cores cylinders for exchange in most cases.
All kits include every thing needed for installation. Bored and plated Cylinder, piston kit, top end gasket set and cam chin link.
Basic kit:
540 kit: 97mm 11:1 compression $470
540 kit: 97mm 12.5:1 compression $470
550 kit: 98mm 13:1 compression $710
570 kit: 99mm 11:1 compression $710
Options:
Installation tool:
MOTION PRO CHAIN RIVETING TOOL
$87.95
Cams:
Stage 1 $145
Stage 2 $145
Stage 3 $150
Stage 4 $260
Stroker Crank $710
Lightened Stroker Crank $1350
Jet kit: $10
Piston Coating: $50
Big bore installation Video $25
There are many options available to enhance the kits as well. Your choice of cams should be based on you riding style and the type of terrain you most frequent.
The stock cam is good for tight single track and gives the most bottom end power increase but it will need to be short shifted to stay in the “meat of the power”. A stage 1 cam will still provide an off idle power increase but is better suited for faster single track, MX and more open style riding. The stage one gives slightly better overrev power and provides a very good low/mid range power improvement when added to the big bore kits. A stage 2 cam provides a strong mid range power increase. This cam is best suited for more open style riding. The stage 3 cam is best suited for our higher compression and/or bigger displacements. The stage 4 is for the power hungry. Bottom end suffers a little about 10% @ 2000rpm unless used with the 98mm+ kits and stroker crank
We also offer a Ceramic dome and wettable solid dry film (SDF) applied to the skirt. This will extend the life of the piston as well as help the engines run cooler by reflecting the heat from combustion back into the chamber.
We offer complete installation services and a full service shop. Please keep in mind if you are going to do the big bore installation yourself there are a few specialty tools you will need (chain peening tool and torque wrench) and a shop manual is recommended.