KTM 380 EXC

KTM EXC380
Manufacturer	KTM
Also called	380 EXC
Production	2000 - 01
Engine	Two stroke, single cylinder, twin valve control exhaust system
Ignition	KOKUSAN 2K-2
Spark Plug	NGK BR 8 ECM, electrode gap 0,6 mm (0,024 in)
Transmission	5 Speed
Final Drive	Chain: 520x118 ‘98-02
Front Sprocket	14T ‘98-02
Rear Sprocket	52T ‘98-02
Frame	Central chrome-moly-steel frame
Suspension	Front: 50 mm WP Extreme upside down forks and shock Rear: WP Progressive Damping System shock absorber, aluminum swingarm
Brakes	Front: Single 260 mm disc, floating caliper Rear: Single 220 mm disc, floating caliper
Front Tire	90/90 - 21 54R
Rear Tire	140/80 -18 70R
Wheelbase	1481 mm / 58.3 in
Weight	109 kg / 240 lbs (dry),
Fuel Capacity	9.5 L or 12 L / 2.5 US gal or 3.2 US gal / 2.1 Imp gal or 2.6 Imp gal
Manuals	Service Manual

Engine

The engine was a Liquid cooled cooled Two stroke, single cylinder, twin valve control exhaust system.

Chassis

It came with a 90/90 - 21 54R front tire and a 140/80 -18 70R rear tire. Stopping was achieved via Single 260 mm disc, floating caliper in the front and a Single 220 mm disc, floating caliper in the rear. The front suspension was a 50 mm WP Extreme upside down forks and shock while the rear was equipped with a WP Progressive Damping System shock absorber, aluminum swingarm. The 380 EXC was fitted with a 9.5 L or 12 L / 2.5 US gal or 3.2 US gal / 2.1 Imp gal or 2.6 Imp gal fuel tank. The bike weighed just 109 kg / 240 lbs. The wheelbase was 1481 mm / 58.3 in long.

Photos

Overview

KTM 380 EXC

Of all the 2 stroke options why the 380 you might ask? Well the 380 was offered from 1998-2002 and shares the same chassis as the 250/300 which means it is much more modern than the larger 440/550 chassis. The 380 also incorporates a power-valve which is one of the reasons it can deliver decent low end power and still rev out fairly well. At the same time it isn’t overly aggressive in its power delivery like a 250 mx bike might be. The 380 delivers its meaty power much slower than an mx style bike. In addition it is still somewhat easy to get parts for the 380, at least for the time being. Finding parts for the true 440/550 big bores is becoming a chore and when you do find them you will pay top dollar.

My target years for a 380 were in the 2000-2002 time-frame because during those years the bikes came with the newer and lighter upside forks as well as the higher-output ignition that would support the future addition of lighting quite well. After scanning the internet for a few months I came across a fairly clean 2000 380MXC. The MXC means it has a close ratio transmission which allows the bike to pull from gear to gear and stay right in the meat of the power. The fact that I intend to use this bike for the open desert with sand washes and hill climbs as well as at the dunes makes the MXC tranny a good choice. From the ad it appeared the bike was mostly stock with the exception of a Pro-Circuit Platinum pipe and a FMF Q spark arrestor. Even the chain and sprockets looked to be stock, overall a good sign.

I fired up the 380 and headed out onto Backbone trail. Backbone trail winds it way up and down along a ridgeline for a few miles before dropping back into the valley. Right away the 380 was lofting its front wheel coming out of the turns and heading down the straights. A little more throttle control was definitely a necessity over riding the 525 on the same trail. The 525 is no slouch but on the 380 things just happen quicker. While the carburetion felt a little rich from ¼ throttle and into the midrange the bike had no trouble revving out when the trail opened up a bit. Upon decelerating into the corners I noticed the bike was surging a bit, a possible sign of a lean pilot and/or misadjusted air screw.

Knowing a little about my friends’ old 380s finicky jetting needs should help me get this bike ironed out in the jetting department. The 380s are known for being somewhat hard to jet in stock form. If you try and richen up the pilot to get rid of the surging then you can run into fouling plugs because the ¼- midrange is already on the blubbery side and you begin compounding the problem. The formula for success on one of my buddies 380 was to get the cylinder head reshaped for cleaner burning which resulted in bike that responded much better to jetting changes. Reshaping the head requires a professional machinist or at least someone with the tools and know how to do the job, neither of which I was able to find just standing around at Gorman that day.

Once off of Backbone trail and onto the valley floor I was able to get into a sand wash and really open up the 380. It really pulls with authority from the midrange through the top-end. The 300 my buddy was riding felt more like a 200 compared to the 380. The 380 has much more low end and midrange power over the 300. Gearing wise the 380 won’t reach the same top-speed as my 525 because it is a 5 speed over the 525s 6 speed wide-ration transmission. In the sand washes the 380 seems to just jump right to the top of the sand and float along instead of sinking in like my 525 tends to do.

Overall I was very happy with the power despite the obvious need for jetting changes but what about the handling? The suspension on the bike was apparently setup by Dicks Racing for around a 220 pound rider, well over my 180 pound riding weight. The spring rates on both the fork and shock are too stiff for me which prevented the bike from wanting to settle into the corners. Despite this fact the valving on both ends felt very controlled and balanced, responding equally well to whoops and trail chop. One of the future changes with the suspension will at a minimum need to be a change to lighter springs.

So far the 380 has not disappointed and getting back on a semi-big bore two-stroke has brought back some great memories. The power delivery and excitement of the 380 two-stroke can’t be matched by any four-stroke that I have ridden to date. I am already looking forward to getting some desert seat time in on the bike to see what it can do. Before that happens however I want to make sure the bike is reliable. Stay tuned as I continue with articles covering my progress of going through the bike, checking and rebuilding anything that looks suspect and then getting it dialed in. Review: Eric Tabb,

Make Model	KTM 380 EXC
Year	2000 - 01
Engine Type	Two stroke, single cylinder, twin valve control exhaust system
Displacement	368 cc / 22.5 cu in
Bore X Stroke	78 x 77 mm
Cooling System	Liquid cooled
Induction	Keihin PWK 38 AG flat slide carburetor
Fuel	1:40 - 1.60 when using high grade two stroke oil
Ignition	KOKUSAN 2K-2
Starting	Kick
Spark Plug	NGK BR 8 ECM, electrode gap 0,6 mm (0,024 in)
Transmission	5 Speed
Final Drive	Chain
Primary Drive Ratio	26:72
Gear Ratios	1st 15:29 1 / 2nd 18:26 / 3rd 19:22 / 4th 21:20 / 5th 23:18
Final Drive Ratio	14:52
Frame	Central chrome-moly-steel frame
Front Suspension	50 mm WP Extreme upside down forks and shock
Front Wheel Travel	280mm / 11.0 in
Rear Suspension	WP Progressive Damping System shock absorber, aluminum swingarm
Rear Wheel Travel	320 mm / 13.6 in
Front Brakes	Single 260 mm disc, floating caliper
Rear Brakes	Single 220 mm disc, floating caliper
Front Tire	90/90 - 21 54R
Rear Tire	140/80 -18 70R
Wheelbase	1481 mm / 58.3 in
Dry Weight	109 kg / 240 lbs
Fuel Capacity	9.5 L or 12 L / 2.5 US gal or 3.2 US gal / 2.1 Imp gal or 2.6 Imp gal

External Links

• http://www.off-road.com/dirtbike/project/project1608.html