The Compleat ATK thread

Discussion in 'Thumpers' started by Gummee!, Feb 8, 2009.

  1. davidmild

    davidmild Adventurer

    Joined:
    Nov 5, 2003
    Oddometer:
    44
    Location:
    PuDong, Shanghai, China
    Hi CnB, thanks for that information. It helps a lot. Cheers.
  2. dcarver

    dcarver Been here awhile

    Joined:
    Oct 5, 2007
    Oddometer:
    118
    Got the forks and rear shock back from Independent Suspension. They are great guys, local, knowledgeable and fun to deal with.​
    First step, check steering head bearings for grease. There was plenty there, it was a waste of time. Kind of. The old grease didn't look like it was waterproof. The new stuff is.
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    Handlebars hanging from the rafters! Someday, a lift with up and down adjustment is in my future.
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    Hell, I even cleaned the fork gotors!
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    She's a purty thing!
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    Now that I'm getting closer to having a runner, I'm thinking more and more about rebuilding the 'race' engine.
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    My buddy Paul, his wife made this for me back in the 1980's. Said it looked just like me! I still have it and love it...
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  3. Island Rider

    Island Rider solo adventurer

    Joined:
    Jan 30, 2010
    Oddometer:
    126
    Location:
    San Juan Island, WA
    I'm adding some fuel and real light output to my 605. 4130 tubing. With a 7" Hella ecode.
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  4. Seavoyage

    Seavoyage Been here awhile

    Joined:
    Dec 20, 2011
    Oddometer:
    133
    Location:
    San Francisco
    Posted on Dirty BARFing to be accessible to current and future ATK 350 or ATK 605 owners:

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    A few things I learned:

    With the exception of the Aermacchi Sprint or the XR750; the ATK is the closest thing to a 'dirt' Harley-Davidson: American made C&J frame with a Rotax engine similar to type used on the Harley-Davidson MT350E or the legendary Ron Woods 'Harley-Davidson' Rotax flat-trackers.

    SPECS: http://www.motorcyclespecs.co.za/model/atk/atk_605 96.htm

    Quite an aesthetic design. Lighter than a BRP (Big Red Pig AKA Honda XR650). Relatively unpolished construction compared to a XR, DR, KLX, or KTM LC4. If the bike is a ATK 605 LE Police bike it has an upgraded electrical system and luggage frame: The CA Police bike contract with ATK was cancelled since it didn't meet CA emission standards.

    ATK built the 605 from 1996-2003. Rotax stopped making the Type 348 motor in 2001, resulting in the end-of-the-line for the 605... and the ATK acquisition of Cannondale 440EFI as a replacement. CCM was affected in a similar way and switched to the DR650 mill.

    Capable desert sled popular with D-37 staff. Was competitive in the LA-Barstow-Las Vegas http://www.desertpistons.com/4strokesd/ATK/atk.htm

    Old-school Thumper power: Lugs low and makes linear power, not like modern 4-stroke MX bike. Handling: Feels top heavy. Long wheelbase.

    Wealth of knowledge on the ATK Forum, ADVrider, and Yahoo ATK Group. Additional maintenance info on ATK Motorsports link.

    Download the:


    Local dealers? I recommend you develop a close relationship with Dan Blum (707) 446-4282 at MotoXotica in Vacaville.

    Fuel range 90-125 miles.: 3.2 gallon, and that's it. This was the limiting factor, with some preferring the Pre-94 single backbone frame that permits aftermarket fuel tank or a CCM 604.

    Bullet proof Rotax motor. Very low engine maintenance required.

    Oil change every 1000 miles. Oil filter every 5000 miles. Oil filter access is on the magneto side (on the right). This is a 3 Quart dry sump system. Rotax used Castrol GTX2 15W50 HD; ATK used Spectro 20W50 in the summer; 10W40 in the winter. One inexpensive alternative is JASO DH2 compliant Shell Rotella T-3 15W40 from Walmart ($4/Qt.) Go cheap and find HiFlo 151, K&N 151 or EMGO 10-26950 oil filters for $3 at your local auto parts sport.

    Interesting belt driven cam. Easy to maintain, but inspect the cam belt often and replace it every year. Here's a video: http://www.apophisparts.co.uk/index.php?p=10_22_Cambelt

    Valve Adjustments: Very easy to check and adjust valves. Screw type adjusters: no shims. The factory calls for .002" (.05mm) for both, Ron Wood, suggests .005" in and ex. I set mine at I: .004" (.10mm) E: .005" (.13mm) .

    Source the Cam belt from Apophis (UK), Force, or cross reference the Gates part (Timing Belt NSN 3030-00-408-2420 Goodyear 322L075 Positive Drive Trapezoidal Tooth Profile Belt, Light, 32.2" Pitch Length, 0.14" Height, 0.375" Pitch, 0.75") at local auto parts store. You'll need a Rotax crankshaft fixation screw M8x30 P/N 241-965, from Apophis or Vintage CanAm Parts, white paint pen, and a straight edge ruler to set cam timing.

    If the air-cooled motor overheats, the belt tensioner nut may come loose... not good.

    Apply Hi-temp silicone on the edge of the lower left side case covers which does not have a gasket. This prevents water/dirt entering the cam belt area.

    Spare parts sourced from ATK (Utah), Ron Woods, or AmericanDirtBike (ADB). Keith @ ADB (951) 283-5447 focuses on pre-96 Horst Leitner designs.

    Rotax parts are much cheaper from ultralight aircraft suppliers: California Power Systems; or from UK suppliers ( Apophis, Haines & Co.) that supports the Armstrong/Harley Davidson MT350E or CCM. The Rotax Type 348 engine family was used in the KTM 504 and eventually evolved into the liquid-cooled version used in the BMW F650/Aprilia Pegaso.

    If you sincerely believe you need more power (and less reliability) explore the Woods-Rotax kits, Swap Rotax 865 for 860 cams with HD springs, larger intake valves; and contact Mike Crowther's EdCO (Nee. Engine Dynamics) in Petaluma. Mike will get you sorted out to get you serious HP.

    Carburetor: 40mm Dellorto with Domino throttle... I'll leave it up to the owner if that's good or bad. Option for remote choke vs. 'flip-up' lever choke at carburetor. Dellorto Spare Parts: Guzzino.com . Many have tried Mikuni 38mm TMX used on the pre-94 models. Lee @ ATK (801) 298-8288 x109 tested Electron and Qwiksilver. Keihin cables are on the wrong side.

    Terrycable has replacement cables.

    WARNING: If you purchase a Rotax 4-stroke that isn't running; DO NOT attempt to electric start prior to confirming the cam belt is OK, and timing is correct.

    To start the ATK605 cold with choke, you have to keep the throttle slightly open to keep revs up until it's warm. This was a common trait.

    Kick Starting routine is like any other big thumper: Ignition on/Fuel on; Kick through 3-5 times with decompression lever pulled in and throttle closed; Set to TDC (decompression 'clicks' out, push don't kick the kick start lever down until you feel tension or it stops, then return kick start lever to top of stroke); Open and shut throttle 3 times (if you have a accelerator pump carb); very slight throttle; give a firm kick... repeat routine. Only kick if at TDC.

    Decompression actuator on headcover can get stuck = no compression. May be challenging to kickstart: get your jetting right, and use the decompression lever.

    Stock air filter is K&N pleated cylindrical type P/N KSP2538E. Get the foam outer wrap ATK P/N 060205 for better filtration.

    Exhaust: Have a header heat shield or header wrap so you don't burn your right leg. Look for Big Gun exhaust (no longer manufactured), much better than the Supertrapp which probably won't pass a 96db sound check. We used a FMF Q2 (P/N Product #: 044120 for '03-'05 YZ450F) and required some mods to the midpipe. Upgrade silencer mount to a 2-bolt design. '96-'97 1-bolt design was prone to fractures.

    Get a Magura hydraulic clutch from ADB. The decompression lever is integrated with the Magura hydraulic clutch (KTM, Husqvarna) master cylinder. The perch is prone to breaking and quite costly. I highly suggest hand guards. Clutch maintenance means access behind the cam belt assembly - a P.I.T.A. Confirm if you have a 8 or a 9-disc clutch.

    Electricals: Nippondenso electronic ignition. 190W Stator is very capable (Harley-Davidson 12V 190W 15.8A 3-phase AC Generator Part #84820620 NSN 2920-01-384-3744). Regulator/Rectifier OEM part#100007 is a Tympanium; tends to overheat, and require replacement; explore TrailTech Regulator/Rectifier (3-phase) if compatible with 190W stator.

    Use a TrailTech dash if the OEM is missing or you need an odometer. I installed a TrailTech Endurance, but you'll have to check if an Endurance II or Vapor for air-cooled motor will work.

    Notorious for going through wet cell batteries, The 190W stator and OEM regulator/rectifier may over charge the battery. A Shorai battery is highly recommended. My regulator/rectifier failed one evening, and I couldn't kick start or bump start. Just glad Tom G and Doc Wong were around, and we ran jumper cables straight to the starter motor. Lesson Learned: carry jumper cables and a tow strap. Starter Solenoid relay 4KB-81940-00-00-4KD from Yamaha. DO NOT jump start using a battery from a running car engine, just connect straight to the 12V battery with the car ignition off.

    Suspension: WP4054 USD forks and WP or Ohlins shock: pretty standard KTM. Yes that is a 40mm mid-80's fork, so quite a bit of flex. primitive by today's standards. Try to get the 1999 and up with the Paioli 46mm forks conventional (Showa innards) with Ohlins rear shock. The rear shock is linkage-less like the KTM PDS so look for a suspension tuner with experience with PDS (Dick's, SPS, etc.) or you'll have a difficult time tuning the rear suspension. Inspect the lower shock mount for fractures.

    Comes stock with Pro-Taper fat bars/handlebars. D.I.D. rims.

    Brembo calipers/master cylinder (KTM). Rear Talon hub is unique, and isn't a cush drive. Rear brake rotor is unobtainium (if you wear down, Good luck on finding a replacement). Answer Radialite Rear Sprocket is a Suzuki standard bolt pattern. Front brake rotor (Front brake rotor: Same part as '06-'09 KTM 450 XC '04-'06 450 MXC; '99-'02 LC4) and Talon hub matches KTM. Front Wheel Bearings 6204-2RS (20 x 47 x 14) ; 2 required. Rear Wheel Bearings: 6005-2RS (25 x 47 x 12) ; 3 required.

    Locktite the Countershaft Retaining Nut, mark so you can check for rotation, and check frequently before and after every ride . It tends to come loose resulting in catastrophic failure and damage to the transmission shaft.

    Plastic: UFO Rear fender is a mid-90's KTM300. Almost impossible to find in white. Still on backorder at ATK. Side panels are unique to ATK and of different color for different years.

    KTM Part#'s
    FF: 50208410100
    RF: 50208414000
    Side Panel (left): 54608441000
    Side Panel (right): 54608541000

    Seat cover: Guts Racing.

    Front hydraulic line plastic protector and decals are hard to source.
    Tank decals are still available.

    Frame: What frame? it's just a 3 Qt. oil tank and steering head attached to the heavy 100 lbs. motor. Yes, it's asymmetrical: a one sided 'frame'. Swingarm bolts to the motor. Inspect the steering head welds for fractures.

    The footpegs are small, and unlike the '88-'94 no aftermarket available, but you can try modifying XR100 mounts then fit Fastways or Pivotpegs.

    The subframe was prone to fractures at the mount points. Aluminium airbox is integrated with the subframe. Since the subframe wasn't designed for significant weight bearing, you may have to make some reinforcing mods. Panniers? Here are some ideas.

    Kickstand: Do not put your weight on the kickstand. It is only designed to hold the bike upright. If you mount the bike with the kickstand down, it will bend and eventually break at the tab on the swingarm. Unobtainium, and any weld just weakens the swingarm.

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    Source an ample field tool kit for field repairs for the Armstrong MT500 or Harley-Davidson MT350 from the British Army or Bundeswehr. For the curious, here's what the Harley-Davidson MT350E looks like:
    [​IMG]
    UK MoD​
    Yes, that Rotax engine is bullet-proof!
  5. Stretch67

    Stretch67 Mad Scientist

    Joined:
    Mar 22, 2006
    Oddometer:
    7,244
    Location:
    Bent, But Not Broken
    '96-'03 605's rock. I still want one.
  6. Rot Box

    Rot Box Been here awhile

    Joined:
    Oct 31, 2010
    Oddometer:
    251
    Location:
    Northern Utah
    Good work Seavoyage :clap
  7. Olas

    Olas the darkness

    Joined:
    Aug 14, 2007
    Oddometer:
    4,093
    Location:
    Boulder, CO
    Wow, this may qualify as the best post ever. Good job!
  8. Island Rider

    Island Rider solo adventurer

    Joined:
    Jan 30, 2010
    Oddometer:
    126
    Location:
    San Juan Island, WA
    That sea voyage post should be sticky under ATK
  9. MZRider

    MZRider Neo-Luddite

    Joined:
    Oct 21, 2007
    Oddometer:
    739
    Location:
    Western MD
    Great post Seavoyage!

    I'd eventually like to buy a late 605 to go along with my '91 ATK "504" (604 with a 504E engine from an MZ Saxon) and the CCM 350 I just bought this past Sunday.

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    Still quite a ways to go on the ATK, but I'm making progress:

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  10. Island Rider

    Island Rider solo adventurer

    Joined:
    Jan 30, 2010
    Oddometer:
    126
    Location:
    San Juan Island, WA
    Did anybody notice that the ATK motorsports forum is gone? My screen says their url expired.There was a lot of good info in all of those old posts
  11. Jeff@TheQuadShop

    Jeff@TheQuadShop TAT survivor

    Joined:
    Nov 28, 2004
    Oddometer:
    4,964
    Location:
    Crestwood, Kentucky
    Yeah, it seems like it happens every year about this time. It will be back up in about a week.
  12. Rot Box

    Rot Box Been here awhile

    Joined:
    Oct 31, 2010
    Oddometer:
    251
    Location:
    Northern Utah
    MZRider, If you weren't on the other side of the country I'd be trying desperately to talk you out of that CCM--awesome hard to find bikes :evil

    Island Rider: This happens from time to time. Give it about a week and they will be back :freaky

    Edit: Jeff beat me to it lol
  13. Island Rider

    Island Rider solo adventurer

    Joined:
    Jan 30, 2010
    Oddometer:
    126
    Location:
    San Juan Island, WA
    Made some progress over the weekend. New fork seals and gaitors, rear fender, LED tailight, LED turn signals, handguards, heated grips, shift and main seals, timing belt, oil filter, spark plug, plug wire and cap. Almost ready to ride.:clap
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  14. elsalvadorklr

    elsalvadorklr southern xr rider

    Joined:
    Nov 5, 2008
    Oddometer:
    4,154
    Location:
    Columbus, GA
    what a sweet ride...congrats island!

    Loving that shock!:D
  15. BronkoRob

    BronkoRob Adventurer

    Joined:
    Mar 6, 2011
    Oddometer:
    72
    Location:
    Oceanside, CA
    Seavoyage - +1 amazing post. has everything the first time ATK owner needs, and even some for the long time addicts. great info and well put together. probably going to print out and add to the manual of manuals i have for mine. lots of good info and part numbers!
  16. Bob Tosi

    Bob Tosi Long timer

    Joined:
    Sep 28, 2008
    Oddometer:
    1,608
    Location:
    Chico, Ca
    It is coming soon and I will join the heard.[​IMG]
  17. Island Rider

    Island Rider solo adventurer

    Joined:
    Jan 30, 2010
    Oddometer:
    126
    Location:
    San Juan Island, WA
    That looks nice Bob. What forks are those? Luggage and everything, you're set.
  18. 2 SPOT

    2 SPOT wannabe

    Joined:
    Dec 14, 2005
    Oddometer:
    3,485
    Location:
    valley of the sunstroke, AZ
    froks are from a honda CRF, repsrung, revalved and custom spacers machined to fit the atk wheel.
  19. Bob Tosi

    Bob Tosi Long timer

    Joined:
    Sep 28, 2008
    Oddometer:
    1,608
    Location:
    Chico, Ca
    Someone has to know something about bigger fuel tanks.......
  20. Rot Box

    Rot Box Been here awhile

    Joined:
    Oct 31, 2010
    Oddometer:
    251
    Location:
    Northern Utah
    You'll have an easier time finding Bigfoot :cry

    Nice bike btw that one was very well cared for and has all the right things in all the right places. I was sad to see the po put it up for sale but its nice to see it went to another member :evil