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Top End Cylinder Plating and Bottom End Resources Guide 2021 KTM GAS GAS HUSQVARNA

I recently blew up my 2021 Gas Gas 300EC racing Last Dog Standing Extreme Enduro Race in a silty dusty hill climb (most likely a filter problem) see video here. I had to get the Cylinder replaced and redo the bottom end in 3.5 weeks before the next race in Idaho: Silver Mountain Extreme. Below are all the links and resources I put together while tackling the rebuild for the first time. It was all manageable just takes some time and a few special tools. I filmed the whole rebuild process but not sure when or if I'll find time to post it on the Trailboundco YouTube 


Disassembly Videos
Tokyo 2017 300

RMATVMC 2015 300 

RMATVMC starter motor 2017+

RMATV bearrings


Assembly Videos
Tokyo 2017 300

RMATV bearrings 

RMATVMC 2015 300 part 1
RMATVMC 2015 300 part 2 


(Might add a more specific parts list later)

RMATVMC Bottom end rebuild parts


Disassembly Tools

  • Gear puller that opens to around 3.25 wide
  • Special pliers for removing starter motor seal ex: this video 30:40 , normal pliers did not work but you can get away with hitting the starter motor out but feels a little more sketchy. Later found this RMATVMC video at 9:00 showing using 2 90* picks to get it out
  • Small punch for moon lock thing
  • Gear jammer: But if you havean old motor gear you can cut a pie piece out of it, thats what I used but wished I had the tool 
  • Clutch holding tool, this is not necessary as you can use a gear jammer on the other side
  • Flywheel puller 26mm x 1
  • Crank case splitting tool 
  • Seal puller 
  • Huge breaker bar/cheater extension or 18v impact gun or pnematic impact gun 
  • Snap ring pliers for cir clips if you remove bearings 
  • 24mm socket 
  • Gasket scrapper + parts cleaner: razor blade works or fancy version: KTC ceramic 12mm KZ4-12
  • Bearing cleaning: kerosene + brush
  • Powervalve cleaning: Chem Dip Parts cleaner 


Assembly Tools

  • Tusk bearing/seal driver or socket, or use old bearings (1 1/4” for one small side of crankshaft), driver set would hav been nice
  • Theres a blind flange bearing that you need a special tusk tool and slide hammer for but I dont think I replied it
  • Propane Torch 
  • Thermaturer gun to heat to 100* for bearing install or just spit on it until it needs up instantly, should be able to touch it quick 
  • Waterproof grease 
  • Assembly lube 
  • Loctite  
  • Might need a friend to help run through the gears but I didnt disassemble my gear box, left it zip tied together
  • Troque wrench for 4.4, 7.4 ft/lb 44.3, 73.8, 88.5, 110.6 
  • Small torx socket (so you can use torque wrench)


Tips for next time:
-If you dont have a strong impact driver (Milwaukee will work) leave the motor in the frame and loosen a few of the hard bolts first before removing the motor. 


Cylinder Plating 
Around $200-$300

Millennium 4.5 weeks  (this is what I used)
Powerseal: 5-6 weeks
LA sleeve: 6 weeks (I think they said they dont have a sleeve for the 2021 yet)
US chrome: 4-6 weeks but only working with dealers right now
Q and E in Anaheim, CA:  2-3 weeks 

Millenium Plating:
Rush order: 9-12 days $75
Double rush order: 6-9 days $150
-they can order a piston (to match it). but wont order until your cylinder arrives so I overnighted the cylinder


New Cylinder
Most likely a new cylinder is sold out but try these places.. 

RMATV Oem cylinder and piston $1037.46
Slavens Full kit $1000 
Judd racing piston and cylinder $1005.40 shipping is 3 days from uk

Rocky Mountain
Dennis Kirk 


Crankshaft Install People 

Ask  around locally you can probably find a metal guy with a lathe and the balancer. Your local shop might know a guy.

-Ask if they do crankshaft bearing install and balancing 
Tell them: 
-I’ve got the crankshaft assembly out of the bottom end
-And have new bearings and crankshaft 
-Need the bearings to be replaced/pressed and balanced 

Millenium crank shaft: 20 days $101? Probably super expense shipping because crankshaft is so expensive 

Buy these parts to bring to the guy with your crankshaft

Rod kit $72
Crankshaft main bearing $71

Or oem: Crankshaft: #288 #54830015244


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