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Yamaha YZ490 1985 Reviews

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bigbirdh2

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My 1985 YZ490, now a 510cc was red and white new. I got this one done last year. motor balanced. Race Tech Gold valves, frame cut/ pulled back 0.03degs more than the 85 YZ250. rear shock drop relocated frame mount to 15mm. 226lbs Dry, 63.8hp rear wheel dyno. This bike has been reworked 4 times in it's life time and people at the track love my new color change, and so do I. : D

 

11/15/2016 

Broc Glover 85YZ490 Replica/ Then I decided to modified the bike my way. 510cc CR (Wisco) piston and motor balanced (Crank Works) with all new bearings. Balance this motor ASAP, They told me they added 26 grams (heavy weight) one side of the crank and drilled 42 Grams off the other and spun 20,000 RPM's till it was done.

 

(Porting, wide on the exhaust and 1mm off the top. polish all the clutch internals and heavy (Barnett) clutch springs, banshee clutch perch and lever, extended 12mm Push Lever Assembly, for one finger pull. Head Moded my own specs, w/Jake brake added. Jetting the 40mm carb, with 3mm cut off the back of the slide. Cut 7/16 manifold spacer made all the jetting problems go away. Yamaha's pipe was a joke.

CR500 (Pro circuit) Pipe cut and TIG welded and fitted and custom shorty old school (DG)  silencer. Now the power comes on smooth for a 500. and Dyno @ 63.8hp to the rear wheel. (stock Flywheel was one of the heaviest ever).

New WR500 Ignition and timing played with till I found where it liked it. 1mm off! than stock, and the Jake Brake works awesome everywhere (re-drilled for max air out of the Cylinder rear brake testing) and if I ever stall it, one pull on the Jake lever fires it right back up.  Brakes!  (Fast-line) front Brake line. Yamaha decided to change the front pads 5 times in it's life, (superseded) on the 1985 125/250/490n so they are 10mm narrower than when they first came on the bike off the show Room floor.  So I run Custom cut (EBS) pads that cover the hole front Rotor and (EBS) is going to a production run of my pads I been selling. (EBS SEMA SHOW Nevada 2016) 1985 Motocross Action said the new YZ250n was one finger brakes only. Yes it was because the front Pads covered all of the Rotor! Why Yamaha changed them? Must have been to close to someone else.   Rear brake, polish all the internals, new grove shoes, extremely heavy brake pedal Spring, (NAPA Auto-parts). Frame cut. 0.3 degrees then pulled back tighter than the 85YZ250n . 1/8"inch cut on the bottom  head stay to the top then pulled back and re-weld.  Shock mount cut off and moved 15mm down to make the linkage work right and added 14.25inch rear travel. Makes woops sections awesome now with a 7.0Kg Rear Spring! (Had to make a frame JIG and cut a square off the sides of the frame to weld the inside then weld the squares back in on each side, Sand all down and put frame in the oven on the JIG @600deg for 3hrs and then a 24hr Oven cool down at a Powder coating shop). Cut the frame front tube off high and cap it,/ weld, so more air flows over the head, and cut off the shock bottle mount and moved it with a lighter mount out of the way (New Silencer location). 

 

It went from a 6.0K spring to a 7.0K Spring. (Race Tech) has the spring rate way off on there Chart even before the shock mount was moved. (Race Tech) Gold Valve rear, Tall Bump Stop, Newer style Bladder. Shock body (CG Industries Albany Oregon) Electroless Nickel plating, no more shock oil contamination or egg shape wearing out the inner shock.  Front (Race Tech) Gold Valves. Custom .44K  Springs. all 5w synth.  Custom monster foot pegs and 15mm longer shifter.  I'm Dropping them down 25mm for a Tall rider (Me) {tried some made off my friends YZ250N bike and loved it}. I threw away all the old frame and motor bolts. I found China Titanium and Aluminum bolts online in any millimeter or size you want. There is Aluminum blots in all the plastic, Titanium bolts sprocket fork clamps shock, linkage,motor mounts, Custom frame mount Aluminum gluid plate. Working on buying/ building newer wheels kit, but now the Wet wight: 226lbs No fuel.

 

  So.... No motor vibration, Rear shock dose not fade and loves big jumps and whoop's. Front forks, cant feel the small stuff, no bottom on big jumps. Turning, Take the sharp inside corner without washing out the front wheel. leave it in 3rd and power out. Braking/one finger front, Rear, Jake takes some getting use to. Feels like ABS. I let people ride it at the tracks in Arizona, California, Oregon, Washington practice and they come back saying, Wow this bike is a 1985? Rides awesome! How did you do this, and how did you fix that? I can never sell it but it sure was fun testing and fixing all those years against my newer bikes to make it better and Re-building crashed helicopters and planes for a living was fun. I rode a stock 1986 YZ490 this year. God it was awful. But... at the same time it wouldn't take me or anyone long to build one race ready again and have all the master cam files on 3 computers and a dyno chassis engineering frame files.

 

 More Race Up Dates soon. 11/15/2016   Weeee! Have Fun Riding.

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