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Old 09-28-2013, 10:23 PM   #1
mudmantra OP
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1982 YZ490 trail machine

I've got the YZ490 running pretty good. I really like the bike and the power, but I think I need to smooth it out a little bit. I need a some idea's on how to make it better for riding in the woods. What are the best mods for it? Carburetor, Pipe, Ports, Flywheel weight, Gearing? Any idea's, or experience's of turning up the old YZ490 would help.
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Old 09-28-2013, 10:36 PM   #2
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i would suggest a 490 isnt a woods bike?
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Old 09-29-2013, 02:40 AM   #3
Twin-shocker
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Why not sell it and buy a 200 of some sort? Using large capacity bikes for competitive woods riding is a bit like choosing a chainsaw for delicate work with wood.
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Old 09-29-2013, 04:24 AM   #4
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IT490 fly wheel and cylinder maybe?

Fly wheel weight and a smaller carb.

No experience with them, just wanted to add something more than the "sell it and by something else" that seems to be popular with some members these days.
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Old 09-29-2013, 05:26 AM   #5
Twin-shocker
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Its very easy to spend a lot of money trying to change an open class MX bike into a capable woods bike. Its possible to improve it certainly, but it will never be as good as a smaller machine. When you figure in the cost of the alterations, selling and getting a more suitable bike seems the best way to go for most.
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Old 09-29-2013, 07:03 AM   #6
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Send the cylinder and head to Eric Gorr. viola! Broad smooth reliable powerband with enough power to scare anyone with sense.
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Old 09-29-2013, 09:13 AM   #7
Twin-shocker
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I wonder if the power of an open class MX bike is ideal for competitive woods riding? Guess it might piss the open class rider off a little if he keeps getting smoked by someone on a well ridden 125......................
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Old 09-29-2013, 11:29 AM   #8
mudmantra OP
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Originally Posted by Twin-shocker View Post
Why not sell it and buy a 200 of some sort? Using large capacity bikes for competitive woods riding is a bit like choosing a chainsaw for delicate work with wood.
I tried some newer machines. They just don't have any charisma. This machine well be set up for having fun, not racing. But I may find a 200 I like someday.
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Old 09-29-2013, 11:44 AM   #9
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Originally Posted by tHEtREV View Post
IT490 fly wheel and cylinder maybe?

Fly wheel weight and a smaller carb.

No experience with them, just wanted to add something more than the "sell it and by something else" that seems to be popular with some members these days.
Thanks. I looked into it. Would be cool, but it's the crankshaft that's heavier on the IT490. It would be a lot of work, but I might try it some day. I just got a stealthy flywheel weight, it should give me a good idea of what to expect.
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Old 09-29-2013, 11:56 AM   #10
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Send the cylinder and head to Eric Gorr. viola! Broad smooth reliable powerband with enough power to scare anyone with sense.
Thanks, I think I'm going to do that. I was going to say more low end and mid range power. But how much can you really use? More and smoother would be excellent.
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Old 09-29-2013, 12:11 PM   #11
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Years ago I had a ride on an ex works Jawa ISDT bike, think it was around 420cc. That pulled like a trials bike on steroids at low speeds, yet was very very quick as soon as the throttle was opened. The porting on an open class MX bike is all wrong for that sort of performance, although I would guess could be altered to suit woods use much better.

Try an older KDX200 if you can.............very surprising little bikes, and pretty much bulletproof in terms of reliability.
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Old 09-29-2013, 12:11 PM   #12
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for just having fun, not competing? i'd say the 490 could be a effing hoot.

i had one that was my primary off road bike... tight single track, mountains, woods, desert, sand, snow, everything. it was a very fun all-around bike. it wouldn't have been competitive in the tight stuff, but i wasn't competing... it was still fun. in the open stuff? it was a monster and competitive. the bike, that is... the rider (me) fell off too much to be competitive.

i sent the jug/head to Eric Gorr for the "head mod" and stated that i wanted low rpm grunt. what i got was a much, much easier starting bike, easy to jet, didn't ping, lugged like a tractor at idle and would rip when demanded. there wasn't a huge hit when it came on the pipe... just more and more thrust feeling.

the forks had race tech gold valve cartridge emulators, sent the rear shock to race tech for their treatment (seem to remember that costing around $500, years ago).

i put an IT flywheel & stator plate on it, a headlight & tail light. don't remember if it was just a drop-in affair or not...
i even rode it on the street reasonably often (usually just connecting trails).

there are bikes of the same era that are way, way easier to ride in the tight stuff (IT175 comes to mind)... but there's something to be said about coming to a clearing, cracking the throttle open and hitting warp speed while throwing a roost of rocks the size of softballs as you hang on for dear life, grinning from ear to ear.

damnit, i'm gonna go find another 490 now...
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Old 09-29-2013, 01:15 PM   #13
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Twin Sucker seems unable to see others may want something different than he does.

Sending the top end off to Gorr will result in a nice rideable albeit fast motorcycle. However do not skip suspension set up. As power levels go up it tends to magnify suspension shortcomings. At the least springs to suit weight/use if not mods like the aforementioned cartridge emulators. I have them in my 465 and big improvement. In fact the 43MM forks are from an '82 490.

Enjoy and post up the results.
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Old 09-29-2013, 02:17 PM   #14
dhallilama
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ok... not a 490... and a '77 so i've got all sorts of yamahop/horrible rear suspension... but i got around the squishy forks and SLS drum with a USD fork swap from a late model YZ450f




got the forks used, cheaper than gold valves would be
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Old 09-29-2013, 05:52 PM   #15
mudmantra OP
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Quote:
Originally Posted by dhallilama View Post
for just having fun, not competing? i'd say the 490 could be a effing hoot.

i had one that was my primary off road bike... tight single track, mountains, woods, desert, sand, snow, everything. it was a very fun all-around bike. it wouldn't have been competitive in the tight stuff, but i wasn't competing... it was still fun. in the open stuff? it was a monster and competitive. the bike, that is... the rider (me) fell off too much to be competitive.

i sent the jug/head to Eric Gorr for the "head mod" and stated that i wanted low rpm grunt. what i got was a much, much easier starting bike, easy to jet, didn't ping, lugged like a tractor at idle and would rip when demanded. there wasn't a huge hit when it came on the pipe... just more and more thrust feeling.

the forks had race tech gold valve cartridge emulators, sent the rear shock to race tech for their treatment (seem to remember that costing around $500, years ago).

i put an IT flywheel & stator plate on it, a headlight & tail light. don't remember if it was just a drop-in affair or not...
i even rode it on the street reasonably often (usually just connecting trails).

there are bikes of the same era that are way, way easier to ride in the tight stuff (IT175 comes to mind)... but there's something to be said about coming to a clearing, cracking the throttle open and hitting warp speed while throwing a roost of rocks the size of softballs as you hang on for dear life, grinning from ear to ear.

damnit, i'm gonna go find another 490 now...
Cool. What year was your YZ490? I had to fix the wires on my stator to get it to run right at first. The 1982 stator/ CDI type is the same as the IT490, only the IT490 has a lighting coil. So yes it would be a drop in mod. My YZ490 had a lighting coil and lights, when I got it. Did your YZ490 have a stock pipe?
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