'88 Yami YZ 490 Is it worth keeping?

[D tom]

]I was looking for a project . $250 later I had it.Some carb cleaning and fuel tank petcock work it started second kick..With a new FMF pipe I took it out.
This thing scared the crap outof me. So I did the head mod and carb cutout as well as some porting.I have not put it back together yet,still working on broken motor mounts,loose swingarm bearings etc.So far every old school guy I could find said I should ditch it for a 250 or a big 4 stroke. But this thing passed those like they were standing still,Its just hard to controll and the rear suspension seems crappy and soft. Any suggestions?

[cetanepusher]

Try and find a later model 250 with a burnt motor, and swap in the 490 motor. Best of both worlds.

[merlyn1965]

What is it that you wanna do? If you wanna race at the track then get a 250 but if you want an adrenaline rush, have a bulletproff machine that will go anywhere to play, pull wheelies on any gear and that is a classic, then I'd say fix the YZ.
Sure many complains about the vibrations and hard to start when warm (God do I know) but most of them never drove one before and are envious that's all.
You have a 88, 5 speed then, the rear shock needs some help (Many shops are able to help for about $300.00) and if you are lucky, you can find a Simonds kit for the front forks. No I can't corner like the new bikes of nowadays BUT holy sh.. do I have fun? Damn right I do. I had a few time where I scared myself (quite a few to be true) when arriving into a corner, this thing accelerate scary fast without too much work. I can go cross-country in trail road and stay on 3rd gear all the time. I do not worry about shifting in the right gear, I just have to give it gas and it goes like a bat out of hell.
So you have to change a few fasteners for the motor mount, big deal, do like the rest of us YZ490 owner and drill those bolt hole bigger and use grade 8 bolts and nyloc nuts and voila. If you have the stock handlebar, cut 1" from each side to have more fun in tight wooden trails.
For the price you paid and the little money you have to put in it, save yourself the pain and regrets of seeing the guy who'd buy it off you passing you on your 250 or 4strokes with a big smile on his face cos believe me, it would happen.

[D tom]

Hey, Thanks for the input. I have the vibration almost eliminated with oversized bolts and lots of rubber. This thing must be a year or two older than I thought , It's red & white ,front disc,but it has a 4 speed.(seems like more than enough) Torque out the A.. When I had it apart the top end checked out really good but there is more noise than I'm used to. Is this normal ? Pinging ? Mostly as it warms up.I did compression check 150 psi.

[DRGSin393]

Originally Posted by merlyn1965

What is it that you wanna do? If you wanna race at the track then get a 250 but if you want an adrenaline rush, have a bulletproff machine that will go anywhere to play, pull wheelies on any gear and that is a classic, then I'd say fix the YZ.
Sure many complains about the vibrations and hard to start when warm (God do I know) but most of them never drove one before and are envious that's all.
You have a 88, 5 speed then, the rear shock needs some help (Many shops are able to help for about $300.00) and if you are lucky, you can find a Simonds kit for the front forks. No I can't corner like the new bikes of nowadays BUT holy sh.. do I have fun? Damn right I do. I had a few time where I scared myself (quite a few to be true) when arriving into a corner, this thing accelerate scary fast without too much work. I can go cross-country in trail road and stay on 3rd gear all the time. I do not worry about shifting in the right gear, I just have to give it gas and it goes like a bat out of hell.
So you have to change a few fasteners for the motor mount, big deal, do like the rest of us YZ490 owner and drill those bolt hole bigger and use grade 8 bolts and nyloc nuts and voila. If you have the stock handlebar, cut 1" from each side to have more fun in tight wooden trails.
For the price you paid and the little money you have to put in it, save yourself the pain and regrets of seeing the guy who'd buy it off you passing you on your 250 or 4strokes with a big smile on his face cos believe me, it would happen.

Awesome reply!! Im agreeing with you, all the way. Lets see some photos of these beasts guys!

[merlyn1965]

4 speed? 84 then. 85 and up is when 5 speed came out. As for the noise, did you put in a new exhaust gasket around the exhaust port? Just asking cos I went through the same debilitating search until I figure it out. Easy way to know, hold the exhaust by the cylinder head with a pair of thick gloves and listen to see if the ringing goes away.

[OLDMXRACER 393]

Originally Posted by D tom

This thing must be a year or two older than I thought , It's red & white ,front disc,but it has a 4 speed.

Keep it and ride it like ya stole it. I think mid 80's bikes are the next big thing collector-wise.

[D tom]

Thanks again guys, I did put an O ring in. There is a recess in the pipe for it but I cant find a gasket yet. Anyways It sounds more like piston pinging or detonation.I think i'll try higher octane fuel. Right now its 85 pump gas.Ski Doo synthetic oil(works great in the sled) If that works the only issue is the rear spring. I guess I'll screw it in all the way so it doesn't look like a duck taking a leak when i sit on it(185lbs)

[Freak]

For $250 I would just ride it till it breaks.

[Ekholm]

Originally Posted by merlyn1965

4 speed? 84 then. 85 and up is when 5 speed came out. As for the noise, did you put in a new exhaust gasket around the exhaust port? Just asking cos I went through the same debilitating search until I figure it out. Easy way to know, hold the exhaust by the cylinder head with a pair of thick gloves and listen to see if the ringing goes away.

Did the red and white bikes go all the way back to '84? Ithought the begining of that era was '87. I've been wrong before though, just ask my wife!!
Plastics could have been changed though.

[D tom]

The plastic is original .It has split front frame center exhaust port.The guy I bought it from said he could only get 4 gears.So can I ,I think. now I wonder! But he never had it running and I havn't had the bottom end apart. I wonder if I just cant get 5th. The shifter is kinda stripped but I can fix. If someone knows how to move pics from ezshare Let me know.

[zepplin]

mate I bought a wr 500 cpl of weeks ago, [yz490 motor in a 92 yz 250 frame] the rattle your describing may just be the standard big bore rattle I've had in every yz490 I've owned keep hold of her, you cant help but smile every time you ride em, took mine out to mx mountain this weekend and there's nothing quite like blasting to the top of the biggest hill climb there while others are falling by the way and doing it so easy,, I'm in australia before you go looking for mx mountain ,, lol

[D tom]

I've got to love the Ausi's . Always extreme always having fun

[YZ pilot]

What does the serial# start with? 88 YZ490 U would start with 2WH. The pinging is normal for an air cooled 2 stroke. I have an 86 YZ490 S . Yahoo group YZ490 is a good place for info and meeting other 490 owners.

[D tom]

I tried and tried and am still on the wait for yahoo.

[Big Maico 393]

Looks like you've done most of the motor work to fix the 490

to fix the pinging you might need to get some VP race fuel & do 50/50 mix with premium pump gas.

I'll check with the YZ guy's & see who the shock guru is, but for the front forks you can get a Race Tech kit for around $200 that will make them almost leik the modern forks.