1982 YZ490 knocking like crazy! Need help!


11 replies to this topic
  • yz490 nightmare

Posted June 07, 2005 - 10:20 AM

#1

Hi ,

I am new to the board and I am trying to find someone who can help me. I just traded for this yz490 and it knocks so bad im afraid to leave it running! It apparently sat in this guys garage for 2 years. The clutch cable needs replacing. The kick wont spring back up but it will start. While it is running it sounds AWFUL it smokes and knocks like it is gonna die. I think I got ripped off bad. Any ideas or suggestions on what I can do to fix this bike? Thanks!

Heather

  • MX37

Posted June 07, 2005 - 10:30 AM

#2

i know running low grade gas in a bike with high compression will cause detonation/pre-ignition, premium is good enough for most bikes (92,93,94 octane) might want to get a new top end since its that old also, you get alot of blue smoke from bad rings. Also, what did you trade for this bike?

  • Flash319

Posted June 07, 2005 - 10:34 AM

#3

Ya sounds like your piston is toast!! Also check the boot between the carb and the cylinder. A leak there will cause knocking.

  • ncmountainman

Posted June 07, 2005 - 10:37 AM

#4

i used to have a IT 490 (same bike with lights) it was lightning fast and handled well for what it was. it doesn't cost that much to throw a crank kit in one. change all the seals while your in there,there are many aftermarket parts still made for them(pipes ,reeds,etc) it might be worth dumping a few bucks into it if its a solid bike. if you keep it grease everything(steering head,axle bearings,susp) rebuild the forks,new brakes and so on and you'll have a real nice peice of history :)

  • yz490 nightmare

Posted June 07, 2005 - 11:34 AM

#5

ok guys lol

I traded this for a 89 fzr600 plus $1500. This is my first bike I have no idea what you guys are talking about crank this, grease that. Sorry to be such a girl but I gotta start somewhere. I am going to get the service manual tonight. From what I know about engines in general it sounds like the pistons are slamming up and down? The noise is coming from the round part of the engine right under the exhaust. What do you suggest I try? Should I just ride it and see what happens? The smoke is grey and white.

  • yz490 nightmare

Posted June 07, 2005 - 11:35 AM

#6

Flash,

whats a boot? between the carb and where the fu-- is the cylinder? :)

Ill buy the beer if one of you boys wanna give me a 101 on engine repair lol

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • ncmountainman

Posted June 07, 2005 - 03:28 PM

#7

ok guys lol

I traded this for a 89 fzr600 plus $1500. This is my first bike I have no idea what you guys are talking about crank this, grease that. Sorry to be such a girl but I gotta start somewhere. I am going to get the service manual tonight. From what I know about engines in general it sounds like the pistons are slamming up and down? The noise is coming from the round part of the engine right under the exhaust. What do you suggest I try? Should I just ride it and see what happens? The smoke is grey and white.

sorry but you got FREAKIN' ROBBED DUDE :) that bike ain't worth $1500 tip top runnin' condition never mind plus a fzr 600, in the immortal words of raymonds dad "HOLY CRAP" was the fzr runnin' good? cuz if it was i'd load that yz up and find a couple of your bigger buddies,buy them that beer and go back and renegotiate that deal :)

  • RCannon

Posted June 07, 2005 - 04:04 PM

#8

The IT 490 was 10 times better than the YZ.

The carb jetting was messed up on these. I changed my needle jet to a Q4 and the main to a 400. It helped slightly.

Overall, the bike was terrible. I hated every minute I owned it. If you cannot return it, check with some older mechanics. There were head mods that helped the 490's.

  • jasilva

Posted June 07, 2005 - 04:37 PM

#9

The YZ490 was without a doubt the biggest bucket of SH!T that Yamaha ever produced. If you don't believe me go to Off-Road.com's dirt bike section and post up a question about that bike in Rick Sieman's Don't Ask column.(He was the original editor of DirtBike mag.) The YZ490 could never be made to run decent they ALWAYS detonate and are a cast iron bitch to start. The guy who traded you must really hate your ass to do that to you. I second the idea of getting your biggest buddies together and getting yourself out of that deal. Here's a little interesting reading about the 82 YZ490. Scroll down the page and read the question about this little gem.

Joe

  • ncmountainman

Posted June 07, 2005 - 05:16 PM

#10

man i didn't realize there was that much of a diff between the IT and the YZ that year. that IT with a couple of the normal mods was one of the fastest bikes i've ever owned. hammered it for 2 yrs and it still ran ok when i sold it,i was told to look out for base gasket problems, but never had any. did they run a higher compression on the yz and screw it up? if thats all it is just run a dish piston,and rejet. our man nightmare seems to be lacking in mechanical skill (as well as some horse tradin' sense) so itr may not be a option to fix it,bring the 12 ga.,the bike,and drunken buddies back to the seen of the crime :)

  • Bamster

Posted June 07, 2005 - 05:52 PM

#11

I had the 1980 YZ 465. It was scary fast and came jetted a little rich.
Never had a hard time starting it.
Nothing came close to it that year and I learned a lot on that beast.
Posted Image


While it is running it sounds AWFUL it smokes and knocks like it is gonna die.

You do realize this is a 2 stroke eh?
Posted Image


http://groups.msn.co...&ID_Message=266

  • JeffWR

Posted June 08, 2005 - 04:56 AM

#12

The YZ490 was without a doubt the biggest bucket of SH!T that Yamaha ever produced. If you don't believe me go to Off-Road.com's dirt bike section and post up a question about that bike in Rick Sieman's Don't Ask column.(He was the original editor of DirtBike mag.) The YZ490 could never be made to run decent they ALWAYS detonate and are a cast iron bitch to start. The guy who traded you must really hate your ass to do that to you. I second the idea of getting your biggest buddies together and getting yourself out of that deal. Here's a little interesting reading about the 82 YZ490. Scroll down the page and read the question about this little gem.

Joe


This thread brings back memories does anybody remember the article written about either the YZ465 or 490 and going thru the picket fence. In the article it talked about depending on seated position and throttle control if you would make the corner or wam bam through the wooden picket fence with wood flying again. Also something about a low flying berm to berm missle. That was a very entertaining article but can't remember the source or year it was written. I'd love to read that again just for an old time laugh. Anyone else remember it? This probably doesn't belong in this forum but since it got started thought I would ask.
Jeff




 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.