Yz Trouble

[shane.ballard.nf]

Should i continue trying to jet my yz490J or is the issue something else.

I noticed that i can push the bike in any gear and the engine will turn over and sometimes make a poping noise thru the exhaust, is this normale or a sign of damage?

never had a look at the topend of the motor

when i drive the bike i can go through all the gears but the bike is not revving high at all its more like bahh bahh and it's low revs and low speed and power

i was thinking it's simply to rich jetting, but maybe the topend is contributing to this problem

i think i will still try to make the jetting more lean or play with the airscrew and see if it will bring better results

I have heard that bad crankseals can immitate rich jetting but i had the cover off the magneto side and no oil also the kickstarter side crankcase cover was removed and put back on with new gasket and sealing stuff

would like to understand the problem and fix it

 

[Satch0922]

The YZ490J has a very bad reputation. It was impossible to jet it properly. I never owned one but I love hearing stories about why this bike was a legendary POS. Here is a funny one from Super Hunky! :D

SUBJECT: YZ490J

I own a 1982 Yamha yz490J. I found it in the desert. I broke my back some years ago, and now I don't have much money. I have been looking for an intake manifold, with seemingly no luck. I have tried at least 3 Yamaha dealers, as well as e-bay. I was either fortunate or unfortunate, as I have found one company that says they have one, but after 3 weeks it still hasn't been mailed. Any suggestions? I am starting to consider using silicone to enclose the rubber housing, but I am trying to save that for an absolute last resort.

Thanking You In Advance,
Brian

Did you ever wonder why the YZ 490 was left in the desert in the first place? It's because when brand new, the 490 was a piece of crap. One that has been left to rot in the sun can only be worse. Your best bet is to sell the parts and get a real bike.

 

[shane.ballard.nf]

Yes, funy thing is after i had the bike bought i came across this site and read alot of bad comments on it and seen it listed in the worst bikes of all time.

i don't care tho, i want to drive it and get it working, i don't have money to buy a good 2stroke that i can jump on and use.

gunna lean the hell out of the mixture and see if i can get some good rides before a seizure happens lol

or i may just sell it off to sum1, i know sumone interested in buying it already hahaha
but i do want to get it working so i can wheelie in 4th gear and stuff and get some nice rides in on it before letting it go

i love bikes i don't want to have nothing, at least i got something which may have some potential