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  #1  
Old 01-09-2011, 08:50 PM
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Moto YZ490 help

     

Ok just got this bike the other nite, been a while since i rode a bike and all but could not pass it up for 150 bucks and still runnin!!! Needs some work but itll b fine. ok what i need help with is what is the shift pattern for this monster, And where is neutral in there. hopefully ill have this thing ready soon. any help would be awesome. thanks
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Old 01-10-2011, 03:29 PM
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down into first up into the other gears and neutral is between first and second, ive got a 89' yz490
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Old 01-10-2011, 04:40 PM
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WOW! Depending on what year it is it might not have very many of them but all of them can be dangerous if your not familiar with that particular bike. LOTS-O-POWER! Hang on and shift up from the very bottom.
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Old 01-10-2011, 06:01 PM
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yeah i know this thing is a monster and its been awhile since i rode ima take it easy at first i appreciate the help guys. ill probably be back with more posts. Its gona be a long spruce up but hopefully it'll pay off
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Old 01-10-2011, 06:30 PM
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what year? a couple years were only 4 speed trans. Fun bikes , I have an 86 YZ490.
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Old 01-11-2011, 07:16 AM
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found out its older than i thought its a 1979 YZ400 NOT a YZ490. So im sry guys for the wrong year. but hopefully i can still get some help when needed. should have never stopped riding. forgot how fun these things r. also Do i need to mix the fuel in this bike or straight gas. dont wanna mess anything else up. ive had a bike but i just rode it thats all Pops took care of the rest. oil fuel and all that stuff. Tryin to get used to the mechanics of these things.Hands on is the best way to learn

Last edited by blazef20; 01-11-2011 at 10:23 AM.
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Old 01-11-2011, 10:50 AM
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yeah its a 2stroke, so u need to mix gas with two cycle oil, i always mix 50:1
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Old 01-11-2011, 10:54 AM
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Quote:
Originally Posted by 2strokecountryboy View Post
yeah its a 2stroke, so u need to mix gas with two cycle oil, i always mix 50:1
I would mix at no higher ratio than 32:1 which is what Yamaha and other Motorcycle Manufactures recommend.

If you find an oil that recommends less than 32:1 mix it according to the Oil's recommendations but a blanket statement of 50:1 is not always the best.

Thanks
Scott
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Old 01-11-2011, 11:39 AM
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thanks guys do you think the previous owner runnin straight gas hurt it any?
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Old 01-11-2011, 12:08 PM
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Quote:
Originally Posted by blazef20 View Post
thanks guys do you think the previous owner runnin straight gas hurt it any?
YIKES!!!! it would burn it down.... no lubrication for the piston / rings. I don't believe that the bike is oil injected or not?

Do you have a container that looks like it has oil in it?

Thanks
Scott
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Old 01-11-2011, 04:33 PM
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1. Shift pattern is 1 down and 4 up for the 79 YZ00.
2. If he ran the bike on straight gas it would have seized up long ago when it was run for even a short period. You need to check the cylinder, piston, rings and crank for damage, if this is the case. The cylinder and the piston will be severely scored. If it still runs well and has good compression it had pre-mix in it.
3. No oil injection on this model or any other YZ for that fact.
4. Depending on the oil you use it should be mixed at 20:1 or 24:1 for an air cooled, open class motor. I used Bel-Ray MC-1 in all my late 70's 2 stroke engined bikes. It is still available and runs very clean, it is a full synthetic oil.
5. Find an owners manual for the make, year and model you have. Try ebay for this old a manual. If you get a Chiltons or Clymer manual be careful, they are notorious for errors on tolerances and dimensions.

Good luck with the YZ it was a great scoot then. You could run evo1 in AHRMA motocross racing.

Bill
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Old 01-11-2011, 04:45 PM
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ok so it was mixed gas, i drained the tank and sure as heck it was. i mixed it 32:1 for now we'll see how it runs with that and if i have to tweak it any. I did just get done riding to see how it is and it seems to be ok. except for the start. i have to kick it like 10 times maybe the choke? or air fuel mix maybe could be the cold weather to,but i had to ride. thats just the bugs to work out. i finally got to ride again. bike has some bite to it to!! not to bad of a deal for $150. thanks guys

Last edited by blazef20; 01-11-2011 at 04:53 PM.
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Old 01-11-2011, 06:43 PM
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i always used 20:1 on my 81 yz465 but with my 97AFC500 i run 32:1....

i was using 927 but its $$$$ so i switched back to YAMALUBE (used that for YEARS in my other 2 strokes) ..

be careful running it around in the cold that ya dont seize it up....

also make sure its jetted correctly for the 20:1 (or whatever you decide to run)
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Old 01-12-2011, 12:04 AM
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i think im gonna run with the 32:1 ratio for now it seems to be working pretty good so till i get the rest of the bike fixed ill tweak later. Seems like 4th gear is gone or going. Kicks in then goes neutral. again again and agian. i dont plan of using 4th that much so. not really alot of places to get up to speed around here. Definetly needs a carb cleaning. and throttle likes to stick. so i got a lot of work ahead of me. but it will be worth the ride.

thanks for the help guys
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Old 01-13-2011, 09:38 PM
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we always ran 50:1 with sythetic racing oil, i run it in my yz490 and we ran it in our 350 banshee, it seems to run better not so rich but not lean enough to hurt it
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Old 01-14-2011, 07:20 AM
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Ill have to try The 50:1 i think thats what the prev owner was using. when i drained the tank it was mixed but not as concentrated as the batch that i mixed. Im gonna mix a batch of the 50:1 tonite and try it. thanks 2strokecountryboy
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Old 01-14-2011, 04:39 PM
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Quote:
Originally Posted by Florida 393 View Post
4. Depending on the oil you use it should be mixed at 20:1 or 24:1 for an air cooled, open class motor. Bill
Stay away from 50:1 in air cooled bike. Do as you want but do not be surprised if you seized the engine. 50:1 is not bad for a water-cooled fast revving engine and many run it to prevent gumming of their power valve but there's none of that on a YZ400 and it doesn't rev that fast for very long anyway.

I run my 490 at 24:1, smoke a little and that's perfect. No major gumming and everything looked fine last time I checked the inside of the cylinder.
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Old 01-14-2011, 05:46 PM
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Im getting smoke with the 32:1 not alot but enough. so i need to tweak the mixture down then right? so more mix and less gas. I'm gona have to find one of those mixing cups.
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Old 01-15-2011, 07:58 AM
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Quote:
so i need to tweak the mixture down then right? so more mix and less gas
Not quite sure what you mean here, i would leave the 2stroke/petrol mix at 32:1 and concentrate on getting the rest of the bike running sweet. It would be worth doing a full strip down to see exactly what state it is in , but as you are learning then maybe 1 thing at a time . !st in my book it is vital you make sure the air/petrol ratio is right - too lean and the bike will seize .Fit a new plug and check the colour after a run , have you got a manual ?
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Old 01-15-2011, 08:28 AM
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ya i have a manual saved to my pc from online. when i say tweak, i mean fix it. sorry for the lingo. but you are right bob-c. i should tear it down and rebuild. to see whats going on with it. it is old and it could use some TLC
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