YZ490, welcom home old friend

Your right Blanchy, the 465's were nuts. Like a scud missile on a rubber band pivot , lol , you just had to hope you were pointed in the right direction when it fired .
I have a good carb mod for the 490's,I will have to go and remember the part #s, as im too old remember off the top of my head.
Nozzle Q2 I think, needle and main, pilot jet #'s iwill have to look up.
We used to road race them on short circuit club days , and stops them from leaning out too much.
Worked so well we used to fit it to all new bikes we sold, to avoid seizeing problems and warranty problems .
Was fun back in the old pre mix days.
Amsoil was the choice oil . We stocked and used it he in oz before anyone.
40-1 with our mods , no probs, any useage.
 
Also forgot to mention , did you pull your crank out and fit a new rod kit ?

By the look of that piston , not all the missing bits get spat out the exhaust and we all know where they end up after that.

Since you did the top end , a common problem is the increased compression will blow out a roller on a worn bottom end quicker than your mrs will empty your wallet .
 
Naw, Old Mate I didn't pull the crank out but I did look around in there best I could, packed some rags in the case. I was worried about the rest of that piston but didn't find it or see any evidence so I'll cross my fingers and hope for the best.
 
New UNI air filter came in and I forgot all about oiling air filters. What type of oil can I use, will 30wt work? 2 stroke oil? can I soak it with wd and squeeze it out? I don't remember having to use special filter oil.
 
Do yourself a favour,

And pull the head and cyl back off , will only cost you a few gaskets.

Grab the rod with 2 fingers and pull straight up and down , if any movement its rooted and ready to blow.

Dont confuse it with side to side movement

Not a foolproof check , but worked well 30 years ago if you didnt wish to split cases.

Also make sure you replace the exhaust rubber mounts with rubber mounts,
If you dont you will only crack your new pipe.
 
# two said:
New UNI air filter came in and I forgot all about oiling air filters. What type of oil can I use, will 30wt work? 2 stroke oil? can I soak it with wd and squeeze it out? I don't remember having to use special filter oil.
Click to expand...

I use K&N filter oil. All of my bikes have rechargable type filters so I have a K&N servicing kit 15.00. I use it on my KTM filter as well.
 
The air filter is the last thing you should be thinking about.

20 yo bottom end = boom
 
It all seemed pretty sturdy in there I made quite a few rotations "inspecting" the insides and looking for piston shrapnel. I guess I'll go ahead and buy the proper filter oil, I was just hoping to use something I had laying around.
 
Here it is up & running and riding! still have a lot of little stuff to do but IT'S ALIVE AALIIIVE HAHAHAHAHA.



[ame=http://www.youtube.com/watch?v=hSmVRcaPyn0&feature=player_detailpage&list=ULhSmVRcaPyn0]yz490 - YouTube[/ame]
Then I had to go rip some holes in the yard just for johnyontherocks.


[ame=http://www.youtube.com/watch?v=rSvJtsfkwJ8&feature=player_detailpage&list=ULrSvJtsfkwJ8]yz490 004 - YouTube[/ame]
 
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