OzVMX Forum

Marque Remarks => Yamaha => Topic started by: silverfox on December 03, 2013, 10:20:37 pm

Title: 82 YZ490 carb issues
Post by: silverfox on December 03, 2013, 10:20:37 pm

Thinking the carb is crook on this 490. Whats a good carb for it?? might have to buy a new one. Also any jetting tips??? recommendations? Will pull this one apart again, but seems to be missing bits!! As it had no Baffell/ washer part under the main jet. Put a new float in it, but will not run without the choke on. Starves for fuel!!

Title: Re: 82 YZ490 carb issues
Post by: evo550 on December 04, 2013, 09:14:20 am

check your pilot circuit, sounds lean. Maybe a blockage or wrong pilot jet.

Title: Re: 82 YZ490 carb issues
Post by: Gerard De Ruyter (Twistandshout) on December 04, 2013, 04:17:02 pm

My TT250 was doing that - found the float level was too low - pilot couldn't access the go fast stuff.

Title: Re: 82 YZ490 carb issues
Post by: silverfox on December 04, 2013, 07:29:30 pm

I will check the float level. Thanks

Title: Re: 82 YZ490 carb issues
Post by: mitch75 on December 08, 2013, 08:28:03 pm

chuck a new needle and seat in before you go adjusting float levels.
http://www.mikunioz.com/

Title: Re: 82 YZ490 carb issues
Post by: tony27 on December 08, 2013, 09:25:09 pm

Float needle & jet was first thing I did when sorting my 465 although that was to cure a richness problem.
If you need a baffle for above the main jet I have a carb for a 250j that I bought for spares that I could take it out of, most internal parts are common to round slide mikunis from what I've seen

Title: Re: 82 YZ490 carb issues
Post by: silverfox on December 08, 2013, 09:42:07 pm

Cheers. I have a baffle to put in it, but it seems like I need a longer threaded main as it will not reach the tube. Tube is all the way down. All a bit strange but will get to look at it again later in the week

Title: Re: 82 YZ490 carb issues
Post by: kim80y on December 09, 2013, 08:55:43 pm

Just get a new carb fom Mikuni oz, YZ490 yahoo forum has all the jetting specs for each model.
Or if you need them PM me and I will copy and send to you, they will be a good baseline.
It will work out cheaper and less hassle to get a new carb.

Cheers
Kim ;) ;) ;)

Title: Re: 82 YZ490 carb issues
Post by: Sorelegs11 on December 10, 2013, 09:22:47 am

Could have the wrong {shorter} neddle jet in it

Title: Re: 82 YZ490 carb issues
Post by: silverfox on January 04, 2014, 08:10:12 pm

Up date here http://forum.ozvmx.com/index.php?topic=32751.0