81 Virago carb adjustment

[Geoffrey Gogan]

Hello all,  I took apart my carbs this spring (left them attached), dipped them, blew out really well, checked and adjusted floats, and now I'm having trouble getting the idle right.  I have to keep the choke open slightly for it to idle.   I've closed the idle screws to soft seat, then turned both  open about 2-1/2 turns.  It does start right up.  I don't have guages, but wanted to make sure I can ride somewhere for help with sync.
After reading a bit, I learned that the main jet is not the same size in each carb.  One is apparently about .04 larger than the other.  I'm worried that I may have put them in the wrong carbs.  
Any advise would be appreciated. - G

[pofarm]

Here is the link to an excellent article on tuning the Hitachi carbs. Yes, the main jets are different sizes, with the smaller one going to the rear (left) carb. You need to make sure you have them right.
http://www.drpiston.com/hitachicarbs.html

[pofarm]

The article mentions the use of Mercury sticks. You can make a sinc tool cheap instead of the mercury sticks.
http://www.powerchutes.com/manometer.asp
http://www.pbase.com/image/19233066

[bstig60]

The size should be stamped on the jet. Check your manual, but I believe the larger main jet goes in the rear (#1) cylinder to aid with cooling. Mixing the jets shouldn't make any difference in the idle, but will make the rear cylinder run a little hot at RPM. The pilot screws adjust the idle mixture and provide fuel up to about 1500 to 2000 RPM, then the main jets take over and pull fuel directly from the bottom of the bowl. The richness/leanness is goverened by the float settings. They need to be adjusted within specification?

Bill

[Geoffrey Gogan]

Thanks for the advise.  I did check the fuel levels and adjusted the floats to spec, just below the seam of the bowl.  I don't ride her that hard, so might leave the carbs in and hope the jets were installed right, but maybe I'll take them off again and check.  Appreciate your time.
Since my choke wants to stay open for idle, that tells me the mixture screws aren't out far enough - too lean.  But I've heard there is a passage from one carb to the other that can get clogged.  Not sure that's true.  It looks like the choke has linkage that opens it on both carbs, but still if the idle screws aren't providing enough fuel, something might be blocked.  They are both turned out 3 turns now, and I'm planning to adjust further with vacuum guages with a friend soon.   I realize too, that the same idle problem would present if there was  a vacuum leak.  - G

[Geoffrey Gogan]

I saw that article, very nice and I purchased the parts.