Mixture on an 80

Joseph · Full Member Joined: May 22, 2007 Posts: 767 Location: NY

Witch way is leaner in or out on the mixture screw for an 1980? Will that affect how the plug looks. My plugs looked good uintill i tuned the carbs now the left is alot darker black realy.

tweedy64 · Posted: April 26, 2008, 8:45 am Post subject: Re: Mixture on an 80

IN is leaner mate

xsjohn · Posted: April 26, 2008, 8:52 am Post subject: Re: Mixture on an 80

Joe with those big pilots you have to be careful......I do the same thing with mine.......if you set them so it starts perfect with no choke after setting and cooling down you probably have them way to far out......I am running the exact 46 custom pilot as your and mine are set just a bit below 2 turns....it will run at 2 1/4 turns and sound wonderful but the plugs cant take it.....there is nothing I can see wrong with the big pilot you just have to be carefull not to set it too far out.....start taking it down and check the soot on the outside ring after 10 miles or so of easy riding......and new plugs take forever to soot up on the outside ring.....just wipe the black used one with a rag and go for a 10 mile "easy" ride which willbe more on the pilots.....what you are looking for is just a very faint trace of soot to almost none on the outside ring.....and set both sides """independly"""......and just a tiny turn is a lot with big pilots......

And on short runs the left takes a lot longer to warm up than the right so it can take more of a beating on beer runs......make your test runs at least 10 miles so the thing can warm up decently....tuning is a practice in brinkmanship for performance.....and the more fuel you give these things the better they seem to run but there is a limit.....you want to be right under that limit.....but heavy MJ's will wash the rings.....been there and done that.......the 135 is plenty for the BS34's.....and stock needles will give you decent performance on the very high end with the 135 but will leave you very lean in the mids and lower throttle settings.....thats why people are trying the 137.5's and bigger to try to get away from that only to find later they have washed the rings and still have a lean piece of crap in the mids and lower throttle setting with no real torque.....cranking the pilots out only to foul plugs at lower throttle......Hence that is why I have been dicking with needles and may just end up jamming one in my arm....(joke of course)....and people bitch about 42 dollars while I sit here for 2 or 3 hours woking on each set and try to help as much as I can.....well let them find out the hard way.......I did....

And you are runnig the first sets I sent out that were for the 132.5 main Jets.....and I have a feeling 135 could cause you trouble uness you had real free flowing exhaust because the needle slope was a bit heavier on those than my current sets for the 135MJ....there is only two or three of those sets out there and am not hearing any problems from them..(yet)

But if the left is your only problem I would think it is your mixture setting or check the compresson on both sides to see what you have ....150 is enough......130 on that side and you could have problems......

xsjohn

Joseph · Full Member Joined: May 22, 2007 Posts: 767 Location: NY

Thanks fellas. Ya It sounds like i have to turn it in a little and give it a 10mi run than check them. I remember when i was inside the carbs the needle valve seemed to fit tighter on the right side. Your needles are a great asset to my 80. Saved me probably years of fine tuning John.

jimdi · 650Rider Supporter Joined: Oct 27, 2005 Posts: 512

I am running with 45's and mine is 2 out - 2 1/4 out.

And mine is slightly rich side of good.

Need choke to start - but only for a block or two.

650tango · New Member Joined: Jun 10, 2008 Posts: 3

I just replaced my mixture screws on my '80 and need to adjust them.

John -I've read your posts and they are very helpful...just need a little more detail Confused

Just so I'm clear, when you write "2 turns out" do you mean to tighten the mixture all the way (screwing clockwise until I feel it stop)...and then make 2 360 degree counter-clockwise rotations of the screw?

Also, I'm not sure where the idle speed screw should be set in relation to the idle mix. I've been increasing the speed to get a decent idle, but if I have the idle mix set properly, should I never have to adjust the idle speed, or just a little when it is cold?

Thx -Sam

xsjohn · Posted: June 10, 2008, 1:20 pm Post subject: Re: Mixture on an 80

Cold it won't idol ....yes till it stops and 360 is one turn....the 80 carbs were the leanest and I used to run my mix screws at almost 4 turns with those epa log needles.......if you stick with the logs then I would use a 45 pilot at least and I use a custom 46 in mine....even with the R/L richer custom needles.....47.5 would be to touchy I would suspect.......and not necessary even with heavy mods......

46 pilot is easy to make with an """exact""" .018 thou debured guitar string......just jam it in the tiny ho...could even use a .016-.017 first to make it easier to get the big johnson .018 in there...takes the virgin out of it for sure.......then 1 1/2 turns for starters but no more...and set each side independly...and just a bit of movement on the mix screw goes a long way then and deceleration and cruise is wonderful...to say the least......remember we are on the mix screws 80 percent of the time........has everything to do with gas mileage and if the pilots are to lean it makes you crank the throttle more and getting on the needles and wastes gas......pilot curcuit for gas mileage and cruise and needles and main jets for halling ass......best of both worlds there.......started with a lean piece of crap at 55MPG and now get 50-52 and none of the old problems......

xsjohn

xsjohn · Posted: June 10, 2008, 1:53 pm Post subject: Re: Mixture on an 80

Won't even mention the cylinder temps that used to make me crazy and hose my summer ride.....and even with all that pretty much straight ....still should be careful on these fricken 99 degree days at high speeds .....which can still get things pretty hot...the cylinder fins are too small to really be perfect........but things can be made decent.....

Since I am babbeling........would someday like to have mikes kit at 8-1 compression so I could run it at about stock 650 which is plenty for my skinny ass and have the big fins for much less heat and the raised clinder would advance the valve timing for some more serious bottom end for the tall gears.....if the 750 didn't vibrate more...?..oh well have to many stock parts to even consider that for a long time......

xsjohn

650tango · New Member Joined: Jun 10, 2008 Posts: 3

Thx for the help...she runs and idles better than ever! Sam

xsjohn · Posted: June 12, 2008, 2:57 pm Post subject: Re: Mixture on an 80

Decent pilot circuit is just the beginnin to getting those 80's to spank......xsjohn

wally · Posted: June 14, 2008, 5:36 am Post subject: Re: Mixture on an 80

Remind me John

y needle would be the 132s
Have some popping problems at idle of late?

wally · Posted: June 14, 2008, 5:47 am Post subject: Re: Mixture on an 80

Remind me John

y needle would be the 132s
Have some popping problems at idle of late?

xsjohn · Posted: June 14, 2008, 6:32 am Post subject: Re: Mixture on an 80

Usually a mix screw turned a bit to far in....guilty of that with the price of oil and all.........xsjohn

jimdi · 650Rider Supporter Joined: Oct 27, 2005 Posts: 512

Now that warm weather has finally returned I am running about 1 3/4 turns out - still fine tuing

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