ROYSTON
XS650 Enthusiast
Mikuni BS38- how many turns out. My manual says pre-set.
Thanks
Thanks
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PMS
- Thread starter ROYSTON
- Start date
angus67
Welder's penetrate deeper!!
What year are the carbs?
ROYSTON
XS650 Enthusiast
1978 PMS on the side.
I'm not sure what the PMS means but if they are 78 carbs the Air screw starts at 1.5 turns out. It may need a bit either way to be right.
In the carb guide is a chart showing all the year carbs and the stock setting. All the jets needles, air screw and float levels.
It also tells how to ID your carbs.
www.amckayltd.com/carbguide.pdf
Leo
In the carb guide is a chart showing all the year carbs and the stock setting. All the jets needles, air screw and float levels.
It also tells how to ID your carbs.
www.amckayltd.com/carbguide.pdf
Leo
ROYSTON
XS650 Enthusiast
PMS = pilot mixture screw. Thanks for the chart, the '78 is 2 1/4, which is where I was at.
That 2 1/4 setting is appropriate only if you have stock exhaust with stock air box, and stock air filters (which seems to be rare these days). Also that is the setting for #27.5 pilot jet. If you have a different size pilot jet, then the mixture screw setting could be quite different.
ROYSTON
XS650 Enthusiast
Thnx genman, I will fine tune with plug chops when it's back on the road.
ROYSTON would you care to share with us, what you have for exhaust, air filters and pilot jet size???
You can't do a fine tune until you have done a coarse tune.
You can't do a fine tune until you have done a coarse tune.
In 78 they made a bunch of changes. I don't recall engine number this happened. The early 78's had the electricals like the 77, I think they still used the 76-77 carb set. The later 78 used the 78-79 carb set.
On the chart I made up is about the same as the carb guide. It just list the Early 78 and late 78.
The early using the 76-77 carbs will have the 4M1 needle and Z8 jet. The 78-79 use the 502 needle and Z2 jet.
If this leads to confusion, Sorry, Blame Yamaha for making changes mid year.
Leo
On the chart I made up is about the same as the carb guide. It just list the Early 78 and late 78.
The early using the 76-77 carbs will have the 4M1 needle and Z8 jet. The 78-79 use the 502 needle and Z2 jet.
If this leads to confusion, Sorry, Blame Yamaha for making changes mid year.
Leo
ROYSTON
XS650 Enthusiast
Looks like the carbs are 78 to 79 years. The stock #27.5 pilot may work or perhaps you will need to go up to a #30 pilot jet.
