Carb jets

[copracr]

Im running 120 main 45 pilots with pods and kerker 4to1. Plugs look good. Its needs some more fine tuning. Now my clutch is unhappy.

Fine tuning where? on the light side of the throttle? Pilot?

[jetmechmarty]

motoman,

Where does all this published information come from that says SG/SH 110, 120, 120, 110? My carburetors had three jet sizes in them, so I know they were tampered with. Research told me those numbers were correct. They're also listed here on channel 11. I'm not doubting you, just looking for an explanation. A note of interest is that my plugs all look the same.

[crazy steve]

Marty, the FSM shows 110s across for the '80 Special, 115 outer/120 inner for the '80 standard. Clymer matches for the standard, but shows the 110/120 combo for the Special, so which would you trust....

[jetmechmarty]

Well Steve, if the plugs look OK and the engine runs well at all useable RPM's, does it really matter? Why would a standard be jetted any differently than a Special? There's something going on here that I don't quite understand, other than assumption of load as suggested by motoman.

[killercummins]

Fine tuning where? on the light side of the throttle? Pilot?

One of my mixture screws are stripped

[crazy steve]

Well Steve, if the plugs look OK and the engine runs well at all useable RPM's, does it really matter? Why would a standard be jetted any differently than a Special? There's something going on here that I don't quite understand, other than assumption of load as suggested by motoman.

I'm simply pointing out that if you want to know what the factory jetting is, I'd have to give the decision to the factory manual. Unless there's a TSB out there that reflects a mid-production change, I'd believe the FSM over the Clymers...

How well an individual bike runs with non-spec jets is up to the well, um, the individual bike...

[copracr]

Hey, while I got your guys' attention maybe you could settle something for me. I'm working on a CV carb on a chinese gy6 dune buggy. My buddy says you tune WOT with the main jet first, then check the needle jet, then adjust idle mixture and if needed change the pilot.
His thinking is the main jet is slightly open at all RPM's so you change that first and work down.
Every post I've read about CV carbs says to get idle set first then work up to WOT. My thinking is the main jet may have a needle shoved in it at idle but the pilot is definetly open at all throttle positions and so would contribute some small amount of fuel.

You guys have 4 CV carbs per bike, what do you think?

[motoman]

ALL CV carb information concerning tuning refers to your friend being correct.

[motoman]

Why would a standard be jetted any differently than a Special? There's something going on here that I don't quite understand, other than assumption of load as suggested by motoman.

As previously stated, the Special and Standard used different configurations of metering rods in each.

[CodyLane]

Interesting that your carbs have 132.5 mains. I've been trying to sort my carbs out for a while. Weird thing is they have these plastic Amal style jets (large hex) that are 210. According to some research these 210 Amal jets are roughly equal to 132.5 Mikuni (large round) jets. I just put rebuild kits into my carbs and the stock 137.5 jet seems too rich. Everytime I switch back to the 210 Amals, it gets better.

There is only one set of carbs that I've found used a 132.5 main and that's the 78 and 80 UK version of our carb. Read it here:

http://clubs.hemmings.com/clubsites/xs11/carbspec.htm

I asked about these amal jets before and nobody knew what I was talking about. Maybe you're just running the UK carbs like I think I might be. From what I understand, they'll look like the early model 78-79 carbs but have a different jet needle and smaller mains.

[copracr]

I dont know, but everything I checked in that link earlier matched my carbs up to the later model guys. They didn't look early style in anything I checked.

[natemoen]

I highly doubt you are using UK carbs. Something else just isn't set up right. Also there should be a number printed on the carbs. If they are UK carbs it should say 2H9.

[Rasputin]

CV carb tuning procedures
http://www.factorypro.com/tech/carbt...m_engines.html

[copracr]

My pilots came in and I went to reassemble the carbs and looked at the other jets. I have a 132.5 in my #1, the rest are 110's. Nice huh. The idle mixture screws were set to reflect that though - 2.25, 1.75, 3.25, and 3 turns. I'm guessing the PO leaned out #2 to smooth things out a bit, I don't know. So I'm gonna order all new 115's and some new gaskets. I figured split 112.5 and 120 and I should be in the neighborhood.

Then I figured I might as well check the valves since the bike was this far apart and the valve cover leaks anyhow. I don't know what spec is but they look very even. front valves are .007, .007, .007, and .006 and the rears are .004, .0025, .0025, and .0025. I did notice the cam chain seemed pretty loose. I have the factory adjuster on it.
Some questions I have is:
What's valve specs?
Does anyone have a part number on the auto adjuster that fits this bike and has that turned out to be a good upgrade?

[copracr]

I just re-thought my jet choice. I'm gonna go 120's cause I'd rather run it rich than lean. And I know if it runs acceptably well I won't tear it back apart to get it spot on