Mixture screw setting.

[Joe Sull]

Are these statements in red correct.
Taken from this carb file link.

http://www.fjowners.com/index.php?topic=580.0


4. Idle and low rpm cruise
Fuel Screw setting (AKA mixture screws)
There is usually a machined brass or aluminum cap over the fuel screws
on all but newer Honda. It's about the diameter of a pencil. Cap removal
details. Newer Honda carbs use a special "D" shaped driver, usually
supplied in the carb recal kit. Set mixture screws at recommended
settings, as a starting point.
For smoothest idle, 2nd gear 4000 rpm steady state cruise, and 1/8
throttle high rpm operation:
Pilot fuel mixture screw settings, float level AND pilot jet size are the
primary sources of mixture delivery during 4000 rpm steady state cruise
operation.
A. If lean surging is encountered, richen mixture screws (turn out) in
1/2 turn increments.
Alternative pilot jets are supplied when normally required.
Pilot fuel mixture screw settings, float level and pilot jet size also affect
high-rpm, 0 to 1/8 throttle maneuvers.
B. Too lean, will cause surging problems when the engine is operated
at high rpm at small throttle openings! Opening the mixture screws
and/or increasing pilot jet size will usually cure the problem. NOTE: A
rich problem gets worse as the engine heats up.
C. If the throttle is lightly "blipped" at idle, and the rpm drops below
the set idle speed, then rises up to the set idle speed, the low speed
mixture screws are probably set too rich: try 1/2 turn in, to lean the idle
mixture. NOTE: A lean problem gets better as the engine heats up.
D. If the throttle is lightly "blipped" at idle, and the rpm "hangs up"
before dropping to the set idle speed, and there are no intake leaks and
the idle speed is set at less than 1000 rpm, the mixture screws are
probably too lean: try 1/2 turn out, to richen the mixture. Be sure there
are no intake leaks and the idle speed is set at less than 1000 rpm!

[Joe Sull]

BBT

[FJ_Hooligan]

I can't confirm the lean or rich, but if you'r experiencing one of the symptoms then start adjusting the mixture screws.  If it gets worse, then go the other way and it should get better,  If it doesn't get better then it's something else.

I think you asked about the fuel level at some time.  I think a higher fuel level could make the mixture more rich.  For a given amount of intake vacuum fuel is more easily pulled from the float bowl if the level is higher, thus more gets pulled = richer.

[Joe Sull]

Thank for the help, Hooligan. I'm starting to get really busy now and the bikes not running right. The next chance I get, I'll pull the carbs and clean the emulsion tubes again and replace the manifold o rings. I might be getting vacuum leak.
I'll be checking the fuel cap for vent problems. I've looked at the routing. It seem to be starving for fuel as I drive sometimes.

It's running good after part throttle.
It starts on choke perfect.
It drops below idle and then comes up when cold, then hangs up and drops to idle when hot.
It seem to be starving for fuel as I drive sometimes.

[andyb]

Why not read the plugs?

In the originally quoted text, I don't set the idle down when I'm doing this sort of testing.  That said, I use a goofy routine for setting mix screws on my own bikes, as taken from the honda V45 manual, as it seemed to work really well.  It's a bit involved to go into, though.

The other thing is that that quoted text is taken from the FactoryPro website (somewhere!) and there's two versions, a high-rpm and a low-rpm version.  The FJ is just about straddling the middle, so mentally swap 4000rpm with 3000rpm and it's a bit more appropriate for our bikes.

[Joe Sull]

That was a mouth full Andy. I had to read it 4 times to understand what you were saying and it going to take me some thought to get my head around it.
I'm shying away from reading the plugs because my petcock is junk. I have to plug it to take the tank off but I'm going to have to do it. Taking the cooling cowls off to get at the plugs is gonna be harder and hot. I'll do the carb work and see were it stand.

[Joe Sull]

Got into my bike. Carbs off, I cleaned the emulsion tubes with a torch tip cleaner. The big thing thats been causing my problems
is this.



The petcock screen was loose and I used silicon to glue it back in. The silicone broke down and had closed off my fuel and also was stuck in the vacuum valve making it not seal.

Two questions;

1) What kind of glue/ epoxy should I use to glue the screen in the petcock.

2) Where is the tank vent on the 85's. The cap on mine looks like it has a lock tumbler and that it.

Thanks

[Pat Conlon]

The screen should be a friction fit. Permex makes a gas resistant glue.

Inside the 84/85 caps is a spring and ball....I removed the ball.

[Joe Sull]

The screen should be a friction fit. Permex makes a gas resistant glue.

Inside the 84/85 caps is a spring and ball....I removed the ball.

I couldn't find that stuff locally. Bought Permatex gasket sealant. It says gas and oil resistant. That fixed the fuel starving problem.
I removed the steel ball in the cap. I needed another hand and a couple more fingers to reassemble. I can hear it venting now.

I believe I'm getting good fuel supply. I tried to sync but didn't do so good. Try again tomorrow. I think thats all it needs.
I took it for a trot today and she moves right along. Love the sound of the F1 cans with little or no packing.
Cherry Bomb screamer!



I got some wallet size if anybody wants one.   

[movenon]

What was the problem syncing the carbs ?  Probably my imagination but my FJ seems to run better (more power) after I repacked the F1's.
George

[Joe Sull]

I think my plugs are shot, George. New plugs and then sync. There nothing else to clean. I got new #40 fuel jets and the float height is right on.
I could hear at least one cylinder was firing off and on. I couldn't get a good reading on my homemade manometer.

Those F1 cans just sound goooood! I can't compare how it runs.

[movenon]

I think my plugs are shot, George. New plugs and then sync. There nothing else to clean. I got new #40 fuel jets and the float height is right on.
I could hear at least one cylinder was firing off and on. I couldn't get a good reading on my homemade manometer.

Those F1 cans just sound goooood! I can't compare how it runs.

Nothing wrong with a home made manometer.  They don't lie. Pure physic's. Let us know what you find out.
George