PLUGS

Can I have an expert opinion please.
this is after 1 hour running, problems encountered were: slight backfiring when accelerating hard, it would idle fast, turn the screw out and it would idle fine then die, turn screw in and repeat process.
thanks guys.

 

I'm no expert, but I've been messing with mine for 4 weeks.
I would say #1 is right on 2 and 4 need to be leaned out.
#3 looks close to fouled.
Maybe it dies when you turn the idle down because you're running rich.

 

How many turns out were you on all of them is sequence?1-4?

 

1 is too lean

2 looks ok

3 is too rich

4 looks ok

 

set all at 2&3/4 turns at carb sync, was getting a poppety popping, so turned all 4 to 3 turns, no real thought other than to enrich.
some history here, when i got the bike there were caps on all 4 carb boot spiggots and the petcock was on prime, i had an idea that something was amiss. my very first post on this site was asking about pipes to the petcock.
now when you look at the state of # 3 plug, you must think there is some connection, is there a problem with the petcock?

 

simple test: set petcock on PRI, block off the vacuum nipple on #3 just like the others. clean or replace #3 plug. go for a ride.

...see if anything changes.

if the diaphragm in the petcock is damaged, I suppose you might be pulling in some fuel through the vacuum line.

 

i have cleaned the plugs and connected the vacuum line to # 4, will ride later and post results, cheers, 2brains.

 

Have set 2-3&4 to match 1 using Ricks fuse method, hardly moved a hair, vacuum tube is now on # 4, this is the result after riding for 3/4 hour.

 

#3 still loooks a bit lean

Might verify that the petcock diaphram is not letting fuel pulled into #4 through the vac line. I've only had one do it where the PO had installed a diaphram and had a hole in it near center.

 

looks like the petcock might need some further investigation...

 

x2

1&2 look good, besides the blurryness. Might wanna get that chked

 

wow, that's amazingly similar to my 1982 SECA.
plug#3 is black soot & I have been assuming that it's float issues...until I swear by moving the petcock to something other than RUN, it seems to alter how it runs..as in better
hmmm

 

today I will ride on prime with the vac' line clamped.
will post results.

 

Cheers Ass. I forgot to turn on the MACRO!

 

by moving the vac line from carb to carb & the fouled plug following faithfully behind, I yanked the petcock, sure enough, pinhole.
Problem now is, to get over this without spending too much.

 

What is Rick's fuse method? Did I miss an excellent read?

 

Sadly, I did the petcock test on my 82' SECA, which is exhibiting the same plug fouling: BUT mine passed the test.
Petcock seems fine.

The sad part, is now I'm pulling the carbs I guess to look at floats..
I'd rather have worked on the petcock...
Rich

 

Rick's Fuse Method: Find a plug that you like, that carb is set-up right.
Drop a glass tube fuse into the pilot screw hole, and mark a line on the fuse, now using the fuse as a ruler, adjust the other 3 pilot screws.

This would still just be a base-line setting; finish dialing in using plug reads, as Rick says, in 3 degree increments, because you're almost home at this point.

This method assumes that you will be able to precisely read your own mark with carbs on the bike, and that all carburetor components are machined identically.

 

I moved the vac' line from 3 to 4 & the fouling followed the vac (clue)
you might just be rich on that one pot. Let us know how it turns out .Wiz.

 

If the fouling follows the placement of the Petcock Vacuum Line ... that is a sure indication that the Vacuum Membrane is punctures and allowing Fuel to be sucked in through the Manifold under vacuum.

Take off the Vacuum Line from the Manifold Fitting.
Place the Vacuum Line to your lips and draw a vacuum on the hose.
If you taste Fuel ...
Your Petcock is to blame ... the Vacuum side is leaking.

 

Well, I think I may have the answer for my SECA.
I took carb rack off, & found the #3 floats riding high.
If memory serves, that would cause too much petrol in the bowl..

I did the simple rev it @ 4000 for 12 sec & kill switch.
I looked at the previously offending plug, & it looked NOT black.
Made me very happy.
Until of course, the next thing needs tweaking...
Why do we do this to ourselves anyway?
Oh yeah, it's fun as all get out to ride!

Rich


Rich

 

No!
It's fun as all-get-out to have the Engine right on the hairy-edge of Fine-tuning!

I like lollie-gagging along in 3rd Gear ... and deciding to crank her wide-open and listen to the Intake sound like I just floored a deuce coupe with 3-two's.

That full-throated "Whoa-waah-aaa-eee" makes all the time spent tweaking worth every second of tweaking to get it right!

 

Yes, third gear from 4 to 6 grand is a great deep throaty sound.
After that it gets loud and sounds like a 650.

 

well, it's not quite like hitting a C natural on the Uilleann pipes during a moving passage, but it's a close 2nd..
sorry Ricko

 

UPDATE:
Petcock repaired.
vacuum line back onto #3 port.
Here are the plugs after 1/2 hour riding.
to me #3 & #4 look a tad lean? but the bike is running so well I am reluctant to alter anything, I think I should run it for a while longer & check the plugs again. What do you all think?

 

I hear what you're saying.
I did the same thing, 2 plugs a little lean, but it's running so good I didn't want to touch it.
So I ran it for a couple hundred miles like that and then had to tweak some more.
To my suprise it got even better.
So yeah run it like that for a while and check again.
You are real close though.

 

sweet man!

 

Those Plugs are within the window of Fine-tuning.
1 and 2 are good.
Lean, but within the "Not too Lean" situation.
Good for High-performance.

3 and 4 are just a shade too Lean.
Move 3 Out about 2 degrees.
Move 4 Out about 3 or 4 degrees.

Then, they should all look like one and two.

 

This degree of fine tuning needs us to step up our game, in the prosecution of which I have developed the tweek gauge.
It consists of a paper protractor, a long screwdriver with a 100mm doll needle fixed into the handle.
Using this metod you can make fine adjustments.
N.B. You should record each movement of the pilot screws for future reference.

 

Rube Goldberg would be proud of you.
But, ... how's it going to fit in to the limited space with the Carbs on the Bike and the Tank lifted just enough to get a Tweak Tool in there.

My Tweaking is done without removing the Gas Tank.
I took a Sears Craftsman Pocket Screwdriver ... the little one with the "Pocket Clip" and altered it to suit being able to Tweak without removing the Tank.

Hacksaw the Plastic Handle right off at the point where the metal shank ends.
Chuck the blade end in your drill and spin it while using medium-coarse sandpaper to shape the cut-off end to a rounded-off and refinished handle.

Grind-off a portion of the shank ... shortening it by 20mm
Grind a new blade-end on the shank using a Pilot Mixture Screw to measure the fit as the grinding progresses.

After you have a new handle and a new tip ...
Cut a shallow straight line along the length of the plastic handle with your hacksaw.
Fill the hacksaw cut line with white paint.

The white line becomes a visual element in watching how much the Screw moves when you make an adjustment.

 

Not to provide a commercial but Chacal sells an adjustment tool. Since I was getting other stuff I bought one. Fits great and was easy to use. I normally stay away from special tools if not absolutely required but this one is a winner.

I used it to colortune today. Bike is running great I just need to get it dialed in. Should be no problem using the collective wisdom on this site.

 

Couple of points, Rick.
I don't think I could get the degree of accuracy required with the fuel tank in place, even lifted, I need to get right over the action & by using the 100mm pointer it indicates what a tiny movement 1 or 2 degrees is.
Having said that, I'm sure a man with your depth of expeirience can judge those tiny increments without recourse to prosthetics.

 

I agree it's hard enough to know+ that the screw has moved with the tank off looking straight down on it.
It's such a smal amount.
I would be hard pressed to be accurate witht the tank on.

 

You have to have the fingers of a safe-cracker!

You "Feel" it.

It really helps if you have treated the threads of the screws with a synthetic waterproof grease of anti-seize lube.

That pesky Number-3 is tough to see with the cables and linkage arms in the way ... but, if you have a tool that fits the slot on the screw just right ... you can get a feel for what you are doing.

Knowing that you only need to nudge the screw helps, too.
If you go by it and make the hole too rich for your liking ... next read you just dial it back a bit.

Pretty soon, you get done tweaking and spend all the time riding.
Sure, you still pull the plugs and look them over ...
But, seeing that they are just right after all your tweaking ...
You just smile and put them back in.